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The physical characteristics, chemical composition, and nutritional value of distillers dried grains with solubles (DDGS) from seven beverage alcohol and two fuel alcohol manufacturers were evaluated in studies with chicks and pigs. Color scores of the DDGS ranged from very light to very dark and odor scores ranged from normal to burnt or smoky. The DDGS ranged from 23.4 to 28.7% CP, 2.9 to 12.8% fat, 8.8 to 36.9% ADIN, 28.8 to 40.3% NDF, 10.3 to 18.1% ADF, and 3.4 to 7.3% ash. Lysine concentrations of the DDGS ranged from .43 to .89%. In the first experiment, 12 corn-based diets were fed to 1-d-old chicks for 21 d to assess the nutritional value of the DDGS sources. A low-protein basal diet was supplemented with soybean meal to provide 13.6, 16.5, or 19.0% CP or supplemented with 20% DDGS, which supplied approximately the same amount of CP as the highest level of soybean meal. Weight gain, feed intake, and feed/gain were influenced (P |is less than~ .01) by source of DDGS. The weight gain of chicks fed the DDGS sources ranged from 85% of that of chicks fed the highest level of soybean meal to less than that of chicks fed the low-protein basal diet. Blends of the three best sources of DDGS and the three poorest sources of DDGS were evaluated in a subsequent chick trial. The relative nutritional values of the two blends were similar to the average of the sources that made up the blends. Performance responses to various blends of DDGS in the pig experiment paralleled those of the chick trial. Rate and efficiency of gain were correlated with color of the DDGS and concentrations of CP, lysine, S-amino acids, ADIN, and ADF in the DDGS. The results indicate that there is a great amount of variability in the physical, chemical, and nutritional properties among the sources of DDGS that are available to the feed industry. Introduction Distillers dried grains with solubles (DDGS) is a byproduct resulting from the fermentation of cereal grains for the production of alcohol for beverage or fuel. It has long been recognized that DDGS is a valuable source of energy, protein, water-soluble vitamins, and minerals for animals. Some of the early research studies with pigs indicated that distillers dried solubles also provided a source of unidentified growth factors (Catron et al., 1954, 1955; Gage et al., 1961), but later studies failed to show an unidentified growth factor effect from the inclusion of distillers dried solubles in practical swine diets (Conrad, 1961; NCR-42 Committee on Swine Nutrition, 1970). Dietary inclusion of DDGS is normally limited to 5 to 10% in swine and poultry diets; however, up to 20% DDGS can be included, on an isolysine basis, in diets for growing-finishing swine with only a slight (3 to 4%) reduction in growth rate and efficiency of feed utilization (Cromwell and Stahly, 1986), Various methods are used in the preparation of DDGS. Often, the end product will vary in physical appearance and in chemical composition, depending on the grains used and the processing and drying procedures. Overheating of oilseed meals and animal protein meals causes reduced availability of lysine (Maillard reaction) and partial destruction of cystine and perhaps of other amino acids (Evans and Butts, 1949; Carpenter, 1960; Rios Iriarte and Barnes, 1966; Hancock et al., 1990; Hurrell, 1990; Parsons et al., 1992), and perhaps this also occurs with DDGS. Whether processing methods and drying conditions have a minor or major effect on the nutritional value of DDGS is not known. The objectives of this study were to assess the degree of variability in the physical properties and chemical composition of various sources of DDGS from beverage and fuel alcohol production, to assess the variability in the nutritional value of different sources of DDGS for chicks and pigs, and to establish relationships between the physical properties, chemical composition, and nutritional value of DDGS for nonruminants. Procedures Nine sources of DDGS were obtained for this study. Seven sources were DDGS that originated from the production of beverage alcohol and two sources were from manufacturers that produced fuel alcohol from corn. The DDGS sources derived from production of beverage alcohol were provided by the Distillers Feed Research Council, Des Moines, IA, and the specific manufacturers were not known to the investigators. These sources were identified as Sources A through G. The other two sources (Sources H and I) were obtained from fuel-alcohol plants in Kentucky and Ohio. Physical characteristics (odor and color) of the nine sources of DDGS were assessed by a three-member panel. Color was subjectively scored from 1 to 5; 1 represented a very light color and 5 represented a very dark color. The nine sources also were ranked by the panel from the lightest to the darkest. In addition, the Hunterlab color procedure (McNaughton et al., 1981) was used to assess quantitatively the lightness, redness, and yellowness of the nine samples. The nine sources were analyzed for DM, CP, ether extract, and ash using standard procedures (AOAC, 1984). The NDF, ADF, and ADIN concentrations were determined by the method of Goering and Van Soest (1970). The samples also were analyzed for amino acids (courtesy of Heartland Lysine, Chicago, IL) by ion-exchange chromatography after acid hydrolysis. Cystine and methionine were protected by performic acid oxidation before hydrolysis. Tryptophan was determined after alkaline hydrolysis. Chick Experiments. Two experiments were conducted with chicks to assess the nutritional value of the nine sources of DDGS. In both experiments, 1-d-old, broiler-type chicks (males of a female parent line, Hubbard Farms, Statesville, NC) were used. The chicks were housed in batteries (Petersime Incubator, Gettysburgh, OH) and were allowed to consume their diets and water on an ad libitum basis. Twelve diets were fed in Exp. 1. Diet 1 was a 13.6% CP, corn-soybean meal diet containing 20% of a starch-cellulose (68:32) mixture. The starch-cellulose mixture was calculated to be isoenergetic TABULAR DATA OMITTED with DDGS (2,480 kcal of ME/kg; NRC, 1984). Diets 2 and 3 contained 16.5 and 19.0% CP, respectively; additional soybean meal replaced a portion of the starch-cellulose mixture. The higher-protein diet was calculated to be slightly deficient in CP compared with levels listed by NRC (1984). Diets 4 to 12 consisted of the basal diet with one of the nine sources of DDGS replacing the starch-cellulose mixture. These nine diets contained approximately 19% CP. The rationale behind formulating the diets this way was so that each source of DDGS could