Hydrolyzed feather meal as a source of amino acids for finisher pigs

Abstract

21 gilts and 21 castrated males were used to evaluate the value of hydrolyzed feather meal (FM) as a source of amino acids for finisher pigs, and to determine the possibility of replacing soybean meal (SBM) completely with FM by lysine supplementation. Dietary treatments consisted of five iso-lysinic (planned, 7.3 g kg −1; actual, 8.0–8.8 g kg −1) SBM diets containing 0 to 120 g FM kg −1. Two additional diets containing 90 g FM kg −1 were formulated to be iso-nitrogenous to the SBM diet containing 0 g FM kg −1. For these FM diets, SBM was replaced completely by FM, and one of the two diets was supplemented with L-lysine · HCl to achieve a target level of 7.3 g lysine kg −1. At an average weight of 67.5 ± 3.4 kg, pigs were assigned randomly within sex to seven dietary treatments. Pigs were housed individually, and allowed ad libitum access to feed and water. All pigs were slaughtered at an average weight of 100.4 ± 3.2 kg to assess carcass traits. The rate (linear, P < 0.05; cubic, P = 0.09) and efficiency of weight gain (linear, P = 0.07) decreased as dietary FM increased. However, the response of pigs to the initial increment of FM (30 g kg −1) in weight gain and greater feed intake of pigs fed the diet containing 120 g FM kg −1 seemed to be responsible for overall decreases in these criteria. The rate and efficiency of weight gain in pigs fed other SBM diets containing FM were similar. Although there were no statistically significant trends among pigs fed the SBM diets, the inclusion of 120 g FM kg −1 seemed to result in the inferior carcass quality as indicated by consistently lower values for carcass specific gravity (1.040 vs. 1.045), proportion of carcass lean (48.7 vs. 51.6%) and the rate of lean accretion (236.4 vs. 301.4 g d −1). Pigs fed the two FM diets (with and without lysine supplementation) grew slower than those fed the SBM diet containing 0 ( P < 0.01) or 90 g FM kg −1 ( P = 0.06). Similar results were obtained for the efficiency of weight gain ( P < 0.05) and rate and efficiency of lean accretion ( P < 0.05). There was no effect of lysine supplementation on the rate and efficiency of weight gain. Pigs fed the FM diet supplemented with lysine, however, had less 10th rib backfat ( P = 0.10), larger longissimus muscle area ( P = 0.08), greater proportion of carcass lean ( P < 0.05), and higher rate ( P = 0.08) and efficiency of lean accretion ( P < 0.05) than those fed the FM diet without lysine supplementation. The results indicate that FM up to 90 g kg −1 may be incorporated in the diet without adversely affecting carcass traits of finisher pigs. In addition, although weight gain may be reduced, FM can be used as the only source of protein supplement without decreasing the carcass quality, provided that the diet is supplemented with crystalline lysine to alleviate its deficiency.