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The experiment was carried out in a 2x2x2 factorial experiment: two weaning ages (4 and 6 weeks), two protein levels (high protein 23% HP; low protein 13%, LP), and the enterotoxigenic Escherichia coli (ETEC) experimental challenge (+ versus -). A total of 32 piglets from each weaning age were individually penned and had ad libitum access to the HP or LP diets, for 14 days. On day 3 post-weaning half part of the animals were orally infected with ETEC (O149). During the experimental period fecal consistency was recorded daily, and samples were collected to determine the presence of ETEC. Additionally six piglets per weaning age were slaughtered on day 0, and four pigs per treatment were slaughtered on day 6, in order to assess digesta pH and the ratio of Lactobacilli to coliforms.
Animals did not show clinical postweaning colibacillosis, and no significant effect of infection on fecal score was found. Howerer, 4 weeks old weaned piglets that were challenged with ETEC showed a tendency to a worse fecal score compared to the 6 weeks weaned challenged piglets. Number of ETEC colonies in the faces was greater and persisted longer in the 4 week weaned piglets compared to the 6 week weaned piglets (P = 0.003). In the case of the 4 week weaned piglets a tendency was found between the HP and LP diets, being the shedding in the LP fed animals lower compared to HP fed animals. Modifications in the pH of the gastrointestinal contents were only found between the two weaning ages, being the values more favourable on the 6 week weaned piglets. Lactobacilli:coliform ratio was higher in the 4 week weaned piglets on day 0, but on day 6 the decrease in the ratio was higher than that found in the 6 week weaned piglets.
Therefore, older piglets at weaning may be more resistant to the postweaning collibacillosis, being a low protein diet favourable in this resistance, especially when young piglets are considered.
Wellock, I.J., Fortomaris, P.D., Houdijk, J.G.M., Kyriazakis, I. (2007) Livestock Science, 108: 102-105
