Currently, a major source of protein in swine diets is soybean meal (SBM). Nevertheless, its application in diets for piglets is limited because it includes some anti-nutritional factors and antigenic proteins, which interfere with nutrient digestion, absorption and utilization. The degradation of most antigenic proteins (glycinin and β-conglycinin) and protease inhibitors in fermented SBM by Bacillus subtilis has shown improvements in intestinal morphology and digestive enzyme activities of weaned pigs. Fermentation also degrades proteins and carbohydrates and lower molecular-weight and water-soluble compounds, therefore diminishing risk of diarrhoea. In order to increase nutritive values of soybean meal (SBM), 3 species of microbes were used to ferment SBM. Through a 3 × 3 orthogonal design and parameter measurements of soybean peptide and anti-nutritional factor contents in the fermented soybean meal (FSBM), it was estimated that the best microbial proportion of Bacillus subtilis, Hansenula anomala and Lactobacillus casei was 2:1:2 for the SBM fermentation. Twenty-five litters of 7-day-old suckling piglets were selected and divided into 5 groups with 5 litters for each group according to their body weight and sex (half male and half female). The 5 diets were: a basal diet containing 10% SBM and 6% plasma protein (PP), or 10% FSBM and 6% PP; or 10% FSBM and 4% PP, or 10% FSBM and 2% PP, or 10% FSBM and 0% PP. The piglets were fed creep diets during suckling period, and weaned at 28 d of age. After weaning, the piglets were continually fed creep diets for 10 d. Another trail with two hundred and fifty 35-day-old pigs was performed. Piglets were assigned to 5 groups with 5 replications for each group and 10 piglets for each replication. The experimental period was 30 d. The five diets were a basal diet as control; a 3.75% FSBM substitute for SBM; a 7.50% FSBM substitute for SBM and wheat bran; a 3.75% SBPC (SB protein concentrate) substitute for SBM and wheat bran; and, a 7.50% SBPC substitute for SBM and wheat bran.
The piglet feeding experiment showed that 10% FSBM substitute for SBM had no significant effect on growth performance of suckling piglets (d 7–28). However, newly-weaned piglets (d 28–38) fed 10% FSBM and different levels of plasma protein obtained higher average daily gain (ADG) and feed conversion ratio (FCR), compared with those without FSBM but with 6% plasma protein. Piglets (d 38–68) fed diets supplemented with FSBM and soybean protein concentrate (SBPC) at 3.75% and 7.5% respectively increased nutrient digestibility, fecal enzyme activity and lactic acid bacteria counts, and decreased fecal Escherichia coli counts, compared with the control. These data indicated that the microbial proportion of Bacillus subtilis, H. anomala and L. casei at 2:1:2 can increase soybean peptide content and nutritive value of SBM, and decrease anti-nutritional factor content in SBM. The feeding experiments of suckling and weaned piglets showed that FSBM could replace plasma protein and SBPC in diets for piglet production and economical profit.
Yuan, L., Chang, J., Yin, Q., Lu, M., Di, Y., Wang, P., Wang, Z., Wang, E., and Lu, F. (2017). Fermented soybean meal improves the growth performance, nutrient digestibility, and microbial flora in piglets. Animal Nutrition, 3(1), 19-24. https://doi.org/10.1016/j.aninu.2016.11.003