Serum leptin levels in cattle with different nutritional conditions

The role of leptin as an energetic state indicator in cattle was evaluated correlating different nutritional conditions and serum leptin levels. Two e xperiments were developed. Experiment I: Polled Hereford heifers were fed i n optimum conditions and assigned randomly to one of three treatment diets: grazing, grazing plus supplementation and feedlot, Experiment II: cattle w ere subjected to feed restriction Oil. Serum leptin levels were measured at pre and post-feeding moments. Using serum free fatty acid (FFA), beta -OH Butyrate (beta -OHB) and protein concentration as serum energetic indicator s in both experiments. In experiment I leptin values were significantly dif ferent between pre and post-feeding moments, similar differences were found among groups when the pre-feeding and post-feeding values were compared. T hese differences may be considered as changes associated to the control of food intake. In experiment II, the serum leptin levels in Group R were sign ificantly lower. The poor energetic status of animals from group R was demo nstrated by the serum FFA, beta -OHB and protein concentrations. These resu lts suggest that the energetic status of animals is correlated with the ser um leptin levels, tending to maintain the energetic homeostasis, (C) 2001 E lsevier Science Inc. All rights reserved.