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| = Female = | | = Female = |
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| + | == Puberty == |
| + | |
| + | * Sexually active at 2 - 3 years of age but usually they are not bred until they are 4 years old. |
| + | * Several factors that can influence the age of the onset of puberty, such as nutrition, season of birth and breed. |
| + | ** The most important factors being the nutrition and adequate growth, as these influence the onset of ovarian activity and chances of conceiving and carrying the pregnancy to term. |
| + | ** If females are bred before they reach 70% of their adult body weight they run a greater risk of abortion. |
| + | |
| + | == Seasonality == |
| + | |
| + | * Seasonal breeders, with a relatively short breeding season. |
| + | * Outside of the breeding season mating activity ceases and the ovaries are inactive or only have a few, small follicles. |
| + | * Breed at a time of low climatic temperature, rain and better grazing conditions. |
| + | |
| + | == Endocrinology of Seasonality == |
| + | |
| + | * Plasma levels of oestradiol 17β very considerably from one month to another but there does not seem to be any association between the level of this hormone and breeding activity. * Concentrations of LH are higher during the breeding season than during the non-breeding season. |
| + | ** During the breeding season the pituitary gland is more sensitive to and releases more LH in response to Gonadotrophin Releasing Hormone (GnRH) release from the hypothalamus. |
| + | |
| + | == Oestrous Behaviour == |
| + | |
| + | The proportion of females displaying strong oestrus behaviour is usually small and not all the females will show all these signs, despite the presence of a mature follicle. Also, receptivity to the male can be displayed by females with no follicles in the ovaries and for up to 7 days after ovulation or when pregnant and progesterone levels are high. Oestrous behaviour therefore cannot be used reliably to decide the timing of breeding. |
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| + | * Mounting other females |
| + | * Restlessness |
| + | * Swelling of the vulva |
| + | * Straddling the hind legs and urinating |
| + | * Vaginal mucus discharge |
| + | * Receptivity to the male |
| + | * lasts on average 4 - 6 days, but can vary from 1 - 21 days. |
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| = Copulation = | | = Copulation = |