By now AB should be well underway and all going well, cows are cycling vigorously. Your bull team has hopefully arrived on farm at this start of AB – at least six weeks prior to use.
Use the 3% +1 rule to decide on the number of bulls you require (for example, if you have 100 cows to get in calf, you want 3 + 1 = 4 bulls). Bulls should be a similar size to the cows (less then 100kg average difference) to prevent injury to both the cows and bulls. Select bulls that are easy calving and exclude any bulls with horns, or feet deformities.
Prior to arriving on farm, the bulls should have been:
- Vaccinated against BVD with two injections 4–6 weeks apart. They should have also been blood tested to show they are BVD antigen negative (not carrying the virus). You should be able to request documentation of this as proof.
- Previously been fertility checked, had a semen evaluation, and libido checked to ensure they don’t have any issues with semen quality or “technique”. If they have not been proven, counteract this by adding more bull power.
At arrival, bulls should be:
- Given a quarantine drench on arrival and kept separate to the herd for at least 14 days. During this time, they should be monitored for signs of ill health or lameness.
- Mixed into their teams at least a month before use to establish a hierarchy. The hierarchy that the bulls teams form can affect their performance, if a bull is too dominant it can cause underperformance as other bulls are not able to get on with the job, or they utilise too much energy fighting amongst themselves.
When in use:
- Monitor the bulls for any sign of ill health or lameness. Any lame or sick bull should be removed from circulation and treated appropriately. Lame bulls will not get the job done but will also potentially prevent other bulls from working.
- Ensure that bulls can serve cows appropriately. Any bulls not seen working should be removed.
- Try to teach bulls to stay in the paddocks when cows are taken to the shed for milking. Not only does this prevent them using excess energy walking, but it can also reduce lameness issues substantially.
Taking time to keep an eye on what’s happening out in the paddock can make a huge difference in the long run.