The effect of nutritional factors in the control of Escherichia coli in the ileum of the weanling pig

Research studies were conducted using weanling pigs cannulated in the terminal ileum to test the effects of several dietary factors on the enteric microbial populations in weanling pigs. Feed treatments tested included a.25%,.5% and 1.0% inclusion of a propionic acid containing feed additive (Luprosil-NC, BASF Corp) and 1% inclusions of galactan and $\beta$-D-galactose. Samples were assayed for total E. coli, lactobacilli, K88$\sp{+}$ E. coli, pH, and volatile fatty acids. A study was also conducted to determine if restriction of feed in the early postweaning stage of young piglets affected E. coli and lactobacilli concentrations in the ileum. In addition to these studies a technique using immunoaffinity paramagnetic particles to separate E. coli based on their fimbrial antigenic properties was tested. No significant differences were found in E. coli or lactobacilli concentrations between ad libitum and restricted feeding regimes. All pigs showed a significant decrease in lactobacilli concentrations on day 2 after weaning. In trials testing various levels of Luprosil-NC (L), pigs fed.25% L had significantly lower ileal pH on day 4, significantly lower E. coli concentrations on days 2 and 14 and lower K88$\sp{+}$ E. coli on day 4 after weaning. Volatile fatty acid profiles were different between diets on days 4, 8 and 10 of the trials. At the end of the trial, there were significant differences in VFA concentrations between diets in all locations tested. The concentration of propionate was highest for pigs fed 1% L in the stomach; acetate concentration was highest in pigs fed.25% L in the duodenum; butyrate, valerate and total VFA concentrations were highest in pigs fed.25% L in the cecum and butyrate, isovalerate, valerate and total VFA concentrations were highest in pigs fed.25% L in the colon. Pigs fed 1% galactan had lower pH values and lower total and K88$\sp{+}$ E. coli concentrations compared to pigs fed the control diet. Pigs fed 1% $\beta$-D-galactose had higher concentrations of lactobacilli and had significantly higher average daily gain than pigs fed the control diet. In both the galactan and $\beta$-D-galactose trials, production of most VFA\u27s was significantly higher on day 0 than on any other day of the experiment. At the end of the trials, production of acetate was significantly lower in the cecum of pigs fed 1% galactan