Monitoring bull fertility during the breeding season

While most of the work arguably has already been done to set up the herd for a successful breeding season in terms of nutrition, vaccinations and pre breeding checks, it is important to monitor bull performance during the breeding period.  

For herds calving in March and April stock bulls will only have been out with cows for a couple of weeks, and irrespective of the age of the bull, it is important to monitor bull performance to ensure that cows are holding to service, to reduce the risk of experiencing losses from bull infertility.  

It is advised to regularly observe bulls out with cows to allow for any concerns to be picked up quickly before these then have an impact on herd fertility and productivity. This is now more important given the Scottish Suckler Beef Support Scheme (SSBSS) requirement for a 410-day calving interval.  

Record when you see a cow mated and watch for her repeating (bulling) 21 days later. A significant number of cows returning to service could suggest bull fertility or libido issues. It is important to remember that although a bull may have undergone a pre-breeding examination and fertility test prior to being turned out with cows he can under form if he has picked up an infection, became lame, or has damaged his penis. There is a lot that can go wrong with a bull, affecting his ability to serve cows. Therefore, monitoring groups for returns is crucial to ensure issues are identified as soon as possible, before herd fertility is compromised.  

For those herds rotating bulls between groups during the breeding season, it is even more important to continue to monitor bulling activity, to avoid fertility loss from bull subfertility. A sub-fertile bull will get some animals pregnant, but this will take longer and several services, making the problem harder to identify, especially in systems where bulls are rotated during mating. 

If you have concerns, seek advice from your farm vet as soon as possible, as waiting until pregnancy scanning is too late to resolve problems.  

Sarah Balfour, Beef Consultant, Sarah.Balfour@sac.co.uk

Posted by SAC Consulting on 16/06/2026