Studies on nutritional significance of rumen ciliate protozoa in cattle. 3. Influence of protozoa on growth rate, food intake, rumen fermentation and various plasma components in calves under different planes of nutrition

Itabashi, H.; Matsukawa, T.

Bulletin of the Tohoku National Agricultural Experiment Station 59: 111-128


Accession: 000756236

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Of 8 female calves (separated from the cows at 3 days of age) 4 had mixed rumen protozoa inoculated into the rumen at 4 to 5 weeks of age and 4 had no protozoa throughout the 36 weeks of the trial. They were given milk to 15 weeks of age and then concentrate at 2 kg daily and chopped hay freely. In a 2nd similar trial the calves were male and after weaning they were given hay freely and no concentrate. There was no significant difference in rate of gain of body-weight between the groups over the whole period of the trial, but over the first 20 weeks the calves given protozoa gained significantly more than calves not given protozoa. Main differences were the greater body length in calves with protozoa and the greater belly girth in calves without. From 4 to 5 months of age in the first trial and from 6 to 8 months of age in the 2nd, inoculated calves given protozoa ate more hay than the other group; both groups ate almost all the concentrate offered in the first trial. Concentration in rumen fluid of ammonia nitrogen was much higher, and that of volatile fatty acid was slightly higher, with than without protozoa. With protozoa there was a higher concentration of butyric acid, causing lower ratios of acetic:butyric and of propionic:butyric acids than in calves not given protozoa. In adult cattle the digestibility of dry matter, crude protein and crude fat in hay and of crude protein in rice straw was significantly higher with protozoa than without. From 16 to 32 weeks of age in the first trial and from 20 to 32 weeks in the 2nd, plasma urea N concentration was higher with protozoa than without. There was no difference between groups in haematocrit or in concentrations of total protein, albumin, glucose, magnesium, calcium or inorganic phosphorus in plasma. At 5 months of age plasma free amino acids tended to be lower in calves with than without protozoa, the difference being greatest in valine, lysine, leucine and glycine. In the first trial, plasma essential amino acids were estimated before and 4 hours after a mixture of starch and glucose was given. During that interval the amino acid decreasing most was lysine, methionine or isoleucine in 3 different calves with protozoa, and in 2 of 3 calves without protozoa it was lysine, and in one other it was methionine. This suggested that lysine would be limiting for protein synthesis in calves without protozoa, but lysine concentration estimated in plasm was consistently higher in calves without than with rumen protozoa.