be directly compared, on a CP basis, with an equivalent amount of soybean meal protein. The amount of corn was held constant in each diet so that it would not be a contributing factor. Each treatment was replicated four times, with eight chicks per pen. The experiment was conducted for 21 d. In Exp. 2, two blends of DDGS were evaluated. One blend was a combination of Sources B, C, and D and the second blend was a combination of Sources A, E, and H. Each blend consisted of equal parts, by weight, of the three sources of DDGS. Diet 1 was a 12% CP, corn-soybean meal diet with 30% cornstarch. Diets 2, 3, and 4 consisted of the basal diet with soybean meal substituted for starch to provide 14.7, 17.4, and 20.1% CP, respectively. Diets 5, 6, and 7 consisted of the basal diet with 10, 20, or 30% DDGS (blend of Sources B, C, and D) replacing cornstarch. These three diets also contained approximately the same levels of CP as Diets 2, 3, and 4, respectively. Diets 8, 9, and 10 were the same as Diets 5, 6, and 7 except that the DDGS blend consisted of Sources A, E, and H. There were four pen-replicates of eight chicks per pen for each treatment, except for Treatment 1 TABULAR DATA OMITTED (the basal diet), in which case there were 12 replications. The experimental period was 14 d. Pig Experiment. This experiment was conducted to evaluate three blends of DDGS for growing pigs. Hampshire-Yorkshire pigs initially averaging 16.0 kg were used in the study. The pigs were randomly allotted to treatments from outcome groups based on weight and sex, with six pen-replicates per treatment and one pig per pen. The pigs were housed in elevated pens (.6 m x 1.2 m) with expanded metal floors in a temperature-regulated building. The pigs were allowed to consume their feed and water on an ad libitum basis. Six dietary treatments were evaluated. Diet 1 was a corn-soybean meal diet containing 23.4% of a dextrose-cornstarch (1:1) mixture. This diet was calculated to contain 8.6% CP. The soybean meal was increased in Diets 2 and 3 (substituted for dextrose-starch) to provide 11.3 and 14% dietary CP. The 14% CP diet was calculated to be slightly deficient in lysine for pigs of this weight classification (NRC, 1988). Diets 4, 5, and 6 consisted of the basal diet with 20% TABULAR DATA OMITTED DDGS substituted for the dextrose-starch mixture. The blends (1:1 by weight) of DDGS were Sources B and D (Diet 4), G and I (Diet 5), and A and E (Diet 6). These three diets contained approximately the same level of CP (approximately 14%) as the diet with the highest level of soybean meal (Diet 3). The level of corn was held constant in all diets. Statistical Analysis. The data of each experiment were analyzed by variance procedures (Steel and Torrie, 1980) using the GLM procedure of SAS (1985). Levels of soybean meal in all three experiments and levels of the DDGS blend in Exp. 2 were tested for linearity and nonlinearity. Individual sources or blends of DDGS were compared using a protected F-test and the LSD test. Correlations were tested between various physical and chemical characteristics of the DDGS and performance traits. In each experiment, the pen was considered the experimental unit. Results Physical Properties of Distillers Dried Grains with Solubles. Table 4 shows the physical characteristics of the nine sources of DDGS. Sources A and F had a slightly burnt odor and Source H had a definite burnt odor. Source E had a definite smoky odor. All the other sources had an odor that was typical of a dried, fermented product such as DDGS. Subjective color scores ranged from 1 (very light) to 5 (very dark). The four samples that had a burnt or smoky odor were darker in color and had subjective scores of 4 or 5. The Hunterlab color procedure gives a score to a sample based on its lightness or darkness, redness, and yellowness. The Hunterlab L score ranges from 0 (black) to 100 (white). Positive Hunterlab a and b scores indicate redness and yellowness, respectively; higher scores indicated a greater degree of each color. The Hunterlab L scores ranges from 53.2 (lightest, Source B) to 28.9 (darkest, Source F). The ranking of the DDGS sources by the Hunterlab L method essentially duplicated the ranking of the sources by the panel. According to the Hunterlab L scores, the nine sources fell into three main categories, B and D (lightest), C, G, and I (medium), and A, E, F, and H (darkest). Again, this agreed very closely with the subjective scores of the panel. The Hunterlab b (yellowness) scores ranked the nine sources in the same order as the L scores, but the Hunterlab a (redness) scores did not. Chemical Characteristics of Distillers Dried Grains with Solubles. The DM content of the nine samples averaged 90.5%, with a range of 87.1 to 92.7%. The CP ranged from 23.4 to 28.7%, with an overall average of 26.9%, which agrees with the value of 27.0% protein listed by NRC (1988). Source E was considerably lower in CP (23.4%) than any of the others. Ether extract averaged 9.7%, which agrees closely with the value of 9.3% listed by NRC (1988), but the fat content among the sources was quite variable. Most of the samples ranged from 9 to 12% fat, but one sample contained only 2.9% fat. The ADIN, NDF, ADF, and ash contents of the nine sources also varied considerably. Lightness or darkness did not seem to be related to any of these chemical measurements except for ADF and ADIN, in which case increasing darkness was associated with increased ADF (r = .62; P |is less than~ .10) and ADIN (r = .79; P |is less than~ .01) concentrations. The indispensable amino acid concentrations of the DDGS sources are shown in Table 6. Lysine concentration was extremely variable, with more than a twofold difference among DDGS sources (.43 to .89%). The TABULAR DATA OMITTED concentrations of the other amino acids also were variable (range of 1.2- to 1.4-fold difference among sources), but not to the same extent as lysine. The average lysine concentration in DDGS (.70%) was the same as that listed by NRC (1988). Average concentrations of methionine (.51 vs .49%) and phenylalanine (1.45 vs 1.47%) were similar to those listed by NRC (1988). Average concentrations of cystine (.53 vs .29%), leucine (3.33 vs 2.21%), arginine (1.06 vs .96%), histidine (.72 vs .64%), threonine (1.01 vs .92%), and tryptophan (.19 vs .17%) were higher than the values listed by NRC (1988), but average concentrations of isoleucine (1.00 vs 1.38%) and valine (1.35 vs 1.48%) were lower. On average, lysine concentrations tended to be highest in the lightest-colored DDGS (.86%, Sources B and D), intermediate in the medium (.74%, Sources C, G, and I), and lowest in the darkest-colored