PSII-22 - Effects of protease supplementation on ileal digestibility of amino acids in pulse grains fed to growing pigs

Abstract: Pulse grains, such as chickpeas, faba beans, and lentils are non-oil seed legume crops and good sources of starch and protein as alternative feed ingredients to cereal grains or soybean meal. This study aimed to determine the effects of protease supplementation on the apparent (AID) and standardized (SID) ileal digestibility of amino acids (AA) in chickpeas, faba beans, and lentils fed to growing pigs. A total of twelve ileal cannulated barrows (55.7 ± 3.6 kg initial body weight) were assigned to one of six dietary treatments in a replicated 6 × 3 incomplete Latin square design, with six treatments and three 7-d periods to give six observations per dietary treatment. Six treatments consisted of one of the pulse grains with or without protease supplementation (250 g/tonne). Each pulse grain was included as the sole source of protein in the diets, and a casein diet was fed to all pigs for a week after feeding experimental treatments to quantify endogenous losses of AA. All diets contained 0.3% titanium dioxide as an indigestible marker. Pigs underwent surgery to install T-cannulas at the distal ileum. Each period lasted for 7 d including 5 d of adaptation and 2 d of ileal digesta collection. Data were analyzed as a 3 × 2 factorial arrangement with the 3 different pulse grains and with or without protease supplementation, using the PROC MIXED of SAS. The statistical model included type of ingredients, protease supplementation, and their interaction as fixed effects, and replication, animal within replication, and period within replication as random effects. Protease supplementation decreased (P < 0.05) the AID of Thr, Trp, Ala, Cys, and Gly, and decreased (P < 0.05) SID of Trp, Ala, and Cys. The SID of all AA except for Gly and Pro were greater (P < 0.05) in lentil and faba bean diets compared to those in the chickpea diet. There were no interactive effects in the AID and SID of AA except for the AID of Pro, where AID did not differ between with and without protease supplementation in chickpea and faba bean diets, however, protease supplementation decreased (P < 0.05) AID of Pro in lentil diet compared to without protease supplementation. In conclusion, the digestibility of AA in growing pigs was greater without protease supplementation, and no interactive effects were observed in general between the type of ingredient and protease supplementation. Future studies will aim to investigate the dose-effect to accurately determine whether the observed effect was attributable to improper enzyme-to-substrate ratio.