News & Advice

Bull Availability and Health

Aug 3, 2021 | Biosecurity, Bulls, Dairy, Dairy Farm Reproduction

Margaret Perry-Hallam, Veterinarian, Anexa Vets Te Aroha

Are your bulls sorted for spring?

Will you be using bulls for your spring mating over your heifers or your herd?  Have you let your heifer grazier know the mating start and end dates, where the bulls will be sourced from, bull numbers and any bull health requirements?  

The bulls should be organised now as bull sales are already taking place.  Will you be using 1 year old, 18 month or 2 year old bulls? If you are using yearlings you should always have more bulls rather than less, because their mating stamina is less than that of an older animal.  

 

Bulls required for yearling heifers 

You will need 1 yearling bull per 15-20 yearling heifers. Always ensure there are at least 2 bulls running with each mob throughout the mating period.  

 

Bulls required for the herd 

For the herd work out the number needed with your veterinarian at your Ready for Mating chat.  You will need 1 bull per 30 empty cows, plus an equal number of bulls resting.  For example, in a 300 cow herd with ~60% of the herd pregnant at the start of the bull mating period you would need 4 bulls working and 4 bulls resting – 8 bulls total.  You also need to factor in having spare bulls available if there is any lameness or injuries in your bull team.  

 

What about bull health? 

Just because they are bulls does not mean they are fertile or free of sexually transmitted disease! There is the obvious visual appearance, animals should have normal conformation and be physically sound, so clear eyes, normal jaw (not undershot), good legs and feet, no lameness, two easily visible even sized testicles, a normal penis without warts. In addition, they should be tested as free of BVD (bovine viral diarrhoea) and vaccinated against BVD. Fertility testing is also recommended, only 80-90% of bulls are fertile, the rest are infertile or subfertile. You can start your bull health plan now; it does not need to wait until September!

Remember your bulls also need to be free of tuberculosis (TB) and Mycoplasma bovis (M. bovis). Make sure you know the disease status of the bull source farms.

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