Bull mating management

With AB well underway for spring calving herds, now is the time to be organising your bull teams.

• Ideally, bulls should be on farm at least 3 weeks prior to going out with the herd. This allows them to work out their social hierarchy beforehand so they can focus on the cows once added to the herd instead of fighting each other.
• Ensure that virgin bulls are used and that they come vaccination certified for Leptospirosis and Bovine Viral Diarrhoea (BVD).
• Veterinary examination of bulls is recommended before they start work. Examinations can range from a physical exam to assessing semen quality and are a great way to remove bulls that are unfit for service before they cause any issues.

The number of bulls required will depend on how many cows are likely to come on heat while the bulls are with the group. Bulls should be used at a ratio of 1:30 for cows and 1:20 for R2 heifers. Use two teams of bulls so that one team is rotated every 1-2 days, reducing the risk of lameness and fatigue. For example, a 300-cow herd with a 50% in-calf rate when the bulls go out will require 5 bulls per term and therefore, 10 bulls in total.

Bulls need to be checked regularly for lameness, illness, or injury and replaced with new bulls if identified. Infections, antibiotic treatment, and elevated temperatures affect sperm production for 30+ days making them ineffective for use. Encourage bulls to stay in the paddock during milkings as reducing time on concrete yarding will also help lower lameness incidence.

If you have any questions regarding getting the most out of your bulls this mating season get in touch with your regular Franklin Vets farm vet.

Dr Neil Murray, Farm Vet at Paeroa.