THE EFFECTS OF THE CARBOHYDRATE AND PROTEIN FRACTIONS OF MILK PRODUCTS ON STARTER PIG PERFORMANCE by MIKE D. TOKACH B.S., NORTH DAKOTA STATE UNIVERSITY, 1986 A THESIS submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Animal Science and Industry KANSAS STATE UNIVERSITY Manhattan, Kansas 1988 Approved by: A \iW^ ijor Professor A112Qfi 130753 TABLE OF CONTENTS ^a§ ,74 R5X c.z I. Milk and Isolated Soy Products - Literature Review A. Introduction B. Processing . . .... ~-. 1. Milk Products 2. Isolated Soy Protein 1 1 2 2 13 C. Dried Whey 15 D. Dried Skim Milk 27 E. Casein 36 F. lactose 42 G. Isolated Soy Protein 45 OF PROTEIN AND/OR CARBOHYDRATE FRACTIONS OF DRIED WHEY ON PERFORMANCE AND NUTRIENT DIGESTIBILITY OF WEANLING II. EFFECT PIGS 50 Summary 50 B. Introduction 51 C. Experimental Procedures 52 D. Results and Discussion 54 A. III. EFFECT OF LACTOSE LEVEL AND PROTEIN SOURCE ON STARTER PIG PERFORMANCE 60 A. Summary 60 B. Introduction 61 C. Experimental Procedures 62 D. Results 63 E. Discussion IV. Literature Cited ABSTRACT 64 71 LIST OF TABLES Page Table II-l Diet Composition 57 II-2 Analyzed Ingredient Composition 58 II-3 Effect of Dried Whey Fractions on Weanling Pig Performance 58 II-4 Effect of Dried Whey Fractions on Apparent Digestibility 59 III-l Diet Composition, Week 68 III-2 Diet Composition, Week III-3 Effect of Lactose Level and Protein Source on Starter Pig Performance (Trial 1) 70 III-4 Effect of Lactose Level and Protein Source on Starter Pig Performance (Trial 2) 70 to 2 3 to 5 69 LIST OF FIGURES Page Figure 1 Milk Processing Flow Chart 4 ACKNOWIEDGEMENTS I would like to express serving as my master's my appreciation to Dr. Jim Nelssen for advisor. The sincere interest that Dr. Nelssen showed towards my program, academics and personal life will never be forgotten. It is an extreme pleasure to have an advisor that is also a good friend. I would also like to extend Robert H. Hines for serving my thanks to Drs. Gary on my master's L. Allee and committee. I have benefitted greatly from their incite and working knowledge of the swine industry. I am also greatful for the assistance of the other graduate students in data collection and analysis of the results. However, I am more appreciative of their friendship and fun and games that made the months away from my family and friends tolerable. Finally, I can not fully express my gratitude for the caring and understanding that my family has shown during my stay at Kansas State. They have made countless sacrifices over the years to allow me to accomplish my goals. I hope that someday I can repay their love. Lastly, I thank my fiance, Lisa Thomas. source that made this thesis possible. on the other end has made the hard work, between us bearable. I wedding on July 16, 1988. Her love is the true Knowing that you are waiting long hours and distance am extremely excited about our upcoming 1 INTRODUCTION Producers are currently weaning pigs at four weeks of age or less to increase sow productivity. However, early weaning often results in a lag in performance, including decreased gain and feed intake and increased morbidity and mortality. Nutritionists are presented with an obvious challenge to devise an economical, nutritional regimen to In order to recommend a eliminate the postweaning lag in the pig. sound nutritional program, the weanling pigs biological status must be understood. Three week old weanling enzymatic systems. A warm, pigs have very immature immune and dry, draft-free environment can help the immune system fight disease while it is maturing; however, the pig also needs time to develop an enzymatically mature digestive system. The enzymes most prevalent at weaning are capable of digesting milk products instead of the plant products which are normally fed. intake is also very low the first two weeks after weaning. highly nutritious and digestible diet performance during this critical period. is milk products, to maximize With these facts in mind, numerous researchers have designed complex, diets for early weaned pigs. essential Feed Thus, a high nutrient density These diets commonly contain 20 to 40% primarily dried whey and skim milk. These milk product additions have proven to be beneficial in increasing gain, intake and feed efficiency. to determine whether the However, limited research has been done protein or carbohydrate fraction of milk products is responsible for the improved performance. 2 Five trials were conducted to evaluate the components of milk products that are essential for performance of the 21-day old pig. The effect of protein and/or carbohydrate fractions of dried whey on pig performance and nutrient digestibility was studied. the of effect lactose performance was daily gain, daily on starter pig Criteria measured included average investigated. average source and protein level In addition, feed feed intake, efficiency, and digestibility of dry matter, energy and nitrogen. FBOCESSWG MIIK rEODUCTS 1. Milk products originally used in the animal feed industry were waste by-products of the cheese-making process or milk designated unfit for human consumption (Scott, 1986) . Once these products proved to be economical to produce and valuable feed ingredients for neonatal runiinants and nonruminants, higher quality sources became Milk processing methods and ultimate product quality have available. been shown to have an effect on the performance of weanling pigs (Pollmann et al., Roy, 1962) . 1983b; Mahan, 1984) and young calves (Shillam and Robinson (1986) also explained that milk proteins are extremely delicate and can be denatured by heat treatment. Thus, processing techniques and their effects on product quality play a major role in determining the value of milk products in swine diets. Since raw liquid milk contains approximately 90% water, the primary step in obtaining finished milk products used in the swine 3 However, as industry is the removal of the high moisture content. figure 1 indicates, milk encounters a number of other processing steps before being marketed (Eckles et al., 1951; Webb and Whittier, 1970; Hall and Hendrick, 1971; Lampert, 1975; Warner, 1976; Kessler, 1981; Robinson, 1986; Scott, 1986) The first processing step for all raw milk must encounter is pasteurization (Warner, 1976) . Pasteurization is a process applied to a product with the object of minimizing possible health hazards arising from pathogenic microorganisms associated with milk, by heat treatment with minimal chemical, physical and organoleptic changes in Pasteurization is designed to inactivate pathogenic the product. organisms originating from within the udder, from the exterior of the teats and udder, and from the milking and storage equipment. are many time-temperature combinations, There ranging from 63 C for 30 minutes or 77 C for 15 seconds to 100 C for .01 second, approved for pasteurization of Grade immediately cooled to 10 A milk. (Robinson, C after heating. relatively mild form of heat treatment. 1986) . Milk Pasteurization is is a Whey protein denaturation is low (between 5 and 15 percent) and there is relatively little loss of other heat sensitive nutrients (Robinson, 1986) found that practically no lysine was . Finot (1983) also rendered unavailable by pasteurization After being pasteurized, milk is homogenized and sold for human consumption, separated to obtain butter and skim milk, or fermented to yield cheese and whey. Hcmogenization is simply the breaking up c c a O •H 4-1 . h n) U s o S 3 OJ 00 .0 qj X> H cfl .e cfl u •u X U w 3 a* CO hJ (3 o cfl •H i-i 4J CO N 0) •H rH CO cu !-i 0) Hc s t3 0) 01 p •H u M O a) "OJ- 3 o •H U CO 60 3 <+-i •H T3 •H a) M 3 s -a) CJ 3 "cr QJ CO a) a) U •h Cu 0) CO X H X 3 O QJ OJ CO -H U 0} 4J o cfl ai M pi •H 3 o< •H — 03 OJ o > B •H 3 3 H Lj a CO cfl p2 _ OJ o u r-i •a o "4J- - co OJ w u 3 3 CO oj cu •u .3 -u (-1 QJ qj u 3 u CO •H cfl a> CO •H 03 PM CO o S 3 Q 3 O cfl -M- •H cfl a B a) co 4J a en CO 3 O 3 O 3 O CO N QJ 00 o 6 o SB CO U -cfl QJ 3 cfl U 3 3 > 4-) •H -3 - O 3 O CJ cfl a) CO CO O OJ •H c o 3 —H •3 ' OJ U a 5 3- o QJ M O PL, 3 O o a) T3 QJ -•H U a M 3 5 of fat globules of milk into very fine particles by forcing them through minute openings to prevent separation and hardening of the fat during storage (Eckles et al, 1951) and Separation fermentation are processes. detailed more Separation is a process whereby an essentially fat-free portion (skim is separated from a fat-rich portion milk) (cream) . The process relies on the density difference between the milkfat in the globules and the aqueous phase in which they are dispersed (Robinson, 1986) If milk is allowed to stand, fat rises and creaming is observed with a fat-rich fraction collecting at the surface. Industry uses the density difference to separate skim milk and cream by centrifugation (Iampert, 1975) centrifuges Early model . which allow air separators were open or semi-open to flow the with entrainment of air in milk inhibits separation. however, milk; Thus, hermetic or air-tight separators were developed to isolate the separation process from the atmosphere. Exiting the separator, cream is standardized to the desired fat content by dilution using skim milk or other cream (Eckles et al., 1951) Heat . treatment by vacreation then destroys pathogenic organisms and enzymes which may cause spoilage (Robinson, 1986) vacreator mixes steam with cream and the condensed . The vapor plus volatiles are removed by flash evaporation under vacuum (Robinson, 1986) . After heat treatment, the finished cream product (half-cream, coffee cream, sour cream, whipping cream or butter cream) for packaging or churned into butter. is ready 6 Separating cream from whole milk also yields skim milk. Skim milk may exit the process here for consumption by diet conscious humans enticed by the low fat and calorie content (Lampert, 1975) . Skim milk that is not sold as fluid milk is dried for preservation or further processed to generate casein. Drying of all milk products is accomplished in the same basic manner. 80%) is The bulk of the water (50 to first removed by evaporation before the remainder of the surface absorbed water is removed in a drier 1971) and Hendrick, (Hall The vacuum evaporator used in industry is based on the fact . that the boiling point of a liquid is lowered when milk is exposed to a pressure below atmospheric pressure (Robinson, 1986) . Skim milk is brought to boil at approximately 70 C in an evaporator with negative pressure to remove the large moisture content. low temperature is used, 1986) Since a relatively nutrient denaturation is small (Robinson, Different types of evaporators remove variable portions of . water; however, a drier must be used to completely dry the product. The two type of driers currently being used in industry are roller and spray driers (Hall and Hendrick, 1971) . The principle of roller drying is that milk is applied in a thin film upon the smooth surface of a continuously rotating, steam-heated, metal drum with the dried milk film being (Robinson, 1986) is high, . continuously scraped off by a stationary knife Protein denaturation associated with roller drying as an extremely high drying temperature (95 to 150 C) used (Lampert, 1975) . is In addition, Finot (1983) showed that roller drying renders 20 to 50% of the total lysine in skim milk unavailable . 7 while spray drying blocks only to 2%. Since there is more protein denaturation with roller driers, spray driers are used to dry nearly all whole milk and about 80% of all skim milk (Iampert, 1975) Spray drying is the instantaneous removal . of moisture from a liquid (Robinson, 1986). The liquid is first converted into an atomized fog-like mist to increase the surface The atomized liquid is exposed to a flow of hot air that area. evaporates the moisture and carries the water vapor away while the dry milk particles fall to the bottom of the drying chamber (Lampert, 1975) The dried product is removed from the drying chamber and . cooled as quickly as possible to minimize heat damage Hendrick, 1971) . (Hall and Spray drying is a gentle drying method as the material to be dried is suspended in air and the drying time is very short (Robinson, 1986) . The air inlet temperature can reach 215 C, but due to evaporation, the product temperature will only reach 65 to 75 C (Robinson, before 1986) . being packaged The skim milk is dried to 3 to 4% moisture and stored at room temperature (Hall and Hendrick, 1971). Dried skim milk is not graded by heat treatment; however, it is classified according to the heat treatment to which the raw milk has been subjected before being converted into powder (Robinson, 1986) The classification procedure is based upon the level of undenatured whey proteins in the dried skim milk. (WEN) This Whey Protein Nitrogen index is the amount of undenatured whey protein nitrogen in skim milk solids measured in milligrams per gram of dried skim milk. 8 The dried skim milk WEN index is normally 8 mg/g. American Dry Milk Institute, Inc. (1971), the According to the heat treatment classifications and corresponding WFN indexes for dried skim milk are low heat, not less than 6 mg/g; medium heat, between 1.5 and 6 mg/g; These levels correspond to and high heat, not more than 1.5 mg/g. less than 25%, 25 to 81% and over 81% denaturation of the whey protein, respectively. The solubility index, which measures the volume of sediment from 50 ml of reconstituted milk, quality. is another indication of skim milk Robinson (1986) explained that denatured whey proteins will redisperse into a stable suspension when skim milk is reconstituted; however, casein coagulated by high heat treatment will not form a stable suspension, but will appear as sediment. Thus, the solubility index is mainly a measure of the coagulated casein. Milk Institute maximum (1971) solubility The American Dry requires that extra grade skim milk have a index of .5 ml of reconstituted skim milk or be 99% soluble. sediment per 50 ml of Obviously, the lower heat treated, lower denaturated, higher soluble, higher quality dried skim milk is desired for swine diets. Very Further processing of skim milk may also yield casein. little casein is manufactured in the United States as the federally supported pricing structure for milk encourages the production of dried skim milk rather than casein (Webb and Whittier, 1970) . New Zealand and Australia are the major casein producers in the world (Galesloot and Tinbergen, 1984) . Acid casein and rennet casein, the . . 