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Protecting The Other Half Of The Breeding Equation

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For purebred breeders, perhaps this article should be passed on to purchasers of your bulls.

The herd bull is often the most neglected part in a cattle operation. Great emphasis is put on him just before and during the breeding season, but the rest of the year bulls are often not thought about.

We must be ever-mindful of not neglecting the huge genetic potential bulls have on our herds. Protecting your investment will help maximize that genetic potential. I will outline health and management procedures on a yearly calendar, assuming breeding season is in the spring.

The easiest way is thinking of your herd bulls every time you process the cows, and deciding then whether anything must be done to them. People often shy away from handling bulls as they are larger and can raise havoc, even with sturdy corrals. Every time bulls are moved the fighting resumes, and the pecking order must be re-established. This can be minimized with good facilities and having a large pen or pasture to return the bulls to. Exercise at all times of the year keeps the bulls fit, and the feet and legs in much better shape.

Vaccinating bulls should correspond to what you do to your cows. All respiratory and reproductive vaccines as well as blackleg are advised. Bulls could be the source or spread of disease, especially the reproductive ones like vibrio, leptospirosis, or trichomoniasis if they are a problem in your area.


The additional vaccination we recommend for bulls is the one for foot rot. A lame bull at breeding season is not desirable. This vaccine only protects for one cause of lameness in bulls, but the foot rot organism can gain entry through cracks in the bull’s feet. It’s a small investment considering the bull is half the breeding equation. An ideal time to vaccinate is at semen evaluations as the bulls are caught.

Deworming and delicing should be done in the fall with a pour-on endectocide. Use the right dosage for the weight of the bull and don’t skimp. The bulls always are the sentinel animals when it comes to lice. Hair loss may indicate lice but often lots of scurf will lead to scratching, especially on hot days.

Semen evaluations are most often performed in the spring before breeding. Producers want them done before bull sales in case decisions have to be made as to new purchases. If insurance was taken out on a bull it is a very wise move to test before the policy expires in case something has happened over the winter. If a bull has been sick, had swellings develop in the sheath or testicles or had cows returning to heat, then a check of his fertility should be made at that time so a replacement can be found if needed. Older bulls (five years or greater) have an increasing likelihood of becoming infertile because of things like testicular degeneration.


Many bulls are culled because of feet and leg problems. As bulls mature and get bigger, tremendous pressure is put on their feet and legs, especially in the breeding season. Preventive maintenance by trimming may extend their useful life as well as preventing lameness problems during the breeding season. Again, lots of exercise on hard terrain (not peat moss) goes a long way towards keeping the toes short.

Many hereditary foot conditions such as corns or spiral and corkscrew claws can be selected against: Even when young bulls are selected with great feet it may be necessary to trim them in their later years. Look very closely at your bull’s feet every year. Trimming one to two months before breeding season is ideal. The trimmer can then be more aggressive, knowing the bull has several weeks to recover before being turned out.

Fly control is imperative for bulls over the summer. If not treated you will notice hundreds of horn flies feeding on the backs of your bulls. Flies have more of a predilection for the bulls so in order to reduce irritation, blood loss and gadding. Cy-lence, a pour-on product is quite effective against flies for 60 days. Otherwise fly tags or back-rubbers may be used.


Treat the bulls as your cows with trace minerals. Maintain a condition score of 2.5 to 3.5. A rising plan of nutrition prior to the breeding season is a good idea. A crude protein level of 12 per cent or higher in their diets is ideal. A leaner bull is more desirable than a fat bull at breeding season. Fat, especially in the scrotum, can impair fertility. After breeding season when bulls are pulled their nutritional requirements decrease substantially.

Since a good breeding bull is always a good investment, he is one worth protecting. If breeding pastures have a lot of bush, make sure bull rings are removed. If hardware (peritonitis) is a problem on your operation, when a bull is first purchased placing a good-quality magnet in his stomach (reticulum) may be good insurance. Most illnesses with bulls come on subtly and weight loss is often the first noticeable sign.

When checking your bull during breeding season, pay particular attention to his gait. Wobbliness or knuckling may be the sign of a back problem. Swelling on the sheath from cuts or a broken penis may require immediate bull replacement. If you have time before next breeding season some of these conditions may be treated

By implementing these strategies, hopefully a long reproductive life can be attained from your bulls. Always buy your bulls from reputable purebred breeders and make sure they have had their initial breeding soundness evaluations done. In some instances testing new bulls for BVD-persistently infected status or bovine leucosis may be warranted, but your herd veterinarian can help with those decisions. Genetic testing may now be done for qualities such as marbling, whether he is homozygous polled, and a red colour carrier in the case of black bulls.

For purebred breeders, perhaps this article should be passed on to purchasers of your bulls. They can then hopefully protect their new herd bull and allow him to fully express his full genetic potential and maximize longevity within the herd. This makes for contented customers and hopefully repeat buyers.

About the author


Roy Lewis practised large-animal veterinary medicine for more than 30 years and now works part time as a technical services veterinarian for Merck Animal Health.



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