* Strategic breeding is essential to be able to maximise milk yields from forage, according to a dairy farmer who has been producing milk with virtually no concentrate input for the past decade.

Like many farmers who aim to maximise milk production from grass, Kim Petty crossed his Friesian herd to Jerseys when he shifted to a block, spring calving system.

His cow type has proven itself in terms of fertility and longevity but, with signs of an improving milk price, he says he can’t ignore production. As a result he inseminated the whole herd with New Zealand Holstein semen this spring.

“We are going back to a slightly more milky animal, but without compromising on size,” says Mr Petty, who farms 174ha (430 acres) in Ceredigion in partnership with his wife, Debbie.

“We have developed a fertile cow and by identifying a fertile strain of New Zealand Holstein we should be able to maintain that.”

The 300-cow herd at Tyddyn Yr Eglwys, Llanfyrnach, yields an average of 4500 litres of milk from less than 200kg of concentrates and, in a good year, none at all.

Mr Petty and his herd manager, Nigel Howells, hope to achieve 5000 litres from the new type of cow, but maintain high constituent levels – the herd’s butterfat average is currently 4.65% and protein is 3.65%.

They say they won’t compromise on size because the weight of the animal is important to the grass-based system.

The bigger the animal, the greater the proportion of grass is used by the cow for maintenance and not milk production.

But Mr Petty admits one of the shortfalls of his system in the past has been to bring some heifers into the herd below target weight. This has resulted from insufficient monitoring of youngstock and also TB movement restrictions which have brought stock into the herd that are undersize. “This has cost us yield a cow in their lifetime,” admits Mr Petty, who now has a robust monitoring system in place.

It is the farm’s first year clear of TB for some time, giving him the opportunity to sell all the late born stock which would have struggled to calve in Feburary.

Any heifers that calved below target weight have been separated from the main herd. “They are out at grass, but are receiving supplementary feed,” says Mr Petty.

The farm is stocked at 2.8 cows/ha, but to achieve that level, cows are no bigger than 500kg. “The larger the animal the greater the cost of maintenance and the more area it needs,” says Mr Petty. “Grassland systems need a cow that is efficient at converting grass into milk.”

The annual dry matter requirement of a dairy cow on a grass-based system is 4500kg, he says, but in the past two years he has struggled to achieve that from pasture alone.

Last summer’s long dry spell cost him between one and two litres a cow below budget and the recent wet conditions have meant a 1.5 litre daily drop in production.

The extremes of the past two years have been integral to Mr Petty’s decision to install feeders in the parlour – a move he admits he would never have considered five years ago.

His aim will be to feed 70t of concentrates in the autumn and 30t in spring, equating to not more than 300kg a cow. “We want to get slightly better performance at certain times of the year by helping cows more than we have in the past,” he says.

“Our cows are producing high quality milk and there is a huge energy demand on them. In ideal conditions grass will support that, but the youngsters can suffer a bit at that time of the year.”

Although Mr Petty plans to feed more concentrates in future his focus will remain on producing as much milk from grass as possible.