Study of the relationship between plasma concentration of leptin and plasma in the Pre- and past puberty in Najdi male calves

The purpose of this study was to investigate the relationship between plasma leptin and blood testosterone concentration before and after puberty. Eight male Najdi calves with mean age of 7 months were used for this purpose. Blood samples were taken three times before and after reaching puberty. At each sampling period, a blood sample was collected to determine the plasma concentration of leptin from all 8 consecutive and 6 consecutive blood samples and at 20 min intervals from 4 animals to determine the plasma level of testosterone. The results of this study showed that the age of puberty in the Najdi race was 13-15 months old and the average weight was 120.08 ± 36.91 kg. Plasma leptin concentration was negatively correlated with testosterone (P <0.05, r = -0.43), age (P <0.01, r = -0.77), body weight (P <0.01, -0.39), testicular environment (r = -0.62, P <0.01) and testicular height (r = -0.72, P <0.01). In general, it can be concluded that with the onset of puberty and the increase in testosterone concentration, leptin concentration decreased due to the negative effect of testosterone on the production of leptin hormone in the body.