Effects of xylanase on growth performance, nutrient digestibility, serum metabolites, and fecal microbiota in growing pigs fed wheat-soybean meal-based diets

Lay Summary The potentiality of wheat on nutritive value is not fully realized because of the presence of (NSP). The arabinoxylan in the wheat represents about 70% of the total NSP, which may bring about the encapsulation of nutrients and increase digesta viscosity. In this experiment, we found that a wheat-soybean meal-based diet supplemented with 500 U/kg xylanases could improve the fecal microbiota and nutrient digestibility, thereby improving growth performance in growing pigs. This experiment investigated the effects of xylanase on growth performance, nutrient digestibility, serum metabolites, and fecal microbiota in growing pigs fed wheat-soybean meal-based diets. Seventy-two crossbred pigs (Duroc x [Landrace x Large White]) pigs (body weight of 23.30 +/- 1.51 kg) were allotted two treatments with six pens per treatment and six pigs per pen. The diets were a wheat-soybean meal-based diet (Control group) and a wheat-soybean meal-based diet supplemented with 500 U/kg xylanases (XYL group). The experiment was divided into two periods (phase 1: days 1 to 35 and phase 2: days 36 to 70). Xylanase improved G:F during phase 1 and the entire experiment (P < 0.05) and tended to improve G:F during phase 2 (P = 0.09). Compared with the control group, pigs in the XYL group had greater apparent total tract digestibility of dry matter, organic matter, and gross energy on days 35 and 70 (P < 0.05) and had greater apparent ileal digestibility of amino acids (histidine, lysine, methionine, and serine) on day 70 (P < 0.05). The fecal microbiota in the XYL group contained greater abundances of g_Terrisporobacter, g_Lactobacillus, g_Clostridium_sensu_stricto_1, and g_Romboutsia than the Control group on day 70. Xylanase increased the fecal Lactobacillus populations on day 35 (P < 0.05). On days 35 and 70, xylanase reduced the fecal E. coli populations (P < 0.05). Supplementing xylanase to wheat-soybean meal-based diets collectively improved fecal microbiota, and nutrient digestibility, thereby improving growth performance in growing pigs. Arabinoxylan cannot be digested in the small intestine of pigs due to the absence of the endogenous enzyme, which leads to the encapsulation of nutrients and increase in digesta viscosity. Xylanase can improve fecal microbiota and nutrient digestibility, thereby improving growth performance in growing pigs.