The functional development of the calf II. Development of rumen function in the calf

Abstract

1. Two experiments were conducted to study the development of rumen function in young dairy calves under different feeding regimes.2. The volume of the rumen contents increased with age whereas the volume of the abomasum contents tended to remain constant.3. The concentration of total volatile fatty acids in the rumen liquor of milk-fed calves with free access to pasture reached constant levels at 5 weeks of age. Restricting calves to an all milk diet delayed the development of adult levels of volatile fatty acids until such time as roughage became available.4. Levels of rumen ammonia were high soon after birth but showed a decline with age. An absence of roughage in the diet tended to maintain higher levels of rumen ammonia.5. The pH of rumen liquor showed a steady increase from birth to 17 weeks of age.6. Both volatile fatty acid and ammonia levels in the rumen showed a characteristic diurnal pattern of variation.7. High figures for the digestibility of pasture by young calves were obtained. When calves which had been restricted to an all milk diet were offered roughage they quickly attained a digestive efficiency comparable with calves which had access to pasture from birth.