Changes in profiles of serum sex steroids of male buffaloes from birth to maturity

Abstract

Age-related changes in testosterone, progesterone and estradiol 17-β were determined by radioimmunoassay (RIA) in the serum of 155 male buffalo calves of varying ages. The calves were classified into 17 age groups. The mean weight of calves increased from 33.6 ± 9.6 kg at one week of age to 531 ± 41.4 kg at 42 months. The testosterone levels were less than 100 pg/ml from birth until 15 months of age, followed by peak concentrations of 422 ± 79 pg/ml at 24 to 30 months and 793 ± 193 pg/ml at 42 to 48 months (corresponding to puberty and maturity, respectively). The progesterone levels were higher in newly born calves and mature bulls. Otherwise, the levels continued to be low throughout the period of growth and development. Estradiol 17-β was significantly higher in postnatal calves up to two months of age. The testosterone revealed a positive correlation with weight and age while E2 17-β showed a negative correlation with age. These results do not support a direct role of peripheral progesterone and estradiol 17-β in the onset of puberty and sexual maturity of buffalo bulls.