All good things must come to an end, so it is now time to pull the bull and end the breeding season on your farm for 2022.

The vast majority of herds aim for a 12-week breeding season, with the goal of getting as many cows as possible in-calf in this period.

Ideally the majority of your cows will go in-calf in the early stages of the season, which will result in more cows calving earlier in the calving season.

The shorter the breeding season, the shorter the calving season should be, but this is not easy to achieve.

But it is important to have a cut-off date; if you started breeding on May 1, week 12 ended yesterday July 24. So it is now time to remove the bull from the cows or stop artificially inseminating (AI) cows.

Cows that are not now in-calf are going to calf outside the ideal calving period; it is possible they have had four chances to go in-calf.

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

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.


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