Amino acid and phosphorus digestibility and concentration of digestible and metabolizable energy in hydrolyzed feather meal fed to growing pigs.

Two experiments were conducted to determine the standardized ileal digestibility (SID) of AA (Exp. 1), the standardized total tract digestibility (STTD) of P, and the concentration of DE and ME (Exp. 2) in hydrolyzed feather meal (FM) fed to growing pigs. Eight samples of FM were obtained from 4 different processing plants (FM1, FM2, FM3, and FM4). Each plant provided samples of FM without and with added blood. In Exp. 1, 10 barrows (initial BW: 24.0 ± 0.8 kg) were prepared with a T-cannula in the distal ileum and allotted to a 10 × 10 Latin square design with 10 diets and ten 7-d periods. A N-free diet, a diet based on soybean meal (SBM), and 8 diets based on a combination of SBM and each of the 8 sources of FM were formulated. Values for the SID of CP and AA in each source of FM were calculated using the difference procedure. The SID of CP and all AA was different (P < 0.001) among sources of FM. Among the indispensable AA, the overall effect of addition of blood was statistically significant (P < 0.05) for the SID of Ile, Leu, Lys, Phe, and Val, but for some sources, the SID of these AA was increased by addition of blood, whereas for other sources, the SID was reduced or not changed (interaction, P < 0.05). As an example, the SID of Lys in FM3 and FM4 with added blood were greater (P < 0.05) than in FM3 and FM4 without blood, but no difference in the SID of Lys was observed for FM1 and FM2 without and with blood (interaction, P < 0.01). In Exp. 2, 72 growing barrows (initial BW: 13.3 ± 1.5 kg) were used with 9 diets and 8 replicate pigs per diet. A corn-diet consisting of 98.4% corn was formulated and 8 additional diets were formulated by mixing corn with 25% FM. The STTD of P and the DE and ME of each source of FM were calculated using the difference procedure. The STTD of P tended (P = 0.09) to be different among FM sources and the STTD of P in FM with added blood was less than in FM without blood. On a DM basis, DE and ME values were affected (P < 0.05) by both source of FM and addition of blood. However, an interaction (P < 0.05) between source of FM and addition of blood for ME was observed because addition of blood to FM3 and FM4 reduced (P < 0.05) the ME, whereas addition of blood to FM1 and FM2 had no impact on ME. In summary, the SID of AA, STTD of P, and the energy concentration vary among sources of FM and the effects of adding blood to FM is not consistent among sources.