Effects of supplemental soy peptide on growth performance and gut health of nursery pigs

Abstract Text: The objective of this experiment was to evaluate the effect of soy peptide (Yunong, China) on growth performance, intestinal morphology, and oxidative stress in nursery pigs. A total of 40 pigs (20 barrows and 20 gilts at 5.33 ± 0.10 kg BW) were randomly allotted to 4 treatments in a randomized complete block design. Sex and initial BW were used as blocks. Pigs were fed a basal diet supplemented with soy peptide at the level of 0, 5, 10, or 15 g/kg based on 3 phases (7, 10, and 10 d, respectively). Soy peptide which was produced by soybean meal fermentation contained a greater amount (P < 0.05) of small sized peptides (< 37 kDa, 100.0%) compared with those of conventional soybean meal (44.7%). Body weight and feed consumption were recorded on d 7, 17, and 27. Increasing supplementation of soy peptide improved gain:feed (0.560 to 0.663, quadratic, P < 0.05) in phase 1 and tended to increase ADG (380 to 453 g/d, quadratic, P = 0.056) and ADFI (522 to 571 g/d, quadratic, P = 0.084) in phase 2. Increasing levels of soy peptide tended to increase villus height in the duodenum (517.6 to 572.5 μm, quadratic, P = 0.083) and the jejunum (442.6 to 504.9 μm, quadratic, P < 0.05). Proliferation activity measured by Ki-67 staining in the duodenum showed higher percentage of positive reactions in the pigs fed soy peptide than those fed a basal diet (10.6 to 18.2 %, P < 0.05). Increasing dietary soy peptide decreased tumor necrosis factor-α (TNF-α) in serum (72.8 to 52.4 pg/mL, linear, P < 0.05). Supplementation of soy peptide reduced TNF-α in the jejunum (1.24 to 0.46 pg/mg, P < 0.05). Pigs fed soy peptide had lower malonedialdehyde in the jejunum compared to those fed a basal diet (0.52 to 0.23, μmol/g protein, P < 0.05). In conclusion, soy peptide supplemented at 5 to 10 g/kg to nursery diets improved growth performance and gut health of pigs in association with enhanced villus development, reduced inflammatory cytokine levels, and reduced oxidative stress products. 

Keywords: growth performance, gut health, soy peptide