Coccidiosis and intestinal pH in chickens

The intestinal contents of white Leghorn cockerels were significantly lower in pH in birds infected with Eimeria mivati, E. maxima, or E. necatrix than in uninoculated control birds. The particular Eimeria species used affected the region of the intestine involved, the days (5-9 postinoculation) on which pH decreased, and the magnitude of the decrease. The effects on the magnitude and frequency of pH decrease were as follows: E. mivati, marked in the duodenum and jejunum, variable in the ileum; E. maxima, slight in the duodenum, variable in the jejunum and ileum; E. necatrix, no change in the duodenum, variable in the jejunum and ileum. Infection with E. tenella did not change the intestinal pH. The pH of the gizzard was occasionally higher in birds infected with E. mivati or E. necatrix than in uninoculated control birds. With all four species, on some days the pH in the ceca was higher than in the ceca of controls. These results and previous reports indicate that infection with one of the above four species or with E. acervulina or E. brunetti produces the greatest and most consistent decrease in pH in the region of the intestine where the particular species characteristically produces the severest infection.