English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Ovariectomized Shiba goats carrying an oestradiol implant (4-10 pg/ml) were kept under a short-day light regimen (10L:14D; Group 1, N = 4) or a long-day regimen (16L:8D; Group 2, N = 4). Plasma LH concentrations were lower (P less than 0.05) in Group 2 than in Group 1 between Days 40 and 200, suggesting an enhanced negative feedback effect of oestradiol on LH secretion under a long-day regimen. On Days 30, 60, 100, 149 and 279, an LH surge was induced by i.v. infusion of oestradiol for 48 h; the infusion rate was gradually increased from 0.5 (0 h) to 4.1 (48 h) micrograms/h, thereby mimicking the preovulatory increase of oestradiol secretion. The duration and magnitude of the induced LH surge were indistinguishable between the groups. The latency from the onset of oestradiol infusion to the LH surge was relatively constant in Group 1, 41.1 +/- 0.9 h (mean +/- s.e.m., n = 17) but was shorter in Group 2 (19.7 +/- 3.7 h, P less than 0.05) on Day 149; less oestradiol was therefore required for induction of the LH surge (27.4 vs 89.7 micrograms, P less than 0.01), suggesting an increased sensitivity to the oestradiol positive feedback under a long-day regimen. These results might be interpreted to indicate that the hypothalamic-pituitary axis of the goat becomes hypersensitive to the positive as well as the negative feedback effect of oestradiol under long-day conditions.

Photoperiodic modification of negative and positive feedback effects of oestradiol on LH secretion in ovariectomized goats