The photoperiod did influence the onset of sexual development (trials 1 and 2) and patterns of secretion of LH and T (trial 3) in male turkeys by 23 wk of age. The birds maintained under LD photoperiods (the LL group) were sexually mature at 23 wk of age based on testis weight, testis histology, and production of semen by most of the turkeys. At 23 wk of age the LL group was characterized by high overall mean and baseline levels of LH and T without an increased number of pulses or an increase in amplitude above baseline of pulses. proventil inhaler
The birds maintained under SD photoperiods (the SL group, trial 3) were all sexually immature at 23 wk of age and had relatively low overall mean and baseline levels of LH and T. The most striking difference in secretory pattern of LH and T between the lighting treatments at 23 wk of age was the increased baseline concentrations of LH and T and the presence of LH and T pulses in the sexually mature birds. This suggests the importance of baseline concentration of LH and T and the presence of LH and T pulses in regulating the onset of sexual maturation in male turkeys. High baseline levels of LH and T with fewer pulses were detected in the SL group at 35 wk of age after the birds were stimulated at 29 wk of age. The increased baseline level of LH and fewer pulses of T seen in the SL group at 35 wk may be related to poorer reproductive performance at even later ages. What relationships exist between pulsatile secretions of the hormones and semen production at various ages throughout a normal 30-wk reproductive period during which semen production usually declines, should be an interesting question for further work.