9 two basic types of casein, are named according to the coagulating agent used in production (Lampert, 1975) Lactic, . the most common casein, hydrochloric and sulfuric casein are the three types of acid casein produced commercially (Robinson, 1986) . Acid casein is produced by adding a dilute acid to liquid skim milk to lower the pH to approximately 4.1. caseinate complex, Lowering the pH will dissociate the calcium causing the casein to coagulate into a gel-like (Webb and Whittier, curd 1970) . The curd is washed and dried to produce dry acid casein (lampert, 1975) . Acid casein is insoluble in water and thus soluble caseinates are produced by adding dilute alkali to the acid curd or to water treated dry acid casein (Webb and Whittier, 1970) commonly . used to Calcium and sodium hydroxide are the alkalis most produce caseinates. Thus, calcium and sodium caseinate are the caseinates most available to the feed industry. The soluble caseinates must then be roller or spray dried by the methods discussed previously. Drying method and temperature are again very important in maintaining product quality (Robinson, 1986) Rennet casein is usually used in the plastics industry 1986) . (Robinson, It is produced by adding calf rennet extract to skim milk and allowing it to coagulate into the gel-like curd which is washed and dried (Lampert, 1975) Separating casein from skim milk leaves whey as a by-product; however, since very little casein is produced in the United States, the majority of whey used in swine diets is a by-product from the cheese industry (Webb and Whittier, 1970) . The method of obtaining 10 whey and cheese from whole milk is very similar to the method of deriving whey and casein from skim milk (Lampert, 1975) In the . making of cheese, lactic acid or rennet is added to the milk, causing it to coagulate and curdle (Kessler, 1981) . After this fermentation process, the curd is removed and processed into cheese leaving liquid whey as the by-product (Scott, 1986) . The liquid whey is segregated and classified according to acidity, as sweet or acid whey. Sweet whey typically has apH of 5.8 to 6.6 and titratable acidity of .1 to .2% (Robinson, 1986). Sweet whey is normally derived from the rennet processed or hard cheeses Edars, etc) , (Mozzarella, Cheddar , Gouda, as rennet extract does not change the pH and acidity during curd formation (Robinson, 1986) Conversely, acid whey, the . by-product of the cottage, ricotta or cream cheese industry, has a pH less than 5.0 and titratable acidity greater than .40% 1986) . (Robinson, The feed industry desires sweet whey as the ash and mineral content are typically lower and the protein and lactose content are typically higher than that of acid whey (1986) (Robinson, 1986) . Scott explains that industry may add neutralizers to acid whey to increase the pH and lower the acidity to levels representing sweet whey; however, ash quality is affected. monitored closely. levels will also increase and ultimate whey Therefore, the level of ash in whey must be Scott (1986) also theorized that a high quality liquid sweet whey must be used to obtain a dried whey suitable for human or livestock consumption. Some sweet whey is fed to pigs in the liquid form; however, the 11 majority is concentrated and roller or spray dried as previously discussed in the skim milk section (Hall and Hendrick, 1971) . Since whey solids contain approximately 70% lactose, whey must also be crystallized before drying (Robinson, 1986) Crystallization . is accomplished by concentrating whey until crystals form spontaneously, a difficult process to control routinely, or by seeding with small quantities of crystals (Webb and Whittier, 1970) . Drying method and temperature have a tremendous effect on ultimate whey quality as whey proteins are easily denatured (Robinson, 1986) . Renner (1983) found that roller drying reduced available lysine levels in whey by 35.3% while spray drying reduced those levels by only 3.5%. study, Pollmann et al. also (1983b) demonstrated In a growth that pigs fed roller-dried whey have lower average daily gains than pigs fed spray- dried whey. Scott (1986) believes that the product temperature simply becomes too high during roller drying causing whey proteins to be denaturated. The remaining sweet whey and most acid whey is ultraf iltrated for further processing (Scott, 1986) majority of the water from whey. . Ultrafiltration will remove a The semi-concentrated whey may then be subjected to reverse osmosis to remove varying lactose levels and some minerals which yields liquid whey protein concentrate 1986) . (Scott, Whey protein concentrate is then spray dried to produce the product used in the swine and dairy industries. Lactose removed during reverse osmosis lactose. is one source of crude Centrifugation is another method of separating lactose from . 12 liquid whey (Kessler, Crystallized whey 1981). yielding crude lactose and the mother liquid, proteins and minerals (Robinson, 1986) . centrifuged, The crude lactose is further . dried to form a 99% lactose finished product 1970) is which contains the (Webb and Whittier, The mother liquid from centrifuging is often dried down to produce delactosed whey, Whittier, 1970) containing 22 to 24% protein (Webb and Delactosed whey also contains the concentrated . mineral portion, and thus, it must be closely analyzed before use as a feed ingredient. Liquid whey may be demineralized before the lactose is separated. The minerals may also be removed from whey protein concentrate to produce a higher quality demineralized product. However, the most prominent use of demineralization is with whole whey (Scott, 1986) The two main methods for demineralizing whey are ion exchange and electrodialysis (Robinson, 1986) The ion exchange method is more . popular since electrodialysis can only achieve 90% demineralization and is more expensive. Robinson (1986) explained that ion exchange is accomplished by trading cations anions in whey for bicarbonate in whey for ammonium ions and ions. The resulting ammonium bicarbonate is recovered for reuse while the demineralized whey is spray dried to create a high quality finished product. Pure whey protein fractions may also be isolated from liquid whey (Kessler, 1981) . Iampert (1975) explained that lac^talbumin is the most prominent whey protein with smaller amounts of lactoglobulins and immunoglobulins also being present. Lactalbumin can be extracted . 13 by simply adding heat and acid to the whey until the protein fraction liquid the from separates (Webb and Whittier, heating also denatures the lartalbumin, destroying Tinbergen, excellent the 1984). as value Robinson (1986) a 1970). However, rendering it insoluble and and (Galesloot foodstuff lists two recent approaches to isolating whey protein without denaturizing the product. The first method involves passing whey through a column containing porous, silica microbeads which specifically absorb protein. The recovered protein fractions are undenatured and contain less than 3-4% ash. The second process developed by Bio-Isolates uses ion exchange to manufacture a 97% protein powder from whey. The product has a digestibility of 99%, biological value of 94% and protein efficiency ratio of 3.2. The protein efficiency ratio is lower for whey (3.0), whey protein concentrate (3.0), skim milk (2.8), casein and (2.5) heat treated lactalbumin (2.8), which provides further evidence of the effect of manufacturing on milk product quality (Galesloot and Tinbergen, 1984) 2. ISOIATED SOY PROTEIN Soy protein products are available in a number of forms, varying in composition, particle size, solubility and percent protein (Wolf, 1971) . The Federal Drug Administration classifies soy proteins according to protein level as soy flour (less than 65% protein) protein concentrate and higher protein) (65-89% protein) (Campbell, , 1979). , soy or isolated soy protein (90% Soy flour and soy protein . 14 contain concentrate a portion soy carbohydrate indigestible the of fraction; and insoluble partly all carbohydrate however, fractions are removed during the production of isolated soy protein. The process results in a highly digestible product (De, 1971) Isolated soy protein production for industrial use began in the 1930 's as a replacement for casein in paper coatings Smith, 1972) (Circle and Since an edible grade was developed in 1959, isolated . soy protein has been compared to casein in infant formulas (Theuer, 1983) , food products (Galeslcot and Tinbergen, 1984) and starter pig As is the diets (Mateo and Veum, 1980; and Giesting et al., 1985). case in milk processing, the method of processing plays a major role in determining isolated soy protein quality. found that De (1971) industrial and edible grade isolated soy protein vary in amino acid composition and protein degradation. Edible isolated soy protein is usually derived from the highest quality soybeans and thus, varies less in composition (Meyer and Williams, 1975) . Ihe soybeans are cracked, dehulled, flaked, solvent extracted and desolventized before entering the protein isolation process as unheated, defatted flakes (Smith, 1977) . Concentrating the protein by isoelectric separation is possible since soy protein globulins have a minimum solubility at pH 4.5, similar to that of milk solubilized by dilute alkali (Meyer, (pH 7-9), Ihe protein is 1967). and the fibrous residue is removed by screening and centrifugation (Meyer, 1967) . The remaining supernatant is adjusted to pH 4.5 to precipitate the major protein fraction into a fine white curd (Meyer and Williams, 1975) . Ihe curd 15 is and separated then to be may curd The constituents. washed remove dried defatted soluble as or such, it flake can be neutralized with food-grade alkali to solubilize the protein and then be dried (Meyer and Williams, Isolated 1975). soy protein is customarily spray dried thus the heat damaging risk of roller drying is reduced (Meyer, 1967) CREED WHEY The milk products manufacturing steps and Whittier, according section describes the numerous Each step adds to the variability of the final product dried whey. (Webb processing that raw milk must encounter before yielding to season, 1970) . The original raw milk may also vary milking stage interval, of lactation and individual cow breed, condition, and feeding regimen (Eckles et al., 1951) . Therefore, ultimate dried whey chemical analysis values may vary extensively. Hall and Hendrick (1971) gave the following ranges as examples: % Lactose 65.0-88.0 Protein 1.0-17.0 Ash 0.7-10.0 Fat Dry Matter Lactic Acid 0.5- 2.0 85.0-98.0 0.1-12.0 16 Industry commonly loses less fluctuating values, as listed by Pond and for lactose (71-74%), protein (12.0-13.4%), ash (7.9- Maner (1984), 10.3%), and dry matter (93-96.5%); however, when fonnulating starter diets containing dried whey, nutritionists must still be aware of the compositional variance. Analyzed values also indicate little about the heating severity and consequent protein denaturation related to whey processing (Robinson, 1986). Therefore, Pollmann et al. (1983b) and Mahan (1984) evaluated whey quality in starter pig diets. Mahan (1984) compared the effects of edible grade and feed grade whey on starter pig performance. in analysis, and acidity difference containing a 12.3 white-yellow between whey The whey sources were very similar to 12.6% color. sources, compared to 10.7% for feed grade. as protein, Ash 2.24% content edible grade was titratable the contained major 7.6% A corn-soybean meal basal diet was used with 25% being the dried whey inclusion level. The feed grade whey source did not improve swine performance over that of pigs fed the basal diet; whereas, the edible grade source improved average daily gain and feed intake. essential for young swine. improvement in daily gain, fed 0, Mahan (1984) concluded that a high edible grade product must be used as whey quality appears quality, 10 or 20% Stoner et al. Stoner et al. feed grade dried whey. (1985) (1986) also found no feed intake or feed efficiency for pigs In a subsequent trial, discovered that pigs fed a diet containing 20% edible grade dried whey gained faster and were more feed efficient than pigs fed a corn-soybean meal diet. 17 Pollmann et al. (1983b) also demonstrated the importance of whey quality in a 2 x 3 factorial consisting of two whey sources (roller At and three lysine levels (.90, 1.05, 1.20%). dried, spray dried) the lowest lysine level, whey source did not effect average daily gain or feed efficiency. However, as lysine level increased, pig improved and whey source differences became apparent. performance Pigs fed the 20% spray dried whey diet had higher average daily gain and were more feed efficient than pigs fed the 20% roller dried whey diets at the higher lysine levels. evaluating the effect of adding levels of discovered lysine that performance. 1.05, (.90, roller 1.20%), whey dried In a separate 2x3 factorial, or 20% roller dried whey at varying did et Pollmann not al. (1983b) starter improve pig The results of these trials emphasize the importance of using a high quality whey when formulating starter diets. Pollmann et al. (1983b) was also interested in determining the optimum lysine level for 20% dried whey starter diets. One trial found a linear improvement in average daily gain and feed efficiency A second when the lysine level was increased from .90 to 1.20%. 