Category Archives: Semen Production

Effects of Photoperiod and Age: DISCUSSION(8)

It has been reported that T4 secretion by the thyroid gland may be involved in photoresponses in birds and in mammals. T4 could be necessary for the onset and continuation of photorefractoriness, since increased levels of T4 were associated with … Continue reading

Effects of Photoperiod and Age: DISCUSSION(7)

Interactions between LH and T have been reported in mammals and birds. LH stimulates T secretion with a time delay of about 10-15 min, and T has a negative feedback on LH secretion. In the present study, concordance between LH … Continue reading

Effects of Photoperiod and Age: DISCUSSION(6)

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) … Continue reading

Effects of Photoperiod and Age: DISCUSSION(5)

Results from trials 1 and 2 show obvious age-related changes in LH and T that are independent of, but modified by, photoperiods. To determine whether pulsatile patterns of LH and T at different ages during growth and development are present … Continue reading

Effects of Photoperiod and Age: DISCUSSION(4)

The levels of LH and T increased sharply after turkeys were switched from SD to LD at 29 wk of age. These photostimulated increases in LH and T were maintained for about 4 wk, then gradually declined until 35 wk … Continue reading

Effects of Photoperiod and Age: DISCUSSION(3)

Semen production at an early age was also observed in male turkeys in the study of Etches et al., but no correlated hormone data were presented by these authors. There are reports that FSH in male chickens increases during development; … Continue reading

Effects of Photoperiod and Age: DISCUSSION(2)

This observation suggests that some turkeys have entered puberty by 18 wk of age under either the SD or LD lighting program. Similar developmental changes in LH and T have been observed in male chickens. The increased hormone concentrations at … Continue reading

Effects of Photoperiod and Age: DISCUSSION(1)

The present studies examined the effects of photoperiod changes during growth and early reproduction on secretory patterns of LH and T in male turkeys. The results demonstrated age-related and photoperiod-related changes in plasma LH and T levels. This is the … Continue reading

Effects of Photoperiod and Age: RESULTS(5)

LH pulse number and pulse amplitudes were highly variable between birds within groups and were not different between ages and between lighting treatments within ages (p > 0.05; Fig. 6, C and D). Overall mean and baseline levels of T … Continue reading

Effects of Photoperiod and Age: RESULTS(4)

At 35 wk of age, testes were large and histologically mature in all 8 birds from both lighting treatments, and all birds were producing semen. Spermatozoa were present in the lumen of seminiferous tubules of all LL birds at 23 … Continue reading

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