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Oestrous Cycle Pharmacological Manipulation - Anatomy & Physiology (view source)
Revision as of 09:41, 12 September 2008
, 09:41, 12 September 2008→Pharmacological: Progestagens
=== Pharmacological: Prostaglandins ===
=== Pharmacological: Prostaglandins ===
=== Pharmacological: Progestagens ===
=== Pharmacological: Progestogens ===
* Used to synchronize groups of cows and heifers for artificial insemination and to overcome problems with oestrus detection.
* Treatment of random cycling animals for 18-21 days results in synchronization of oestrus.
* When the treatment ceases, oestrus occurs in 4-6 days.
* Fertility at first oestrus is lower, due to impaired sperm transort as a result of the atypical hormone balance after treatment is withdrawn.
* To ensure the natural corpus luteum of the cycle has regressed by the time of progestogen withdrawal, progestogen treatment is often combined with a luteolytic factor:
** Oestradiol at the start of treatment or prostaglandin analogues at the end of treatment.
** Oestradiol is best because as well as inducing luteal regression, it affects follicular dynamics so improves fertility at first oestrus.
* In non-cyclic cows, progestogens sensitize the hypothalamic-anterior pituitary-gonadal axis. This approach can be used in cattle with innactive ovaries.
* Injecting with eCG at progestogen removal stimulates follicular maturation and ovulation.
* Oestrus and ovulation after treatment with progestogens occurs earlier and with more precise timing than following injection of prostaglandin alone.
== Mare ==
== Mare ==