Influence of rumen ciliate protozoa and protein level on rumen fermentation, enzyme activities and blood metabolites in crossbred cattle calves.

摘要

The influence of rumen ciliate protozoa on fermentation, rumen fluid enzyme activity and blood metabolites was examined in crossbred (Bos taurus X Bos indicus) calves fed on 2 levels of protein. 16 crossbred male calves, separated from dams between24 and 48 h of birth, were divided into 2 groups - faunated and defaunated and fed on a diet of normal protein or low protein (75% of the requirement). Calves were reared in isolation stalls to avoid contact with faunated calves. At 3 months of age rumencontents were collected at 4 h post feeding and analysed. pH, total volatile fatty acids, carboxymethylcellulase, xylanase and protease activities were similar in faunated and fauna-free calves. Ammonia-nitrogen, trichloroacetic acid-soluble nitrogen, urease activity, plasma protein and urea levels were significantly lower in defaunated calves, whereas, plasma glucose level was significantly higher in defaunated animals. Blood haemoglobin level was not affected by the presence or absence of protozoa orby the protein level in the diet. It is concluded that the rumen ciliate protozoa exert a large affect on N metabolism of rumen microbes.