The objective of the present study was to record the occurrence of predation and cannibalism among ciliate protozoans in the rumen of sheep. The analyzed samples consisted of ruminal contents of five fistulated Santa Inez crossbred sheep, maintained in a natural caatinga (scrubland) pasture in the municipality of Sertânia, Pernambuco. Six samples of ruminal content were obtained from each sheep (total of 30 samples) and fixed in formalin at 18.5% (v/v). One 1 ml aliquot was obtained from each sample of ruminal content and received tree drops of a lugol solution for staining and identification of protozoa ciliates. These aliquots were analyzed in slides and coverslips, at randomly determined fields. An instance of predator-prey interaction was observed among ciliates of Ophryoscolecidae Stein, 1859, where Elytroplastron bubali (Dogiel, 1928) preyed on Enoploplastron triloricatum (Dogiel, 1925) and on species of Epidinium Crawley, 1923 and Entodinium Stein, 1859. Cases of cannibalism were observed among specimens of E. bubali, which consist of the first record this type of interaction in this species. This is, moreover, the first record of occurrence of E. bubali in the rumen of sheep in Brazil.
Caatinga; competition; entodiniomorphs; predator; prey
