Promising results from methane reducing feed additive in Irish winter-milk system

A research trial undertaken at the Teagasc Johnstown Castle Dairy Unit over the winter of 2022/2023 has generated promising results following the inclusion of 3-NOP, a methane reducing feed additive, in the diets of Irish winter-milk cows.

Methane is a greenhouse gas produced by the rumen during the digestion process; it contributes to 62.5% of Irish agricultural emissions. As Ireland is required to reduce GHG emissions by 25% by 2030, developing solutions to reduce methane emissions will be crucial. Work has been ongoing in Teagasc research centres since 2019 to identify these solutions. One of the many areas being studied is the use of feed additives.

Conducted over a seven-week period, this trial aimed to evaluate the impact of including the feed additive, which is licenced for use in the European Union, on both the methane emissions and milk production performance of winter-milk cows.

Dr. Michael Dineen and Dr. Ben Lahart, Teagasc Research Officers, presented the findings of this study as part of the recent Winter Milk Open Day, held in Teagasc Johnstown Castle on September 6^th.

To investigate the effect of 3-NOP on methane production, two experimental diets were established and 44 cows were assigned to each. The diets, which had the same level of grass silage, maize silage and concentrate supplementation, differed only by inclusion (additive diet) or exclusion (control diet) of 3-NOP, which was supplied through Bovaer farm packs, and offered at a rate of 1.8g of 3-NOP per cow per day.

Michael explained: “We measured methane for a seven-week period while the cows were indoors on their winter diet, as we wanted to quantify if it was an effective solution for Irish winter-milk cows.

“Overall milk yield was quite similar – 29.8kg for the control and 30.4kg for the additive diet. Milk protein percent was slightly higher – 3.51% for the control versus 3.57% for the additive diet. Milk fat was very similar – 4.60% and 4.63% - and we saw milk solids yield of 2.45kg/day for the control versus 2.50kg/day for the additive diet – a 2% increase in milk solids yield when 3-NOP was included in the diet.

“The more crucial metric for this investigation was looking at methane production. We looked at in terms of absolute methane – the grams of methane per cow per day - and we found on the control diet with no 3-NOP, the cows produced 447g/day of methane, whereas the 3-NOP fed cows produced 330g/day of methane which equates to a 26% reduction in methane output per cow.

“We also looked at it in terms of the intensity of methane production – grams of methane per kilogram of milk solids - and we found that the control cows produced 182g of methane per kilogram of milk solids, whereas the 3-NOP fed cows produced 132g of methane per kilogram of milk solids – a 27% reduction in methane output.”

Table 1: Results for the Teagasc Johnstown Castle Dairy Unit trial on the effect of 3-NOP

Previous international research has shown that the inclusion of 3-NOP has the potential to reduce the methane emitted by cows on a TMR diet by 20-30%, with Michael adding: “It is promising that it stood up to our research, which shows that it works effectively for Irish winter-milk cows and that it is a promising solution going forward.

“Currently, there are a number of solutions to help us meet our targets in terms of reducing methane production. The EBI is a very effective solution to help us achieve our targets, whilemaximising the amount of high-quality grass is another solution that can help reduce our methane output. We need to keep developing these solutions to have a wide breath of tools to help us meet our targets and to help drive the industry forward in meeting our climate ambitions” Michael concluded.

Also read: Examining the costs of winter milk production

Photo caption: Dr. Michael Dineen presenting at the Teagasc Winter Milk Open Day in Teagasc Johnstown Castle