a1 Animal Nutrition and Health Department, Scottish Agricultural College, West Mains Road, Edinburgh, EH9 3JG, UK
a2 Department of Animal Production, School of Veterinary Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
a3 Faculty of Veterinary Medicine, University of Thessaly, Trikalon 224, 43100 Karditsa, Greece
An experiment was conducted to investigate the effects of post-weaning dietary protein supply and weaning age on the performance of pigs in the absence of in-feed antimicrobial growth promoters (AGP) when artificially challenged with enterotoxigenic Escherichia coli (ETEC), a pathogen associated with post-weaning colibacillosis (PWC). The experiment consisted of a complete 2 × 2 × 2 factorial combination of two weaning ages (4 v. 6 week), two levels of dietary protein (H, 230 g CP/kg v. L, 130 g CP/kg) and challenge with ETEC (+ v. −). An additional four treatments were added to test for the effects of protein source (DSMP, dried skimmed milk powder v. SOYA, soybean meal) and AGP inclusion (yes v. no) on challenged pigs of both weaning ages. At weaning (day 0), pigs were assigned to one of the experimental treatments for 2 weeks. On day 14 post-weaning, the same standard grower ration was fed to all animals until 10 weeks of age. On day 3 post weaning, challenged pigs were administered per os with 109 cfu ETEC. The ETEC challenge had a detrimental short-term effect on performance, decreasing average daily gain (ADG) (days 3 to 6; P = 0.014) in both 4- and 6-week weaned animals. Compared with their non-infected counterparts, challenged 4-week weaned pigs on the H diet demonstrated a larger decrease in ADG immediately post infection than those on the L diet, −42% and −25%, respectively (P = 0.088). This effect was smaller in the 6-week weaned pigs, −26% and −19% for the H and L diets, respectively. Pigs fed SOYA had lower (P < 0.001) daily intake and ADG (day 0 to 14) than those fed DSMP, with 6-week weaned pigs being affected to a greater extent than 4-week weaned pigs. In the absence of AGP, increasing weaning age and decreasing dietary protein level, especially in earlier weaned pigs, may help to minimise the effects of PWC on performance, particularly in sub-optimal environments.
(Received December 07 2006)
(Accepted November 13 2007)
p1 Present address: ABN, Oundle Road, Peterborough, PE2 9PW, UK