Evaluation of the efficacy of exogenous enzymes on nutrient digestibility of ducks in vitro and in vivo.

Our study aimed to investigate the efficacy of exogenous enzymes on the nutrient digestibility of ducks in vitro and in vivo. First, a two-stage simulated digestion assay for ducks was used to evaluate the in vitro digestibility of dry matter (IVDMD) and energy (IVED) of wheat, rice, and broken rice samples, as well as cottonseed meal (CSM), rapeseed meal (RSM), and peanut meal (PNM) samples. Then, the improvements in IVDMD and IVED in wheat 3, rice 4, CSM 3, and RSM 3-the ingredients with the lowest nutritive values-with and without exogenous enzyme supplementation were evaluated. To verify the efficacy of exogenous enzymes on nutrient digestibility in vivo, four diets, including a positive control (PC) diet (corn-wheat-soybean meal-RSM-based diet), a negative control (NC) diet with a low nutrient level, an NC diet + non-starch polysaccharide (NSP) enzymes, and an NC diet + NSP enzymes + protease, were fed to Cherry Valley ducks from days 14 to days 42. Compared with the control, single-NSP-enzyme supplementation increased IVDMD by 3.27% and IVED by 2.85%, and the combined-enzyme addition increased IVDMD by 6.04% and IVED by 6.20% in wheat 3, respectively (p < 0.05). Supplementation of NSP enzymes alone or with the protease increased the final BW and average daily gain (ADG) and improved the feed/gain ratio (F/G), as well as the digestibility of DM, energy, crude protein, and some amino acids (Thr, Met, Ile, Lys, Arg) in ducks fed the NC diet (p < 0.01). In conclusion, exogenous enzymes improved the nutrient digestibility of wheat and RSM as well as the corn-wheat-soybean meal-RSM basal diet in vitro and in vivo, respectively, contributing to the improvement in growth performance of ducks fed a diet with reduced nutrient levels. The consistency of the beneficial effects of exogenous enzymes between in vitro and in vivo conditions suggests that an in vitro assay could be developed into a quick and reliable method for assessing the efficacy of exogenous enzymes in ducks.