EFFECT OF DIETARY DIETHYLSTILBESTROL ON POPULATIONS AND CONCENTRATIONS OF CILIATE PROTOZOA IN DAIRY CATTLE

Abstract

Two experimental diets with or without diethylstilbestrol (DES) were fed to four fistulated dairy cows in a 4 × 4 Latin square design. A continuous feeding system was used to give each cow 13–15 g of diet every two minutes. The continuous feeding appeared to remove the usual variation in the numbers of protozoa in the rumen content. This facilitated the sampling for studies of the effect of the diet on the concentrations and varieties of protozoa. Numbers of protozoa among days were similar with no significant differences. Total protozoa numbers were significantly higher (P < 0.01) for cows fed natural diets than for cows fed semi-purified diets. In addition, the feeding of DES resulted in a significant increase in total protozoa numbers. The inclusion of DES in the experimental diets aided the retention and establishment of different ciliate protozoa.