Teaser Bulls for heat detection
September 2023

We all know the importance of heat detection – every missed heat means a delay of 3 weeks before the cow’s next chance of getting back in calf. And no matter how good your heat detection practices are, a human is never going to detect as many cows on heat as a bull will. (Sex is a powerful motivator.)

Teaser bulls are vasectomised bulls – they still have testes so they still produce testosterone, and they look and act like bulls, but the vas deferens (the tube that sperm swim down) is tied off so that they’re no longer fertile.

Using teaser bulls:

  • Use around 1 bull per hundred cows.
  • Put them in on the first day of mating, and take them out at the end of AB.
  • No need to rest them – they’re not getting cows in calf; they’re just finding cows on heat.

Creating teasers:

You can buy or hire a teaser bull for the season –alternatively, you can make your own. Keep a few bull calves and get them vasectomised by the vet around the time of weaning. Our normal protocol is to castrate one side and vasectomise the other – they still make plenty of testosterone, but with only one testicle, they are easily identified as teasers. (We can vasectomise bigger bulls too; it’s just a bit scarier to stand right behind a bigger animal while you do surgery on his scrotum.)

A vasectomised bull calf will be working as a teaser the next season, at 15 months old. After he’s been used in the herd, he can be kept another year – or, if you prefer not to keep bulls on farm year-round, we can castrate him so he can be fattened for the freezer.