3 factorial, three lysine evaluating two spray dried whey levels levels (1.2, 1.3 or 1.4), (0 2 x or 20%) and revealed whey additions increased gain by 5.6% with the lysine effect being a quadratic improvement. (.95, 1.05, Pollmann et al. 1.15, 1.25, (1983a) 1.35%) analyzed varying lysine levels in 20% dried whey starter diets. Increasing lysine level to 1.25% improved average daily gain and feed efficiency; however, gain was reduced at 1.35% lysine. Consequently, 18 the researchers concluded that pigs weaned at 3 to 4 weeks of age and fed a corn-soybean meal diet with 20% whey require 1.25% lysine. Fralick and Cline 1.20%) (1983) also compared varying lysine levels (.90, in dried whey diets and concluded that pigs fed supplemental lysine gain faster than those fed a corn-soybean meal basal diet. Mahan ( Fralick (1984), and Cline (1983) et Pollmann and al. demonstrated that with the appropriate lysine level and 1983a, b) whey source, dried whey additions will improve average daily gain and feed efficiency. found no These data cast some doubt on earlier trials that response to dried whey when low lysine levels or an unspecified whey source was used. In a 2 x 2 factorial, Meade et al. (1965) analyzed dried whey 10%) and fish meal (0, 3%) additions to 3-week old starter (0, pig diets. Neither component improved average daily gain or feed efficiency over the corn-soybean meal control. (.84 to .96) However, the calculated lysine levels were considerably lower than suggested by Pollmann et (1983a), and the whey drying method was not specified. al. Hendrick (1971) Hall and explained that the harsher roller drying was still very popular during the mid 1960's when this trial was conducted. Wahlstrom et al. (1974) also found that 10% low lactose dried whey had no effect on average daily gain, average daily feed intake, or feed efficiency when added with or without 5% sugar or .5% salt to a 10% oats, corn-soybean meal starter diet. The low lactose whey quality may be questioned as it contained 14.1% ash. explained that low lactose whey is formed by Robinson (1986) simply removing a 19 portion of the protein amino and The process concentrates the desirable lactose. however, acids; unless demineralized, the undesirable ash and salt content are also concentrated to extremely The lysine levels used in the trial were also slightly high levels. low at .9 to 1.0%. Dried whey experiments levels. additions have also beneficial proven Miller et al. (1971) some in with unspecified whey quality or questionable lysine discovered the addition of 7.5% dried whey improved average daily gain and feed efficiency of pigs fed a 16% protein negative control diet. The 7.5% dried whey diet also provided equal performance and less expensive gains than the 19% protein, positive control, complex diet. Newman (1985) determined that pigs fed complex diets containing 15% dried whey gained faster and were more feed efficient than pigs fed simple corn-soybean meal or barley-soybean meal diets. The complex diets also contained 10% oat groats and 3% lard; thus, dried whey may not be responsible for the entire increase in performance. Graham et al. (1981) compared a 20% protein, corn-soybean meal, 10% rolled oats diet to diets containing 25% delactosed whey, lactose or 15% skim milk. 51% Pigs fed the 25% delactosed whey diet had higher average daily gain than pigs fed the 15% skim milk or control diets. Feed significant, efficiency and feed intake differences although the numerically highest were average daily not feed intake occurred when pigs were fed the 25% delactosed whey diet. Pope and Allee (1982) also found delactosed whey to be beneficial to 20 starter pig performance. Delactosed whey from two different sources and dried whey were compared to a 1.2% lysine, milo-soybean meal Three-week old pigs fed the 20% dried whey diet or the 20% diet. delactosed whey diets were heavier two and five weeks postweaning than pigs fed the basal diet. Clarkson and Allee (1982) supplemented delactosed whey for 20% dried whey on a protein basis rather than by equal weight and found no difference in pig performance. However, pigs fed either whey diet had higher average daily gains at two and five weeks postweaning than pigs fed the 1.2% lysine, milo-soybean meal control diet. In a 2 x 2 factorial, Cera and Mahan (1985) evaluated corn oil 6%) and dried whey (0, 25%) additions to starter pig diets. (0, The main effects of the 25% dried whey diets revealed higher average daily gains during each of the 4 improved weeks postweaning and utilization during the first 3 weeks. feed The addition of 6% corn oil to diets containing dried whey did not effect performance; however, a constant calorie-lysine ratio was not maintained. (1982) lard combined two lysine (1.10, 1.18%), two whey (0, 6%) Stanly et al. (0, 10%) and two levels to form eight dietary treatments to analyze the effects of calorie-lysine ratio, spray-dried whey, and fat on starter pig performance. The addition of 10% spray-dried whey improved daily gain by 7%, feed efficiency by 3%, and survival by 1% during the 4- week postweaning period. Average daily feed intake and average daily gain were depressed by the addition of fat, regardless of the presence of whey in the diet, unless a constant calorie-lysine ratio was 21 The dietary inclusion of fat in the corn-soy-whey diets maintained. enhanced daily gain and feed efficiency when a constant calorie- The authors concluded that the presence lysine ratio was maintained. of spray-dried whey in the diet enhances the ability of weanling pigs In cxsncurrence, to utilize dietary fat. Cera and Mahan (1985) reported that dried whey additions resulted in an improvement in Van Wbrmer and Pollmann apparent fat digestibility. addition of found the efficiency of pigs fed Thus, 4% choice white grease feed 20% spray-dried whey diets. is beneficial to starter pig performance when other dietary nutrients, particularly lysine, are adequate. unclear. also the it can be concluded that high quality, spray-dried, edible grade whey mode of (1985) iirproved action deriving the improvement However, the in performance is still Among limited research investigating the mode of action, Cwsley et al. (1986a) discovered a 20% dried whey diet was higher in dry matter and energy digestibility than a corn-soybean meal basal diet for pigs weaned at 28 days of age. found that pigs fed intestinal trypsin, the 1.2% the 20% Owsley et al. (1986b) also dried whey diet had higher total chymotrypsin and amylase activity than pigs fed lysine control; however, no differences were found when enzyme activity was calculated as units per kilogram of body weight or units per gram of pancreas. The authors theorized that the increase in feed intake caused by dried whey additions to the diet immediately after weaning will increase pancreas weight and the amount of pancreatic enzymes synthesized and secreted, thus improving 22 pig performance. Graham et al. also found pigs fed a 25% (1981) dried whey diet had the highest amylase and protease enzyme activity The authors also in the pancreas and small and large intestines. felt that enzyme activities appeared to be influenced by the higher feed consumption and gains for the pigs fed the dried whey diet. Total lactase activity in the small intestine mucosa and both the small and large intestine contents was also higher when dried whey Lindemann et al. was included in the diet. (1986) , who also examined the effect of dried whey on digestive enzyme levels, found that pigs fed a diet containing 20% dried whey tended to have larger pancreases and greater pancreatic and gastric pancreas for all pancreatic enzymes. has sufficient pancreatic and enzyme activity per gram of It was concluded that the pig gastric enzyme performance should not be limited; however, activity so that diet digestibility and subsequent pig performance may be more directly related to the extent of release of these enzymes into the intestines. The data suggests that the presence of dried whey in the diet will increase the amount of enzymes presence in the intestinal tract resulting in improved digestibility and performance. Cera et al. (1987) also investigated the dried whey mode of action by studying small intestinal growth and jejunal morphology directly after weaning. fold reduction in villus height by 3 Weaning resulted in a 3- days postweaning; however, addition of 25% dried whey to the basal diet had no influence on the villus height reduction. Although the mode of action of dried whey is still controversial, 23 most researchers agree that early weaned pig performance will improve However, the when a high quality dried whey is included in the diet. Becker et al. optimum inclusion level to be used is also debatable. (1957) diets. conducted the Ihe 60%. first work analyzing whey level in starter Ihe dried whey levels used in the first trial were additions. second trial Although analyzed dried whey 0, 10, 20 additions and did performance over a simple corn-soybean meal diet, 30% not 0, improve (1972) pig the dried whey quality was questionable as a roller dried product was used. al. 30 and dried whey Orr et conducted two feeding trials and one nitrogen balance trial to investigate the optimum whey level. A 19% protein diet containing 10% skim milk and 10% oat groats served as the positive control with a 16% protein, corn-soybean meal grower ration serving as the negative control. Dried whey corn in the negative control diet. (5, 10, 15, or 20%) replaced In the first feeding trial, pigs fed the 15 or 20% dried whey diets gained as rapidly as pigs fed the positive control. In the second feeding trial, increasing dried whey level resulted in a linear improvement in average daily gain. nitrogen balance study, increased from to 15%. Clarkson and Allee (1982) 10, 20 In the nitrogen retention improved as whey level added spray-dried whey at the rate of or 30% to a milo-soybean meal diet with lysine level remaining constant at 1.2%. Pigs fed the 20% dried whey diet gained faster at two and five weeks postweaning than pigs fed the control. len percent dried whey did not improve performance over the control, and 30% 24 Therefore, dried whey did not have an advantage over 20% dried whey. Fralick and 20% was concluded to be the optimum inclusion level. Cline (1983) found similar results when comparing 0, 15 and 30% dried whey a in corn-soybean meal starter Pigs diet. fed the diet containing 15% dried whey gained faster than those fed the control and no particular advantage was found at the 30% dried whey level. When evaluating barley particle size and spray dried whey level 10, (0, and or 20%) average increased. , Goodband and Hines (1987) daily feed intake increased found average daily gain linearly as whey Using the same whey levels, Thaler et al. found a linear increase in average daily gain, intake and feed efficiency. Thaler et al. (1986) level also average daily feed (1986) conducted a second 15 or 20%) experiment to determine the optimum whey level (0, when copper sulfate was present in the diet. Results indicate that 5, 10, copper sulfate may enhance the dried whey effect on starter pig performance as the 5% dried whey addition produced the same response as the 20% dried whey addition when copper sulfate was present in both diets. Edmonds and Baker (1984) for copper sulfate and dried whey. also reported an interaction The inclusion of 25% dried whey or 250 ppm copper in starter diets improved average daily gain and feed efficiency as compared to the corn-soybean meal control. An additive effect was found as pigs fed diets containing copper sulfate and dried whey gained faster than pigs fed diets containing the additives separately. Mahan et al. (1981) evaluated the optimum inclusion level of dried 25 The whey levels whey in diets for pigs weaned at 14 days of age. evaluated were average daily increased. 0, 15, feed 20, 25, 30 and 35%. intake were improved Average daily gain and linearly as whey level Ihe results indicate that the optimum inclusion level for dried whey may be higher than 20% for pigs weaned earlier than three weeks of age. The appropriate weaning age and feeding length for optimum whey Pollmann et al. utilization has also been subject to question. (1983b) weaned pigs at 2, 3, 4 or 5 weeks and fed a 1.3% lysine, milo-soybean meal diet with or without 20% dried whey to determine the weaning age effect. Pigs weaned at all ages fed the 20% whey diet weighed more at 8 weeks than those fed the diet without whey. Pigs weaned at 3 to 5 weeks performed similarly and were heavier at eight weeks than those weaned at two weeks. The data suggests that pigs weaned earlier than three weeks may require higher nutrient levels than those provided in this trial. Pope and Allee (1982) evaluated the length of time a 20% dried whey diet should be fed to pigs weaned at three weeks. 