Effects of exogenous phytase and β-mannanase on ileal and total tract digestibility of energy and nutrient in palm kernel expeller-containing diets fed to growing pigs

The objective of the present study was to determine the effects of phytase and β-mannanase on apparent ileal and total tract digestibilities of energy and nutrients in diets containing 10% palm kernel expellers fed to pigs. A basal diet was mainly based on maize, soybean meal, and palm kernel expellers without inorganic P. Four experimental diets were prepared in a 2 × 2 factorial treatment arrangement with 2 concentrations of supplemental phytase at 0 or 1000 U/kg and 2 concentrations of supplemental β-mannanase at 0 or 1600 U/kg. Eight pigs with an initial body weight of 70.9 kg (SD = 11.9) were fitted with ileal T-cannulas and were fed experimental diets in a replicated 4 × 4 Latin square design with 4 dietary treatments and 4 periods. In each period, faeces were collected on d 7 and ileal digesta samples were collected on d 8 and 9. Supplemental phytase increased the coefficient of ileal apparent digestibilities (CIAD) and the coefficient of total tract apparent digestibilities (CTTAD) of P by 0.161 and 0.191, respectively (P < 0.01). Supplemental β-mannanase increased CIAD of dry matter, organic matter and energy by 0.035-0.038 (P < 0.05), and CTTAD of energy by 0.019 (P < 0.05). However, no interaction between phytase and β-mannanase was observed in the digestibility of nutrients. Phytase increased CIAD of aspartic acid, glutamic acid, and serine, by 0.021-0.029 (P < 0.05), and β-mannanase increased CIAD of leucine and phenylalanine by 0.018 and 0.019, respectively (P < 0.05). In conclusion, phytase and β-mannanase improved P and organic nutrient digestibilities, respectively, and to a lesser extent, the 2 enzymes improved amino acid digestibility.