DDGS (.62%, Sources A, E, F, and H). The correlation between the Hunterlab L score and lysine concentration was .67 (P |is less than~ .05). The four darker sources of DDGS had lower concentrations of arginine (.99 vs 1.12%), cystine (.49 vs .56%), and total S-amino acids (.99 vs 1.09%) than the other five sources, and the Hunterlab L scores were slightly correlated with arginine (r = .44; P |is less than~ .25), cystine (r = .65; P |is less than~ .10), and total S-amino acid concentrations (r = .51; P |is less than~ .15). There seemed to be no pattern between color and concentrations of the other amino acids in the nine sources of DDGS. The lysine concentration of DDGS decreased as CP concentration decreased. The correlation between CP and lysine was high (r = .80; P |is less than~ .01), but this was partially due to Source E's being considerably lower in CP and lysine than the other eight sources of DDGS. When Source E was excluded, the correlation between protein and lysine among the remaining eight sources of DDGS was considerably less (r = .43) and not significant (P |is greater than~ .20). The low correlation between CP and lysine is characteristic of corn (Reese and Lewis, 1989; NRC-42 Committee on Swine Nutrition, 1992) as well as other cereal grains. TABULAR DATA OMITTED TABULAR DATA OMITTED Chick Experiment 1. Weight gain and feed intake increased linearly (P |is less than~ .01) and feed/gain decreased linearly (P |is less than~ .01) as the level of soybean meal increased in the diet. Growth rate differed (P |is less than~ .01) among chicks fed the various source of DDGS, ranging from 488 and 489 g/d for those fed Sources B and C, respectively, to 364 g/d for chicks fed Source E. Gains of chicks fed Sources B or C were approximately 85% as great as those of chicks fed the highest level of soybean meal. Source E (which had a TABULAR DATA OMITTED smoky odor and possessed the lowest lysine content) was consumed in the least amount and resulted in the poorest gain and feed/gain of the nine sources tested. In fact, the weight gains of chicks fed Source E were lower than those of chicks fed the low-protein basal diet, which contained no added soybean meal beyond the basal level. On average, chicks fed diets containing DDGS gained more slowly (434 g/d) and required more feed per unit of gain (1.64) than those fed diets in which an equivalent amount of CP was supplied by soybean meal (577 g/d; 1.49 feed/gain). Chick Experiment 2. The purpose of this experiment was to evaluate two blends of DDGS. Selection of the DDGS sources for the two blends was based on the performance of chicks fed the individual sources of DDGS in Exp. 1, in which Sources B, C, and D (Blend 1) resulted in the greatest weight gains and Sources A, E, and H (Blend 2) resulted in the three lowest weight gains. The growth rate and feed/gain of chicks improved linearly (P |is less than~ .01) with increasing levels of soybean meal in the diet. Improvements in performance also occurred (P |is less than~ .01) with increasing dietary additions of DDGS, but the improvements were less than for soybean meal additions. The blend of Sources B, C, and D was clearly superior (P |is less than~ .01) to the blend of Sources A, E, and H in terms of chick growth rate, feed intake, and feed efficiency. Pig Experiment. The purpose of this experiment was to determine whether the relative nutritional values for the DDGS sources obtained in the chick experiment would also apply to pigs. The three blends of DDGS tested in this experiment represented two each of the best (Sources B and D), average (Sources G and I), and poorest (Sources A and E) sources of DDGS, based on the results of the chick tests. Growth rate and feed/gain of pigs improved linearly (P |is less than~ .01) with increasing level of soybean meal in the diet. There were differences (P |is less than~ .05) in gain, feed intake, and feed/gain among the three TABULAR DATA OMITTED blends of DDGS; the order was the same as that predicted from the chick data. Table 10. Correlations of physical and chemical properties of distillers dried g rains with solubles with performance of chicks Item Weig ht gain Feed/gain Physical properties Color score .63(a) .60(a) Hunterlab L .74(b) .69(b) Hunterlab a .09 .11 Hunterlab b .72(b) .74(b) Chemical properties CP .51 .67(b) ADIN .86(c) .72(b) Ether extract .32 .07 NDF .31 .07 ADF .59(a) .38 Ash .22 .40 Lysine .62(a) .85(c) Cystine .62(a) .81(c) Methionine + cystine .57(a) .70(b) a Correlation significant (P |is less than~ .10). b Correlation significant (P |is less than~ .05). c Cor relation significant (P |is less than~ .01). Correlation of Physical and Chemical Properties with Performance. Table 10 shows the correlations of color and chemical properties of DDGS with weight gain and feed/gain of chicks fed the nine sources of DDGS. These data are based on the results of the first chick experiment because blends (and not individual sources) of DDGS sources were used in the other experiments. Subjective color score and Hunterlab L (lightness/darkness) and b (yellowness) scores were highly correlated with growth rate and feed/gain, whereas Hunterlab a (redness) scores were poorly correlated. Crude protein, lysine, cystine, and total S-amino acid concentrations of the DDGS were highly correlated with feed efficiency and moderately correlated with growth rate. The ADIN concentrations were highly correlated with both gain and feed/gain. The ADF concentrations of the DDGS were more highly correlated with performance than were NDF concentrations. Percentages of ash and fat in the DDGS sources were not closely associated with performance. Discussion The results of this research indicate that there is a high degree of variability in the physical, chemical, and nutritional properties among sources of DDGS that are available to the feed industry. Physical appearance (color) was highly related to nutritional properties of DDGS in our study, in that dark-colored DDGS was lower in nutritional value than light-colored DDGS. Those DDGS sources with dark color had a burnt or smoky odor, indicating that the color probably was caused from overheating of the DDGS during the drying process. The higher ADIN values in the darker-colored DDGS also are suggestive of greater heat damage. Overheating of soybean meal, fish meal, and milk products reduces their nutritional value because of binding of lysine (Maillard reaction) and partial destruction of cystine and certain other amino acids (Evans and Butts, 1949; Carpenter, 1960; Rios Iriarte and Barnes, 1966; McNaughton and Reece, 1980). Hancock et al. (1990) and Parsons et al. (1992) recently reported that