A new cattle-feeding system could improve milk output by 8%, according to a group of farming leaders and animal nutritionists.

The Forum for Food Production has called on retail buyers from Tesco, Sainsbury's, Morrisons and Waitrose to support the new system, which has been developed by nutrition business Keenan.

The system, which tops up the nutrients an animal gets from grazing so it gets what it needs to digest properly, would cut feed costs, improve animal health and boost productivity, it claimed at its inaugural meeting a fortnight ago.

Farmers were currently wasting millions of pounds by feeding the wrong material to cows at the wrong time, said Manchester University economist David Coleman.

"Scientific analysis showed that the system improved milk output by 8%, without any extra cost," he said. "It boosts feed conversion efficiency so you get up to 0.2 litres more milk from every kilo of feed."

Farmers who participated in trials run by Keenan in First Milk's Highlands and Islands milk fields earned an extra £182 per cow per year while the creamery's cheese yield from the milk increased.

"For the farmer, the benefit is profit, pure and simple," said Keenan MD Gerard Keenan. "But the incentive for the retailer is the consistency of the product, and the opportunity to talk to consumers about the welfare and environmental benefits."

Keenan said he hoped backing from the new group would boost take-up of the system. "The group is a vehicle to promote the system independently," he added.

Feeding animals according to Keenan's system had the added benefit of slashing an animal's methane emissions by up to 20% and was also effective for beef cattle, he said.