Blood leptin concentrations in Japanese Black cattle

Abstract

Abstract The objective of this study was to examine the changes of serum leptin levels in heifers and steers during fattening. Seven steers and seven heifers at 14 months of age were used in the experiment. Live weight and serum leptin levels were determined at 2-month intervals. Initial live weight was greater in steers than heifers and a similar trend of growth was recorded during the experiment. As a result, live weight was higher in the steers than in the heifers during the experiment. Serum leptin concentration in both groups increased during the experiment and reached optimum level at 22 months of age and did not change thereafter. The increase in serum leptin level was more marked in heifers and leptin level was higher (P < 0·05) in heifers than steers between 18 and 26 months of age. The results suggest that serum leptin level increases during fattening in cattle and the trend is possibly affected by gender.