When it comes to fertility within a herd, the main focus tends to be on the fertility and health status of the cow, but it is important not to ignore the bull.
Whilst cow status is vitally important to hit the targets for many fertility key performance indicators (KPIs) it has, however, been shown that between 20-40 per cent of bulls have reduced fertility and that, in the UK, 25 per cent of bulls fail a pre-breeding examination, according to AHDB figures.
Veterinary surgeon, Jess Partlett of Torch Farm Vets, Devon, says: “Although bulls are rarely infertile there are many factors that can be involved in causing sub-fertility. “This reduction in fertility can have a large impact reducing conception rates at each service, increasing the length of the calving block and increasing the number of barren cows at the end of your breeding period.”
A standard target KPI for cows calving in the first three weeks of a standard 12 week calving block is more than 65 per cent and more than 90 per cent in the first nine weeks.
Miss Partlett says: “This means that a fully fertile bull that has been put in with a group of cows should have a minimum 65 per cent conception rate on first service. A subfertile bull would struggle to reach these KPIs which would be seen as an increase in barren cows or an extended calving period if the bull has been left in.
“Cows which conceive early in the bulling period calve early in the calving block, giving them longer to recover before mating again. This also allows calves more time to grow before weaning which has financial advantages.”
There are many things that can affect a bull’s fertility and ability to achieve high conception rates. These include:
Many of these things can be tested in a bull breeding soundness examination or controlled with good management.
Miss Partlett says: “Your vet can perform a bull breeding soundness examination, 10 weeks before the start of the breeding season or pre-purchase. Production of sperm takes 60 days so pre planning is very important.
“This also means that a soundness examination is only a snap shot in time and although an excellent guide, farmers must ensure all aspects of bull health are managed to secure a good fertility is maintained throughout the bulls working life.”
A bull breeding soundness examination includes:
There are many things that can be done to prepare a bull for work and while at work. These include: