The effect of a cold environment on protein and energy metabolism in calves

摘要: Eleven Holstein bull calves 35 d of age were assigned to one three treatment groups: (1) W72, warm environment (20 degrees), 72 g feed/kg body weight (BW)0.75 per d, (2) C72, cold (-5 BW0.75 or (3) C90, 90 d. Fractional synthesis rates (FSR) protein in the rumen wall, papillae, omasum, duodenum, kidney, liver, heart, longissimus dorsi, biceps femoris and skin determined following a continuous infusion [3H]phenylalanine. Phenylalanine flux was elevated both groups cold-adapted calves. FSR two muscles reduced along with N retention C72 group compared other groups. Muscle degradation, estimated from urinary tau-methylhistidine excretion, tended be Reduced increased degradation contributed muscle gain. It appears that when feed intake is limited animals, have lower priority for nutrients than organs tissues, resulting synthesis. seems unlikely thermogenesis due enhanced heat production cold.