the analyzed lysine concentration in soybean meal was reduced by overheating. They attributed this to the formation of advanced Maillard reaction products (Hurrell, 1990), in which some of the lysine is not released during acid hydrolysis. The low analyzed lysine concentrations in the darker-colored DDGS sources suggest that these processes may also have occurred with overheating of DDGS. The DDGS in our study were variable in CP (23.4 to 28.7%), but even more pronounced was the variability in lysine concentration (.43 to .89%). Other amino acids also were somewhat variable (1.2- to 1.4-fold differences), but the degree of variability was less than that for lysine (2.1-fold difference). Lysine, arginine, and cystine concentrations were related to color, but concentrations of other indispensable amino acids were not, suggesting that lysine, arginine, and cystine were more sensitive to overheating than were the other amino acids. Lysine and S-amino acid concentrations in the DDGS were highly predictive of chick and pig performance. This is not surprising, because the basal diets for both chicks and pigs were marginal in CP, thus marginal in lysine, the first-limiting amino acid for pigs (NRC, 1988), and in methionine and lysine, the first- and second-limiting amino acids for chicks (NRC, 1984). The DDGS sources also were quite variable in their fat (2.9 to 12.8%), fiber (28.8 to 40.3% NDF; 10.3 to 18.1% ADF), and ash (3.4 to 7.3%) concentrations, but only ADF seemed to be related to nutritional value. The relationship of increased ADF concentration of DDGS with reduced chick performance is plausible, because ADF is associated with the more indigestible components of feed (Goering and Van Soest, 1970; NRC, 1988). Considerably greater amounts of spent grains are likely to be available in the future as more grains are used in the production of ethanol for fuel. Processing and drying of these byproducts are not as carefully controlled as they are in the beverage industry. Of the two fuel-alcohol DDGS sources tested, one seemed to be overheated (burnt odor, dark color) and one was not. The nutritional value of these two sources fell within the range of the DDGS sources that originated from beverage alcohol production. Although only two sources of fuel alcohol-derived DDGS were tested, the results imply that the nutritional properties of this type of DDGS are not greatly different from those of beverage alcohol-derived DDGS. Finally, the consistency of the results obtained from the chick and pig trials indicates that chicks can serve as a useful model in predicting the nutritional value of DDGS for pigs. Implications There is considerable variability in the nutritional value of sources of distillers dried grains with solubles (DDGS) that are available to the feed industry. Odor and color seem to be important in determining the nutritional value of DDGS for nonruminants; light-colored DDGS, free from burnt or smoky odor, are more likely to have good nutritional properties. The nutritional value of DDGS is related to its lysine content and is more closely related to acid detergent fiber and acid detergent insoluble nitrogen than to neutral detergent fiber content. The nutritional value of DDGS from fuel alcohol production seems to be similar to that from beverage alcohol production. Literature Cited AOAC. 1984. Official Methods of Analysis (14th Ed.). Association of Official Analytical Chemists, Arlington, VA. Carpenter, K. J. 1960. The estimation of the available lysine in animal-protein foods. Biochem. J. 77:604. Catron, D. V., F. Diaz, V. C. Speer, and G. C. Ashton. 1954. Distillers dried solubles in pig starters. Proc. Distillers Feed Conf. 9:49. Catron, D. V., F. Diaz, V. C. Speer, G. C. Ashton, and C. H. Liu. 1955. Distillers dried solubles in starter and growing-finishing rations for swine. Proc. Distillers Feed Conf. 10:58. Conrad, J. H. 1961. Recent research and the role of unidentified growth factors in 1961 swine rations. Proc. Distillers Feed Conf. 16:41. Cromwell, G. L., and T. S. Stahly. 1966. Distillers dried grains with solubles for growing-finishing swine. Proc. Distillers Feed Research Conf. 41:77. Evans, R. J., and H. A. Butts. 1949. Inactivation of amino acids by autoclaving. Science (Washington DC) 109:569. Gage, J. W., Jr., R. D. Wilbur, V. W. Hays, V. C. Speer, and D. V. Catron. 1961. Sources of unidentified growth factors for baby pigs. J. Anim. Sci. 20:168. Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analyses (apparatus, reagents, procedures, and some applications). Agric. Handbook 379. ARS, USDA, Washington, DC. Hancock, J. D., E. R. Peo, Jr., A. J. Lewis, and J. D. Crenshaw. 1990. Effects of ethanol extraction and duration of heat treatment of soybean flakes on the utilization of soybean protein by growing rats and pigs. J. Anim. Sci. 68:3233. Hurrell, R. F. 1990. Influence of the maillard reaction on the nutritional value of foods. In: The Maillard Reaction in Food Processing, Human Nutrition and Physiology. pp 245-258 Birkhauser Verlag, Basel, Switzerland. McNaughton, J. L., and F. N. Reece. 1980. Effect of moisture content and cooking time on soybean meal urease index, trypsin inhibitor content and broiler growth. Poult. Sci. 59:2300. McNaughton, J. L., F. N. Reece, and J. W. Deaton. 1981. Relationship between color, trypsin inhibitor contents, and urease index of soybean meal and effects on broiler performance. Poult. Sci. 60:393. NRC-42 Committee on Swine Nutrition. 1970. Cooperative regional studies with growing swine: Effects of unidentified factor ingredients on rate and efficiency of gain of growing swine. J. Anim. Sci. 31:900. NRC-42 Committee on Swine Nutrition. 1992. Variability among sources and laboratories in chemical analysis of corn and soybean meal. J. Anim. Sci. 70(Suppl. 1):70 (Abstr.). NRC. 1984. Nutrient Requirements of Poultry (8th Ed.). National Academy Press, Washington, DC. NRC. 1988. Nutrient Requirements of Swine (9th Ed.). National Academy Press, Washington, DC. Parsons, C. M., K. Hashimoto, K. J. Wedekind, Y. Han, and D. H. Baker. 1992. Effect of overprocessing on availability of amino acids and energy in soybean meal. Poult. Sci. 71:133. Reese, D. E., and A. J. Lewis. 1989. Nutrient content of Nebraska corn. Nebraska Swine Report EC 89-219. pp. 5-7. Lincoln. Rios Iriarte, B. J., and R. H. Barnes. 1966. The effect of overheating on certain nutritional properties of the protein of soybeans. Food Technol. 20:835. SAS. 1985. SAS User's Guide: Statistics. SAS Inst. Inc., Cary, NC. Steel, R.G.D., and J. H. Torrie. 1980. Principles and Procedures of Statistics: A Biometrical Approach (2nd Ed.). McGraw-Hill Book Co., New York.

