Sperm production in rams

Sperm production in rams takes 49 days. You must ensure rams are well looked after during the 7-8 week period leading up to joining, to avoid factors that could adversely affect the sperm and lead to temporary infertility.

Checking ram sperm reserves

The epididymis is a part of the ram's testicles that absorbs testicular fluid and enables large quantities of sperm to be stored in the smallest possible space. It's located in the back rear section of each testicle.

Checking the tail of the epididymis can give you a useful guide to the level of sperm reserves in rams. A large, firm (but not hard and diseased) epididymis is an indication of good reserves, while a small, soft tail indicates the opposite.

Testicle size in rams

Testicle size is a good indication of the sperm producing ability of individual rams. Sperm are produced by testicular tissue at a reasonably constant rate of about 20 million sperm per gram of testis per day.

You can check the size of a ram's testicles for a reasonably good judgement of the ram's stores of sperm. Large testicles can also be an indicator of higher levels of testosterone, which is an important factor in the ram's sexual interest.

It's important to avoid selecting rams with small testicles, as this is equally likely to be a sign of low sperm availability in the animal.

Temperature and sperm production in rams

For normal sperm production to occur, the testes need to be kept cool. A ram's natural cooling mechanism includes large sweat glands in the skin of the scrotum and a system of muscles that raise or lower the testes into the body for the purpose of temperature regulation. Blood flow to the testes also helps to regulate temperature through a heat exchange mechanism.

Hot weather, such as long periods of temperatures over 32 degrees Celsius, or short spells of very high temperatures (38 degrees Celsius or higher), affects the production of viable sperm. Rams that are heat stressed before joining could still successfully serve ewes up until the sperm stored before the heating are used (about 2-3 weeks), but it will then take 7 weeks to produce new viable sperm.

Before and during joining you should, where possible:

  • ensure rams have adequate shade in the paddock
  • continually look out for fever resulting from fly strike or infection.

Nutrition and sperm production in rams

Nutrition also plays a large part in ram sperm production. Find out about maximising ram fertility through nutrition, health and husbandry.

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