Amino acid supplementation of hydrolyzed feather meal for finisher pig diets

Abstract

The objective of this study was to determine the possibility of replacing soybean meal (SBM) in pig diets completely with hydrolyzed feather meal (FM). Corn-SBM, finisher 1 and 2 positive control (PC) diets were formulated to contain 6.1 and 4.7 g apparent ileal digestible (AID) Lys/kg, respectively, and corn-FM, negative control (NC) diets were formulated to be iso-N to the PC diet. The NC diet were supplemented with AA to satisfy all the AID indispensable AA requirements based on the 1998 NRC AID AA (NRC; NC + Lys and Trp) and the assumption that the apparent ileal digestibility of all indispensable AA in FM is 40% (40-2AA = NC + Lys, Trp, and Thr, but no His and Ile, and 40All = NC + Lys, Trp, Thr, His, and Ile). Forty-five gilts and 45 castrated males (57.8 ± 0.8 kg; 3 gilts or 3 castrated males/pen) were randomly assigned to 5 finisher 1 diets. At 81.0 ± 1.4 kg, pigs were offered finisher 2 diets. Pigs had ad libitum access to feed and water, and blood samples were collected before slaughter. Pigs were slaughtered at the end of the study (112.1 ± 1.8 kg). As expected, overall ADFI, AID Lys (representing indispensable AA) intake (LysI), ADG, and G:F were greater and G:LysI was lower in pigs fed the PC diet than those fed the NC diet. (P < 0.001). Overall G:LysI tended to be lower in pigs fed the NRC diet than those fed the PC diet (P = 0.083) or the 40-2AA and 40All diets (P = 0.094), and pigs fed the 40All diet had numerically higher G:F (P = 0.119) and G:LysI (P = 0.160) than those fed the 40-2AA diet. Pigs fed the PC diet had more serum albumin and total protein (P < 0.001) but less glucose (P = 0.031) and cholesterol (P < 0.001) than those fed the NC diet, and total protein was higher (P = 0.031) in pigs fed the 40All diet than those fed the 40-2AA diet. Diets had no effect on urea N or triglycerides. Pigs fed the PC diet had less average backfat than those fed the NC diet (P = 0.016) or the NRC diet (P = 0.020). The LM was greater (P < 0.001) in pigs fed the PC diet or the 40All diet than those fed the NC or the 40-2AA diet, respectively. Pigs fed the PC diet had greater (P < 0.01) % fat-free lean, lean gain (LG), and LG:F than those fed the NC diet, but their LG:F or LG:LysI was similar to those fed the NRC diet. The LG:F (P = 0.030) and LG:LysI (P = 0.028) were lower in pigs fed the NRC diet than those fed the 40-2AA and 40All diets, and LG:LysI tended to be higher (P = 0.068) in pigs fed the 40All diet than those fed the 40-2AA diet. Pigs fed the 40All diet had greater (P < 0.001) meat color, firmness, and marbling scores than those fed the 40-2AA diet. Diets had no clear effect on organ weights. The results indicated that the FM diets supplemented with crystalline AA were not as good as the corn-SBM diets in terms of supporting weight gain. However, the results seemed to indicate that pigs fed the FM diets supplemented with the necessary AA can utilize AA and feed for weight gain and LG as efficiently as those fed the corn-SBM diet.