Agriculture, farming, animal husbandry, animal health, bulls, health risks, how to avoid risks, protecting herd health
By Dr Clive Dalton
On farms where Artificial Insemination )AI) is not practical or cost effective, bulls are used for natural mating. On dairy farms this is done after the AI period is finished and only a few cows should be returning to oestrus. It's clearly not worth dairy farmers keeping a bull for 12 moths just for mating over a 6-week period. So bulls are leased from specialist bull farmers and there are clearly health risks involved in this.
On small farms where bulls are shared and moved from farm to farm, there is also a risk of disease spread.
Here are some health issues to consider, and for which you should seek veterinary advice :
- Leptospirosis: Has the bull got a record of its vaccination history? If not it should be considered as a risk of carrying Lepto and should be treated him on arrival with an appropriate antibiotic.
- EBL: Is the bull from a clear herd or should you insist he be tested before arrival?
- BVD: Should the bull be tested for EBL, and what are the risks of introducing the disease? Has the the herd been vaccinated?
- TB: Check the Tb status of the herd the bull comes from and/or the testing history.
- Internal parasites: Is there a risk of a bull introducing drench resistant worms? Quarantine drench all bulls on arrival with a broad spectrum drench.
- Fertility: Will the bull be fertile? It’s no good finding out three weeks after he has been put with the cows and those mated start to return to oestrus. Vet testing consistently finds 10% of bulls are infertile. Make sure the bull comes with some guarantee of having been checked by a veterinarian which means a semen test.
- Libido: This is the sex drive to mate cows and is not necessarily linked to fertility. In beef bulls reared in homosexual mobs, surveys have found up to 20% of bulls have low libido and are slow to mate cows on heat. Some breeders give their bulls a libido test, which must be done under veterinary supervision.