4 or 5 weeks postweaning. performed similarly The dried whey diet was fed for 1, 2, 3, Pigs fed the 20% whey diet for two weeks to pigs fed the whey diet for five weeks. Feeding dried whey for only two weeks also markedly reduced the cost of gain. Martino and Mahan (1983) also examined whey feeding length by feeding a 25% dried whey diet for 1, 2, or 3 weeks postweaning. Pigs consuming the dried whey diet had higher growth rates and feed intakes with longer access to the dried whey diet. The improvement 26 in gain and feed intake was also enhanced to a greater extent with lighter weaning weight pigs (4.54 kg) . In a nitrogen balance study, the lighter weight pigs also had greater relative nitrogen retention They suggested feeding a than pigs with a heavier weaning weight. dried whey diet for 2 to 3 weeks postweaning for pigs weighing less than 4.54 kg and only for one week for heavier pigs. In addition to dried whey and delactosed whey, demineralized whey and whey protein concentrate available to the swine industry. are additional whey based products The inclusion of demineralized whey in starter pig diets has not been investigated. However, Robinson (1986) explained that removing the minerals in the demineralized whey production process elevates the lactose and protein content. Thus, the expected feeding value for demineralized whey would be equal or superior to a high quality dried whey. Cinq-Mars et al. (1986) did examine the effect of whey protein concentrate on early weaned pig performance. Pigs fed diets containing 16.2 or 33.7% whey protein concentrate gained faster and were more feed efficient than pigs fed diets without whey protein concentrate. No performance differences were found between whey protein concentrate levels. The results indicate a level of whey protein concentrate of 16.2% is adequate to improve starter pig performance. The effect of dried skim milk-dried whey combinations on starter pig performance has also been investigated. Danielson et al. (1960) found that pigs weaned at 16 days had the highest average daily gain when fed a diet containing 30% skim milk and 10% dried whey. The 27 other milk product combinations vised were 40%-0%, 20%-20%, 10%-30%, and 0%-40%; skim milk and dried whey, Pigs fed all respectively. milk product combinations showed superior performance to those fed The optimum the corn-soybean control diet without milk product. dried skim milk-dried whey ratio can't be determined from this trial as the whey was roller dried. Mahan (1983) , Results from this trial, Martino and and Pollmann et al. (1983b) indicate light weight pigs or pigs weaned earlier than three weeks may need higher milk product inclusion levels than 20% to obtain peak performance. Nelssen (1986) reported that pigs fed a high nutrient density diet containing 20% dried whey and 20% skim milk gained faster and were more feed efficient than pigs fed a 20% dried whey diet or a 1.25% lysine, corn-soybean meal diet. Based on these results, a three phase starter program was recommended for early weaned pigs to optimize performance and minimize production costs. Phase one involves feeding the high nutrient density diet until pigs reached 7.0 kg body weight. From 7.0 to 11.5 kg, a 1.25% lysine, corn-soybean meal diet containing dried whey is fed. The last phase calls for a 1.10% lysine, grain-soybean meal diet to be fed from 11.5 to 23 kg. CRIED SKIM MILK Research conducted with dried skim milk has taken a different direction than dried whey research. Instead of concentrating on determining the optimum inclusion level, feeding length, or possible lysine level interaction, most researchers have simply used skim milk 28 in complex diets or as a means of ccnparing milk protein with other protein sources. Dried skim milk is an excellent protein source as it contains 33.5% protein and 2.4% lysine (NRC, 1979) The main difference between the conposition of whey and skim milk is that skim milk contains a large casein portion in addition to the whey fractions (lactose, lactalbumin and minerals) ; (Robinson, 1986) The addition of casein allows skim milk to have the higher protein and amino acid levels while lowering the percentages of mineral and ash. Dried skim milk also encounters fewer processing steps and, thus, varies less in composition and quality than whey 1975) . (lampert, Processing effects on quality must still be considered as heat can denature the whey proteins and insolubilize the casein (Robinson, 1986) When feeding a complex diet containing dried skim milk, several researchers have shown an improvement in performance of pigs weaned at three weeks. However, it is difficult to credit skim milk with the entire response as other nutrients were also added to form the complex diet. A corn-soybean meal diet was used as the simple diet in the following experiments. Meade et al. (1969b) found pigs fed complex diets containing 10% dried skim milk, 10% sucrose and 3% fish meal had higher average daily gain and average daily feed intake than pigs fed the simple diet. Meade et al. (1969a) fed a similar complex diet containing 5% skim milk, 5% sucrose and 3% fish meal; however, no response was found. (1970) The complex diet used by Bayley and Carlson contained 15% skim milk, 25% wheat, 5% oat groats and 5% fish 29 meal. Pigs fed the complex diet gained faster than pigs fed the Himmelberg et al. (1985) conducted five trials with 30% simple diet. dried skim milk, 10% 5% dried fish solubles and 1% dried sugar, Ihe optimum postweaning time for brewers yeast in the complex diet. The changing pigs from a complex to a simple diet was also explored. complex diet improved average daily gain, average daily feed intake Average daily gain also increased and feed efficiency in all trials. linearly increased as day from of change 5 from the complex to pronounced for lighter weight pigs. the simple diet The effect was more to 20 days postweaning. Similar to the results of the dried whey research, these results indicate lighter weight pigs may require diets containing high levels of milk products to optimize performance. Okai et al. (1976) also investigated the effect of diet complexity on starter pig performance. Pigs were allotted to dietary treatment at 10 days of age and were weaned at three weeks. complex or complex postweaning phases. diet. diets were fed during the Simple, semi- prestarter and The simple diet was a wheat-barley-soybean meal The semi-complex diet additionally contained 25% oat groats, 6.4% herring meal and 10% skim milk. The complex diet was semi- purified and contained dextrose, sucrose, corn starch, soybean meal, 11% herring vermiculite. meal, 20% dried skim milk, 15% dried whey and 3% Creep feed intake was extremely low for all diets and no differences were found in average daily gain or feed efficiency in the preweaning phase. In the postweaning period, an increase in diet 30 complexity led to a corresponding increase in feed intake and weight gain. The results indicate young pigs utilized the semi-complex and It is difficult to credit skim milk complex diets extremely well. with the entire improvement in performance found in any of these trials because the diets contained a variety of other ingredients. Further complicating the results, lysine level increased linearly with diet complexity in most trials. A few researchers have explored the addition of dried skim milk to starter diets without Kbrnegay et al. (1974) other confounding the results. ingredients and Wahlstrom et al. (1974) compared a corn- soybean meal diet with a 10% dried skim milk diet with or without 5% sugar. No performance differences due to dietary treatment were found. The calculated lysine levels (0.9 to 1.0%) were lower than those recommended by Pollmann et al. three-week old pig. in both trials (1983a) for the Meade et al. (1965) added 10% dried skim milk to a corn-soybean meal diet containing 20% rolled oats and 10% sucrose. Pigs fed the 10% dried skim milk diet tended to gain faster and were more feed efficient than pigs fed the control. It was suggested that pigs fed the diet containing skim milk may have digested dry matter and protein more efficiently than pigs fed the control. Seve (1984) also found an improvement in average daily gain when 10 or 15% dried skim milk was added to the basal diet. Higher protein quality and digestibility was again attributed as the reason for the improvement in performance. digestibility of Owsley 1.15% et al. lysine, (1986a) examined corn-soybean meal the diets nutrient with or 31 without control, addition the of 20% Compared to the dried skim milk. the addition of dried skim milk to the diet nitrogen, energy, and dry matter digestibility. increased Graham et al. (1981) further investigated the digestibility of diets containing skim milk by analyzing digestive enzyme activity and performance of two-week old weaned pigs. Pigs fed the 15% skim milk diet tended to gain faster and be more feed efficient than pigs fed the 10% rolled oats, corn-soybean meal diet. amylase or protease Dietary treatment had no effect on total activity in the pancreas, small and large intestine contents, or in the small intestine mucosa; however, total lactase activity in the small intestinal mucosa and the small and large intestine contents was higher when dried skim milk was provided in the diet. The high lactase activity would suggest that the lactose fraction of skim milk may be responsible for a large portion of the improvement in performance. Giesting et al. (1985) conducted three trials to determine whether the major protein (casein) or carbohydrate (lactose) fraction of skim milk is responsible for the beneficial performance found when skim milk is fed to the young pig. Casein, soy protein concentrate or isolated soy protein were added along with lactose or corn starch to the basal diet to simulate the protein and carbohydrate fractions provided by a 25% dried skim milk diet. A negative control, corn- soybean meal diet and a positive control, corn-soybean meal, 25% skim milk diet were also fed. Pigs fed the positive control diet had higher average daily gains and average daily feed intake than pigs 32 Diets containing lactose or casein also fed the negative control. supported higher gains and feed intake than the negative control, but the corresponding values were lower than those listed for pigs fed the positive control. casein performed indicating sources. an Pigs fed the diet containing both lactose and to similarly effect additive From this trial, pigs to fed the positive the protein and control, carbohydrate it appears that casein and lactose are equally important in explaining the beneficial response found when feeding dried skim milk to the young pig. As explained earlier, the majority of the research has used skim milk as a means of comparing alternative protein sources. Fish meal, peanut meal, full-fat soybeans, soybean meal and isolated soy protein have been compared to skim milk as protein sources. The same general results were found in most trials with skim milk being the superior protein for the young pig. deMoura and Fowler (1983) found pigs gained faster when equal parts of fish meal and skim milk were used as the protein source as compared to full-fat soybeans and soybean meal. also combined fish meal Lucas et al. (1959) and skim milk as a protein source. No improvement in performance was found when skim milk was added to the diet as compared to when fish meal was the only protein source. However, the skim milk was roller dried and, thus, a portion of the protein may have been denatured. Average daily gain and feed efficiency were also poor for all treatments. Bayley and Holmes (1972) fed semi-purified diets to pigs weaned at 33 ten days of age. soy protein The protein sources analyzed were dried skim milk, flour, fish protein a and concentrate concentrate-dried whey combination. fish protein Pigs fed the diet containing dried skim milk gained faster than pigs fed diets containing the other protein sources. Partridge (1981) demonstrated that pigs fed diets containing dried skim milk as the only protein source gained faster during the starter phase than pigs fed diets containing a The pigs consuming the combination of skim milk and soybean meal. high skim milk diet during the starter phase also increased their weight advantage by the completion of the grower period. Investigating the mode of used half or total (1979) action of dried skim milk, Newport replacement of dried skim milk with a combination of dried whey and fish protein concentrate as the protein supplement in liquid diets for pigs weaned at two days of age. Protein digestion was also studied in pigs sacrificed at six days of age. A 26-day growth trial was also conducted. Average daily gain was slightly improved when half of the dried skim milk was replaced. Total replacement of skim milk reduced gain and the gain to feed ratio. Increasing the proportion of fish protein reduced apparent digestibility, nitrogen stomach, trypsin intestine. and retention, and total chymotrypsin pepsin activity activity in the in the small Trypsin and chymotrypsin activity in the pancreas were not affected by the source of dietary protein. It was suggested that total replacement of dried skim milk with fish protein concentrate and dried whey may increase the flow rate of digesta through the 34 The author theorized that the increased rate of small intestine. flow, and reduced nitrogen digestibility and reduced amounts of trypsin c±ymotrypsin the in digesta could reduce the efficiency of However, using protein digestion and adversely affect performance. 35-day old pigs, Asche et al. (1987) found digesta flowed faster when skim milk was the only protein source as compared to soybean meal and corn gluten meal. However, skim milk protein was digested and absorbed more rapidly than the other proteins. Combs et al. (1963) compared dried skim milk, fish meal as protein sources for the young pig. soybean meal and Pigs fed the diet containing dried skim milk gained faster, consumed more feed and were more feed efficient than pigs fed diets containing the other protein sources. 