I first heard of teaser rams from a retired roustabout when touring Australia two years ago. The concept seemed simple enough: you take a vasectomized ram, mark his belly fur with paint and introduce him into a flock of ewes. The teaser ram will jump the ewes which are on heat and some colour will remain on their coats. You then go and pick the marked ewes and either inseminate them artificially or give her to the chosen sire.
Sounds easy? And a cool concept? However, while researching I found out that there is much more to sheep breeding than I'd have thought there was. In the following I'll try to give an overview of this information. However, since I doubt that very many everythingians are interested in potential careers as sheep breeders I'll leave out the less interesting details.
First things first: What's a teaser ram?
A teaser ram is a vasectomized ram. In vasectomy only the spermic duct (vas deferens) is severed and a little part of it is removed to insure that no semen reaches the outside world. The testicles remain, so unlike a castrated ram the teaser ram still produces male hormones. He acts and reacts like a normal ram. That means he still produces pheromones and he's still capable of detecting a ewe on heat.
Now that I have a teaser ram, what do I do?
Well, you now need a flock of ewes, a couple of real rams and the intention of going into sheep-breeding. There are mainly two uses of teaser rams.
The first use of teaser rams is the one I heard about in Australia. Equipped with a marking harness or "brisket paint" the teaser rams are used to detect which ewes are on heat. (Brisket paint is a paste made of paint powder and mineral oil applied to a ram's brisket, which rubs off easily). The ewes thus marked are then taken and put with the fertile ram.
Advancing and synchronization of the breeding season
The teaser rams can be used to advance the lambing season and to decrease the variation in the birth dates of the lambs. Breeders wish for this mainly for marketing and economic reasons. Fertile rams are often hired, so the less often you have to bring them in, the cheaper. The same goes with lambing. You need manpower present when the sheep are lambing. The tighter the time period is, the less hours have to be paid.
If kept normally with male animals nearby, a ewe usually has her first heat at a random point in time in the season. To make this work you have to ensure that your ewes haven't started their natural cycle yet and that they haven't been in touch with any rams for 6 to 8 weeks. That is not too easy as they can smell a ram's pheromones for a long way down wind.
After the ewes have been isolated for so long from sexually active males, the introduction of a teaser ram induces a first silent heat after approximately 6 days. "Silent heat" means that the ewes are not receptive to the rams. However, this event starts the ewes' natural cycle and it starts it for all of them at the same time. Your ewes are now synchronized.
There are two kinds of ewes in each flock: some with short and some with normal cycles. About 50% of the ewes will be on heat after about 17 days after the introduction of the teaser ram. The other half of your flock will be on heat approximately 28 days after introduction. You want to have your intact and fertile rams in the flock by about two weeks after introduction of your teaser ram. They can then go about their business and bring a bit of fun into the flock. You on the other hand have your flock's lambing cycle synchronized and can go about planning your evil marketing schemes for lambs' meat.
Words of caution
- My sources didn't seem to agree on the exact numbers of days it takes for the two peaks of heat to occur. If you really want to go into the sheep breeding business you better talk to your vet about this.
- A teaser ram may become fertile again, as the spermic duct can grow back together (recanalisation). It is therefore advisable to check your teasers for their fertility each year.
- I've only written about natural insemination. Teasers can also be used in artificial insemination and embryo transfer programs. How that works however should be subject of the respective nodes.
Numbers and hints
Sources and more information:
- http://www.agric.gov.ab.ca/livestock/sheep/fact_sheep_3.html (a readable approach)
- http://www.sheepdairying.com/ShhlthRam.htm (a practical approach)
- http://www.pipevet.com/articles/Teaser_Ram_Effect.htm (a medical/scientific approach)