19 January 1996

Keeping them out late saves £1800 in SAC trial

Extended grazing last season at the SAC saved on silage and concentrates and improved milk protein contents as Allan Wright reports

LATE grazing of 65 dairy cows saved 90t of silage during October and November at the Scottish Agricultural Colleges Acrehead unit, Dumfries.

John Bax, who led the trial, puts the cash saving at £1800. He also reports only 15% of grazing finally available for sheep was lost compared with other areas on the farm.

The late grazing area was shut off in early September and the cows grazed from Sept 30 to Dec 6. A key to the system is that the cows graze strips from the back of the field, so they walk over long grass and do not poach the land.

"We still have some work to do on arranging the strips because, although there is no poaching, there is greater wastage in the final strips where the cows have been walking over the land for some time," says Mr Bax. But he reckons there is no difficulty in getting the cows used to walking towards the rear of the field. "They have to be driven for a few days but quickly learn the system and recognise the electric fences."

At Acrehead 16ha (40 acres) was used with the 65 cows getting 0.2ha a day (0.5 acre a day) to give 80 days of late grazing. Apart from the saving in silage Mr Bax is confident there are welfare benefits from a more gradual move to complete housing. Stress is reduced and there are fewer foot problems.

On milk production and quality Mr Bax is certain there is no fall in either and supports Northern Ireland research suggesting an extra litre or more milk a day with slight improvements in fat and protein.

"There is no doubt late grazing offers considerable potential for dairy farmers and especially those who might be short of silage in any season," he says. But he advises that the system is best reserved for milking cows. "It would be far too easy for dry cows to put on too much condition at late grazing."

The colleges dry cow system involves housing the animals and restricting silage to 30 or 35kg fresh weight and supplementing with 0.5kg a day of a high available protein concentrate. "I am sure it is this system that has pushed up our milk protein from 3.2% to 3.4%," says Mr Bax, who advocates the same protein supplement and high stocking density for dry cows at grass.

A variation on the late grazing trial at Acrehead this season was that the cows went out twice a day – three hours in mid-morning and 2.5 hours in the late afternoon. That was maintained until the clocks changed at the end of October and worked very well, according to Mr Bax.

He had planned to reduce the area set aside for late grazing but was worried about the effects of the summer drought and pasture recovery. "As it turned out the grass/clover sward recovered very well, there was plenty of late growth and we always had more grazing than we needed."

Refining the Acrehead grass and clover system in the year ahead involves a trial in conjunction with seedsmen Sinclair McGill.

Nine different mixtures of grass and clover are being tried with three large plots for each mixture. They will be part of a whole-field approach, with the plots band-sprayed round the edges but otherwise given the same management.

"Our aim is to extend the benefits of clover at both ends of the season and it is important to test the mixtures under commercial farm conditions," says Mr Bax.

Although he feels the clover season can be extended, especially with earlier varieties, Mr Bax says that in eight years of work at Acrehead turnout has, on average, been only two days later than to grass-only swards. &#42

Above: Late grazing saved 90t of silage during October and November at the SAC – a saving worth £1800. Right: The SACs John Bax… "I am sure it is this sytstem that has pushed up our milk protein from 3.2% to 3.4%."