27 March 1998

Night and day…out and grazing grass – expert

By Jessica Buss

MOST dairy cows should be out day and night taking advantage of this years early spring growth, and silage feeding should stop to reduce feed costs.

The dairy herd grazing both day and night can save £1 a cow a day compared with winter diets, and most farms have enough grass to get cows out, says New Zealand grazing consultant Paul Bird working for British Grassland Society.

According to Mr Bird, March grass growth rates have equalled a normal April. Grass should be 12ME, so is higher in energy than silage, and is 25-30% crude protein, so lower protein concentrate can be fed.

"When average grass cover over the farm is above 2000kg DM/ha or 8-9cm in height, whether set stocking or rotational grazing, cows can go out day and night. Turn out gradually over a week to 10 days, allowing cows rumens to adjust. Then stop feeding silage, which cows will substitute for grazed grass."

"Autumn calvers should have both silage and concentrates removed from their diet. It is uneconomic to feed concentrates to autumn calvers for an extra one or two litres of milk," he says. But fresh calvers and high yielders at grass may need some concentrates to maintain body condition for good fertility or to achieve the required yield.

He advises maximising grass intakes for high yielders by leaving more residual grass after grazing, so they dont have to work as hard. But maintain grass quality for the next rotation by following milkers with dry cows, mowing or cutting for silage.

Michael ODonovan, grassland researcher at Teagasc, Moorepark, Co Cork, Ireland, says that Irish milk producers who stopped grazing cows before December and applied nitrogen early need cows out at night to keep fast growing grass under control.

"Grazing management must depend on grass supply. You can graze tightly in the first grazing round which will ensure high quality regrowth. But to get round the grazing area more quickly when there is surplus grass, grazing can be more lenient, providing grass is cleaned down to 5.5cm," says Mr ODonovan.

"Producers with restricted areas accessible for grazing should ration out grass to last until Apr 15-20, when supply is likely to equal demand. Silage feeding should have finished so cows may need supplementing with low levels of concentrates at up to 4kg a cow." Some cows are currently averaging 31 litres with just 2kg of concentrates, he says.

But further north there is less grass, so turn out cows with more caution, says Dumfries-based SAC dairy specialist John Bax.

However, he recommends producers consider the benefits of turning out cows for three hours a day. This can increase yields by two litres a cow and improve milk protein, or allows concentrates to be reduced, lowering feed costs, says Mr Bax.

"If producers turnout when there is insufficient grass or in poor weather and set stock cows, they risk over-grazing which can slow grass recovery." For successful set stocking, there must be 7cm (2.8in) of grass over the grazing area.

He explains that there is less risk of damaging recovery with rotational grazing when cows are removed from an area quickly. &#42

GRAZING ADVICE

&#8226 Cows out full time in south.

&#8226 Consider short turnout in poorer conditions.

&#8226 Maintain sward quality.