Hormonal profiles in buffalo bulls

Serum samples from male buffaloes were radioimmunoassayed for steroid and thyroid hormones to investigate circadian rhythms, the effect of growth and season. An evaluation of RIA of serum testosterone with and without extraction yielded unacceptably low recoveries in unextracted serum samples. Studies on temporal variations during the day revealed three peaks for testosterone, four peaks for cortisol and one peak each for T4 and T3. In growing calves the testosterone levels were low (0.1 ng/mL) up to 15 months of age but exhibited peaks at puberty (0.4 ng/mL) and maturity (0.8 ng/mL). Cortisol, T4 and T3 also exhibited peaks at puberty and maturity. Progesterone and oestradiol remained at basal levels throughout growth and development. Breeding buffalo bulls exhibited significant seasonal variations in testosterone, progesterone and oestradiol but not in T4 and T3. Semen quality and sexual behaviour did not vary between seasons. (author)