Low-protein, crystalline amino acid-supplemented, sorghum-soybean meal diets for the 10- to 20-kilogram pig.

Five randomized block design experiments were conducted to determine the limiting amino acids (or other nutrients) in low-CP (12%) sorghum-soybean meal (S-SBM) diets for the 10- to 20-kg pig. Average initial weights were 10.7, 10.5, 9.1, 10.2, and 10.9 kg in Exp. 1, 2, 3, 4, and 5, respectively. The nine treatments in Exp. 1 were 1) Basal (B, 12% CP), 2) B + .26% methionine (Met), 3) B + .24% histidine (His), 4) B + .21% isoleucine (Ile), 5) B + .12% tryptophan (Trp), 6) B + .24% valine (Val), 7) B+Met+His, 8) B+Met+His+Ile+Trp+Val (AllAA), and 9) S-SBM positive control (PC, 21.81% CP). All diets provided 1.10% Lys and .83% Thr. Individual addition of His and Val to the B diet increased (P < .10) gain. The gain of pigs fed the AllAA diet did not differ (P > .10) from that of pigs fed the PC diet. Experiment 2 consisted of the nine treatments used in Exp. 1, except that Treatment 7 in Exp. 2 contained His+Val (H+V) rather than Met+His. Individual additions of Ile, Trp, and H+V increased (P < .10) gain/feed compared with the B diet. Performance of pigs fed the AllAA diet was not different (P > .10) from that of pigs fed the PC diet. Addition of NaHCO3 (Exp. 3), Phe (Exp. 4), or nonessential N (Exp. 5) to the AllAA diet did not affect (P > .10) pig performance compared with pigs fed the AllAA diet. However, in Exp. 3, pigs fed the PC diet grew faster (P < .03) and had greater (P < .10) apparent N digestibilities than pigs fed the AllAA diet. In summary, low-CP, S-SBM diets may be equally third limiting in His, Ile, Trp, and Val for the 10- to 20-kg pig.