Effects of dietary crude protein content on intestinal indicators of infection and diarrhoea in pigs challenged with enterotoxigenic Escherichia coli (ETEC) K88 have been investigated by Martin Nyachoti of the University of Manitoba in Canada and co-authors there and at the University of Prince Edward Island and Evonik Degussa in Germany.

In a paper published in the Canadian Journal of Animal Science, they explain that 40 piglets (bodyweight 6.96±0.45kg, mean±SD], housed four per pen, were randomly allotted to two diets (five pens per diet): a 22.2 per cent or 17.3 per cent crude protein supplemented with amino acids. Diets contained the same amount of standardised ileal digestible lysine, methionine plus cystine, threonine and tryptophan based on the ideal amino acid ratio. Isoleucine and valine were added to the 17.3 per cent protein diet up to the level in the 22.2 per cent protein 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. These data have been reported elsewhere, the authors noted.

On day 8 post-weaning, the remaining pigs were inoculated with 6mL of ETEC suspension (10¹⁰CFU per ml) and slaughtered 20 hours later.

Mucosal-associated ETEC was detected in higher counts (3.17±0.63 log-10 CFU per gram of digesta) in 80 per cent of pigs fed the 22.2 per cent protein diet compared with 20 per cent of those fed the 17.3 per cent protein diet in which the counts were also lower (2.00±log₁₀ CFU g−1 digesta).

Pigs fed the 22.2 per cent protein diet tended (P=0.09) to have fewer goblet cells with sialomucins in jejunal villi compared with those fed the 17.3 per cent protein 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 per cent protein diet than the 17.3 per cent protein diet.

Nyachoti and co-authors concluded that feeding a low-crude protein diet decreases ETEC proliferation and attachment in the intestinal mucosa and this is accompanied by a reduced expression of sodium-coupled glucose transporter 1.

Reference

Opapeju F.O., J.C. Rodriguez-Lecompte, M. Rademacher, D.O. Krause and C.M. Nyachoti. 2015. Low crude protein diets modulate intestinal responses in weaned pigs challenged with Escherichia coli K88. Canadian Journal of Animal Science, 2015, 95(1): 71-78, 10.4141/cjas-2014-071.

March 2015