3 Digestibility information was also collected when pigs were to 4, 5 to 6 and 7 to 8 weeks of age. the protein source improved dry Including dried skim milk as matter, nitrogen and energy digestibility during the periods when pigs were 3 to 4 and 5 to 6 weeks old. Dietary treatment did not affect digestibility during the last time period. Hays et al. (1959) was also interested in the effect of protein source on growth and diet digestibility as the pig increases in age. Soybean meal and spray dried skim milk were the protein sources evaluated in this 35-day growth trial. Digestibility determinations were also made at two and five weeks of age. Pigs fed diets containing skim milk gained faster and were more feed efficient than pigs fed diets containing soybean meal. improved dry matter digestibility, The skim milk diet also nitrogen digestibility and 35 apparent nitrogen retention for two and five week old pigs. The digestibility differences between protein sources were less at five weeks as the digestibility of the soybean meal diet improved. Lecce et al. determined soy flour can replace a portion of (1979) dried skim milk as the protein source for pigs over three weeks of age without adversely affecting performance. However, average daily gain was reduced when soy flour was included as a portion of the protein source for pigs less than three weeks old. (1964) Pekas et al. found pigs gained faster and were more feed efficient from 1 to 28 days of age when skim milk was the only protein source as compared to soybean meal. However, dietary treatment had no effect on four to five week performance. Ihe literature indicates the performance advantage found when feeding dried skim milk as the only protein source diminishes as the pig becomes older. Exactly when the skim milk advantage is lost is still questionable. Wilson and Leibholz (1981a,b,c,d) conducted the most in-depth research investigating milk and soy proteins and their effects on digestion in the pig between 7 and 35 days of age. dried skim milk as the containing soybean meal, various experiments. improved average digestibility, source were Diets containing compared to diets soybean flour or isolated soy protein in The inclusion of dried skim milk in the diet daily gain, feed efficiency, dry matter nitrogen digestibility, amino acid digestibility and nitrogen retention source. protein in all trials, regardless of the soy protein Digestibility of the skim milk diets remained similar for 36 pigs at 14 and 35 days of age, while digestibility of the soy protein The author concluded that diets increased with increasing pig age. the reduced performance of young pigs fed soybean protein diets is the result of the lower digestion of amino acids, nitrogen and dry matter prior to the ileum as compared to pigs fed milk protein diets. CASEIN The most abundant milk protein Casein casein. is is used principally as an adhesive or binder in paper coating, wood glue, concrete and plastic (Robinson, 1986) In . recent years, been given to the utilization of casein attention has nutrition and research trials (Fox, 1983) more in human Casein has been used as a . substitute for skim milk by swine researchers interested in comparing milk protein with other protein sources. skim milk, By using casein instead of the researcher may investigate protein source effects, while reducing the possibility of a carbohydrate source interaction. Galesloot and Tinbergen (1984) suggested casein should be an excellent feed ingredient for ronruminant diets, as it contains high levels of all essential amino acids. However, the actual performance response found in feeding trials has been extremely variable. reason casein hasn't consistently improved pig performance, fully understood. Erbersdobler (1983) Poor casein demonstrated quality that may be overheating suspected, casein processing may reduce total digestibility from 95 to 75%. Robinson (1986) The is not as during However, explained that the processing temperature must be 37 significantly higher than normal to cause protein denaturation since Webb and Whittier casein is much more stable than whey protein. also explained that the quality and composition of casein (1970) doesn't vary as much as the composition of dried whey and skim milk. When adding 2% casein to the corn-soybean meal, Miller et al. gain for improve old three-week demonstrated a control diet, found an improvement in rate and efficiency of (1971) relatively Giesting pigs. low As pig performance. level of et al. explained in (1985) also in the diet will casein the dried skim milk section, casein was added to a corn-soybean meal diet to simulate the Pigs fed the diet casein fraction provided by a 25% skim milk diet. containing casein had improved average daily gains and feed efficiency as compared to pigs fed the corn-soybean meal negative control; however, the gains of pigs fed the casein diet were still lower than those of pigs fed a 25% dried skim milk, corn-soybean meal diet. These trials indicate that low levels of casein in the diet will improve pig performance. The results have been less favorable in experiments where casein was the only protein supplement. Walker et al. (1986a) conducted the only research showing an improvement in performance when high levels of casein were compared to other protein sources. Casein, isolated soy protein, ethanol extracted soy protein and soybean meal were the protein sources compared in .91% lysine, corn-based diets for three- week old pigs. average Pigs daily gains fed the diet containing casein had higher than pigs fed the diets containing ethanol 38 extracted soy protein or soybean meal. There was no difference in average daily gain between pigs fed casein or isolated soy protein as the protein Pigs source. fed the casein diet were more feed efficient than pigs fed any of the soy protein diets during the first week on trial; however, treatment differences diminished after the Dry matter, first week. lysine, valine, methionine and proline digestibilities were higher for pigs fed the diet containing casein than for pigs fed any of the soy protein diets. The authors felt the difference in digestibility and possibly in amino acid availability might account for the differences in average daily gain and feed In a follow-up study, Walker et al. efficiency. (1986b) found no differences in apparent nitrogen or essential amino acid availability between diets containing protein or ethanol casein, extracted hydrolyzed soy protein casein, isolated soy as the protein source. However, pigs fed these protein sources had higher apparent nitrogen and essential amino acid availability than pigs fed diets containing soybean meal as the protein source. Roos et al. ( 1986a, b) formulated corn-soy protein concentrate and corn-casein diets to evaluate the effect of fumaric acid on starter pig performance. There were no differences in average daily gain, average daily feed intake or feed efficiency due to protein source. Rodriguez and Young performance when (1980) comparing also a herring meal as a protein source. al. (1983) found no effect casein-buttermilk on starter pig combination with In a 2 x 2 factorial, Richard et examined the effect of protein source (casein or isolated 39 soy protein) and fat type (tallow or soybean oil) performance and body composition. pig performance, Etheridge et body al. digestibility, bone weight or bone calcium. composition, (1984) found on starter pig Protein source had no effect on no blood composition or differences in performance, intestinal microflora between pigs fed an oat groats-casein diet and those fed a corn-soybean meal diet. From these trials, it appears that casein does not significantly improve weanling pig performance when it is used as the only protein source in the diet. The response found when pigs were fed diets containing casein as the only protein source has also been very inconsistent for pigs less than three-^weeks old. Pond et al. (1971) fed liguid diets containing 33% casein, isolated soy protein or fish protein concentrate to pigs weaned at two to three days of age. performance between pigs There were no differences in fed casein and fish protein concentrate diets; however, both diets were superior in average daily gain and feed efficiency as compared to diets containing isolated soy protein as the sole protein source. Since the protein sources have different amino acid profiles and were added at the same level, the varying amino acid levels in the diet may have discriminated against isolated soy protein. Mateo and Veum (1980) also compared casein and isolated soy protein as protein sources for 1 to 29 day old pigs. Pigs fed the diet containing casein gained faster and were more feed efficient from 1 to 15 days of age than pigs fed diets containing isolated soy protein. Protein source had no effect on pig performance from 15 to 40 29 days of age. Digestibility criteria were also analyzed from 11 to Ether extract, crude protein, energy, ash and dry 15 days of age. matter digestibilities were greater for pigs fed diets containing casein than for those fed the diets containing isolated soy protein. Pigs fed a dried skim milk control diet had digestibility values very similar to those fed the casein diet; however, from 1 to 15 days of age, they gained faster and were more feed efficient. The results indicate casein is superior to isolated soy protein, but inferior to skim milk as the sole protein source for the extremely young pig. However, the advantage over isolated soy protein rapidly deteriorates over time. Maner et al. (1962) found the rate of passage for soy protein slows as the pig gets older; whereas, the rate of passage for casein is constant over time. The change in the rate of passage for isolated soy protein may explain the decrease in the advantage for casein as the pig increases in age. Leibholz (1982) fed dry diets containing skim milk, casein, isolated soy protein, soy protein concentrate, fish meal or soybean meal as protein sources to pigs between 7 and 28 days of age and found results similar to Mateo and Veum (1980) . Pigs fed the casein diet had higher average daily gains and were more feed efficient than pigs fed the diets containing the other protein sources except skim milk. Pigs fed the skim milk diet had the highest gains and were the most feed efficient. Diets containing dried skim milk and casein were very similar in digestibility. casein diets had higher dry Pigs fed dried skim milk or matter digestibility, nitrogen 41 digestibility, and nitrogen retention than pigs fed diets containing Pettigrew et the other protein sources. al. (1977) compared a combination of sodium caseinate and dried whey to dried skim milk as a protein source for pigs weaned at 2 to 3 days of age. Pigs fed the dried skim milk diet gained at a faster rate than pigs fed the There were no differences in digestibility, empty casein-whey diet. stomach weight, gut pH or histology of the gastrointestinal tract for pigs fed the different protein sources. apparent that diets From the literature, it is casein or skim milk as the containing sole protein source are equal in digestibility; however, skim milk diets support higher average daily gains. Ihe reason skim milk and casein don't provide equivalent performance is not fully understood. There is some indication in the literature that a certain ratio of casein to whey proteins must be maintained to optimize performance in the young pig. Newport and Henschel (1984) combined spray dried whey protein concentrate and spray dried skim milk to provide casein: whey protein ratios of 80:20 or 40:60. There were no differences in pig performance due to the casein: whey protein ratio; however, the higher level of whey proteins reduced the concentration of urea nitrogen in the blood and the proportion of urea nitrogen nitrogen. in total urinary Newport and Henschel (1985) also combined spray dried whey protein concentrate and spray dried skim milk to analyze the effects of casein: whey protein ratio metabolism in neonatal pigs. were 80:20, 60:40, 20:80, on growth, digestion and protein The casein: whey protein ratios analyzed or 0:100. A ratio of 60:40 gave maximum 42 growth rate, feed efficiency and nitrogen retention, and the lowest blood urea concentration. From the data, the authors estimated that the optimum casein: whey protein ratio is approximately 50:50, similar to that in sow's milk. Pettigrew et al. (1977) also suggest that for maximum performance young pigs may require a dietary source of intact Since dried whey protein concentrate and dried skim milk proteins. milk are intact milk protein sources, further research may be needed to determine if 50% casein - 50% lactalbumin is the optimum milk protein combination for the young pig. IACTOSE Lactose is the carbohydrate fraction of milk. Dried skim milk and dried whey are extremely high in lactose at 50% and 70%, respectively (Robinson, whey to 1986) . starter Since the addition of dried skim milk or dried diets improves pig performance, expected to respond favorably to lactose additions. pigs would be Similar to the response found with other milk products, lactose utilization appears to be dependent on the age of the pig. Aherne et al. (1969) compared lactose, glucose, fructose as energy sources for pigs weaned at two, days. sucrose and four or seven Pigs fed diets containing lactose or glucose as the energy source performed similarly and gained faster and were more efficient than pigs fed diets containing sucrose or fructose. feed Pigs fed sucrose or fructose diets also had higher mortality rates when weaned at two and four days than pigs fed lactose or glucose diets. 