Comparison of Digestibility of Amino Acids in Full-Fat Soybean, Soybean Meal, and Peanut Flour Between Broiler Chickens and Pigs

The objective of this experiment was to compare the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP and AA for broiler chickens and pigs fed full-fat soybean (FFSB), soybean meal containing 430 g/kg CP (SBM-43), soybean meal containing 470 g/kg CP (SBM-47), and peanut flour (PNF). Four semi-purified diets were formulated to contain FFSB, SBM-43, SBM-47, and PNF, respectively, as the sole source of nitrogen. One nitrogen-free diet was also formulated to determine the basal ileal endogenous losses of CP and AA for broilers and pigs. In Exp. 1, a total of 416 twenty-one-day-old male broiler chickens were assigned to 5 dietary treatments in a randomized complete block design with BW as a blocking factor. Each dietary treatment contained 8 replicates with 10 birds per cage except for the nitrogen-free diet, which contained 12 birds per cage. On d 26 post-hatching, birds were euthanized by CO₂ asphyxiation and ileal digesta samples were collected from distal ileum. In Exp. 2, twenty barrows (initial BW = 62.0 ± 6.89 kg) surgically fitted with T-cannula at the distal ileum were individually housed in metabolism crates and assigned to quadruplicate 5 × 2 incomplete Latin Square design with 5 diets and 2 periods. Each period consisted of 5 d of adaptation and 2 d of ileal digesta collection periods. Interactions between ingredients and species were not observed except for Cys (P < 0.01). Pigs had the greater (P < 0.01) AID of CP and indispensable AA in test ingredients compared with broiler chickens. In both broilers and pigs, the AID of CP and indispensable AA in SBM-47 were greater (P < 0.05) than those in FFSB, and the AID of Lys in PNF was less (P < 0.05) than FFSB, SBM-43, and SBM-47. Except for Trp, pigs also had greater (P < 0.01) SID of CP and indispensable AA in test ingredients compared with broilers. Birds fed SBM-43, SBM-47, and PNF had greater (P < 0.05) SID of CP, Ile, Leu, Thr, Trp, and Val than those fed FFSB. Pigs fed SBM-43, SBM-47, and PNF had greater SID of Arg, Ile, Leu, Met, Phe, and Val than those fed FFSB. In conclusion, pigs had greater SID of CP and most AA in test ingredients compared with broilers but the pattern of differences in SID of CP and AA among ingredients was similar between broiler chickens and pigs.