Impact of xylanase and protease supplementation on digestibility in growing pigs fed diets with varying levels of zinc and copper

This study aimed to evaluate the effect of dietary copper (Cu) and zinc (Zn) levels and xylanase and protease supplementation on apparent digestibility of nutrients at the end of the ileum (AID) and large intestine (ALID). Using a 2 × 2 factorial design, 24 weaned pigs were assigned to one of the four barley-wheat-soybean meal diets, supplemented with two levels of Cu/Zn (20/125 and 40/250 mg/kg) and either a mix of xylanase and protease (ENZ) or no enzyme supplementation. Neither the Cu/Zn level nor ENZ affected AID of nutrients. However, ALID of dry matter and fibres (ADF and NDF) increased with ENZ supplementation (<i>p</i> < 0.010). Enzyme supplementation also influenced the ALID of crude protein and phosphorus, depending on the Cu/Zn levels (Mineral × ENZ, <i>p</i> < 0.050). Specifically, ENZ increased the ALID of crude protein in the high Cu/Zn diet, while ALID of phosphorus increased by 63% with ENZ in low Cu/Zn diet but only by 23% in the high Cu/Zn diet. The high Cu/Zn level increased the ALID of dry matter but had no effect on the ALID of other nutrients. In conclusion, ENZ supplement increased the apparent digestibility of nutritional compounds, but this effect was dependent on the level of Cu/Zn in the diet. Further research is needed to explore the interaction between xylanase/protease and nutritional components of feed to maximise the benefits of these supplements.