The breeding season is fast approaching and to improve the chances of successful matings, especially on farms using AI, farmers need to identify bulling cows.

One of the most effective ways of doing so is through the use of a vasectomised or ‘teaser’ bull. Sexually-mature dairy-bred bulls, such as Holstein Friesians and Jerseys, tend to work best.

According to Teagasc, the cost of vasectomy ranges from €90 to €120 and the procedure should be carried out at least 40-60 days before the ‘teaser’ bull is introduced to the herd.

For the most part, these bulls work best in the first three weeks of the breeding season or towards the end of the season when the level of heat activity falls off – as the number of pregnant cows in the herd increases.

A chin-ball harness can be fitted to ‘teaser’ bulls to identify any cows the bull may mount – this may be a clear indication that the cow is an ideal recipient for an AI straw.

However, the chin-ball harness should be fitted at least two-to-three weeks before the planned start date, to allow the bull time to adjust to the heat detection aid.

A word of warning

‘Teaser’ bulls have been shown to be effective at picking up bulling cows on farms throughout Ireland, but there are a number of risk factors associated with these animals.

At the end of the day, a vasectomised bull is still a bull and warrants respect. These animals will retain all the testosterone of a non-vasectomised bull and need to be treated with caution.

Recommendations suggest that vasectomised bulls should only be used for one breeding season, after which they should be slaughtered or castrated.

The health status of the bull must also be considered, especially if you have to source the bull from an outside herd.

A bull with an unknown health status or vaccination history could introduce disease into your herd – the negative consequences of which may far outweigh the benefits.