Observações pertinentes à instalação da fauna de protozoários ciliados no rúmen de bezerros de raça Holandesa (Bos taurus, L.), criados em Pindamonhangaba, S.P., Brasil

Forty five Holstein calves, from 7 to 270 day old, were used to estimate the ciliated protozoa fauna present in the ruminal liquid. For this purpose, the Sedgwick-Fafter chamber has been choiced. Species of five genus were detected: Entodinium, Diplodinium, Epidinium, Isotricha and Dasytricha. The Entodinium Spp constituted the most numerous protozoa in the whole populations for the different ages. After birth, species of Entodinium and Diplodinium were the firs t to be present, third month after birth, with an average ruminal pH 4,90. Species of Epidinium were found in calves with four months and ruminal pH about 5,38. Species o f Isotricha and Dasytricha were the last to be present, in calves with six months and a ruminal pH of 6,0.