299 Poultry Meal Autoclaving Time-Related Reduction in Amino Acid Digestibility for Broiler Chickens and Growing Pigs

Abstract Poultry meal (PoMe), a rendered product of slaughtered poultry carcasses, is widely used in swine and poultry diets because of its highly digestible protein and balanced amino acid profile. Rendering may reduce amino acid digestibility of PoMe because rendering can induce heat damage to PoMe, and the effect of heat damage on amino acid digestibility in PoMe may be different between broiler chickens and growing pigs. For this reason, the objective of this study was to determine the effect of autoclaving on standardized ileal digestibility (SID) of amino acid in PoMe fed to broiler chickens and growing pigs. Poultry meal from the same batch was autoclaved at 134°C for 0, 30, 60, 90, 120, 150, or 180 min for 7 samples. Eight experimental diets consisted of 7 diets containing each PoMe sample as a sole source of nitrogen and a nitrogen-free diet. In Exp. 1, 656 male broiler chickens (initial BW = 719 ± 97 g) at d 18 post hatching were assigned to the 8 diets in a randomized complete block design with BW as a blocking factor. On d 23, birds were euthanized by CO2 asphyxiation and dissected for the collection of ileal digesta. In Exp. 2, 16 barrows (initial BW = 23.3 ± 0.7 kg) surgically fitted with T-cannulas at the distal ileum were allotted to duplicate 8 × 4 incomplete Latin square design with the 8 diets and 4 periods. Each experimental period consisted of 5-d adaptation and 2-d ileal digesta collection periods. Data for Exp. 1 and 2 were pooled together as a 2 × 7 factorial treatment arrangement with the effects of species (i.e., pigs and broiler chickens) and autoclaving time (i.e., 0 to 180 min). An Interaction between species and linear effect of autoclaving time was observed (P < 0.05) in SID of nitrogen, arginine, and threonine in PoMe. To be specific, the linear decrease in ileal digestibility of nitrogen and those AA with increasing autoclaving time was greater in pigs compared with broiler chickens. The SID of AA both linearly and quadratically decreased (P < 0.05) as autoclaving time increased. The SID of isoleucine, leucine, methionine, phenylalanine, and tryptophan in PoMe was greater (P < 0.05) in growing pigs compared with broiler chickens regardless of autoclaving time. In conclusion, increasing autoclaving time decreases SID of amino acids in PoMe, and SID values in some indispensable amino acids are greater in growing pigs compared with broiler chickens.