Pubertal development in the male buffalo: Longitudinal analysis of body growth, testicular size and serum profiles of testosterone and oestradiol

Abstract

Body growth, testicular size and peripheral steroid levels were studied longitudinally from birth to puberty in ten Nili-Ravi buffalo bulls raised under strictly identical feeding and managemental conditions. The attainment of puberty was related to the time of first ejaculation with motile sperm. Mean pubertal age, body weight and testicular volume of these animals, were 22.8 ± 1.1 months, 421 ± 19 kg and 188 ± 12 cm 3, respectively. Correlations among age, body weight and testicular volume were >0.95 ( P < 0.01). Increase in body weight and testicular size was markedly greater from 8–15 months of age than during any other period of development. A significant ( P < 0.05) relationship was found between age at puberty and the time when a maximal increase in testicular growth rate was observed during the prepubertal period. Season of birth did not influence ( P > 0.05) age, body weight or testicular volume at puberty. Mean serum testosterone concentrations remained low from birth to 12 months of age (0.3 ± 0.1 ng/ml). A marked rise in testosterone was observed at 14 months of age (2.7 ± 0.9 ng/ml) followed by a second peak at 18 months of age (3.3 ± 1.2 ng/ml). Serum oestradiol levels increased during the early part of prepubertal development attaining a mean concentration of 27 ± 3 pg/ml at 5 months of age and remained more or less unchanged until the age of 15 months. The levels declined thereafter and were low throughout the rest of the pubertal development. These results suggest that in the buffalo testicular quiescence extends from 0 to 7 months of age, followed by a period of rapid testicular growth and considerable androgenic activity. The investigation identifies some of the physical and endocrine correlates of pubertal development in the male buffalo which may be helpful in selection of sires at a stage prior to sexual maturation.