In the Philippines, female goats generally come to heat when the weather is cool and the days are short, that is, from September to February. The long period of anestrus (non-ovulating) from March to August thus limits conception, making it difficult for farmers to provide a consistent supply of goat meat throughout the year.
Since the goal is to shorten the kidding interval and keep the doe in heat for rebreeding after weaning, raisers must ensure that does will come to heat even during off-season. Stimulation of ovulatory activity in goats is usually done using chemical hormones. In areas where these hormones are not readily available, not acceptable (e.g. in halal goat raising), or too expensive to be availed of, alternative methods have to be introduced.
To stimulate estrus and induce off-season breeding among does, three non-invasive heat induction techniques (NIHIT) have been tested on-station and on-farm by a DOST-PCAARRD funded project of University of Southern Mindanao (USM). Depending on the resources available to farmers, any of the following can be employed to induce estrus in does:
- Manipulate the darkness in the pen. Cover the walls of the pen for 14 hours (from 6 pm to 8 am), as increasing the period of darkness can trigger excitement in the does that can lead to behavioral and standing estrus; however, be sure to roll up the cover after 8 am as the pen will get uncomfortably hot, especially in summer and will reverse the effect of the treatment.
- Keep an adult male nearby. Keep a buck near the does for 12 hrs, as the exuberant vocal expressions of the buck, as well as its odor, can trigger excitement in the does. However, prolonged exposure to the buck for 24 hrs will not help stimulate estrus among does.
- Maximize dorm effects. Keep does with about 5 other does in a pen, as the presence of other females, especially cyclic does, can induce ovulation. This phenomenon is known as social facilitation, wherein the stimulation is provided by social cues from the other females.
These techniques provide a cheap way of inducing heat among does during off-season and sit well with the halal system of goat production, where the use of chemical hormones to artificially induce heat is prohibited.