‘Wean heifers at 100kg for healthier herds’

Holstein Friesian calves weaned at 100kg will be stronger and less susceptible to disease than lighter animals, according to a leading research scientist.

Emer Kennedy, who is in charge of a heifer rearing study at the Moorepark Dairy Research Centre in the Republic of Ireland, reckons a bigger calf at weaning will be both healthier and able to come off concentrates a month earlier. This saving will offset extra costs associated with feeding calves on milk or a replacer for longer.

At Moorepark, this year’s spring-born Holstein Friesian calves were weaned at between 85-90kg, but next year’s target is 100kg. “Weaning at 100kg gives them a good start. If you have a sturdier, well-grown calf the chances are it will be healthier,” says Dr Kennedy.

“Average birthweight for Holstein Friesian calves is 35kg. They have a lot of growing to do to get to 330kg at mating which is why farmers need to look after them to get them to this point.”

Moorepark has experimented with weaning early, but these calves have yet to achieve the weights of the later-weaned animals. “It’s worth feeding that extra milk, it does give them a boost,” says Dr Kennedy.

Calf production has become a major focus of dairy farming research in Ireland as the country prepares for the removal of EU milk quotas in 2015. Milk production is set to increase by 50%, but heifer replacements currently average just 26 for every 100 cows and only 74% of heifers calve at two years.

By increasing heifer replacements and focusing on the health of these animals, farmers can increase their profitability too, says Dr Kennedy.


For many producers, expanding cow numbers means managing more calves without additional housing space and this can be a challenge, she admits. “There are lots of challenges in calving sheds. Particularly in a block-calving system where the disease burden is increased by having so many animals at the same stage together,” she says.

At Moorepark, a polythene wind tunnel, to improve ventilation, was put in the roof space of the calf shed, where there are 24 calves to each pen.

Milk-fed calves grow at 0.85kg a day and are introduced to once-a-day feeding from as young as 10 days, although two or three weeks old is more usual. There are no issues with scours because, although the calves are getting a large intake of milk, they have longer to digest it. Equally good results are achieved with a milk replacer, says Dr Kennedy.

“Once-a-day feeding is a great labour-saving technique; calves will do just as well on it,” she insists.

From weaning at 15-16 weeks, daily liveweight gains of up to 1kg are achieved on a grass-only diet. Post weaning, the calves are moved onto a fresh block of grass twice a week and are encouraged to graze pasture down to 4cm. “Calves are every bit as good at grazing as cows, it’s good training for them,” says Dr Kennedy.

She recommends getting calves out to grass as early as possible because of the extra growth that can be achieved at less cost. During the winter period, indoor-reared calves grow at between 0.6kg and 0.7kg, but 1kg gains can be achieved from grass.

“It’s really important to get the heifers out early. Rearing calves on concentrates is an expensive system,” says Dr Kennedy. She calculates that it costs about 30p/kg of dry matter a day to feed calves on concentrates compared to 8p/kg DM on grass.

“There is scope for additional weight gains of up to 0.4kg a day on grass. It doesn’t take rocket science to work out the benefits,” she says.

Gareth Davies, UK grassland genetics manager for Genus, and grassland specialist Justin Rees recently took a group of UK dairy farmers to visit some of Ireland’s top grassland farms.

Mr Davies says these farmers place great emphasis on weaning weights rather than age, targeting 85-100kg at weaning.

Daily liveweight gains of up to 1kg are achievable, but only on the highest-quality pasture. This is being achieved through first-class grazing management, he says.

“Putting good-quality grass in front of calves at the earliest opportunity not only ensures they will reach target weights for mating, but it will train them to graze well before they join the herd,” says Mr Davies.

“Farmers can make big savings by getting calves out to quality pasture, but they must have a grazing plan in place so covers are consistently of the highest quality.”