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