Controlled Reproduction for Off Season Milk Production
While there have been great improvements made in ensuring that the volume of milk production is consistent throughout the year, there are still periods in the spring and summer where milk production levels are too high. With most of the major brokers of goat milk having contracts stating that at least 50% of the milk must be produced in the "off season", it is more important than ever to have control of your breeding program.
Goats are seasonal breeders, thus their breeding cycle is heavily influenced by daylight intensity and length. That means that goats in Ontario will naturally start their estrus cycles as the day length diminishes in the fall. In order to get more does pregnant in the 'off' season, we need to influence the natural estrus cycle of the doe so that she can breed when we want her to.
A few options to bring does into heat in the off season include the use of hormones, light manipulation, introduction of a breeding buck and combinations thereof.
Introduction of a Breeding Buck:
One of the more common, albeit least successful methods, is to simply introduce a breeding buck to the does. Many producers report that a few, or some of the does, will conceive in the off season using this method, however it is rare to have a large number bred and pregnant using this method. In fact, it is quite common to have no results whatsoever.
One option that is very inexpensive is to manipulate the length of time the goats are exposed to light so as to simulate the daylight lengths experienced in the fall period. This requires sufficient light for a minimum of 18 hours per day for a minimum of 45 days, and it is recommended that the light intensity be 12-15 foot candles (129-161 lumens) when measured at the eye level of the doe. This level of light can be achieved with 400 watts of incandescent light for an approximate pen area of 12 feet by 12 feet (13.5 m2). The length of light period is then gradually and steadily decreased by 1-2 hours per week, until 8-10 hours of light per day is achieved. It is very important that the breeding bucks intended for use are exposed to the same light regime such that they are equally prepared for the upcoming breeding period. Approximately 6-8 weeks after the termination of the light treatment the breeding bucks should be introduced to the does, with fertile estrus occurring 10-20 days after the introduction of the buck.
Use of Hormones:
Another option involves using hormones to jump-start the estrus cycle. A Controlled Internal Drug Releasing Device (CIDR), which is a plastic intra-vaginal implant that contains progesterone, can be very effective when used in a program with additional hormone injections.
The protocol for the use of CIDRs is:
Day One-Implant CIDR.
Day 12-Inject prostaglandin.
Day 14-Remove CIDR and inject Pregnant Mare Serum Gonadotropin (PMSG).
Day 15-Expose doe to sight and smell of buck.
Day 16-Breed doe 43-48 hours after removal of CIDR
Feeding Melangesterol Acetate (MGA), which is a progesterone like compound, for a period of time mimics a similar effect that the CIDRs have and can be used to induce estrus. It is important to note that MGA cannot be used on lactating animals, and can only be used in non-lactating animals under a veterinarian's prescription to avoid drug residues in milk. Utilizing hormone injections in combination with MGA can increase the number of pregnancies; consult your veterinarian for a protocol.
Injections of Prostaglandins, such as Estrumate or Lutalyse, can also be used on their own; however these hormones will only work on active corpus luteum, and will have no effect if the ovary is not already active. Any of these hormone products must be used in conjunction with a veterinary consultation, as not all products are suitable for all animals. It is important to recognize that although these hormone preparations are safe they are considered 'off- label' and must be used with veterinary approval.
A combination of hormones, light manipulation, and introduction of a breeding buck may be the most effective means for maximizing pregnancies in the off-season and ensuring even milk production throughout the year. Many producers report having good success with inserting CIDRs into 20-25% of the does while at the same time using light manipulation to stimulate both the does and breeding bucks. No method will work perfectly, and what works at the neighbour's may not work at your farm. As with any aspect of your operation, record keeping and following protocols are the keys to success.
For more information:
Toll Free: 1-877-424-1300