Effects of growth hormone and monensin on adipose tissue lipogenesis in transition cow

摘要

Twenty nine multiparous, Holstein dairy cows in late gestation were used to evaluate the effect of prepartum administration of monensin (M) and/or bST on prepartum and postpartum adipose tissue lipogenesis. During the prepartum period 300 mg of M wasadded to the total mixed ration, and 500 mg slow release bST was injected on d 28 and 14 prior to calving. Subcutaneous adipose tissue samples were taken at 3 weeks prepartum and 2 weeks postpartum. Rate of lipogenesis was assessed by measuring the incorporation of labeled acetate into total lipids of adipose tissue explants over 2-h period of incubation at 38 C. On the week of the adipose tissue biopsy, blood samples were collected and analyzed for insulin, growth hormone, IGF1, NEFA and glucose. In prepartum cows, lipogenesis was increased by bST treatment but not by M. Postpartum lipogenesis was about 200 fold lower than the prepartum values, and was not affected by M or by bST. In prepartum cows the level of NEFA tended to decrease by 20% in bST orM treated cows. Concentration of GH was elevated by 60% in bST treated cows. Level of insulin, IGF1 and glucose were similar among treatments. In postpartum cows DMI tended to increase by 11% in M treated cows. Levels of GH, insulin, and IGF1, NEFA andglucose were not affected by M and bST.