43 The results indicate lactose and glucose are excellent carbohydrate sources for the pig during the first week of life. Entringer et al. compared lactose, glucose and corn starch (1975) These older pigs did not as carbohydrate sources for 20 kg pigs. respond as favorably to lactose additions to the diet as pigs in the Pigs fed the diet containing corn starch had higher previous trial. and nitrogen dry matter digestibilities as well as improved performance as compared to pigs fed diets containing lactose. From the literature it appears the utilization of lactose by the pig decreases sources over age, while the utilization of other carbohydrate increase with age. This system of the pig as lactase, corresponds with the enzymatic the enzyme capable of breaking down lactose, is high in concentration during the first few weeks of life and decreases over time. Amylase, the enzyme necessary for the digestion of starch, is low in concentration at birth and increases as the pig grows older (Corring et al. 1978) . Previous diet and management scheme may also influence the development of the enzymatic system, thus, the exact age when lactase level decreases and amylase concentration increases is not fully understood. Numerous researchers have investigated the effect of lactose additions to the diet on performance of three to four-week old pigs. Sewell and West (1965) evaluated the effect of lactose on the efficiency of isolated soy protein as a protein source for the young pig, as compared to dried skim milk. In separate diets, two sources of lactose, beta-lactose and dried whey, were added to the isolated 44 soy protein, negative control diet to provide the same amount of lactose as supplied by the 42% dried skim milk, diet. positive control Pigs fed the diets containing lactose gained faster, were more efficient in feed utilization, and had higher nitrogen and ether extract digestibilities than pigs fed the negative control diet. significant differences No in performance were observed between pigs receiving diets containing the various lactose sources. When adding 13% lactose to a corn-soybean meal diet for three- week old pigs, Clarkson and Allee (1982) found no effect on average Giesting et al. daily gain or feed efficiency. (1985) reported pigs fed diets containing 12.5% lactose had higher average daily gains and average daily feed intake than pigs fed a corn-soybean meal diet. However, pigs fed the lactose diet were lower in average daily gain as compared to pigs fed a 25% skim milk, Corbin and McConnell (1986) also corn-soybean meal diet. found pigs fed a complex diet containing 50% lactose gained faster and were more feed efficient than pigs improvement fed in a 20% dried whey, performance can not corn-soybean meal be entirely diet. The credited to the lactose addition as the complex diet also contained 10% fat and was pelleted. Turlington et al. (1987) also suggested that lactose will improve nutrient digestibility and slow digesta flow rate as compared to dextrose as carbohydrate sources for 21 to 35 day old pigs. The literature suggests that the addition of lactose to corn-soybean meal starter diets will improve performance of pigs weaned earlier than . 45 four weeks of increase in The mode of action may be an age. digestibility due to slower digesta flow and a higher concentration of lactose enzyme or a simple improvement in feed intake. ISOIATED SOY PROTEIN As explained in the processing section, protein products are produced. various types of soy Soybean meal is the product most often used in the swine industry; however, soy flour, soy protein concentrate and isolated soy protein are also available (Campbell, 1979) Soy flour (Wilding, 1971) contains . approximately 53% protein and 3.3% lysine Since it is produced by simply removing the fat and hulls from soybeans, soy flour also contains the insoluble and partly indigestible soy carbohydrate (1977) fraction (De, 1971) . Jones et al. fed liquid diets to pigs weaned at three weeks of age to compare soy flour and dried skim milk as protein sources. Pigs fed diets containing skim milk were more feed efficient than pigs fed diets containing soy flour; however, protein source had no effect on average daily gain. The data suggests that pigs weaned at three weeks of age can productively utilize soy flour when fed in liquid diets on an hourly feeding schedule. Lecce et al. (1979) used the same hourly feeding schedule to compare soy flour and skim milk as protein sources for pigs weaned at 14 days of age. reduced during the however, first week on trial for pigs Daily gain was fed soy flour; after the pigs reached 21 days of age no differences were 46 found. Soy protein concentrate commonly contains 65 to 70% protein and to 4.4% 4.2 constituents lysine are (Meyer, removed concentrated product (Meyer, The water-soluble nonprotein 1967). from flour soy 1967). to obtain the more Although the protein level is increased, the insoluble and indigestible soy carbohydrate portion is also concentrated, and thus, the value of soy protein concentrate as a feed ingredient is questionable (De, 1971) Stanly et al. meal as (1983) compared soy protein concentrate and soybean the protein source Average daily gain, were depressed for pigs weaned at 28 days of age. average daily feed intake and feed efficiency linearly as increased in simple, the level of soy protein concentrate corn-soybean meal diets. However, when 15% dried whey was present in the diets, pigs fed diets containing soy protein concentrate were more feed efficient than pigs fed diets containing soybean meal. Leibholz (1982) found apparent nitrogen and dry matter digestibilities were higher for soy protein concentrate than for soybean meal when fed to 7 to 28 day old pigs. However, since the inclusion of soy protein concentrate in the diet decreased feed intake, pigs fed the soybean meal diet gained faster. et al. (1985) to lower feed concentrate. Giesting also found a slight decrease in average daily gain due intake for pigs fed diets Giesting and Easter (1985) containing soy protein found no differences in average daily gain, feed intake or feed efficiency for pigs fed diets containing soy protein concentrate or soybean meal as the protein 47 source. Frcm the literature, soy protein concentrate appears to be more digestible than soybean meal; however, the reduction in feed intake must be eliminated before soy protein concentrate will improve pig performance. Isolated soy protein typically contains 92 to 93% protein and 5.5 to 6.0% lysine (Meyer, 1967). The high protein content is achieved by removing the insoluble carbohydrates along with the fat, hulls and soluble carbohydrates from raw soybeans (De, 1971) . Since isolated soy protein is the most purified soy protein product, researchers have used it as a standard for comparing plant proteins with other protein sources for the young pig. The casein section lists numerous isolated soy protein with casein. protein have protein (Mateo and Veum, had lower amino acids (Walker et al., the sole protein source. Leibholz, 1986a) have compared Diets containing isolated soy digestibilities 1980; that trials for dry matter, 1982) energy, and the essential than diets containing casein as Walker et al. (1986b) found no differences in apparent nitrogen or amino acid availability between the protein sources. results; Casein appears superior to isolated soy protein from these however, performance values indicate the response due to protein source is age dependent. al. (1986a) found no Richard et al. (1983) and Walker et difference in average daily gain or feed efficiency for three-week old pigs fed isolated soy protein or casein as the protein source. Pond et al. (1971) and Leibholz (1982) found pigs weaned earlier than three weeks gained faster and were more feed . 48 efficient when fed diets containing casein as corpared to isolated Maner protein. soy et al. (1961) Mateo and and Veum (1980) demonstrated that the digestibility of diets containing isolated soy protein increases as the pig matures while the digestibility of diets Ihe increased utilization of containing casein is constant over age. isolated soy protein may be due to the maturation of the digestive and enzymatic systems (Corring et al., 1978) or a slowing of the rate of passage of soy proteins (Maner et al. 1962) , Although the literature indicates casein and isolated soy protein provide comparable performance when fed to pigs over three weeks of age, it should not be assumed eguivalent for pigs of this age. demonstrated that skim milk, an superior to isolated soy protein. milk gained faster, were more that soy and milk proteins are Wilson and Ieibholz (1981a,b,c,d) intact milk protein source, is Pigs fed diets containing skim feed efficient and had higher digestibilities of dry matter, nitrogen, energy and essential amino acids. Giesting et al. (1985) also found the inclusion of dried skim milk in the diet improved average daily gain and feed efficiency as compared to isolated soy protein for pigs weaned at four weeks of age. Limited research is available comparing isolated soy protein with other soy protein sources. Ieibholz (1982) Wilson and Ieibholz (1981a, b,c,d) and corpared isolated soy protein and soybean meal as protein sources for pigs between 7 and 35 days of age. Pigs fed diets containing isolated soy protein had higher digestibilities for 49 dry matter, nitrogen and the essential amino acids than the pigs fed containing diets soybean meal. Although diet digestibility was due to a reduction in feed intake, pigs fed isolated soy higher, protein diets had lower average daily gains than pigs fed soybean meal diets. and Walker et al. essential amino acid (1986a, b) also found dry matter, nitrogen digestibilities were higher for diets containing isolated soy protein than diets containing soybean meal when fed to pigs weaned at three weeks of age. Feed intake was not depressed for these older pigs, and thus, isolated soy protein tended to improve average daily gain and feed efficiency. (1985) Giesting et al. also found the inclusion of isolated soy protein as a portion of the protein source improved feed efficiency as compared to using soybean meal as the sole protein source. isolated soy protein, The literature indicates similar to soy protein concentrate, is more digestible than soybean meal; however, the reduction in feed intake must be overcome performance. before an improvement will be seen in pig 50 EFFECT OF PROTEIN AND (OR) CARBOHYDRATE FRACTIONS OF DRIED WHEY ON PERFORMANCE AND NUTRIENT DIGESTIBILITY OF WEANLING PIGS Summary One hundred and eighty 3-wk old pigs (initial weight 4.8 kg) were utilized in a 35 d growth trial to determine the effects of the carbohydrate and performance. In addition, 30 3^wk old pigs (initial weight 4.9 kg) (or) protein fraction of dried whey on pig were used in two digestion trials to study the effects of the whey fraction on nutrient digestibility. corn-soybean meal control + 14% control lactose (CON), (CHO) , Dietary treatments included a control + 20% dried whey control + 2.1% lactalbumin (WHE) (PRO), control + 14% lactose + 2.1% lactalbumin (CHO + PRO), and control + 8.4% whey protein concentrate balanced on an isolysine basis. (WPC) . Diets were pelleted and Lactose and lactalbumin were added at the same levels as provided by a 20% dried whey diet. Pigs fed diets containing milk products exhibited superior average daily gain; feed efficiency; and apparent dry matter, energy and nitrogen digestibility (P<.05) compared to pigs fed the control diet. results indicate that both the carbohydrate (lactose) These and protein (lactalbumin) fractions of dried whey are important in explaining the beneficial response to dried whey elicited by the weanling pig. (Key Words: Weanling Pigs, Dried Whey, Lactose, lactalbumin, Whey Protein Concentrate.) 51 Introduction Several researchers have shown that the inclusion of dried whey in the starter diet will improve performances of pigs weaned at 3 to 4 wk of age (Miller et al., 1971; Graham et al., 1981; Cera and Mahan, 1985: Goodband and Hines, 1987) . Additional research with dried whey (Mahan et al., has investigated the optimum inclusion level and Allee, Clarkson 1982; Fralick and Cline, weaning age and feeding length (Pope and Allee, 1981; 1983), appropriate 1982; Pollmann et al., 1983b), and possible interaction with fat (Stahly et al., Van Wbrmer and Pollmann, 1986) 1985) or copper sulfate 1982; (Thaler et al., However, few researchers have examined the mode of action of . dried whey that derives the beneficial growth response. Owsley et al. was higher in (1986a) discovered a diet containing 20% dried whey dry matter and energy digestibility than a soybean meal diet for pigs weaned at 28 d. Lindemann et al. pigs fed (1986) and Owsley et al. Graham et al. corn(1981) (1986b) also reported that diet containing dried whey had higher total intestinal chymotrypsin, amylase, protease and lactase activity than pigs fed a corn-soybean meal diet. The effects of the individual carbohydrate and protein fractions of dried whey on starter pig performance and nutrient digestibility have not been determined. . Results from Giesting et al. protein fractions of (1985) skim milk have indicate the carbohydrate and an additive effect on the performance of starter pigs; however, such research has not been done with dried whey. Therefore, the objective of these studies was to 52 determine whether the protein (lactalbumin) or carbohydrate (lactose) fraction of dried whey provides the beneficial growth response in the young pig. Experimental Procedures Composition of the dietary treatments used in the three trials is shown in table 1. 10.5% lactalbumin. Dried whey was assumed to contain 72% lactose and the 20% dried whey diet (WHE) would Therefore, These assumptions were contain 14.4% lactose and 2.1% lactalbumin. used to formulate the PRO CHO, and CHO + A diet PRO diets. containing whey protein concentrate was also evaluated in the growth trial to further fractions. lactalbumin. This the explore diet was practical also application formulated to of the whey contain All diets were pelleted and contained 1.3% lysine, 2.1% .8% calcium, and .7% phosphorus. Pigs were not allowed access to creep feed during the lactation period. During this period, pigs were housed in a total confinement, environmentally controlled, farrowing facility. Growth Trial One hundred and eighty weanling pigs (21 + 3d) were allotted by litter, sex and weight to the initial weight was 4.8 kg, six dietary Average treatments. with a range of 2.4 to 7.0 kg. replications per treatment were used with six pigs/pen. Five Pigs were housed in an environmentally controlled nursery in pens (1.2 m x 1.5 m) with woven wire floors and a Y-flush gutter, with one nipple 53 waterer and one four hole self-feeder per pen. offered ad Temperature and air libitum. Feed and water were flow were adjusted to maintain optimum comfort for the pigs. Criteria measured were average The study was conducted for 5 wk. daily gain efficiency (ADG) (F/G) , average daily feed intake (ADFI) , and feed Feeders were checked twice daily and individual . pig weights were collected at the end of each 7 d period. Digestion Trials In each of two trials, weaned at 16-18 15 pigs (average initial weight 4.9 kg) d were randomly allotted by litter to dietary Pigs were housed in individual 37 cm x 45 cm x 45 cm treatment. metal cages in an environmentally controlled feeding room maintained Pigs were fed twice daily and water was offered between 29 and 32 C. Pigs were brought to maximum feed intake during a 5 d ad libitum. adjustment period, with feces being collected for the next 5 d. Pigs were then reallotted by litter in a crossover design to a different dietary treatment. 