Effects of different fermented soy protein and apparent ileal digestible lysine levels on weaning pigs fed fermented soy protein-amended diets.

Two experiments were conducted to evaluate the effect of different fermented soybean proteins and the apparent ileal digestible lysine levels on weaning pigs fed fermented soy protein (FSP)-amended diets. In Exp. 1, 70 crossed piglets (6.25 ± 0.40 kg) were used in a 5-week trial to evaluate two different FSP. In Exp. 2, 20 weaning barrows (6.15 ± 0.45 kg) were used in a metabolism trial to determine the effects of the apparent ileal digestible (1.2, 1.3, 1.4 and 1.5%) lysine levels in weaning pigs fed FSP (5%) diet. In Exp. 1, pigs fed the diet containing Lactobacillus spp. FSP showed higher nitrogen (N) digestibility (P<0.05), lower blood urea nitrogen and serum creatinine levels (P<0.05) than those fed the Aspergillus oryzae FSP diet. In Exp. 2, increasing dietary lysine levels increased the average daily gain, apparent dry matter, N digestibility, N retention and essential amino acids in the current study (P<0.05), with the 1.5% showing the highest value. In conclusion, pigs fed Lactobacillus spp. FSP had a higher N digestibility than those fed A. oryzae FSP. The optimal apparent ileal digestibility lysine level in fermented soy protein diets (3550 kcal/kg metabolizable energy) for maximizing growth performance and N utilization in the first 7 days (6.25 kg) was 1.5%.