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Avian Breeding, Ovulation and Oviposition - Anatomy & Physiology (view source)
Revision as of 14:03, 5 July 2012
, 14:03, 5 July 2012no edit summary
== Breeding Cycles ==
== Breeding Cycles ==
* Classified according to length of cycle and the time of year when the species becomes reproductively active.
** Continuous breeders are reproductively active throughout the year e.g. Khaki Campbell duck.
** Most wild species that breed in temperate, subarctic and arctic zones display yearly cycles.
* Tropical or desert species may breed with cycles less than a year, at 6-month intervals or when conditions are favourable (opportunistic breeders).
* Usually lay one or more eggs in a clutch and terminate laying to incubate the eggs.
* Number of eggs per clutch and total number of clutches vary with species and season.
== Endocrine Control ==
== Endocrine Control ==
* In females, '''FSH''' is mainly responsible for follicular growth.
* Developing follicles produce '''Oestrogen''' from '''Theca and interstitial cells''' and '''Progesterone''' from '''Granulosa cells'''.
* Increasing levels of Oestrogen stimulate an '''LH surge''' to cause the [[Follicles - Anatomy & Physiology|follicle]] to split and release the primary [[Oogenesis - Anatomy & Physiology|oocyte]].
* '''Oestrogen mobilizes calcium''' from the bone, increasing plasma concentrations for [[Egg Composition and Formation - Anatomy & Physiology|egg formation]].
* '''Progesterone''' secretion continues to inhibit further ovulation and stimulate behavioural changes associated with '''broodiness and incubation'''.
* '''Prolactin''' stimulates the production of '''crop milk''' in male and female columbiformes.
* '''Oviposition''' is controlled by '''prostaglandins and Arginine Vasotocin'''.
== Ovulation==
* Number of ovulations varies with species, mostly lay one clutch a year.
* [[Avian Female Reproductive System#Infundibulum|Infundibulum]] catches the [[Oogenesis - Anatomy & Physiology|oocyte]], facillitated by the left abdominal air sac which tightly encloses the [[Avian Female Reproductive System#Ovary|ovary]].
* Once ovulation has taken place, the [[Follicles - Anatomy & Physiology|follicle]] shrinks and regresses.
* '''No [[Corpus Luteum - Anatomy & Physiology|corpus luteum]]''' remains, as there is no developing embryo to maintain.
== Oviposition ==
== Oviposition ==
* Expulsion of the egg
* Contraction of the [[Avian Female Reproductive System#Vagina|Uterine shell gland (Vagina)]] with relaxation of abdominal muscles.
* Minutes to hours
** Cuckoos lay their eggs in seconds so they can get away before the host returns.
== Post-Lay ==
* Enters a non-breeding state whilst incubating and caring for the brood.
* Resting ovary appears shrunken, similar to the juvenile [[Avian Female Reproductive System#Ovary|ovary]].
* [[Avian Female Reproductive System#Oviduct|Oviduct]] regresses into an inconspicous, narrow tube.
[[Category:Avian Reproduction]]
[[Category:Bullet Points]]