Efeito da inclusão da torta de macaúba na população de protozoários do rúmen de vacas leiteiras

Abstract

The effects of meal macaúba (MM) inclusion on the concentration and profile of the ciliate protozoa of the bovine rumen were evaluated. Eight Holstein cows were used during second lactation, with average 480 kg of body weight, arranged in two 4x4 Latin squares simultaneously and fed four diets with different concentrations of the MM (0, 100, 200 and 300 g kg-1). For identification and quantification of protozoa, samples of ruminal fluid from each animal with 1 ml were diluted in 9 mL of 10% formaldehyde. After consecutive decimal dilutions in saline solution, protozoa were assessed in a Sedgewick chamber. The identification was carried out under the optical light microscope using a 40x objective to characterize at least 100 individuals per sample. The concentrations of small (P < 0.01), medium (P=0.05), large (P= 0.01), and the total number (P < 0.01) of protozoa decreased linearly with the increasing MM inclusion. Morphological characteristics typical of 16 genera of ciliates were found, being the Entodinium spp. and Eodinium spp. the most frequent in the rumen fluid of animals evaluated. The profile of the population of ciliated protozoa suffer minor changes with the addition of MM, with a change in the percentage share of Charonina spp. (P = 0.03) and Polyplastron spp. (P < 0.01). The use of the MM in the cattle diet promotes reduction in the concentration and change in the profile of the population of rumen ciliates protozoa.