Goats are seasonal breeders and in our region the breeding season GENERALLY extends from September to February, although exceptions occur. Meat type goats such as the Pygmy and the Tennessee Stiffleg apparently have the ability to breed out of season. The same appears to be true for the Boer breed. There are even indications that in dairy herds some does (Saanen, Alpine, Nubian) have the ability to breed out of season and as early as July if housed or grazed with a buck. Two factors playing an important role in the ability of goats to breed out of season are plane of nutrition and body condition.
Segregating does from bucks is crucial in the development of sound breeding programs that should be paralleled with feed resources and market demands. The best approach to separate does from bucks is to develop a secure buck pasture. The buck pasture should be far enough from the breeding doe herd, otherwise scent emitted by glands located behind the base of the bucks' horns will induce estrous in does. This is called the "buck effect". It is a good strategy to use to naturally synchronize breeding does at the start of the breeding season.
During the breeding season, goats come into heat or estrus approximately every 18 to 22 days. Does in heat become vocal and some bleat very loudly as if in pain. Constant tail wagging from side to side is another sign of heat. In addition, the vulva will appear slightly swollen and reddened and the area around the tail may look wet and dirty because of vaginal discharge. Other signs of heat include decreased appetite and an increased frequency of urination. Does in heat also are easily identified if a mature and smelly buck is nearby. They will pace restlessly along their enclosure looking for a way to get to the buck or stand close to the fence. Finally, a doe in heat may mount another doe as if she were a buck or let another doe mount her.
In spite of all these signs, it is still sometimes possible to miss heat. In general, people experiencing most trouble in detecting estrus usually have only one or two goats. In some instances, it may be very useful to run a teaser (vasectomized) buck with the does to detect estrus. A vasectomized buck is rendered infertile through surgery by cutting the tubes carrying the sperm from the testes to the penis. However, his libido and interest in mating still remains. An intersex animal exhibiting female genitalia with an enlarged clitoris but male mating behavior has been used to detect estrus at the NCSU Meat Goat and Educational Unit. Animals used to detect estrus can be fitted with a harness containing a crayon that will mark the females in heat when they are mounted. If the herd is checked twice a day, marked females can be separated and mated to the appropriate male.
The duration of estrus varies from 12 to as long as 48 hours. Within that duration standing heat (the period the doe stands firmly when a buck attempts to mount) lasts approximately 24 hours. On occasion, some does may find the buck sexually unattractive and will not stand to be bred. Ovulation usually occurs 12 to 36 hours from the onset of standing heat. At the beginning of the heat cycle, the vaginal discharge is clear and colorless. It becomes progressively whiter and more opaque towards the end of standing heat.