Here's how to halve the carbon footprint of dairy diets

The study, conducted by Mole Valley Farmers at Duchy College's Future Farm, demonstrated that reducing the carbon footprint of dairy rations by more than 50 per cent is possible without affecting milk yields.

The trial also found that this reduction could boost milk proteins.

The study involved 140 cows from the 210-cow dairy herd at Stoke Climsland, Cornwall.

These cows were given one of two diets: a standard higher fibre, low starch diet commonly used on UK farms, and a low carbon footprint, high starch, low fibre, soya-free ration.

The low carbon footprint diet was specifically designed to have a 58 per cent lower carbon footprint compared to the standard diet, and to produce five per cent less methane.

Both diets were balanced using Mole Valley Feed Solutions' Precision Nutrition software, which can predict the carbon footprint of specific rations.

The results of the trial showed that milk yields were not significantly different between the two diets.

However, the lower carbon footprint diet resulted in higher milk protein due to starch levels driving propionate production.

There was no impact on cow body weight, calving interval, or metabolic status.

Senior nutritionist Dr Robin Hawkey and nutritionist Pete Reis from Mole Valley Farmers, who ran the trial in collaboration with Duchy College's Future Farm team and its Rural Business School, believe the results are positive for the industry.

Reis said: "The fact we can feed a no-soya ration with a lower environmental impact and produce similar yields is a real positive.

"In addition, doing that whilst raising milk protein levels could be a plus for farmers on cheese contracts."

The Future Farm's milk buyer, Saputo, produces brands such as Cathedral City and Davidstow cheddar.

To build further on the results, Mole Valley Farmers is conducting a new 90-day trial at Duchy College to see whether it's possible to produce high yields and constituents on a grass-based, low-carbon footprint diet.

The same grass-based diet is being used in both groups, with nutrient levels changed in the accompanying meal to deliver milk constituents of either 3.6 per cent fat and 3.6 per cent protein, or 4.2 per cent fat and 3.2 per cent on yields of 38 litres a cow a day.

Both are 17 per cent crude protein diets and incorporate amino acids.

Results are expected in spring 2025.