A comparison of feeding acetylated high-amylose maize starch and zinc oxide in weaned pigs experimentally inoculated with an enterotoxigenic strain of <i>Escherichia coli</i>

Post-weaning diarrhea (PWD) remains a major problem for some pork producers, exacerbated by restrictions or bans on the use of antimicrobial compounds. Acetylated high-amylose maize starch (HAMSA) delivers acetate to the large bowel and may reduce the severity of enteric infections, including those caused by Escherichia coli (E. coli). This study examined the effects of HAMSA and zinc oxide (ZnO) supplementation on PWD and performance in pigs experimentally inoculated with an F4 enterotoxigenic strain of E. coli (F4-ETEC). Seventy-two weaned pigs were divided into three dietary groups: 1) control (no antimicrobial compounds); 2) control plus 3,000 mg ZnO/kg; and 3) control plus 50 g HAMSA/kg. Pigs commenced diets on the day of weaning, were inoculated with an F4-ETEC strain on days 5 and 6, and were fed diets ad libitum for 21 days. The incidence of PWD (χ2 = 0.035) and the diarrhea index (P = 0.032) were both lowest, commensurate with a lower plasma haptoglobin concentration (P = 0.010), in pigs fed ZnO than pigs fed other diets, despite there being a trend for an interaction (P = 0.088) in pigs fed HAMSA to have a lower F4 E. coli:total E. coli ratio on d 11 after weaning. Pigs fed ZnO and HAMSA grew faster (P = 0.009) and ate more (P = 0.048) in week 3 than control pigs. Overall, there was a trend (P = 0.065) for pigs fed the ZnO diet or HAMSA diet to eat ~ 20% more than those fed the control diet that resulted in a trend (P = 0.064) for ZnO- and HAMSA-fed pigs to weigh ~ 10% more than control-fed pigs at the end of the study. The HAMSA-fed pigs had a lower (P = 0.044) FCR in week 3, and overall (P = 0.003). Pigs fed HAMSA did not show any increase (P > 0.05) in their fecal short-chain fatty acid or acetate concentrations. The significant effect of HAMSA on FCR justifies further investigation as this may improve production efficiency in the post-weaning period following an enteric F4-ETEC infection.