PUBLISHED BY SOYBEAN GROWERS FOR THE FEED INDUSTRY	JUNE 2008
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Phytase and Amino Acid Availability The effect of microbial phytase on true and apparent ideal amino acid digestibilities in growing-finishing pigs. Fifteen kilogram barrows fitted with cannulas at the ileo-cecal junction were fed a semi-purified corn starch and soybean meal-basal diet formulated to contain 3.4 Mcal digestible energy per kilogram, 17.0% crude protein, 0.8% calcium and 0.6% phosphorus (0.13% phytate-phosphorus). The basal diet was supplemented with either 0 or 1,000 units of microbial phytase per kilogram. Biological samples and digestibilities were determined three times at four week intervals starting when the pigs were seventy days of age. Pigs fed phytase-supplemented diets excreted less phosphorus in the feces (P=0.003) and more in urine (P=0.001), however, total phosphorus excretion was similar to pigs fed diets without phytase supplementation. Phytase additions to the semi-purified diet did not affect the apparent ideal digestibility or true ideal digestibility of nitrogen or most amino acids. The researchers reported that apparent ideal digestibility of arginine and methionine were increase by phytase supplementation. Pomar, C. and co-workers. 2008. The effect of microbial phytase on true and apparent ideal amino acid digestibilities in growing-finishing pigs. J. Animal Sci. Epublished on March 28. Soybean Glycerol Energy Values The apparent digestible energy (DE) and metabolizable energy (ME) values of crude glycerol for growing pigs were determined in five experiments using a crude glycerol (86.95% glycerol) from a soybean biodiesel production facility. Digestible energy of the diet was calculated by subtracting fecal energy from the gross energy in the feed, whereas ME was calculated by subtracting the urinary energy from DE. The DE and ME values of crude glycerol were estimated to have a DE of 3,344 ± 8 kcal/kg and an ME of 3,207 ± 10 kcal/kg. The researchers concluded that crude glycerol is a highly available energy source for growing pigs. Lammers, P.J. and co-workers. 2008. Digestible and metabolizable energy of crude glycerol for growing pigs. J. Animal Sc. 86:602-608. Comparison of Soybean Products for Beef Cows Two experiments compared whole soybean and soybean meal/hull supplements on the performance of beef cows. The experiment design was a 2 x 3 factorial with two supplements and three age groups of cows. The cows were fed either 1.36 kg/d of whole raw soybeans or 1.56 kg/d of a soybean meal/hulls supplement (dry matter basis) and free choice access to bermuda grass hay. Supplements were formulated to provide similar amounts of protein and energy, but a greater fat content with the whole soybeans. In the first experiment, 166 crossbred beef cows individually fed supplements for an average of 80 days during mid to late gestation. During the first 50 d of supplementation, cows fed soybean meal/hulls gained more body weight (10 kg) and had better body condition scores (0.18 units) than cows fed whole soybeans. However, for the entire 296-day experiment no significant differences in body weight or body condition scores were reported for the two supplements. Calves from cows fed soybean meal/hulls were 2 kg heavier at birth, however, there was no difference in calf body weights seen at weaning between supplements. First service conception rate (68%) and pregnancy rate (73%) were not different between supplements. In the second experiment, the effect of supplement composition on forage intake and digestion were determined. No treatment differences were observed in forage intake or digestibility of dry matter, fiber or crude protein. The researchers concluded that compared to supplementation with soybean meal/hulls, whole soybean supplementation during mid to late gestation resulted in reduced body weight gains and had no effect on calf weaning weight, subsequent reproduction, forage intake or nutrient digestion. Bottom line-both whole soybeans and soybean meal can be used to supplement low quality roughage in beef cow operations. Banta, J.P. and co-workers. 2008. Whole soybean supplementation and cow age class: Effects on intake, digestion, performance and reproduction of beef cows. J. Animal Sci. Epublished on April 25 Lysine Requirements-Swine A total of seven experiments were conducted to determine the optimum lysine to calorie ratio (grams total dietary lysine/Mcal ME) for 35- to 120-kg barrows and gilts. Six treatments with increasing lysine to calorie ratio were used in each study by adjusting the amount of corn and soybean meal. No crystalline lysine was used to formulate the treatments. The researchers reported a lot of data for each of the experiments. In general, the results indicated that feed cost per kg of gain decreases, reductions in pig performance and income over feed costs are rather modest when feeding marginal lysine-deficient diets early (35 to 70 kg) in the grower-finishing period. More severe penalties in growth and economic performance occur when feeding marginally deficient diets in late finishing (70 kg to slaughter). The research group concluded that the equations:   lysine:calorie ratio = - 0.0133 x body weight (kg) + 3.6944 (barrows)   lysine:calorie ratio = - 0.0164 x body weight (kg) + 4.004 (gilts) These equations best describe the lysine:calorie ratio that met biological requirements and optimized income over feed costs in these experiments. Bottom line-the essential amino acid lysine is critical to pig performance and feeding diets with marginal levels of lysine may adversely impact profitability. Reducing soybean meal levels in swine rations with ingredients containing lower levels of lysine will place more pressure on assuring that the lysine needs of the pig are met for optimum performance and unit profits. Main, R.G. and co-workers. 2008. Determining the optimum lysine:calorie ratio for barrows and gilts in a commercial finishing facility. J. Animal Sci. Epublished on May 9.