Breeding is a central pillar to any farm system and Tullamore Farm is no different. At the outset, the farm wanted to breed profitable cows and operate a system where minimum labour was needed around calving time.

While indices are not everybody’s cup of tea, the management team felt the replacement index should be used to drive farm performance and breed functional animals.

The farm is operating an under-16-month bull beef system for the male progeny and selling females as in-calf heifers at 20 months of age.

Cows calve in February, March and April and ewes lamb in March and April.

Cows are predominantly Limousin and Simmental, with about one-third being first-cross Limousin-Friesian and the other two-thirds being second- or third-cross suckler animals.

These cows are then crossed with high replacement index AI bulls. It’s important that these bulls also have a good terminal index.

The herd is in the top 2% in the country for the replacement index, with the average replacement index of the herd at €129.

This year’s heifers, which will start breeding later this month, have the highest index as a group that the farm has ever had at €146.

The herd is operating at a high level of technical efficiency, with calves per cow per year at 1.01 and a calving interval figure of 357 days.

The herd calves all heifers at 24 months and the six-week calving rate in 2020 was 76%. Table 1 outlines the 2021 breeding plan.

AI v stock bull

Since 2017, most of the cows on the farm have been bred to AI.

Some farmers argue that trying to AI 90 cows is not practical and the stock bull route would be a lot easier on labour and time during the breeding season.

The farm had a bad experience with stock bulls in 2017, with two bulls having fertility issues. Since then, AI has been the preferred method. It’s not without its challenges, but the positives outweigh the negatives.

The farm specialises in the production of high-replacement index in-calf heifers and there is a definite premium in the market for AI-bred heifers.

The farm is well set up with roadways and fences to facilitate AI and we are also embracing technology, using the Mooheat system for heat detection.

Cows are generally grazed in two groups along with a group of heifers, so cows can be filtered out of paddocks without bringing the full group in.

Using AI also gives farm manager Shaun Diver the benefit of matching bulls to different cows on the farm, something which can’t be facilitated with a stock bull. Figure 1 outlines the replacement index of the 2020-born female progeny on the farm.


The farm is currently undergoing a review and we are looking at options to increase profitability. While technical performance has been good, the high concentrate input into the bulls is crucifying the system.

There is currently a €450/head meal cost going against the male progeny, while there is a €50/head meal cost going against the heifers.

We are looking at female sexed semen as a possibility to increase the margins on the farm, where 100% of the progeny would be sold as in-calf heifers at 20 months of age.

Dr Paul Crossan of Teagasc Grange is modelling this system, along with weanling production, finishing steers as opposed to bulls and organic production. His results will be covered on the beef pages of the Irish Farmers Journal in the coming weeks.