On average, the menstrual cycle (oestrus) of a female goat occurs approximately every 17 to 23 days.
If you are talking about oestrus to do with female animals (e.g. the cow in oestrus) it means that that animal is in heat. They are ready and capable to mate.
Oestrus
it means that your cat is not healthy
about three weeks
Oestrus, also known as estrus, is the period in the sexual cycle of female mammals when they are sexually receptive and able to conceive. It is characterized by hormonal changes that result in behavioral and physical signs indicating fertility. Oestrus cycles vary in duration and frequency among different species.
it is a period in animals where they become sexually active
Oestrus cycle are present is most of the mammals. The females becomes sexually receptive during the oestrus phase. They express the desire for mating at this stage. In case of the humans the females are more receptive at the time of ovulation. But there are many exceptions. In case of the oestrus cycle the endometrium is reabsorbed. In case of the menstruation the endometrium is shed away to give the phenomena called as menstruation.
The opposite of a she-goat (nanny goat, doe) would be a he-goat (billy goat).
A billy goat (also known as a buck) is a male goat so the opposite would be a nanny goat (also known as a doe) which is a female goat.
goat
The capital one goat is an Alpine goat and the Aflac goat is a Nubian.
"Goat" is a generic term for the animal and refers to both genders. A male goat is called a "Billy Goat" and a female goat is called a "Nanny Goat". A young goat is called a "Kid".