Comparative effects of replacing soybean meal in feeds with processed soybean meal on intestinal health and growth of nursery pigs when fed pharmacological level of zinc.

OBJECTIVE: The objective was to evaluate the effects of partially replacing soybean meal (SBM) in nursery pig diets with enzyme-treated soybean meal (ESBM), fermented soybean meal (FSBM), or fermented soybean meal containing probiotic microorganism (PFSBM) on jejunal mucosa-associated microbiota, immune responses, intestinal morphology, and growth performance of nursery pigs. METHODS: Forty-eight weaned pigs (initial body weight = 7.8 ± 0.7 kg) were randomly allocated to four dietary treatments in a randomized complete block design and fed for 25 d in three phases (5, 10, and 12 d, respectively). Dietary treatments were corn-SBM-based diet (SBM diet) and the SBM diet in which 70 g/kg of SBM was replaced with ESBM (ESBM diet), FSBM (FSBM diet), or PFSBM (PFSBM diet). Zinc oxide was supplemented at 2.5 g/kg (2,000 mg/kg of zinc) in the experimental diets for phases 1 and 2. Pigs were housed individually in pens (1.50 m×0.74 m) equipped with a feeder and a nipple drinker. Serum was collected on d 24 and pigs were euthanized on d 27 to collect tissues and mucosa in the jejunum. RESULTS: The PFSBM diet increased (p<0.05) the relative abundance of Lactobacillus, whereas it tended to decrease (p = 0.072) the abundance of Pseudomonas compared with the SBM diet. The ESBM diet increased (p<0.05) gain to feed ratio from d 5 to 15 compared with the SBM diet. However, partially replacing SBM at 70 g/kg with ESBM, FSBM, or PFSBM did not affect immune responses in serum and jejunal mucosa, intestinal morphology in the jejunum, and overall growth performance of nursery pigs. CONCLUSION: Partially replacing SBM with various processed SBM did not affect immune responses, intestinal morphology, and overall growth performance when diets were supplemented with zinc at pharmacological level in early phases.