Vasectomy means cutting or removal of the vas deferens. The vas is the tube that carries the sperm (the male "seeds") from the testicles (testes, balls or nuts) to where they are mixed with seminal fluid (that nourishes and carries the sperm). Once they are mixed, they are ready for ejaculation to fertilize an egg inside a female, such as in a ewe.

Vasectomy prevents the sperm getting out, while allowing seminal fluid (the liquid without any sperm) to be ejaculated and the animal to function normally except that it is sterile.

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It is different from castration that usually means removing all of the testicles and much of the scrotum (bag, sack). As well as making the animal sterile, castration prevents many normal male functions such as full hormone production and the resulting sexual maturation. It also reduces aggressive behaviors if done before sexual maturity and to some degree if done after sexual maturity.

Many sheep farms would have as many as or more vasectomized farmers than vasectomized rams because it is a very effective human birth control method.

It can be a very useful operation for a farmer to perform as well, not on himself or other humans, just on rams for use as teasers. Normally the operation is done under local anaesthetic by a vet. However, the average sheep farmer can do it without resorting to the vet.

Note: Check whether it is legal to do this in your jurisdiction and under what conditions. Rams typically must be under six months of age for welfare reasons but your law may be different.

My tame vet Roy gave me the following method and I've used it successfully. Note that I always tested a teaser by giving him a play with some old fertile ewes for a while to make sure that none got pregnant. This is a summary of what Roy suggested:

Vasectomizing rams

With a lamb marking knife With rubber rings
Note: I would not rely on this method - see below.

See also Rubber rings may not be good for animal welfare or your profit
Restrain the animal humanely, such as in a lamb marking cradle
Be as quick, clean and gentle as you can, this animal's survival (and your future profit) is in your hands.
Restrain the animal humanely, such as in a lamb marking cradle
Be as quick, clean and gentle as you can, this animal's survival (and your future profit) is in your hands.
Ensure the scrotum and surrounding areas are clean Ensure the scrotum and surrounding areas are clean
With a clean, sharp lamb marking knife, remove the end of the scrotum (bag or sack) and then remove one testicle (ball) as you would if castrating the lamb.

Use the knife to remove the knob on the bottom of the other testicle (the encased epididymis) plus any of the vas that is attached to it.
Push one testicle up into the body.

Expand the ring using the ring pliers and ensure that you get the WHOLE of the scrotum and ONE testicle, keeping the other testicle up inside the body and above the ring. The ring should be placed right against the body. Theoretically the sperm will be infertile because they will be too hot inside the ram's body. However, this may not be as effective with some rams as others. Some sperm may mature and be able to impregnate a ewe. For this reason alone, it is not a method I would rely on.
Carefully place the ram on all fours and let it free with minimum shock. Allow normal healing and growth. Good feed and water plus freedom from dust and stress will help.

Some farmers will get better results than others.

Be careful you do the job well for the welfare of the animal and so you don't end up with a rig or a stag. This is a ram with one functioning testicle and he is fertile.

The normal reason for creating a teaser ram is so that you can let him loose to allow you to improve your management. So, there is little point in creating what seems to be a teaser ram but in fact is a fertile ram who will have the run of the place and thus could create all sorts of problems.

Testing vasectomized rams

No testing will be effective until the ram has finished maturing, otherwise any absence of sperm may be because he is too young.

The most certain and the quickest way to test is to have the seminal fluid tested for the presence and effectiveness of sperm. However, that could be expensive unless you are able to do it yourself with a microscope and not have to send samples to a laboratory.

The alternative is to field test it by putting him with some ewes that have proven fertile before. Once he is mature, he can be tested with ewes that are known to be or can be expected to be coming into regular season (coming on heat). The more ewes he mates with, the better your chances of an accurate result. Absolute minimum is six, 50 is better.

Run him with a light colored raddle on and in a small field with the ewes. After one oestrus cycle (normally from 16 to 21 days, depending on the breed) change the color of the raddle to a darker color so it will show.

If any ewe that was raddled with the first color is raddled with the second color
If some that were raddled the first time don't get raddled the second time, there is a good possibility the "teaser" is in fact fertile.

To make testing and detection easier, you could use a totally different breed of sheep, preferably one that produces lambs that look distinctly different so that any offspring of that ram would be easy to pick. But this would only work if that characteristic were dominant.

And by the time the lambs drop, you would have to be sure you hadn't used him where you didn't want to.

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This page was updated on December 27, 2007