14 February 1997


Suckler producers considering breeding their own replacements should give milkiness priority when selecting breeds.Jonathan Riley reports

BEEF producers considering a closed herd policy should avoid heavy Continentals, and use breeds which confer milkiness within the herd.

Michael Drennan of Teagascs Grange Research Centre, County Meath, Ireland, admits his advice represents a change in thinking.

Suckler cow numbers in Ireland have increased from 440,000 to 1m head in under 10 years, he says, and the proportion of Continental breeds has risen from 6 to 48% in under 20 years.

"This is because these breeds confer leaner and larger carcasses than traditional breeds, and cow sizes are beginning to increase."

Studies at Grange, near Dublin have highlighted the risks of breeding towards a larger purebred Continental cow because maintenance feeding, hybrid vigour and milk production are reduced when compared with a dairy crossbred.

"In our trials spring calving Hereford Friesian dams produced 12kg milk a day from grass, while a heavy Continental – bred to seven-eighths pure – produced only 8kg of milk a day," says Dr Drennan.

Calves of the milkier Hereford crosses grew faster at grass for every 1kg increase in milk output, calf growth rates increased by 30g/day pre-weaning. This meant the Hereford cross calves weighed 20kg more than the Continentals at weaning. And when slaughtered at 24 months the Continental had not caught up.

"As well as the lower milk yield we put the Continentals reduced performance down to a loss of hybrid vigour – which also appeared to affect calf liveability," explains Dr Drennan.

"The Continentals had lower colostrum levels and blood tests revealed that crossbred calves had far higher immunoglobulin levels," he says.

The Continental cows were also heavier. They averaged 722kg with a maximum weight of 900kg liveweight, which incurred far higher ME requirements than the cross breeds. And up to calving Continentals consumed 85.6MJ ME/kg compared to 78.5MJ ME/kg for the Hereford x Friesians.

"Best results have been achieved using a smaller Continental, such as the Limousin Friesian cow. This had few calving difficulties and a final size only 15-20kg greater than the Hereford Friesian.

"Their progeny produced similar performance when heifers were finished at 20 months and bulls at 16 months. "

Limousin bulls produced carcasses of 350kg and heifers about 300kg. These weights were only 10kg heavier than the Hereford, but Limousins reached the weights at fat class 3 compared with the Herefords which averaged fat class 4L.


&#8226 Better milk production.

&#8226 Lower maintenance feeding.

&#8226 Improved hybrid vigour.


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