To understand the physiological bases of the bovine reproductive system, the generalities of the main reproductive hormones of the female bovine and their interaction are presented here.
GONADOTROPINE LIBERATING HORMONE (GnRh)
- Stimulates the production and release of FSH and LH by the adenohypophysis (anterior pituitary).
- Stimulates the growth and maturation of the ovarian follicle.
- It contributes to the last stage of maturation of the follicle (which has become dominant) to trigger its ovulation.
- It helps so that the clot formed after ovulation becomes a corpus luteum.
- It generates changes in the uterus that favor the transport of sperm.
- It helps to express sexual behavior of female (heat), acting on the central nervous system.
- It also stimulates the release of GnRH.
- It inhibits the release of FSH without altering the release of LH.
- It inhibits the release of GnRh, which will also reduce the levels of FSH and LH. This avoids new ovulations.
- Prepares the uterus to receive an embryo, generating changes in its mucosa so that it can be nourished during the first days of pregnancy.
- It produces the regression or destruction of the corpus luteum (favors luteolysis).
Factors to be considered
- The day on which the release of endometrial PGF-2alpha is given to lyse the luteal body, varies according to the literature:
-On day 16 or 17 (According to E.S.E. HAFEZ).
-On day 14 (According to Cunningham).
-It begins on day 14 after ovulation and produces a decrease on day 18 (According to García Sacristán)
- Low estrogen concentrations together with high concentrations of progesterone, constitute a strong inhibitor of Gonadotropins secretion.
– Cunningham’s Textbook of Veterinary Physiology.
– E.S.E. Hafez. Animal reproduction and artificial insemination.
– García Sacristán. Fisiología veterinaria.