Effects of Eimeria brunetti on intestinal pH in conventional and gnotobiotic chickens

White Leghorn cockerels, 2-4 weeks of age, inoculated with sporulated oocysts of Eimeria brunetti had a lower mean pH in the middle and lower small intestine than did uninoculated controls by 5-9 days post-inoculation. No effect of the infection on pH was seen in the upper intestine while pH in the gizzard and caeca was occasionally higher than in controls. Magnitude of pH. decrease did not correlate with increases in oocyst dosage and severity of infection as measured by lesion score. Studies with germ-free (GF) and gnotobiotic chicks showed that host bacterial flora was essential for a pH decrease in the middle and lower small intestine with E. brunetti infection. Inoculation of GF birds with Lactobacillus acidophilus or L. acidophilus plus Streptococcus faecalis, in addition to E. brunetti resulted in some decrease in pH.