News & Advice

Maximising Bull Fertility and Reproduction

Sep 7, 2017 | Bull Fertility, Dairy, Dairy Farm Reproduction

Margaret Perry, Anexa Vets, Veterinarian Te Aroha

Mating time is just around the corner, and with the new norm of shorter mating periods, it is vital that your natural mating goes as well as your AB period. For most farmers the bull mating period has been reduced to four or five weeks, which means that cows not yet pregnant at the end of AB may only get one chance with the bull before the end of mating. It is therefore vital that you get the bull mating period right.

  • Bulls should come from a reputable source and arrive on farm several weeks before they start work to give them time to settle in and any issues to become apparent. Insist on bulls that have been BVD blood tested and double vaccinated. In an ideal world, they should also be vaccinated against Lepto and blackleg. 
  • If a bull gets lame he won’t work as hard, and if he gets sick or has a temperature his sperm quality will drop. It takes up to 60 days for new healthy sperm to be produced and you don’t have time for that, so any bull with any problem needs to be replaced as soon as possible. It is hard work at first, but consider training bulls to stay in the paddock or not come onto the yard as a way of reducing lameness. 
  • Bull power is a paramount consideration. With an 8 or 10-week bull mating period the length of mating could compensate for low bull numbers, but with shorter mating periods this is no longer the case. For a typical 300 cow herd, with average reproductive performance, you should have 6 bulls in with the herd at any one time (usually 2 teams of 3). There should also be an equal number of spare bulls, so they can be regularly rotated to keep them keen. This means that there should be at least 12 bulls on farm from about the middle of October through to around Christmas time. 

We know that bulls are a pain, and that they fight and dig holes and break fences, but if you have enough bulls and manage them well, then you can see a big improvement in your conception rates over that period.

Repro Ready consults are happening right now. This is an excellent time to discuss your bull management and get a plan in place well in advance.

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