Bull & Ram Fertility Testing


Keeping a defective bull or ram can be a costly business. Figures from the SAC show that the average cost of keeping a bull can be about £1000 per year. Large studies into bull and ram fertility have shown that about three in ten are defective.

Completely infertile bulls and rams are rare, but cause serious disruption to breeding programmes and take several years to recover from. It can be very difficult to identify an infertile bull, particularly on farms where several bulls are kept and rotated and where there is no accurate recording of which animals have been running with which bull at what time. Finding a sub-fertile bull or ram can be even more of a challenge.

A sub-fertile bull or ram will get some animals pregnant, but it will take several services and therefore more time. As most people calve their animals only in the spring or the autumn, the consequence of a sub-fertile bull is more empty females at the end of the breeding season. A sub-fertile bull will also lead to a spread out calving pattern. This is not only a nuisance, as pregnant animals need to be checked longer, but it will lead to a variation in the age of the calves, which will have an impact on calf health. Calf scour pathogens, for instance, need time to build up and therefore calf scour is normally a problem at the end of the calving season. The longer the calving season, the worse the problems. A variation in calf ages can also result in an increased risk of pneumonia as older calves carry and spread pathogens to which they are immune to younger and more susceptible animals.

Therefore, sub-fertile bulls and rams are just as much of a nuisance as infertile bulls and rams. They cost money and create a health risk, and should therefore be identified.

The Electro-ejaculator

Since 2008, we have been using an electro-ejaculator to test bulls’ semen. It is a sophisticated version of the one we use to test rams. The electro-ejaculator stimulates more precisely the internal male sex glands and has less effect on the nerves of the hind legs. As bulls can be tested in a crush it is a relatively safe (for human and animal) quick and easy way to test a bull’s fertility.

The Procedure

When the bull is entering the crush, his gait and feet are inspected. He gets a full clinical examination of external and internal sexual organs and the size of the testicles is measured. This reflects directly on the quantity of the semen. After manual stimulation of the internal sexual organs, a probe is inserted and gentle electro-stimulation is applied until ejaculation.

The semen is scored for volume, concentration and contamination before being examined under a microscope for gross motility and motility of individual sperm cells. All this takes place on-farm. A sample of the sperm cells is stained and back at the surgery the morphology of 100 sperm cells will be examined.

Our Initial Findings

Semen is extremely sensitive to cold shock. Consequently semen testing cannot be done in poor weather conditions because it could lead to poor semen motility and tertiary abnormalities of morphology (high numbers of loose heads and bent tails).

A number of our progressive beef suckler clients have had bulls tested and we have tested sweeper bulls in dairies. We have seen a range of abnormalities: scrotal hernia, testicular deformation, infections, small or overly large testicles, “fat” scrotal necks, Summer mastitis, “broken penis” and, of course, reduced ability to mate due to lameness. The semen has shown contamination with urine and pus(!), deformed sperm cells (a wide variation), but the most common abnormality of semen was poor concentration and/or motility, i.e. less than 30% of sperm cells with a forward progression motion.

Most bulls were re-tested before a negative prognosis was given. The bulls that were condemned ranged in age from eighteen months to ten years. Some were after a pre or post sale check, others had been on the farm for many years and some bulls were tested following poor PD results.

It has become clear that an annual bull fertility check can be very beneficial, as bulls can become sub-fertile at a later age. Most farms spend a lot of time and money checking their cows’ fertility, so why not also pay attention to their bulls’ fertility, which is equally vital?

Ram Testing

An often forgotten, but vital component of all flocks is the rams. If undetected, an infertile or sub-fertile ram can have a significant effect on lambing percentages and overall flock profitability. We would therefore recommend that all rams, but particularly new additions to the flock are examined at least 2 months prior to tupping, to ensure that they are fit for purpose. This gives enough time for replacements to be sought if any rams are found to be inadequate.

The fertility of a ram can be relatively reliably assessed by physical examination alone. Fertility examination includes gross examination of the testicles (including measurement of scrotal circumference), scrotum and penis. The rams are also checked to ensure they have no lameness or other abnormalities or disease that would affect their ability to service the ewes. We have the equipment to perform electro ejaculation for semen collection. This can be used to further assess any ram found to have abnormalities on gross examination. Semen is examined for volume, colour and consistency as well as for the motility of the sperm and any microscopic abnormalities.

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