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.