http://americashorsedaily.com/mare-hunt/ The Complete Source for All Things Horse Fri, 10 Sep 2010 02:32:05 +0000 http://wordpress.org/?v=2.9.2 hourly 1 http://americashorsedaily.com/mare-hunt/comment-page-1/#comment-8467 A Shot Against Estrus? – America’s Horse Daily Sat, 28 Aug 2010 18:53:27 +0000 http://americashorsedaily.com/?p=4979#comment-8467 [...] Mares come into heat or estrus due to rising estrogen levels produced by developing ovarian follicles. Mares typically do not show heat during the winter when they have small, inactive ovaries. Heat is also not exhibited after ovulation when mares have a corpus luteum producing progesterone. Ultimately, expression of behavioral estrus occurs in the presence of estrogen and the absence of progesterone. Absence of estrus is a function of low estrogen levels and/or elevated progesterone levels. [...] [...] Mares come into heat or estrus due to rising estrogen levels produced by developing ovarian follicles. Mares typically do not show heat during the winter when they have small, inactive ovaries. Heat is also not exhibited after ovulation when mares have a corpus luteum producing progesterone. Ultimately, expression of behavioral estrus occurs in the presence of estrogen and the absence of progesterone. Absence of estrus is a function of low estrogen levels and/or elevated progesterone levels. [...]

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