5 This was followed by a second 5 d adjustment and d collection period. Feces were collected and frozen daily throughout each collection period. At the end of each period, the feces were dried in a forced air oven at 38 C until equilibrated to a constant weight. Feces, along with diet samples, were ground in a Thomas-Wylie experimental grinder equipped with a 1 mm screen. analyzed methods. for nitrogen Gross and dry matter All samples were chemically according to AQAC (1975) energy content was determined by adiabetic bomb 54 calorimetry. Apparent digestibility coefficients were calculated for dry matter, nitrogen and energy. Statistical Analysis The data were analyzed vising the General Linear Models .procedure of the Statistical Analysis System 1979) (SAS, Data . from the digestion trials was analyzed for each period and trial; however, since no trial by trial, trial by period, or period by period interactions were found data was pooled for the final analysis. was considered the experimental unit for the growth Pen trial. Preplanned orthogonal contrasts were used to separate treatment means in the digestion and growth trials. were CON vs all other The orthogonal comparisons made treatments, WHE vs the containing whey fractions (CHO, PRO, and CHO + PRO) (CHO + PRO) vs the individual fractions (CHO, three , treatments the combination PRO), and the individual fractions against each other (CHO vs PRO) Results and Discussion The dried whey and whey protein concentrate chemical analysis is shown in Table 2. The high lactose, low ash and low salt levels indicate that a high quality demineralized whey was used, as Lampert (1975) reported that edible grade dried whey typically contains 72% lactose, 8% ash and 3% salt. The excellent quality dried whey may have influenced the performance and digestibility of pigs fed the WHE diet. Mahan (1984) demonstrated that pigs fed diets containing an edible grade dried whey with a low ash level had higher ADG and ADFI 55 than pigs fed a feed grade dried whey with a high ash content. The effect of dried whey fractions on weanling pig performance is in Table shown Pigs 3. fed diets containing milk products had improved (P<.05) ADG and F/G at 2 and 5 wk postweaning, as compared to those fed the control. (1985), Stahley et al. Miller et al. (1981), (1986), and Thaler et al. Cera and Mahan (1986) also found that ADG and F/G were improved when dried whey was incorporated in starter pig diets. (1981), Clarkson and Allee (1982), Graham et al. and Goodband and Hines (1987) also reported pigs fed diets containing dried whey gained faster than pigs fed corn-soybean meal without dried whey; however, there were no differences in F/G. Mars et al. (1986) diets Cinq- also reported an improvement in ADG and F/G when whey protein concentrate was added to starter pig diets. Pigs (P<.07) fed the PRO diet also tended to be more than pigs fed the CHO diet after 5 wk. found in ADFI at 2 and 5 wk. feed efficient No differences were In addition, no differences in ADG at 2 and 5 wk or F/G at 2 wk were found between the lactose (CHO) lactalbumin (PRO) diets. and lactose additions to starter pig diets have previously been shown to improve pig performance (Sewell and West, 1965; Giesting et al., swine diets have not 1985). Although lactalbumin additions to previously been evaluated, these positive results were expected since lactalbumin has an excellent amino acid profile, a digestibility of 99%, biological value of 94% and protein efficiency ratio of 3.2 (Robinson, 1986) . However, no additive effect was found when the lactose and lactalbumin were added together in the 56 CHO + PRO diet. Table 4 shows the effect of dried whey fractions on apparent digestibility. Pigs fed diets containing milk products had higher (P<.05) apparent dry matter, nitrogen, and energy digestibility than pigs fed the control. As was the case in the growth trial, there were no differences between the diets containing the dried whey fractions for any of the criteria measured. Owsley et al. (1986a) also reported an increase in dry matter and energy digestibility with the addition of 20% dried whey to a corn-soybean meal diet. Wilson and Leibholz (1981b, c) and Leibholz (1982) found similar improvements in digestibility when skim milk was used as the milk product. Lactose has also previously been shown to improve nitrogen and dry matter digestibility (Sewell and West, 1965) The results from these trials provide further evidence that milk products improve performance and nutrient digestibility in 3-wk old pigs. It appears that both the carbohydrate (lactose) and protein (lactalbumin) fractions of dried whey are important in explaining the dried whey response; however, when both fractions were present in the diet, no additive effects were found. 57 Table 1. Diet Composition, %a Dietary Treatments13 Ingredients Corn Soybean meal Soybean oil Dried whey lactose lactalbumin Whey protein concentrate Dicalcium phosphate Limestone Salt Trace mineral mix Vitamin mix" L-Lysine HCL Selenium mix6 Antibiotic mix^ Copper sulfate*? CON WHE CHO FR0 CHO + FRO WPC 55.14 38.07 3.00 41.53 32.25 3.00 20.00 39.30 39.43 3.00 60.28 30.68 3.00 44.48 32.00 3.00 53.68 31.23 3.00 2.10 14.40 2.10 1.60 1.77 8.34 1.49 .89 .50 .10 .25 .10 .15 .25 .10 .80 .50 .10 .25 .10 .15 .25 .10 .81 .50 .10 .25 .10 .15 .25 .10 14.40 1.49 1.14 .85 .50 .10 .25 .10 .15 .25 .10 .63 .50 .10 .25 .10 .15 .25 .10 1.66 .76 .50 .10 .25 .10 .15 .25 .10 aDiets were calculated to contain 1.3% lysine, .8% calcium, and .7% phosphorus. kcON = control, WHE = control + 20% dried whey, CHO = control + 14.4% lactose, FRO = control + 2.1% lactalbumin, CHO + FRO = control + 14.4% lactose + 2.1% lactalbumin, WPC = control + 8.34% whey protein concentrate. cPercentage composition was Fe, 10; Zn, 10; Mh, 10; Cu, 1; I, .3; Co, .1. aComposition per kg premix: vitamin A, 1,762,080 IU; vitamin D3, 132,156 IU; vitamin E, 8,810 IU; riboflavin, 1,982 mg; menadione, 683 mg; pantothenic acid, 6,793 mg; niacin, 11,013 mg; choline chloride, 203,080 mg; vitamin B± , 9.7 mg. 2 ®Fremix provided complete diet with .3 ppm supplemental selenium. tAntibiotic contains 44 g chlortetracycline, 44 g sulfamethazine and 22 g penicillin per kg. 9premix supplied complete diet with 250 ppm supplemented copper. . 58 Table 2. Analyzed Ingredient (imposition, %. Ingredient Demineralized Dried Whey Protein Lysine lactose Ash Salt Table 3. Whey Protein Concentrate 36.64 3.63 50.20 6.08 1.84 13.24 .94 80.50 1.24 .05 Effect of Dried Whey Fractions on Weanling Pig Performance. Dietary Treatment3 CON WHE CH0 PRO CH0 + PRO Week to 2 Daily gain,^ Daily feed,g Feed/gain13 229 287 1.24 280 329 1.17 289 335 1.15 283 312 1.10 263 294 1.11 262 306 1.17 Week to 5 Daily gajj^g*3 Daily feed,g Feed/gain130 369 565 1.52 423 619 1.46 405 605 1.49 408 582 1.42 411 592 1.44 404 581 1.44 WPC aC0N = control, WHE = control + 20% dried whey, CHO = control + 14.4% lactose, PRO = control + 2.1% lactalbumin, CHO + PRO = control + 14.4% lactose + 2.1% lactalbumin, WPC = control + 8.34% whey protein concentrate. bcontrast, CON vs others (P<.05). cContrast, PRO vs CHO (P<.07) 59 Table 4. Effect of Dried Whey Fractions On Apparent Digestibility. Dietary Treatment3 Apparent digestibility Dry matter13 Nitrogen13 Energy13 CON WHE CHO FRO CHO + FRO 86.8 83.2 86.3 88.7 85.2 88.3 88.1 84.2 88.7 87.9 85.3 87.7 88.5 85.8 88.1 (%) aO0N = control, WHE = control + 20% dried whey, CHO = control + 14.4% lactose, FRO = control + 2.1% lactalbumin, CHO + FRO = control + 14.4% lactose +2.1% lactalbumin, WFC = control + 8.34% whey protein concentrate. kcontrast, CON vs others (P<.05). 60 EFFECT OF IACTOSE LEVEL AND PROTEIN SOURCE ON STARTER PIG PERFORMANCE Summary A total of 390 weanling pigs (21 + 3 d) 2x3 were used in two factorial experiments to evaluate the effect of lactose level 12.5%, and protein source 25%) starter pig performance. (isolated soy protein, casein) (0%, on In addition, a corn-soybean meal negative control diet (0% lactose) was also evaluated in trial 2. All pigs received the experimental diet for the first two wk and were fed a 20% dried whey, corn-soybean meal diet for the last three wk of the five wk trial. No interaction (P>.05) occurred between lactose level and protein source in either trial. The only treatment difference found in trial 1 was that pigs fed the 25% lactose, isolated soy protein diet were less (P<.05) feed efficient (F/G) after two wk than pigs fed the other diets. In trial 2, pigs fed the diets containing isolated soy protein had higher (P<.05) average daily gain (ADG) and average daily feed intake casein diets. In (ADFI) addition, pigs after two wk than pigs fed the fed the soybean meal diet had improved (P<.01) ADG, ADFI, and F/G after two wk as compared to pigs fed the isolated soy protein or casein diets. The performance advantages were eliminated during the last three wk of the trials when all pigs consumed the 20% dried whey diet. These results indicate that starter pig performance will not be maximized when casein or isolated soy protein are used as the only protein source in the diet. Furthermore, the addition of lactose resulted in no 61 beneficial effects when casein or isolated soy protein served as the only protein source. (Key Words: Weanling Pigs, Lactose, Casein, Isolated Soy Protein) Introduction Performance of young pigs weaned earlier than 28 days of age is usually improved when starter diets contain protein from milk sources rather than protein from soybean meal (Hays et al., 1959; Combs et al., 1963; Walker et al., 1986), soy flour (Bayley and Holmes, 1972; Lecce et al., 1979), soy protein concentrate (Giesting and Easter, 1985), or isolated soy protein (Wilson and Leibholz, 1981a; Leibholz, 1982) . diets casein, Nutrient digestibility is also improved when pigs are fed containing skim milk (Wilson and Leibholz, the major milk protein, (Leibholz, 1982; 1981a, b,c,d) or Walker et al., 1986a, b) rather than soybean meal or isolated soy protein as the only protein source. The addition of lactose to corn-soybean meal diets has also been shown to improve starter pig performance (Giesting et al., 1985; Corbin and IfcConnell, 1986) and diet digestibility (Sewell and West, 1965). Turlington et al. (1987) also suggested that the addition of lactose to corn-casein or corn-soybean meal diets will improve diet digestibility by slowing the digesta flow rate for pigs between 21 and 35 d of age. The relative response to lactose was greater for pigs fed corn-soybean meal diets than for pigs fed corn-casein diets. Whether an interaction between lactose level and protein source may . 62 effect starter pig performance has not been reported. These studies were conducted to determine the effect of lactose additions to starter pig diets when either isolated soy protein or casein is Pig performance was utilized as the protein source. measured from 21 to 35 d of age. Subsequent performance was also analyzed from 35 to 56 d of age when all pigs received the same diet. Experimental Procedures Two 5-wk growth trials were conducted to evaluate the effects of lactose level and protein source on starter pig performance. One hundred and eighty weanling pigs averaging 6.1 kg (5.0 to 7.0 kg) were used in trial 1. In trial 2, 210 weanling pigs averaging 5.5 kg (4.6 to 6.4 kg) were utilized. In both trials, pigs were weaned at 21 + 3 d and allotted treatments. Prior by to litter, weaning, sex pigs and weight were to housed dietary the in a total confinement, environmentally controlled, farrowing facility and were not allowed access to creep feed. At weaning, pigs were moved to an environmentally controlled nursery equipped with 1.2 m x 1.5 m pens with woven wire floors and a Y-flush gutter, with one nipple waterer and one four hole self-feeder per pen. ad libitum. Temperature and optimum comfort for the pigs. individual Feed and water were offered airflow were adjusted to maintain Feeders were checked twice daily and pig weights were collected at the end of each week. Criteria measured were average daily gain (ADG) intake (ADFI) , and feed efficiency (F/G) , average daily feed 63 A two-phase starter program was used to evaluate the dietary treatments. Composition of the diets fed during the first two weeks is shown in table 1. A x 2 factorial consisting of two protein 3 sources (isolated soy protein or casein) and three lactose levels 12.5 or 25%) was used in both trials. on an equal weight basis. corn-soybean meal, (0, lactose replaced corn starch Trial 2 also contained a 25% corn starch, control All diet. diets were pelleted and contained 1.4% lysine, .8% calcium, and .7% phosphorus. At the end of the second week, feeders were weighed and emptied and the feed was replaced by a corn-soybean meal diet containing 20% edible grade, spray dried whey. shown in table 2. The composition of this diet is The diet was