Thyroid hormones are permissive for various species to enter seasonal anestrus.
2
In addition, reproductive hormone levels were determined during ovine anestrus and the breeding season.
3
Thyroid hormones permit the increase in response to estradiol negative feedback in ewes at the transition to anestrus.
4
Furthermore, the levels of estrogen, progesterone and LH in ovine anestrus were significantly lower than those in the breeding season.
5
This finding contrasts with the changes in estradiol negative feedback at the transition to anestrus, which are entirely thyroid hormone dependent.
1
Seasonal anoestrus in the ewe results from enhanced oestrogen negative feedback.
2
This study addressed whether NO acts within the vmPOA to inhibit LH during seasonal anoestrus.
3
It is concluded that long post-partum anoestrus leads to prolonged calving intervals and poor reproductive performance.
4
Oestradiol was slightly less effective in eliciting oestrous behaviour in anoestrus and during the transition to the breeding season than at other times.
5
In the first experiment, LH pulse frequency was measured on days 0, 1, 7 and 14 of treatment during seasonal anoestrus.