Comparison of amino acid digestibility coefficients for soybean meal, canola meal, fish meal, and meat and bone meal among 3 different bioassays.

The objective of this study was to determine amino acid digestibility of 4 feedstuffs [soybean meal (SBM), canola meal, fish meal, and meat and bone meal (MBM)] using the precision-fed cecectomized rooster assay (PFR), the standardized ileal assay (SIAAD), and a newly developed precision-fed ileal broiler assay (PFC). For the PFR, cecectomized roosters were precision-fed approximately 30 g of feed sample, and excreta were collected 48 h postfeeding. For the SIAAD, 16-d-old broilers were fed a semipurified diet containing the feed samples as the only source of protein from 17 to 21 d, with ileal digesta collected at 21 d. For the PFC, 22-d-old broilers were precision-fed 10 g of feed sample mixed with chromic oxide, and ileal digesta were collected at 4 h postfeeding. Digestibility coefficients were standardized using a nitrogen-free diet for the SIAAD and PFC and using fasted roosters for the PFR. There were generally no consistent differences in standardized amino acid digestibility values among assays, and values were in general agreement among assays, particularly for SBM and MBM. Differences did occur among methods for amino acid digestibility in fish meal; however, these differences were not consistent among methods or amino acids. The results of the study indicated that all 3 bioassays are acceptable for determining the amino acid digestibility of SBM, canola meal, MBM, and fish meal for poultry.