19 April 1996

Higher grass intakes will be future dairy challenge

By Jonathan Riley

THE future challenge facing dairy producers with high genetic merit cows is how to lift grass intakes.

"This will be particularly so," said Sinclair Mayne, of the Hillsborough Agricultural Research Institute, Northern Ireland, "if in the future the UK milk price falls towards world market prices".

Dr Mayne told a conference on breeding and feeding high genetic merit dairy cows at Myerscough Agricultural College Preston, Lancs, that the difference between high and low genetic merit cows was how they partitioned nutrients between milk production and body reserves. High merit cows devoted more to milk production.

"To feed the higher merit cow, an increase in dry matter intake is needed, as grass intake and milk yield are closely related, with 0.4kg to 0.5kg DM producing a litre of milk in the cow," said Dr Mayne.

"Cows cannot physically graze faster and DM intakes are about 3kg/hour. That equates to an intake of 0.8g DM a bite. At this level high merit cows may be unable to express their full genetic potential."

Dr Mayne advised maximising forage intake early in lactation, to make higher digestibility silage from a crop with longer wilting periods. And to allow five-week regrowth periods to achieve total DM intakes of 25.5kg a day.

Lower stocking rates and controlled grazing were essential. This should be on tall, dense, leafy swards and by adopting rotational grazing with the high genetic cows followed on to pasture by the rest of the herd, said Dr Mayne.

"Concentrates must be fed to yield at grass when cows are producing more than 30 litres a day.

Sinclair Mayne: Graze high merit cows on tall, leafy, dense swards.