The length of the oestrus cycle in goats is typically 18 to 21 days. The oestrus cycle is the period in which a female goat is receptive to mating and can become pregnant. During this time, the goat will show signs of heat, such as increased activity, restlessness, and a swollen vulva. The length of the cycle can vary slightly between individual goats, but it is typically between 18 to 21 days.