A fertile bull is defined as one that should be able to get 95% of 50 normally cycling cows in calf, over a 9 week period (3 heat cycles). A single infertile bull can be picked up due to poor PD results or higher than expected return rates.
However, if using a pair of rotating bulls, the duff one can often go undetected. Indeed, a sub-fertile bull is one that can impregnate cows, but does so at a much lower level than required and so, again, can rumble on unnoticed. This lowered fertility performance will directly affect the efficiency and economics of the farm. It is generally thought that as many as 20% of all working bulls are sub-fertile.
This month's newsletter focuses on Bull Fertility testing. Click the image or click here to view the full newsletter from The George Farm Vets.