A trial involving feeding a batch of continental, suckler-bred bulls on a diet of zero-grazed grass is currently underway at the Irish Cattle Breeding Federation's (ICBF's) Tully Progeny Test Centre in Co. Kildare.

Agriland recently visited the facility and met the site manager Stephen Conroy, who explained that the trial is taking place in association with Teagasc as part of the Department of Agriculture, Food and the Marine (DAFM)-funded Methane Abatement in Grazing Systems (MAGS) project.

As part of the trial, 43 continental, suckler-bred bulls were purchased in. These bulls were bred from a range of artificial insemination (AI) sires with different methane evaluations.

Explaining the trial, Conroy said: "Effectively, what happens is they go on 70 days of a diet of zero-grazed grass and we look at the rumen microbiome. We sampled them a couple of weeks ago, half way through the 70 days.

"Then we put them on the total mixed ration (TMR) finish to look at the change in the rumen microbiome going from grass only to TMR.

"We have the methane data coming from the GreenFeed boxes and we also have the feed-intake data."

Commenting on how the weanling bulls have been performing on the trial, Stephen said: "They have been doing 1.2kg/day on average just on grass indoors."

Conroy said the trial is unique, with no other similar trials currently underway that he is aware of.

The site manager said he is happy with the performance of the bulls on the grass-only diet.

He noted: "We would be aiming to get 1.9kg/day out of an intensive, ad-lib, concentrate diet on the bulls."

The grass is sampled every week and currently, is being cut fresh every day.

Conroy said: "They're eating 12kg dry matter, so depending if the grass is wet, they're eating up on 70kg of grass fresh weight/day."

Once the 70 days on grass is completed, the bulls will go on a concentrate diet for 40 days pre-finishing to ensure optimum fat cover ahead of slaughter.

The bulls are bedded on a mixture of sawdust and grain dryer chaff.

Results from the trial are expected before the end of the year, and it is hoped the trial will be rolled out on batches of steers and heifers also next year.