Effects of supplemental xylanase and β-mannanase on in vitro disappearance of nutrients in feed ingredients for pigs

The objective of the present study was to determine the effects of supplemental xylanase and β-mannanase on the in vitro disappearance of nutrients in wheat, copra meal, and palm kernel expellers for pigs. The ingredients were finely ground and divided into the control and treatment groups. Treatment samples were prepared to contain 999 g/kg of a test ingredient with 1 g/kg of a xylanase product (150 xylanase unit/g in the mixed sample), 997 g/kg of a test ingredient with 3 g/kg of a β-mannanase product (600 unit/g in the mixed sample), and 996 g/kg of a test ingredient with 1 g/kg of the xylanase product and 3 g/kg of the β-mannanase product. The in vitro ileal disappearance (IVID) of dry matter (DM) and crude protein (CP) was determined using a 2-step in vitro procedure, representing the digestion and absorption processes in the stomach and small intestine. The in vitro total tract disappearance (IVTTD) of DM and organic matter was determined using a 3-step in vitro procedure, which additionally simulates the digestion process in the large intestine. The magnitude of increase in IVID of DM in copra meal by β-mannanase tended to be greater with supplemental xylanase compared with no supplemental xylanase (interaction p = 0.056). The magnitude of increase in IVID of DM in palm kernel expellers by β-mannanase was less with supplemental xylanase compared with no supplemental xylanase (interaction p = 0.045). The IVID of CP increased by supplemental β-mannanase in copra meal (p = 0.051) and palm kernel expellers (p = 0.042). Supplemental β-mannanase tended to increase (p = 0.073) the IVTTD of DM in copra meal. In conclusion, supplemental xylanase and β-mannanase can synergistically increase ileal digestibility of DM in copra meal in contrast to palm kernel expellers, and supplemental β-mannanase can increase the ileal digestibility of CP in copra meal and palm kernel expellers for pigs.