Effects of Photoperiod and Age on Secretory Patterns of Luteinizing Hormone and Testosterone and Semen Production in Male Domestic Turkeys
Changes in gonadotropins and sexual steroids have been determined in the male of many species in order to advance understanding of regulation of reproduction. Determination of changes in hormone concentrations in animals serially bled for several hours shows that both LH and testosterone (T) are secreted in pulsatile patterns in male mammals, ineluding humans, and in avian species. In avian species, the occurrence and duration of reproduction are primarily influenced by photoperiods. Reproduction of some mammals is also influenced by photoperiods, but responses to photoperiods in mammals and birds may be different. Effects of photoperiod on changes in LH and T secretion have been studied in chickens, turkeys, and Japanese quail.
However, detailed studies utilizing serial bleeding to determine pulse characteristics in response to photoperiod changes have been not conducted in male avian species during development and early reproduction. The mechanism through which photoperiods induce changes in circulating hormone levels remains largely unknown in male birds. Interactions between LH and T have been proposed in a number of species, including chickens and humans; however, the way in which these interactions affect reproductive performance is not clear. In order to understand effects of photoperiod and age on secretory patterns of LH and T, as well as the regulatory mechanism of these hormones on semen production, three trials were conducted to study secretory patterns of LH and T and semen production in male turkeys exposed to different photoperiods, starting at 10 or 12 wk of age. birth control yasmin
Thyroxine (T4) affects the reproductive cycles in mammals and birds. In birds, photoresponses may involve T4, since T4 may be necessary to induce and maintain the photorefractory state. However, little information is available on the relationships of T4 to reproduction in male turkeys. To investigate potential relationships of T4 to male turkey reproduction, plasma T4 was also measured during growth and early reproduction.
Category: Semen Production
Tags: Luteinizing Hormone, Male, Semen Production, Testosterone