Zur Kontrolle von Fortpflanzungszyklen bei V�geln: Untersuchungen an Bergfinken

Effects of seasonal and social factors on testicular activity and hormone levels in domestic pigeons

Testicular morphology and plasma concentrations of luteinizing hormone (LH), testosterone, progesterone, and estradiol-17beta were compared in paired (n = 8) and unpaired (n = 7) racing pigeons killed in December. The birds were housed mixed together under natural lighting conditions in two unheated lofts which contained no nesting facilities, in Kiel (54 degrees N), Germany. The paired birds had been paired for at least two months. Testicular weights and diameters of tubules were significantly higher (p less than 0.05) in paired (1.64 +/- 0.25 gm; 218 +/- 12 mum) than in unpaired birds (0.79 +/- 0.25 gm; 165 +/- 20 mum). The testes of paired birds were spermatogenetically more active than those of unpaired birds. Plasma concentrations of some hormones concerned with reproduction were, in paired and unpaired birds respectively: LH, 2.28 +/- 0.43 ng/ml and 0.98 +/- 0.36 ng/ml (significantly different, p less than 0.1); testosterone, 1.24 +/- 0.51 ng/ml and 0.59 +/- 0.12 ng/ml (not significantly different); progesterone, 0.58 +/- 0.08 ng/ml and 0.90 +/- 0.12 ng/ml (sifnificantly different, p less than 0.05); and estradiol-17beta, 16.3 +/- 0.95 pg/ml and 18.7 +/- 2.25 pg/ml (not significantly different). Thus, the stimulatory effects of a mate on gonadotropin secretion and gonadal activity which have often been reported for female ring doves and domestic pigeons are also demonstrable in males during the late fall. Seasonal testicular regression in the unpaired males at this time of year was not prevented by the presence of paired females.