Low crude protein diets modulate intestinal responses in weaned pigs challenged with Escherichia coli K88

Opapeju, F. O., Rodriguez-Lecompte, J. C., Rademacher, M., Krause, D. O. and Nyachoti, C. M. 2015. Low crude protein diets modulate intestinal responses in weaned pigs challenged with Escherichia coli K88. Can. J. Anim. Sci. 95: 71-78. Effects of dietary crude protein (CP) content on intestinal indicators of infection and diarrhea in pigs challenged with enterotoxigenic Escherichia coli (ETEC) K88 were investigated. Forty piglets [body weight (BW)=6.96±0.45, mean±SD], housed four per pen, were randomly allotted to two diets (five pens per diet): a 22.2% CP or a 17.3% CP supplemented with amino acids. Diets contained the same amount of standardized ileal digestible Lys, Met+Cys, Thr, Trp based on the ideal amino acid ratio. Isoleucine and Val were added to the 17.3% CP diet up to the level in the 22.2% CP diet. All other nutrients were as per National Research Council (1998) specification. Three piglets per pen were serially slaughtered on days 3, 5, and 7 after weaning for evaluation of intestinal hydrolases (data reported elsewhere). On day 8 post-weaning, the remaining pigs were inoculated with 6 mL of ETEC suspension (10¹⁰ CFU mL⁻¹) and slaughtered 20 h later. Mucosal-associated ETEC was detected in higher counts (3.17±0.63 log₁₀ CFU g⁻¹ digesta) in 80% of pigs fed the 22.2% CP diet compared with 20% of those fed the 17.3% CP diet in which the counts were also lower (2.00±log₁₀ CFU g⁻¹ digesta). Pigs fed the 22.2% CP diet tended (P=0.09) to have fewer goblet cells with sialomucins in jejunal villi compared with those fed the 17.3% CP diet. The expression of toll-like receptors 4 and 5 was unaffected by diet but the expression of sodium-coupled glucose transporter 1 was higher (P=0.04) in the jejunum of pigs fed the 22.2% CP diet compared with those fed the 17.3% CP diet. The results suggest that feeding a low-CP diet decreases ETEC proliferation and attachment in the intestinal mucosa and this is accompanied by a reduced expression of sodium-coupled glucose transporter 1.