In four trials, 480 weanling pigs were housed in a conventional nursery maintained at 20 or 30 degrees C, which represented a cool and hot thermal environment, respectively. They were allowed ad libitum access to corn-soybean meal-dried whey diets containing .7, 1.0, or 1.3% lysine and 0 or 5% added fat (choice white grease). The pigs were weaned between 27 and 33 d of age (7.27 plus or minus .90 kg) and penned in groups of five for the duration of the 42-d trials. Pigs housed in the cool environment consumed more feed (P < .01), gained more weight (P < .01), and utilized feed more efficiently (P < .01) than those in the hot environment. As dietary lysine levels were increased in the 20 and 30 degrees C environments, daily weight gains and gain:feed ratios increased linearly (P < .01) from d 0 to 21 and quadratically (P < .01) from d 0 to 21 and quadratically (P < .01) from d 21 to 42. However, the magnitudes of the increases were less in the cool environment, resulting in temperature x lysine interactions (P < .05). As the pig's feed intake, body weight, and heat production increased over time, the 20 and 30 degrees C environments became progressively warmer relative to the animal's zone of thermoneutrality. The associated reductions over time in energy and lysine intakes relative to the pigs' maintenance needs resulted in an increase in the concentration of dietary lysine needed to maximize rate and efficiency of gain in the 30 degrees C environment but not in the 20 degrees C environment (temperature x lysine x period interaction, P < .10). The addition of fat to the low-lysine diet further decreased (P < .05) daily energy and lysine intakes, causing a reduction in growth rate of pigs in the 30 degrees C environment but not in that of pigs in the 20 degrees C environment, which resulted in a temperature x lysine x fat interaction (P < .05). Based on these results, the optimal dietary amino acid regimen for weanling pigs is dependent on the thermal environment in which the pigs are housed.

