Difference between revisions of "Avian Breeding, Ovulation and Oviposition - Anatomy & Physiology"
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* Enters a non-breeding state whilst incubating and caring for the brood. | * Enters a non-breeding state whilst incubating and caring for the brood. | ||
− | * Resting ovary appears shrunken, similar to the juvenile ovary. | + | * Resting ovary appears shrunken, similar to the juvenile [[Exotics_-_Anatomy_of_the_Female_Reproductive_System_-_Anatomy_%26_Physiology#Ovary|ovary]]. |
* Oviduct regresses into an inconspicous, narrow tube. | * Oviduct regresses into an inconspicous, narrow tube. |
Revision as of 14:33, 21 July 2008
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
- 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 follicle to split and release the primary oocyte.
- Oestrogen mobilizes calcium from the bone, increasing plasma concentrations for 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.
- Infundibulum catches the oocyte, facillitated by the left abdominal air sac which tightly encloses the ovary.
- Once ovulation has taken place, the Follicle shrinks and regresses.
- No corpus luteum remains, as there is no developing embryo to maintain.
Oviposition
- Expulsion of the egg
- Contraction of the 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 ovary.
- Oviduct regresses into an inconspicous, narrow tube.