A tryptophan-enriched diet improves feed intake and growth performance of susceptible weanling pigs upon oral E. coli K88 challenge

We tested the effect ofthe addition of 1 g L- tryptophan/kg to a stardard weaning diet and of oral challenge with E. coti K88 (ETEC), on grovth and health of piglets susceptible or not to the intestinal adhesion of ETEC. Were used 64 pigs weaned at 21d of age: a contol group (8 pigs) fed a basal diet (B) and two challenged groups each of 28 pigs: one group fed B diet (group BE) and the other fed a diet with tryptophan (group TE). On d5 pigs were orally challenged with 1010 CFU E. coli K88 and sacrificed on d9 or 23. By in vito test,t he subjects ofBE and TE groups were classified as susceptible( s') or non-susceptible( s) to the intestinal ETEC adhesion.In the first four days post-challenge, the challenge reduced ADG (P<0.05), and this reduction was greater in susceptible pigs (P<0.05). Tryptophan increased ADG and feed intake in susceptible pigs (P<0.05) from challenge to d4, but not later. The K88-specific IgA activity in blood serum was higher in challenged pigs (P=0.102) and was not affected by the diet. Moreover, as compared to standard diets, the supplementation with tryptophan, allows susceptible pigs to partially compensate for the effects of challenge. This is of practical relevance for improved genotypes due to the association of positive subjects with lean growth.