Nutritional evaluation of poultry by-product meal as a protein source for ruminants: Small intestinal amino acid flow and disappearance in steers

Six Angus steers (260 +/- 4 kg initial BW) fitted with ruminal, duodenal, a nd ileal cannulas were used in a 6 x 6 Latin square design to evaluate the effect of feeding poultry by-product; meal (PEM) on small intestinal flow a nd disappearance of amino acids; The diets were provided at 2% of BW on a D M basis, formulated to contain 11.5% CP, and consisted of 49% corn silage, 36% cottonseed hulls, and 15% supplement on a DM basis. Supplements were fo rmulated to contain 37% CP with sources of supplemental N being soybean mea l (100% SBM) and 0, 25, 50, 75, and 100% PBM, with urea used to balance for N. Duodenal flow of all amino acids increased linearly (P < .07) as PBM in creased in the diet and, except for His, increased(P < .09) for 100% PBM co mpared with 100% SBM. Similar results were observed for duodenal flow of no nbacterial amino acids, which linearly increased (P < .05) with PBM and wer e greater(P < .05) for 100% PBM than for 100% SBM. Soybean meal increased ( P < .09) the duodenal flow of nonbacterial Lys compared with 0% PBM, acid 0 % PBM increased (P < .04) flow of Val, Ala, and Pro compared with 100% SBM. Duodenal bacterial essential, nonessential, and total amino acid flows wer e not affected(P > .80) by PBM; however, they were greater (P < .02); for 1 00% SBM than for 100% PBM. In addition, nonessential and total bacterial am ino acid flows were increased (P < .06) for 100% SBM compared with 0% PBM. Small intestinal disappearance of Lys and Pro increased linearly (P < .09) as PBM increased, and 100% PBM increased (P < .07) disappearance of Arg and Ala compared with 100% SBM. Supplemental N source had no effect (P > .31) on apparent small intestinal disappearance of essential, nonessential, and total amino acids. These data suggest that when PBM, SBM, and urea were use d as sources of supplemental N, the daily disappearance of amino acids from the small intestine of steer calves consuming a corn silage- and cottonsee d hull-based diet was similar.