The breeding season on some farms is approaching climax, as dairy farms head into week ten of breeding.

Farms that use a stockbull for mopping up the last of the cows now in-calf likely have them running with the cows already, so the next question will be: When to pull the bull?

Pulling the bull, or removing him from the cows will signal the end of the breeding season on farms.

Breeding season

The grass-based system used on the majority of Irish dairy farms requires a compact calving in the spring to make the most of grass growth.

The aim is to allow farmers to maximise profits by using the cheapest feed available to them, grass, to feed their cows.

Leaving the bull out for too long will extend the calving season, resulting in cows calving later.

Late-calvers have a lower milk production compared with a February-calved cow producing 6,500L, so this is not ideal.

Specifically:

  • An April-calving cow produces 900L less;
  • A May-calving cow produces 1,200L less; and
  • A June-calving cow produces 1,800L less.

Pulling the bull

The six-week calving rates and calving interval has improved on farms in recent years, but further improvement is needed.

Most farmers have a set start-date for their breeding season, but the same is needed for end of the season.

With this in mind, it is important that the bull is removed or that artificial insemination (AI) stops on a certain date, to avoid cows calving later than what is wanted.

Ending the breeding season on or before July 20, will confine your calving season to April 2022. Continuing to breed cows beyond this means less milk produced next year, which is why pulling the bull at the appropriate time is important.

Breeding start dateFinish of 10 weeksFinish of 12 weeks
April 20June 29July 13
April 27July 6July 20
May 1July 10July 24
May 7July 16July 30