EFFECT OF COLD-ACCLIMATION ON THE OXIDATIVE CAPACITY OF SKELETAL-MUSCLES AND LIVER IN YOUNG BANTAM CHICKS

1. 1. The effect of intermittently cold exposing newly hatched bantam chicks on the activities of cytochrome c oxidase of skeletal muscles and liver, have been investigated. 2. 2. The cytochrome oxidase activities of these tissues were significantly elevated in chicks acclimated to cold for 2 weeks, the activity in pectoral muscle being 153%, in thigh muscle 158%, and in liver 119% that of controls. 3. 3. The total enzyme activity of the red thigh muscles per unit weight was found to be 2.4 times that of the white pectoral muscles. Due to their larger mass, however, the muscles of the lower extremities of the young of this species have 3.4 times higher heat producing capacity than the pectoral muscles. 4. 4. When exposed to 0°C, the cold acclimated chicks appeared to utilize more of the total oxidative capacity of the skeletal muscles than the control chicks. The consequences of these changes in thermogenic capacity for the cold defence of bantam chicks are discussed. © 1979.