Enzyme Activities in Liver, Muscle, and Adipose Tissue of Calves and Steers

Abstract

Enzyme adaptations associated with the development of a functional rumen were investigated in liver, skeletal muscle, and abdominal adipose tissue. The activities of several enzymes representative of pathways of carbohydrate metabolism were determined in tissues from milk-fed calves, early weaned calves, and finished steers. Associated with a functional rumen there was, in liver, a reduced capacity for glucose oxidation via the Embden-Meyerhof and hexose monophosphate pathways and an increased gluconeogenic capacity. In muscle, rumen development caused a reduction in capacities of the Embden-Meyerhof and glycogen synthetic pathways. The magnitude of enzyme adaptation in the bovine liver and muscle was low relative to adaptations observed previously in the rat. Activities of enzymes related to fat synthesis were greater in adipose tissue than in the liver, suggesting that adipose tissue is a relatively more important site of fatty acid synthesis. There were indications that enzyme adaptations in bovine adipose tissue are more dramatic than in liver and muscle. © 1968, American Dairy Science Association. All rights reserved.