Two trials involving 96 weanling pigs were conducted in which pigs were maintained in constant thermal environments of 20 degrees (cool) or 32 degrees C (hot) and self-fed fortified corn-soybean meal-whey diets that contained three amino acid regimens (.7, 1.0, or 1.3% lysine; approximately 13.6, 17.8, and 22.0% CP) without and with 5% added fat (choice white grease) for 42 d. The pigs were weaned between 28 and 32 d of age (8.07 plus or minus .58 kg) and penned in groups of two. Pigs in the cool environment consumed more (P < .01) feed and ME, gained more (P < .01) weight, and retained more (P < .01) body protein, fat, and water than those housed in the hot environment. As dietary lysine level increased, daily BW gain and body protein and water accretion increased linearly (P < .01) from d 0 to 21 and quadratically (P < .01) from d 21 to 42 in both environments. However, the magnitude of these responses was less (P < .05) in the cool than in the hot environment. Dietary fat addition decreased (P < .05) gain:ME ratios and body protein and water accretion from d 0 to 21 in both environments, but the magnitude of the reduction was greatest in pigs fed the low lysine diets in the hot environment. Based on these data, the growth response of weanling pigs to dietary lysine and fat levels is dependent on the thermal environment in which the animals are housed.

The influence of genetic capacity for lean tissue (LT) growth on responses of pigs to ractopamine, in terms of rate and efficiency of body growth and the distribution and accretion rate of body tissues, was determined in this study. Two sources of pigs representing low and high LT genotypes were used. Within each source, two littermate barrows from each of eight litters were individually penned and given ad libitum access to a lysine-supplemented, corn-soybean meal diet (17.7% CP, 1.08% lysine) containing 0 or 20 ppm of ractopamine hydrochloride from 63 to 104 kg. Carcasses were physically dissected into muscle, fatty tissue, skin, and bone. Within each source, four additional pigs were killed for determination of initial body composition. Pigs of high LT genotype gained BW and muscle faster (P < .01), required less (P < .01) feed per unit of gain, and produced carcasses that contained more (P < .01) muscle and bone and less (P < .01) fatty tissue. Ractopamine increased (P < .01) weight gain and improved (P < .01) feed:gain ratio in both genotypes. Ractopamine enhanced the accretion rate and the amount of carcass muscle in both genotypes, but the degree of improvement was greater in pigs of the high than in those of the low LT genotype (genotype x ractopamine, P < .02). Ractopamine also reduced the accretion rate and amount of dissectible fat by a greater magnitude in the high LT genotype (genotype x ractopamine, P < .04). Based on these data, ractopamine increases muscle accretion to a greater degree in pigs with a high genetic capacity for LT growth than in those with a low capacity. Key Words: Pigs, Ractopamine, Genotypes, Growth, Muscle, Fat, An experiment was conducted from two sources of pigs possessing low and high lean tissue genotypes to study the influence of genetic capacity for lean tissue growth on responses of pigs to ractopamine. Results of the study show an increase in rate and efficiency of growth as well as improvement of carcass characteristics in pigs with ractopamine added diets. It was further shown that this response to ractopamine is greater in pigs with a high genetic capacity for lean tissue growth compared to those with a low genetic capacity.

