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Keeping a defective bull can be a costly business. Figures from the SAC show that the average cost of keeping a bull is about £1000 per year. While complete infertility of bulls is rare, sub-fertile bulls are common (approximately 20% of bulls tested are sub-fertile). A sub-fertile bull 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 inefficiency results is a significant reduction in farm profits. Therefore, sub-fertile are just as much of a nuisance as infertile bulls and should therefore be identified.
The Bull Breeding Soundness Evaluation performed 4-6 weeks prior to the service period allows a proactive approach to screening out sub-fertile bulls. Our advice would be that all bulls you intend to use should be tested, plus any new arrivals. This really should be regular annual routine on beef breeding herds and will give you valuable information on how your bulls will breed this year, and will allow you to make best use of the bulls you currently have. Furthermore, a judgement as to how many cows may be served by a bull can be attempted, rather than proceeding with no assessment of likely performance. The best time to test is about 4-6 weeks before mating begins, this allows time for any re-tests or more importantly time to find replacements, or juggle around the mating groups if any bulls are identified as sub-fertile. Pre-sale fertility testing can also be carried out and the bull can be accompanied to sale by a BCVA bull breeding certificate.
Electro-ejaculation is now the safest and standard method of semen collection used by trained veterinary surgeons in the UK including Emer Macken. The procedure is relatively quick (about 60 minutes) and safe providing an appropriate crush is available. The majority of the semen evaluation is carried out on farm giving you a quick idea as to the ability of your bull. The remainder is done in our own lab giving you a quick turn-around of results. We do not require the use of teaser cows for sample collection, only a side access crush.
Before entering the crush, the bull's gait is observed. His feet are inspected when in the crush. 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 occurs.
The semen is scored for volume, concentration and contamination before being examined under a microscope. All this takes place on-farm. Under the microscope, the sample is examined for gross motility and motility of individual sperm cells. A sample of the sperm cells is stained and back at the surgery the morphology of 100 sperm cells will be examined.
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?