Effect of Feeding Enzymolytic Soybean Meal on Performance, Digestion and Immunity of Weaned Pigs

The objective of this study was to investigate the effect of enzymolytic products of soybean meal (ESBM), as one of the protein sources in the diet, on the growth performance, nutrient digestibility and immune function of weaned piglets. Soybean meal produced by bioprocessing with fermentation and enzymolysis contains reduced anti-nutritional factors and improved protein utilization. A total of 240 weaned piglets (Duroc${\times}$Landrace${\times}$Yorkshire, $9.01{\pm}0.22\;kg$ body weight) were randomly allocated to 4 treatments with 6 pens per treatment and 10 piglets per pen. The diets were based on corn-soybean meal and ESBM partially replaced soybean meal and soybean protein isolate at the inclusion level of 5, 10 or 15% in the basal diet. Feed intake and body weight were measured weekly. On days 24 to 27, faeces of each replicate were proportionally collected to determine the nutrient digestibility. On day 28 of the experiment, one piglet from each replicate was slaughtered humanely to collect immune organs. The results showed that inclusion of ESBM increased (p<0.05) the final weight, daily feed intake and daily gain of weaned pigs compared with the control diet, and ESBM at the inclusion levels of 10 and 15% improved (p<0.05) the feed/gain compared with the control diet. There were no differences (p>0.05) in daily feed intake among the levels of ESBM, but increasing the levels of ESBM from 5 to 15% improved (p<0.05) the final weight, average daily gain of pigs and feed/gain. The inclusion of ESBM at 5 to 15% increased (p<0.05) the digestibility of crude protein (CP) by 5 to 16%, and ESBM at 15% increased (p<0.05) the digestibility of digestible energy (DE), Ca and P compared with the control diet. ESBM increased (p<0.05) the relative weights of thymus and mandibular lymph nodes by 57.7 and 29.6%, respectively. The percentages of T lymphocytes, CD4+ and CD8+ in peripheral blood of weaned piglets were also increased (p<0.05) by feeding ESBM. The results suggest that ESBM can be a better protein source in improving growth performance, nutrient digestibility and immune function of weaned piglets.