Cattle Today

Cattle Today



by: Bethany Lovaas
University of Minnesota Beef Team

As the breeding season approaches, generally everyone is thinking about getting cows and heifers in shape for the breeding season. A nice, tight breeding season results in a nice tight calving season, which generally is the most economical for producers. However, the cow is only half of the equation. Don't forget about the bulls! Here are some things to consider:

A breeding soundness exam. One of the most Important, and often under utilized tools available to beef producers is the bull breeding soundness exam (BSE). A BSE will allow the technician/veterinarian to assess the fertility of a bull based on scrotal circumference, sperm motility, and sperm morphology.

Feet and legs. When selecting herd bulls, emphasis is placed on growth performance, EPD's, and soundness. These are all good criteria, and no one should try to use a lame or unsound bull for breeding. However, there is nothing wrong with putting a bull on the table for a good foot trim, if he needs it, a month before the start of the breeding season. If he's going to hit the ground running, he should have the best set of wheels he can get.

Vaccination/deworming. If bulls are housed separately from the cows for most of the year, they are often forgotten and do not receive the same herd health protocol. The herd bulls should be on the same vaccination/deworming schedule as the cows are. Since vaccination schedules vary as much as production systems do, there is no "correct" schedule. If in doubt, vaccinate and/or deworm your bulls about two weeks before they go out to pasture.

Body condition. When a bull is out on pasture breeding many cows, his mind is only on one thing, and it's not feed. In the peak of the breeding season, some bulls will breed six to eight cows a day, and will hardly eat. Bulls should be in a similar body condition score as replacements heifers, ideally, from 5 to 6.5.

Bull:cow ratio. There is a lot of variation in producer opinions about how many cows a bull can service during the breeding season. Instead of trying to memorize numbers, try this little rule of thumb: one bull can service as many cows as he is months old, up to fifty months. For example: A 15-month old bull can service 15 cows, a 24 month old bull can service 24 cows, and a 50 month old bull can service 50 cows. After 50 cows, you are starting to really push the limits of what even an older, more experienced bull can accomplish in a 60 day breeding season.

Fertility Associated Antigen. Some bulls are inherently more fertile than others. This is due in part to a protein called Fertility Associated Antigen (FAA). The FAA protein is found on the sperm cells of some bulls and results in a higher percentage of sperm capacitation, and therefore a higher rate of fertilization. Studies show that FAA positive bulls are about 17 percent more fertile, and get more cows bred in a 60 day breeding season.


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