Rumen ciliated protozoa of crossbred sheep kept in natural pasture of caatinga

Abstract

Effects of the sampling time and ruminal pH on the concentration of ciliate protozoa in the rumen of five fistulated Santa Inez crossbred sheep, reared in natural caatinga (scrubland) pasture were evaluated. Ruminal content samples were obtained at zero hour (before the animals were released to the pasture, at 7:00h) and 2, 4, 6, 8 and 10 hours thereafter. Samples were fixed in formalin at 18.5% (v/v). It was identified and quantified organisms of the genera Dasytricha, Diplodinium, Diploplastron, Entodinium, Eodinium, Elytroplastron, Enoploplastron, Epidinium, Eremoplastron, Eudiplodinium, Isotricha, Metadinium and Ophryoscolex. Among them, only Diploplastron and Entodinium presented variations at their population concentrations in function of the sampling time. The number of ciliates undergoing division was not correlated with the sampling times. Stable division rate seemed to contribute the maintenance of ciliates concentrations in the rumen. Ruminal pH was negatively correlated with sampling time, and was not correlated with the number of protozoa, probably because the variations observed included parameters considered ideal for establishment and maintenance protozoa populations of rumen.