formulated to contain 1.25% lysine, .8% calcium, and .7% phosphorus. All pigs received this diet for the last three weeks of the trial. The data were analyzed using the General T.i of the Statistical Analysis System (SAS, 1979) the experimental unit for both trials. additional Preplanned treatment, orthogonal the trials contrasts were r**ar . Models procedure Pen was considered Since trial 2 contained one were used analyzed to separately. separate treatment means, to compare protein and carbohydrate source main effects, and to check for quadratic or linear effects due to lactose level. Results The effect of lactose level and protein source on starter pig performance for trial 1 is shown in table 3. Although there were no 64 carbohydrate and protein source interactions (R>.05), the interaction No differences were found in ADG or ADFI at two means were reported. Pigs fed the 25% lactose, isolated soy protein diet were or five wk. less (P<.05) diets. feed efficient after two wk than pigs fed the other However, this difference was eliminated by the end of the trial. The effect of lactose level and protein source on starter pig performance for trial 2 is shown in table 4. Although there were again no carbohydrate by protein source interactions interaction means were reported. Analysis of (P>.05), the the main effects revealed that pigs fed diets containing isolated soy protein as the only protein source had higher (P<.05) ADG and ADFI at two wk than pigs fed the casein diets. Increasing the lactose level in the diet had no effect on starter pig performance. Pigs fed the soybean meal diet had improved (P<.01) ADG, ADFI and F/G after two wk as compared to pigs fed the diets containing isolated soy protein or casein as the protein source. Pigs fed the soybean meal diet for the first two wk had also consumed more (P<.05) feed at the end of the five wk period than pigs fed the other diets; however, the differences in ADG and F/G were eliminated during the last three wk of the trial when all pigs consumed the 20% dried whey diet. Discussion There were differences in the performance of trial 1 compared to trial 2. In trial 2, pellet guality was poor with an excessive 65 amount of fines present. a large amount of sorting and feed Thus, wastage occurred with the casein and isolated soy protein diets. feed wastage may have distorted the ADFI and F/G values. The The amount of fines present may have also lowered actual feed consumption and reduced ADG. Although the performance tended to be lower similar general trends can be seen in both trials. in the trial 2, Performance was not improved when pigs were fed diets containing casein as compared to pigs fed diets containing isolated soy protein as the sole protein source. al. Richard et al. (1983) (1986) , Etheridge et al. (1984) and Walker et reported similar results as no performance differences were found when casein or isolated soy protein was used as the only protein source in diets for pigs weaned at three to four wk of age. The response appears to be age dependent as pigs weaned earlier than three wk of age consistently gained faster and were more feed efficient when fed diets containing casein as compared to isolated soy protein 1984) . (Pond et al., 1971; Leibholz, 1982; Mateo and Veum, Maner et al. (1962) found the rate of passage for soy protein slows as the pig gets older; whereas, the rate of passage for casein is constant over time. The change in the rate of passage for isolated soy protein may explain the decrease in the advantage for casein as the pig increases in age. The literature suggests that diets containing casein or skim milk as the only protein source are similar in dry matter digestibility, nitrogen digestibility and nitrogen retention; however, the diets 66 containing dried skim milk consistently support higher ADG (Pettigrew et al., not 1977; Leibholz, provide 1982). equivalent Pettigrew et al. (1977) The reason skim milk and casein do performance is not fully understood. suggested that for maximum performance young pigs may require a dietary source of intact milk proteins. There is also some indication from the literature that a certain ratio of casein to whey proteins must be maintained to optimize performance in the young pig. Newport and Henschel (1984, 1985) combined spray dried skim milk and spray dried whey protein concentrate to determine that 50:50 was the optimum casein: whey protein ratio. Since dried whey protein concentrate and dried skim milk are intact milk protein sources, further research may be needed to determine if 50% casein- 50% lactalbumin is the optimum milk protein combination for the young pig. The results of the second trial indicate that soybean meal is superior to isolated soy protein and casein when used as the only protein source for pigs between 21 and 35 d. When comparing the same protein sources for pigs weaned at three wk of age, Walker et al. (1986a) found different results. They reported that pigs fed diets containing isolated soy protein or casein gained faster than pigs fed diets containing soybean meal; however, simple corn-protein source diets with lower nutrient levels and energy density were used. When feeding diets containing isolated soy protein, Wilson and Leibholz ( 1981a, b,c,d) and Leibholz intake may be a problem. (1982) discovered that maintaining feed They found that pigs fed diets containing 67 isolated soy protein had higher digestibilities for dry matter, nitrogen and the essential amino acids than pigs fed diets containing soybean meal; however, due to a reduction in feed intake, ADG was lower for pigs fed the diet containing isolated soy protein. The lactose results may have been sources used in this trial. influenced by the protein Several researchers have shown that the addition of lactose to the diet will increase ADG for pigs weaned at three to four wk of age (Sewell and West, 1965; Aherne et al., 1969; Giesting et al., 1985; Corbin and McConnell, 1986) using intact protein sources, . Further research such as soybean meal and dried skim milk, may be needed to determine whether lactose level and protein source interact to effect starter pig performance. 68 Table 1. Diet Composition (%) , to 2. a Week Protein Source ISP15 Lactose level, % 12.5 25 42.86 17.29 42.86 17.29 Corn ISP Casein Soybean meal Lactose Hydrolyzed corn starch Soybean oil Dicalcium phosphate Limestone Salt Trace mineral mix4 Vitamin mix6 Selenium mix* Antibiotic mix? Copper sulfate*1 L-Lysine HCL DL-rMethionine DL-Tryptophan L-Threonine 42.86 17.29 SEM° CASEIN 12.5 25 44.57 44.57 44.57 15.93 15.93 15.93 12.5 25 12.5 10 10 22.37 38.39 25 10 12.5 25 12.5 10 10 25 10 25 10 2.35 2.35 2.35 2.36 2.36 2.36 2.13 .65 .50 .10 .25 .15 .25 .10 .20 .20 .05 .05 .65 .50 .10 .25 .15 .25 .10 .20 .20 .05 .05 .65 .50 .10 .25 .15 .25 .10 .20 .20 .05 .05 .46 .50 .10 .25 .15 .25 .10 .20 .03 .05 .05 .46 .50 .10 .25 .15 .25 .10 .20 .03 .05 .05 .46 .50 .10 .25 .15 .25 .10 .20 .03 .05 .05 .36 .50 .10 .25 .15 .25 .10 .20 .10 .05 .05 aDiets were calculated to contain 1.4% lysine, .8% calcium, and .7% phosphorus. "ISP = Isolated soy protein °SEM = Diet containing 48.5% protein soybean meal as the protein source, used only in trial 2. ^Composition per kg premix: vitamin A, 1,762,080 IU; vitamin D3, 132,156 IU; vitamin E, 8,810 IU; riboflavin, 1,982 mg; menadione, 683 mg; pantothenic acid, 6,793 mg; niacin, 11,013 mg; choline chloride, 203,080 mg; vitamin &, 2 , 9.7 mg. premix provided complete diet with .3 ppm supplemental selenium. fAntiobiotic contains 44 g chlortetracycline, 44 g sulfamethazine and 22 g penicillin per kg. 9premix provided complete diet with 250 ppm supplemental copper. 69 Table 2. Diet Composition, week Ingredient Corn Soybean meal Dried whey Soybean oil Dicalcium phosphate Limestone Trace mineral mix*3 Vitamin mix Selenium mix^ Antibiotic mix6 Copper sulfate^ L-Lysine HCL 3 to 5. a % 42.50 31.80 20.00 3.00 1.28 .47 .10 .25 .15 .25 .10 .10 aDiets were calculated to contain 1.25% lysine, .8% calcium, and .7% phosphorus. ^Percentage composition was Fe, 10; Zn, 10; Mn, 10; Cu, 1; I, .3; Co, .1. cComposition per kg premix: vitamin A, 1,762,080 IU; vitamin D3, 132,156 IU; vitamin E, 8,810 IU; riboflavin, 1,982 mg; menadione, 683 mg; pantothenic acid, 6,793 mg; niacin, 11,013 mg; choline chloride, 203,080 mg; vitamin B^, 9.7 mg. dPremix provided complete diet with .3 ppm supplemental selenium. eAntibiotic contains 44 g chlortetracycline, 44 g sulfamethazine and 22 g penicillin per kg. fPremix provided complete diet with 250 ppm supplemental copper. .. . 70 Table 3. Effect of Lactose Level and Protein Source on Starter Pig Performance (Trial 1) Protein sou tee ISP3 Lactose lev< al, % 12.5 25 CASEIN 12.5 25 Week to 2 Daily gain, g Daily feed, g Feed/gain13 200 1.10 180 208 1.16 173 253 1.46 231 1.20 197 233 1.18 184 224 1.21 Week to 5 Daily gain, g Daily feed, g Feed/gain 393 592 1.50 412 621 1.47 394 611 1.55 434 644 1.48 424 622 1.47 397 593 1.49 183 194 aISP = isolated soy protein. kcontrast, 25% lactose - ISP vs other (P<.05) Table 4. 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Effects on performance and digestibility. J. Anim. Sci. 63:505. C. V. Maxwell, F. N. Owens and D. S. Buchanan. 1986b. Milk versus soybean protein sources for pigs: II. Effects on amino acid availability. J. Anim. Sci. 63:513. Walker, W. R. , Warner, J. N. 1976. Principles of Dairy Processing. John Wiley and Sons, New York. Webb, B. H. and E. 0. Whittier. 1970. Byproducts From Milk (2nd Ed.) The AVI Publishing Co. , Inc. , Westport. Wilding M. D. 1971. Processing of soybeans. In: Soy: The Wonder Bean. Southern California Section AACC Symposium, pp 8-25. Westview Press, Boulder. Wilson, R. H. and J. Leibholz. 1981a. Digestion in the pig between 7 and 35 d of age. 1. The performance of pigs given milk and soya-bean proteins. Br. J. Nutr. 45:301. 79 Wilson, R. H. and J. Leibholz. 1981b. Digestion in the pig between 7 and 35 d of age. 2. The digestion of dry matter and the pH of digesta in pigs given milk and soya-bean proteins. Br. J. Nutr. 45:321. Wilson, R. H. and J. Leibholz. 1981c. Digestion in the pig between 7 and 35 d of age. 3. The digestion of nitrogen in pigs given milk and soya-bean proteins. Br. J. Nutr. 45:337. Wilson, R. H. and J. Leibholz. 1981d. Digestion in the pig between 7 and 35 d of age. 4. The digestion of amino acids in pigs given milk and soya-bean proteins. Br. J. Nurt. 45:347. Wolf, W. J. 1971. What is soy protein? In: Soy: The Wonder Bean. Southern California Section AACC Symposium, pp 25-39. Westview Press, Boulder. THE EFFECTS OF THE CARBOHYDRATE AND PROTEIN FRACTIONS OF MILK PRODUCTS ON STARTER PIG PERFORMANCE by MIKE D. TOKACH B.S. North Dakota State University AN ABSTRACT OF A MASTER'S THESIS submitted in partial fulfillment of the requirements for the degree MASTER OF SCIENCE Department of Animal Science and Industry KANSAS STATE UNIVERSITY Manhattan, Kansas 1988 , ABSTRACT Three growth trials and two digestion trials were conducted to determine the effects of the carbohydrate and protein fractions of milk products on starter pig performance and diet digestibility. In the first study, 180 3-wk old pigs (initial weight 4.8 kg) were utilized in a 35 d growth trial to determine the effects of the fraction protein of dried whey pig on carbohydrate and performance. In addition, 30 3-wk old pigs (initial weight 4.9 kg) (or) were used in two digestion trials to study the effects of the whey fraction on nutrient digestibility. corn-soybean meal control control + 14% lactose control + 14% lactose 8.4% whey (CX3N) (CHO) +2.1% , Dietary treatments included a control + 20% dried whey control + 2.1% lactalbumin (WHE) (PRO), lactalbumin (CHD + PRO), and control + concentrate protein , balanced on an isolysine basis. (WPC) . Diets were pelleted and Lactose and lactalbumin were added at the same levels as provided by a 20% dried whey diet. Pigs fed diets containing milk products exhibited superior average daily gain; feed efficiency; and apparent dry matter, energy and nitrogen digestibility (P<.05) compared to pigs fed the control diet. results indicate that both the carbohydrate (lactose) These and protein (lactalbumin) fractions of dried whey are important in explaining the beneficial response to dried whey elicited by the weanling pig. In the second study, a total of 390 weanling pigs (21 + used in two lactose 2x3 level (0%, 3 d) were factorial experiments to evaluate the effect of 12.5%, 25%) and protein source (isolated soy on starter pig performance. protein or casein) An additional 0% lactose, corn-soybean meal control treatment was also evaluated in trial 2. All pigs received the experimental diet for the first two weeks and were fed a 20% dried whey, corn-soybean meal diet for the last three weeks on trial. No interaction (E>.05) occurred between lactose level and protein source in either trial. difference found in trial 1 was that pigs isolated soy protein diet were less (P<.05) two weeks than pigs fed the other diets. diets containing daily gain (ADG) The only treatment fed the 25% lactose, feed efficient (F/G) at In trial 2, pigs fed the isolated soy protein had higher (P<.05) average and average daily feed intake (ADFI) at two weeks than pigs fed the casein diets. meal diet had improved (P<.01) In addition, pigs fed the soybean ADG, ADFI, and F/G at two weeks as compared to pigs fed the isolated soy protein or casein diets. The performance advantages were eliminated during the last three weeks of the trials when all pigs consumed the 20% dried whey diet. These results indicate that starter pig performance will not be maximized when casein or isolated soy protein are used as the only protein source in the diet. Furthermore, the addition of lactose resulted in no beneficial effects when casein or isolated soy protein served as the only protein source.
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