Low dietary protein decreases ETEC proliferation and attachment in the intestinal mucosa

Low-protein amino acid-(AA) supplemented diets may be a successful way of managing postweaning diarrhea in piglets, by feeding a low-protein AA-supplemented diet reducing toxic intestinal protein fermentation products. It was hypothesized that feeding a low-CP, AA-supplemented diet to piglets challenged with Escherichia coli (ETEC) K88 would reduce ETEC proliferation and colonization of intestinal mucosa thereby maintaining intestinal function and gut health, reducing indices of bacterial concentrations. The objective of this study was to determine the effects of dietary CP content on intestinal indices of ETEC infection and health in piglets challenged with ETEC K88.

Forty piglets with 6.96 ± 0.45 kg of body weight, housed four per pen, were randomly allotted to two diets: a 22.2% CP or a 17.3% CP supplemented with AA. Diets contained the same amount of standardized ileal digestible Lys, Met+Cys, Thr, Trp based on the ideal AA ratio. Isoleucine and Val were added to the 17.3% CP diet up to the level in the 22.2% CP diet. Three piglets per pen were serially slaughtered on days 3, 5, and 7 after weaning for evaluation of intestinal hydrolases. 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 of the current study show that low dietary CP content results in a significant depression of both content and colonization of the jejunal mucosal by ETEC K88 at 20 h after an acute challenge.

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: 7178. doi:10.4141/CJAS-2014-071