The injection of porcine somatotropin (pST) to sows in late gestation or during lactation did not improve milk production. Treatment with pST resulted in lower feed intakes and increased backfat loss. Sows given pST had increased susceptibility to heat stress, although dietary fat supplementation appeared to decrease this effect. Neither treatment was found to have an effect on litter size, but weaning weight appeared to be favorably affected by fat supplementation.

Digestibility of protein in low-trypsin-inhibitor and conventional soybeans was determined in ileally cannulated pigs. The effect of heat treatment on protein digestibility was likewise evaluated. Results revealed that low-trypsin-inhibitor soybeans were more digestible owing to its reduced proteinase inhibitory properties. Heat treatment was also found to improve protein digestibility in both the low-trypsin-inhibitor and conventional soybeans. Extrusion of low-trypsin-inhibitor soybeans is recommended to optimize its superiority as swine feed.

Brewers dried yeast, as a source of mannanoligosaccarides (MOS), was assessed as an alternative to an antimicrobial agent (carbadox) for young pigs. Seven pen-replicates of 22-d-old pigs (n = 140, five pigs/pen) were fed four diets: non-medicated basal diet, carbadox (55 mg/kg), MOS (3% yeast), and MOS+organic acid (3% yeast, 2% citric acid) for 28 d, from 6.6 to 18.0 kg. The basal diet (1.4% Lys for 2 wk, then 1.2% Lys) was corn-soy-dried whey-dried plasma/cells. Feces were collected from all pigs at 2 and 4 wk for pH, VFA concentrations, and enumeration of microbial populations. Three pigs/pen were bled at 4 wk for immunoglobulin quantification, and one pig/pen was killed at 4 wk for gut morphology. Agglutination tests indicated that MOS was effective in binding E. coli and Salmonella spp. In this experiment, neither carbadox, MOS, nor MOS+acid improved growth rate (431, 418, 393, 391 g/d), feed intake (709, 671, 633, 636 g/d), or feed:gain (1.64, 1.60, 1.62, 1.63, respectively). Pigs fed carbadox gained faster and consumed more feed than those fed MOS or MOS+acid (P Key Words: Pigs, Yeast, Carbadox

Ileally cannulated pigs were used to assess the effects of four dietary levels of microbial phytase (Natuphos) on the apparent and true digestibility of Ca, P, CP, and AA in dehulled soybean meal. Fourteen pigs (25 kg initial BW) were surgically fitted with T-cannulas at the terminal ileum and assigned to diets in a replicated 7 x 7 Latin square design. Following a 14-d recovery, four diets consisting of 30.5% soybean meal with 0, 500, 1,000, or 1,500 units of phytase/kg of diet were fed. Diets 5 (1.05% lysine, 0.90% Ca, and 0.75% P) and 6 (1.05% lysine, 0.90% Ca, and 0.75% P) contained 35.25% soybean meal and 27.0% soy protein concentrate, respectively. Diet 7 (0.37% lysine, 0.03% Ca, and 0.05% P) was a low-CP, casein-based diet used to estimate the nonspecific endogenous losses of Ca, P, CP, and AA in order to estimate the true digestibility of these nutrients. All diets contained cornstarch and dextrose and were fortified with vitamins and minerals. Chromic oxide was used as an indigestible indicator. The diets were fed daily at 9% of metabolic BW ([BW.sup.0.75]). Apparent and true ileal digestibility of P increased quadratically (P < 0.01) and true digestibility of Ca increased linearly (P < 0.07) with increasing levels of phytase. Apparent digestibility of Ca was unaffected (P = 0.15) by phytase level. Apparent and true ileal digestibility of CP and most AA increased slightly with the addition of 500 units of phytase/kg of diet, but not at higher levels of phytase supplementation (in most cases, cubic effect, P < 0.05). Apparent and true ileal nutrient digestibility coefficients were unaffected by soybean meal source (Diet 1 vs Diet 5), except for arginine and Ca. The apparent and true digestibility coefficients for most of the AA tended (P < 0.10) to be lower in diets containing soy protein concentrate vs the common source of soybean meal used in Diet 5, but ileal digestibilities of Ca and P were unaffected (P = 0.15). In this study, supplemental microbial phytase did not improve the utilization of AA provided by soybean meal but was an effective means of improving Ca and P utilization by growing swine fed soybean meal-based diets. Key Words: Amino Acids, Digestibility, Phosphorus, Phytase, Pigs, Soybean Meal

