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==Introduction==

==Introduction==

Unlike polyoestrus animals such as the cow or sow which can reproduce all year round some species such as the mare, ewe, goat, rabbit, hamster and doe have an '''anoestrus''' phase to their reproductive cycling. This means that for part of the year they are not experiencing oestrous cyclicity and so are not reproductively active. Such animals can be long or short day polyoestrus breeders. Seasonality of reproduction is due to the effect of light levels on the brain. Reproductive seasonality maximises the chance of offspring survival by timing parturition to coincide with spring when nutritional and climate conditions are optimum for lactation and for growth of the offspring. It is important to be able to distinguish between seasonal anoestrus and pathological infertility. Both males and females exhibit reproductive seasonality. However, the female is more strongly influenced by season.

Unlike polyoestrus animals such as the cow or sow which can reproduce all year round some species such as the mare, ewe, goat, rabbit, hamster and doe have an '''anoestrus''' phase to their reproductive cycling. This means that for part of the year they are not experiencing oestrous cyclicity and so are not reproductively active. Such animals can be long or short day polyoestrus breeders. Seasonality of reproduction is due to the effect of light levels on the brain. Reproductive seasonality maximises the chance of offspring survival by timing parturition to coincide with spring when nutritional and climate conditions are optimum for lactation and for growth of the offspring. It is important to be able to distinguish between seasonal anoestrus and pathological infertility. Both males and females exhibit reproductive seasonality. However, the female is more strongly influenced by season.

==Manipulation of Seasonal breeders==

==Manipulation of Seasonal breeders==

Apart from [[Oestrous_Cycle_-Pharmacological_Manipulation_of_Oestrous_Cycles_- Anatomy & Physiology|pharmalogical manipulation]] of the oestrous cycle, photoperiod, nutrition and temperature may also play a part in the controlling entry into the breeding season in some species.

Apart from [[Oestrous Cycle Pharmacological Manipulation - Anatomy & Physiology|pharmalogical manipulation]] of the oestrous cycle, photoperiod, nutrition and temperature may also play a part in the controlling entry into the breeding season in some species.

===Reasons for controlling breeding seasons===

===Reasons for controlling breeding seasons===

'''The Mare'''

'''The Mare'''

*To shorten the Anoestrus period after foaling.

*To shorten the Anoestrus period after foaling.

*In order to synchronize a group of mares so that they may all be mated at the same time or to make [[Reproductive_Technologies_-Multiple_Ovulation_and_Embryo_Transfer- Anatomy & Physiology|Embryo Transfer]] possible.

*In order to synchronize a group of mares so that they may all be mated at the same time or to make [[Embryo Transfer - Anatomy & Physiology|Embryo Transfer]] possible.

*Control of entry into the breeding season is particually important in producing foals for the racing industry. Racehorses run from the age of two years old, with the age of the horse being measured from the 1st of January. Producing horses born as close to the 1st of January as possible gives them a performance advantage when racing.

*Control of entry into the breeding season is particually important in producing foals for the racing industry. Racehorses run from the age of two years old, with the age of the horse being measured from the 1st of January. Producing horses born as close to the 1st of January as possible gives them a performance advantage when racing.

[[Category:Reproductive System]]

[[Category:Female Reproduction]]