The ram effect: an archaic tradition
When it comes to tupping season, the so-called “ram effect” is one of the oldest and most successful tricks in the book. Sheep farmers have probably been using this breeding technique since the first ovines were domesticated by humans about 10,000 years ago.
The ram effect is, in short, a reliable, low input and completely natural way of ensuring that all the ewes in a flock come on heat within a short period of time. This in turn will ensure that the following lambing season will be relatively compact.
How does the ram effect work?
As a species, sheep are seasonal breeders. Their natural breeding season begins in the autumn, when the gradual shortening of the days kickstarts the ewe’s reproductive system. While the precise date at which the breeding season begins depends on several factors, including sheep breed and local climate, it usually takes place in either September or October.
There is a great deal of complex biology in place when it comes to the ram effect. Rams – like other male animals – produce a particular kind of hormone called pheromones. When the ewe comes into contact with them, these pheromones act as a sort of stimulant for her reproductive system. A ewe’s reproductive system will usually restart when she comes into contact with a ram.
Planning is key
That the ewe's reproductive system responds to the introduction of a ram may seem like a very simple and obvious observation, and so it is. However, it is important to remember that the ram effect will only succeed with a certain amount of planning.
In order for the introduction of the ram to kickstart the ewe’s reproductive system, the ewe must be kept away from all male sheep for at least one month prior. During this month, she should have neither sight nor smell of any male sheep, including lambs. In practice, this means making sure that all ram lambs are weaned by mid-summer at the very latest. If ram lambs have been left running with the ewes in August and September, for example, then the ewe will be less sensitive to the ram’s pheromones when he is introduced for tupping.
A Teaser Ram
Farmers tend to use a teaser ram for the purposes of bringing ewes on heat (i.e. inducing the ram effect). A teaser ram is usually a vasectomised ram, who is capable of producing the necessary pheromones but not of reproducing. If the ram effect is successful, some of the ewes will respond to the ram’s introduction immediately by coming on-heat. The remainder of the ewes will come on heat about 6 days later. Ewes that come on heat at this point will rarely show any outwards signs of it (i.e. a silent heat). This silent heat means that the ewe’s reproductive system has started to function.
Introduction of Breeding Ram
A fertile ram should be introduced two weeks after the introduction of the vasectomized ram, as most research indicates that the ewes will start to ovulate about 17-23 days from the initial introduction of the teaser ram. All going well, this should mean that the majority of your ewes will be tupped within the space of a few days, leading to a very compact - and hopefully less stressful - lambing season.
