Publicação online; 31 ref.; 3 tables; Summary (En)

ABSTRACT - This study aimed to quantify and identify the profile of the rumen protozoa population of beef steers fed with or without roughage. Nellore crossbred steers raised in extensive system on lignified tropical pastures with mineral supplementation and steers confined for 60 days only receiving pelletized concentrate and whole corn kernels were evaluated. After slaughter, rumen fluid was collected and one ml aliquots were diluted in nine ml formaldehyde solution at 10%. The counts of small, medium and large protozoa were held in Sedgewick Rafter chambers and identification of genus was possible after staining lugol and optical microscope with a 40X objective. The concentration of rumen protozoa positively correlated with pH ruminal. Cattle fed without roughage had significantly lower rumen protozoa population (P<0.05). Animals fed roughage had higher occurrence of Dasytrichia genus, Charonina, Entodinum, Diplodinium, Ostracodinium and Epidinium while those fed without bulk, the Buetschilia, Isotricha, Eodinium, Polyplastron, Elyplastron, Metadinium and Enoploplastron were the most frequent
genus.


Keywords: ciliates, rumen microorganisms, beef cattle, ruminal acidosis, termination