Navas et al., 1992. Livest. Res. Rural Dev., 4 (1): 55-63

Elimination of ciliate protozoa from the rumen (defaunation) improves the protein to energy ratio in the nutrients absorbed by increasing the amount of bacterial and sometimes dietary amino acids available for absorption at the small intestine. The increased ratio of amino acids to volatile fatty acids in the nutrients absorbed leads to the better performance observed in defaunated animals. There are however no commercial alternatives to obtain defaunated ruminants at the farm level. The present paper discusses the effect of supplementing sheep with different levels of tree legumes (Enterolobium cyclocarpum) on the concentration of ciliate protozoa in the rumen fluid. The inclusion of E. cyclocarpum as supplement or basal diet in the diet of sheep, does not eliminate protozoa from the rumen, but causes a significant reduction of total protozoa numbers and a variation in the species of protozoa present in the rumen. Holotrichs are the most susceptible species to E. cyclocarpum. Supplementation with E. cyclocarpum may be an alternative to increase the protein to energy ratio in the nutrients absorbed, by increasing the flow of dietary amino acids to the duodenum. At high levels of inclusion in the diet, it may also increase the flow of bacterial-N to the small intestine due to the lower number of protozoa in the rumen. However, the reduction in dry matter intake may affect animal performance when the proportion of E. cyclocarpum in the diet is high.