Effects of Photoperiod and Age: RESULTS(1)
In trial 1, the plasma concentrations of LH were not different between lighting treatments from 10 to 18 wk of age but were then generally higher in the LL group until 29 wk of age (Fig. 1A). In both the LL and the SL treatments, concentrations of LH increased significantly after 18 wk of age, but a higher sustained increase was noted in the LL group. This increased level of LH was maintained in the LL group until 29 wk of age, when the SL group was switched to LD. After the switch to LD, LH levels increased significantly in the SL group at the last samples taken 2 days later and LH was higher in the SL group. canadian family pharmacy com
A pattern similar to that of LH was observed for T (Fig. 1B). Increases in T levels occurred at 19 wk of age in both groups and were then sustained. Levels of T were not different between lighting treatments but increased sharply in the SL group by 2 days after the switch to LD, at which time T became higher in the SL group. Production of semen was first detected in an individual bird in the LL group at 22 wk of age, and 13 of 13 birds were producing semen by 25 wk of age (Fig. 2A). Semen was first detected in an individual bird in the SL group at 23 wk of age, but only 4 of 14 birds were producing semen at 29 wk of age. Overall mean semen volume was significantly greater (0.30 ± 0.03 g/ejaculate, n = 8) from the LL birds than from the SL birds (0.14 ± 0.01 g/ejaculate, n = 7). Mean weekly semen volumes are presented in Figure 2B.
FIG. 1. Mean concentrations (mean ± SD) of LH (A and C) and T (B and D) in male turkeys maintained under either LL (open symbols) or SL (solid symbols). A and B from trial 1 (n = 13 for LL or SL); C and D from trial 2 (n = 8 for LL, n = 9 for SL). Different letters with thin lines indicate significant differences of hormone levels between ages (p < 0.05). * Differences between treatment groups at each age (p < 0.05).
FIG. 2. Percentage of male turkeys producing semen at each age (A and C) and volume of semen production (B and D, mean ± SD). Turkeys were maintained under either LL (open symbols) or SL (solid symbols). A and B from trial 1 (n = 13 for LL or SL); C and D from trial 2 (n = 8 for LL, n = 9 for SL).
Category: Semen Production
Tags: Luteinizing Hormone, Male, Semen Production, Testosterone