0
Sixty-four crossbred piglets, weaned at 21 d of age were assigned to the treatments as follows: 8 piglets that received the basal diet without challenge with ETEC (B), 28 piglets that received the basal diet and challenged with ETEC (BCh) and 28 piglets that received the basal plus Trp diet and challenged with ETEC (TrpCh). All the pigs were fed diets with colistin (250 mg/kg) for 4 d to ensure similar health conditions in the gut. On d 5, each pig from groups BCh and TrpCh was orally dosed with 1.5 mL suspension containing 1010 CFU of E. coli K88ac O149/mL. Pigs in treatment B received a placebo solution. Based on in vitro villus adhesion assay, the pigs (except the B group) were classified as susceptible (s+) or nonsusceptible (s?) to the intestinal ETEC adhesion. Thus, after the challenge, treatments were B, BChs-, BChs+, TrpChs-, and TrpChs+. Pigs were individually weighed at the start of the trial and on d 5, 9 and 23. Blood and fecal samples were obtained immediately before the challenge and at the first and second slaughter days. At slaughter, stomach and small intestine were removed and weighed full and empty. Segments of the jejunum and ileum were collected for morfometrical measurements. Samples of ileal content were collected for the determination of total E. coli and ETEC plate counts.
For the susceptibilities of ETEC, the frequency of pigs susceptible or unsusceptible to ETEC was very similar, especially if pigs that died of colibacillosis are included. The frequency was also similar among the 3 treatment groups. Tryptophan increased ADG and feed intake in susceptible pigs (P < 0.05) from challenge to d 4, but not thereafter. The K88-specific immunoglobulin A activity in blood serum tended to be greater in challenged pigs (P = 0.102) and was not affected by the addition of Trp. Villous height was affected by the addition of Trp and challenge in different ways, depending on the site of small intestine. The need to consider the phenotype for the adhesion of the ETEC in studies with different supply of Trp was clearly evident.
In conclusion, when compared with practical weaning standard diets, Trp supplementation allowed susceptible pigs to partially compensate for the effects of ETEC challenge by increasing feed intake, maintaining an adequate BW growth.
P Trevisi, D Melchior, M Mazzoni, L Casini, S De Filippi, L Minieri, G Lalatta-Costerbosa and P Bosi. 2009. Journal of Animal Science. 87:148-156