We conducted two experiments to determine whether the efficacy of chromium picolinate (CrP) on growth performance, carcass composition, and tissue accretion rates is dependent on the lean gain potential of the pigs. In Exp. 1, 40 barrows (20 from each of two genetic backgrounds; two pigs per pen, five pens per treatment) were fed a fortified, corn-soybean meal basal diet (.95% lysine from 19 to 55 kg BW; .80% lysine from 55 to 109 kg BW) without or with 200 [[micro]gram]/kg of Cr from CrP. The addition of Cr had no effect on performance, carcass measurements, or accretion rates of carcass protein or lipid, regardless of the lean gain potential of the pigs. In Exp. 2, 60 group-penned pigs (three pigs per pen; five pens per treatment) were fed a fortified, corn-soybean meal basal diet without or with 200 [[micro]gram]/kg of Cr from CrP from 21 to 104 kg BW. Within the dietary Cr treatments, half of the pigs received daily injections of 3 mg of porcine somatotropin (pST) from 54 to 104 kg BW. The pST administration resulted in faster growth rates (P < .007), improved feed efficiency (P < .001), increased longissimus area (P < .001), and decreased 10th-rib backfat (P < .001). Administration of pST also increased the percentage and accretion rate of carcass protein (P < .001) and decreased the percentage and accretion rate of carcass lipid (P < .001). The addition of CrP to the diet had no effect on any variable measured in either the untreated or pST-treated pigs. In these studies, Cr was ineffective at altering the composition of the carcass and its effects were not dependent on the pig's potential for lean gain. Key Words: Pigs, Chromium, Lean, Growth Rate, Body Composition

Evaluates the effects of dietary zinc oxide concentrations with or without an antibacterial agent on postweaning pig performance. Composition of basal diets; Growth response of pigs that were weaned early; Efficacy of supplemental carbadox on postweaning pig performance responses.

Presents information on a study which determined the variability among sources and laboratories in analyses of wheat middlings. Materials and methods; Results and discussion; Implications.

Examines the effects of recombinant porcine somatotropin (pST) on the requirement for phosphorus (P), to minimize lean tissue accretion and to minimize fat tissue accretion in finishing pigs. Experimental procedures used to conduct the study; Effects of pST and dietary P on chemical composition and accretion rates of components in the skinned ham; Results and discussion of the study.

Discusses the abstract of the study 'Effect of chromium source on tissue retention of chromium in pigs,' presented at the American Society of Animal Science's Midwestern Branch conference on March 17-19, 2003, in Des Moines, Iowa.

Discusses the abstract of the study 'Efficacy of phytase in diets containing high and low-phytate corn and high and low-phytate soybean meal,' presented at the American Society of Animal Science's Midwestern Branch conference on March 17-19, 2003, in Des Moines, Iowa.

Discusses the abstract of the study 'Phosphorus balance in growing pigs fed semi-purified diets adequate or low in dietary phosphorus,' presented at the American Society of Animal Science's Midwestern Branch conference on March 17-19, 2003, in Des Moines, Iowa.

Discusses the abstract of the study 'Whole body composition and phosphorus accretion in growing pigs,' presented at the American Society of Animal Science's Midwestern Branch conference on March 17-19, 2003, in Des Moines, Iowa.

Discusses the abstract of the study 'Virginiamycin influences mineral digestibility of pigs,' presented at the American Society of Animal Science's Midwestern Branch conference on March 17-19, 2003, in Des Moines, Iowa.

Discusses the abstract of the study 'Effect of altered dietary n6/n3 fatty acid ratios and endotoxin injection on performance and immune parameters in nursery pigs,' presented at the American Society of Animal Science's Midwestern Branch conference on March 17-19, 2003, in Des Moines, Iowa.