Soybean Hulls-Swine

Researchers at Purdue University reported the effect of soybean hulls on nitrogen and amino acid digestibilities of soybean meal in growing pig diets. Soybean hulls were incorporated at levels of 0, 3, 6, and 9% in a 17% crude protein, semi-purified, diet containing 33.25% soybean meal. The hulls that replaced cornstarch and soybean meal levels were adjusted for the crude protein contribution of the hulls. The diets were fed to pigs that were surgically fitted with a T-cannula at the distal ileum. Standard feeding rates and collection periods were employed. Results indicated the apparent ileal digestibilities of dry matter and gross energy were decreased by about six percent with the addition of soybean hulls (linear trend, P<0.05), whereas nitrogen digestibilities were not affected. Both the apparent and true ileal digestibilities of arginine, histidine, lysine, phenylalanine, aspartic acid, serine and tyrosine were linearly reduced (P<0.05) up to five percentage units by the added hulls. The true ileal lysine digestibility of soybean meal was reduced from 90.3 to 87.7 percent with the addition of nine percent hulls. The researchers concluded their data indicates that a 0.2 percent decrease in some of the true ileal indispensable amino acids may result from each one percent increase in soybean hull addition in the semipurified diet containing soybean meal as the sole source of amino acids for growing pigs. (The practical importance of this research is that it helps justify greater use of dehulled soybean meal compared to 44 percent protein soybean meal in diets for swine, especially when crude protein levels are reduced.)

Dilger, R.N. and co-workers. 2004. Digestibility of nitrogen and amino acids in soybean meal with added soyhulls. J. Animal Sci. 82(3): 715-724.