How Cornish farmer cut feed emissions but maintained output

A Cornish dairy farm has slashed emissions by 170g of carbon a litre by removing 75t of soya from its cow rations.

Soya has been a staple foundation of livestock diets for many years.

However, with hefty carbon emissions associated with the crop, dairy farmers are facing the introduction of penalties for including “non-sustainable” soya in feed, leaving many grappling for an alternative.

See also: Can palm-oil be replaced in feed to help cut dairy emissions?

One farmer who has found a solution is Andrew Griffin. He has removed 75t of soya from the diets of his 150-head Holstein herd at Lower Wheatley Farm, near Launceston, without affecting yield.

Feeding regimes

The herd is milked using two Lely robots, which were bought in 2020. After switching to this system, Mr Griffin found the diet had to be tweaked to get the best performance from both the robots and the herd.

Previously, cows were put to grass in the summer, but are now fed a summer diet of zero-grazed grass and silage, split 50-50 on a dry matter (DM) basis.

This is supplemented with a crimped wheat and a protein blend that is fed according to the protein content and DM of the grass, which is fed typically from March to October, weather permitting.

In winter, the diet is made up of a total mixed ration (TMR) that includes grass silage, crimped wheat, molasses and, traditionally, soya. Concentrates are also fed to yield.

Sustainability goals

Soya has historically been fundamental in producing the litres at Lower Wheatley Farm. However, Mr Griffin recently reviewed his system ahead of a new pricing structure set up by his milk buyer, Arla. The Sustainability Incentive model comes into force from July this year.

The aim of the scheme is to reward producers via increased milk prices for taking action on various sustainability measures, such as feed, fertiliser and land efficiency.

These measures are part of the processor’s ambition to reduce on-farm carbon dioxide equivalent (CO2e) emissions/kilogram of milk by 30% by 2030.

To achieve the highest milk yield and constituents possible, Mr Griffin has put a focus on his feed and production efficiency, which has meant further tweaks to the diet.

These include producing silage with a higher protein content to reduce overall bought-in protein and the emissions associated with this. Last year, first cut averaged 15% crude protein and second cut was 13.8%.

“It’s all about timing [of silage cuts] and getting a good application of slurry as early as you can to get grass growing well,” he says.

“We haven’t done anything really different – it’s just perfecting what we were already doing.” Mr Griffin aims to take three cuts in total, the first at the beginning of May.

Soya alternatives

A switch to a new compound and protein blend has also enabled him to reduce his overall soya usage.

In October last year, he exchanged a soya-based compound for Planet 17%, a dairy nut from Harpers Feeds. This includes ingredients such as beans, rapeseed meal and sunflower, but no soya or palm kernels.

He also replaced the soya inclusion (total of 800g a cow a day) in the TMR with a 40% protein blend based on rapeseed and protected rape, also from Harpers Feeds.

Richard Waters, the company’s ruminant feed specialist and development manager, has worked alongside Mr Griffin in the transition away from soya.

He says raw materials such as rapeseed meal and protected rapeseed are proven to have less environmental impact compared with soya.

This is because they contain less excess metabolisable protein from nitrogen  – which is a waste product when fed in excess – but have comparable bypass and metabolisable “usable” protein from energy to ensure yield is maintained (see “Raw material protein values”).

Benefits

As a result of the changes, Mr Griffin has been able to remove all soya from the diet – a total of 75t – which has resulted in an emissions saving of 375t CO2e, or 170g CO2e/litre of milk.

Mr Griffin says the cows have continued to perform well on the new diet too, despite initial concerns that yield might be affected.

Yield is being maintained at an average of 10,680 litres at 4.44% fat and 3.38% protein, and fertility does not seem to have been affected by the dietary changes either, he adds.

“This week, we’ve actually just gone to 50% [conception rate at] first service.”

As well as the environmental advantages, Mr Griffin says he has also noted cow health benefits since removing soya from the diet.

“Acidosis loading has reduced. With high-yielding cows, you’re going to have acidosis and it’s something we always have tried to reduce. Moving to the Planet range has definitely helped.

“The way the world is going, with sustainability and protein sourcing, soya isn’t going to be there forever. The price alone seems to be rocketing more and more too.

“My biggest fear going to rape was the amount of oil in it, which I worried would affect our butterfat. It’s really good to know there are other products that can help us maintain yield and be more sustainable.”