8 August 1997

Supplements now can help growth gains

By Jessica Buss and Jonathan Riley

WITH grass growth and quality declining on some pastures, grazing beef cattle and dairy heifers should be offered supplements to maintain liveweight gains.

Grass growth rates are declining with rates down to 25-35kg DM/day in some drier areas, reports dairy consultant Paul Bird.

"Grass quality could also be falling – particularly where grass has been grazed laxly through the season and dead material at the sward base has built up," he says.

Forecasts of unsettled weather could mean lower intakes, too. Cattle dont graze as well in wet weather and dry matter intakes are lower on wet grass, adds beef consultant David Allen.

"Target liveweight gains of over 0.8kg/day are, therefore, unlikely to be met by grazing alone. Some cattle may have to be finished out of yards unless supplementary feed is offered."

Dr Allen points out that yarding incurs a growth check which can take six weeks to make up. "This shortfall then has to be made up on a winter ration costing about 80p/head/day – about twice as costly as offering supplementary concentrates at grass."

He advises building up feed levels slowly from mid August at 0.5-1kg/head/day to 2 and 3kg/head/ day over a six-week period.

But he warns that while supplementary feeding at grass helps to sustain growth rates, grass management must ensure grass heights of 9cm (3.5in) with any excess made into big bale silage.

Dairy heifers must also be supplemented at grass as its quality and availability declines, stresses nutritionist Ivor Bending.

"Heifers must grow at 0.8-0.9kg/day every day to reach adequate weight at calving, but 90% are not achieving this growth weight now the flush of grass has gone," he says.

Yearling heifers become underfed as they cannot eat enough long or poor quality grass. They need 2-3kg of concentrates, or chopped grass silage, or maize silage every day. Maize gluten could be fed provided it is balanced for minerals. And it will be important to ensure enough protein is included in diets of animals between four and 10 months old.

Monitor growth rates to ensure heifers will be 570kg post-calving and 140cm (55in) at the withers. When heifers are too light at calving it restricts potential yield.n

SUPPLEMENTS AT GRASS

&#8226 Maintain growth rates.

&#8226 Avoids rehousing beef.

&#8226 Heavier heifers at calving.