25 July 1997

Late summer concentrates may boost beef

FEEDING concentrates to beef cattle at grass in late summer could improve killing out percentages and sustain growth rates, so cutting finishing times and avoiding rehousing.

This increases maintenance feed costs and may mean cattle need rehousing, incurring additional labour costs, says Irish researcher Padraig French, based at the Grange Research Centre, Dublin.

In late summer grass growth and quality decline, and cattle growth rates fall, increasing the length of the finishing period.

"Transferring cattle to winter rations also checks growth rates while their systems adapt to the change in diets," says Mr French.

Studies at Grange have, therefore, examined the effect of feeding 570kg steers at grass on either no concentrate, 2.5kg a day or 5kg a day, under controlled grazing conditions which allowed grass intakes of 6kg, 12kg or 18kg a head a day to be established.

Cattle consuming grass alone from late summer, achieved only 0.1kg to 0.4kg growth rates a day across the three herbage allowances, while animals fed 2.5-5kg concentrates a day at the highest grass intake achieved growth rates of up to 1.12kg a day.

"This higher growth rate meant animals reached a saleable weight in the autumn before housing was necessary, unlike the cattle fed grass alone, which, in a commercial system, would have needed rehousing.

"In the trial all cattle were taken on to slaughter during December because we wanted to assess carcass traits on the different feed regimes," he says.

Steers fed only grass at the lowest level of 6kg a head a day reached only 590kg, while those fed 5kg concentrates a day plus grass reached 670kg on the same date.

"Concentrate fed cattle also had better killing out percentages – 53% compared with 51% for the lowest grass allowance and zero concentrate animals. We also compared killing out percentages with a group of animals fed only concentrates and found that these had percentages of only 51%. &#42

GRAZING SUPPLEMENTS

&#8226 Faster growth rates.

&#8226 Avoids rehousing.

&#8226 Improves killing out percentages.