Determination the Relationship between Blood Plasma Leptin and Progesterone Concentration in Pre and Post Sexual Maturity in Najdi Female Calves

The aim of this study was to determine the relationship between blood plasma leptin and progesterone concentrations in pre and post sexual maturity in Najdi female calves. For this purpose 7 female Najdi calves of Shushtar Breeding Station of Najdi cattle with average ages of 8 months and the average weight is 85/00±9/72 were used. For determination of the leptin and progesterone concentrations, multiple sampling before and after sexual maturity were performed. The results of this study indicate that in female Najdi calves, 13-16 month with 137.81±13.5 kg body weight was considered the age of sexual maturity. No significant correlation was found between plasma leptin and progesterone concentrations before (r=0.082, p>0.05) and after sexual maturity (r =0.096, p>0.05). There was a significantly positive correlation (r=0.73, p<0.01) between leptin concentration and body weight. Significantly positive correlation (r=0.84, p<0.01) were found between plasma leptin and age. The significantly positive correlation between plasma progesterone concentration and age (r=0.45, p<0.01) as well as body weight (r=0.44, p<0.01) were observed. In conclusion, the results showed that there was no significant relationship between leptin and progesterone concentration, but there was a positive correlation between leptin, progesterone and body weight and bud age of Najdi female calves.