Concentrações de testosterona no soro sangüíneo de búfalos durante 24 horas, no inverno e no verão | Testosterone concentration in blood serum of buffalo bulls during 24 hours in winter and summer seasons

Portugués. Concentrações de testosterona foram determinadas por radioimunoensaio em 30 amostras de soro sangüíneo obtidas cinco vezes durante 24 horas, de 6 búfalos adultos Jaffarabadi x Mediterrâneo. As amostras foram obtidas durante um dia do inverno e um dia do verão de 1991. As concentrações de testosterona variaram de 0,10 a 1,36 ng/ml no inverno e de 0,10 a 2,454 ng/ml no verão. Valores máximos foram obtidos às 6,00 horas (0,52 ng/ml) no verão e 0,82 ng/ml no inverno, ocorrendo então duas quedas abruptas, a primeira às 12 horas (0,37 ng/ml) no verão e 0,21 ng/ml no inverno e a segunda 24 horas (0,17 ng/ml) no verão e 0,49 ng/ml no inverno. No verão, níveis mais altos de testosterona sérica foram observados durante o dia.

Inglés. Testosterone concentration was measured by radioimmunoassay in 30 samples of blood serum obtained five times at each 6 hour’s interval during 24 hours from 6 Jaffarabadi x Mediterranean buffalo bulls. Blood samplings were carried out twice, respectively, in one day of summer and one day of winter season. Testosterone concentration ranged from 0.10 to 1.36 ng/ml in the winter day and from 0.10 to 2.54 ng/ml in the summer day. Maximum values were obtained at 6:00 p.m. (0.52) in summer and 0.82 ng/ml in winter, then abrupt drops occurred, first at 12 m. (0.37) in summer and 0.21 in winter, and the second one at 24 p.m. (0.17) in summer and 0.49 ng/ml in winter. In summer, higher serum testosterone levels were observed during the day.