7 March 1997

SACswitch to rotational grazing

ROTATIONAL grazing is the key to improving grass intakes of high yielding cows.

Johnny Bax, of the Scottish Agricultural Colleges Crichton Royal Farm, Dumfires,is so convinced of this he is ditching set-stocking this season for their moderate input, high output herd.

"Were aiming for 9000 litres off as much forage as possible – including grazing," he told the Royal Association of British Dairy Farmers conference. It made sense to maximise use of grazed grass. At Crichton grass/clover swards offered the cheapest feed at £17/t of dry matter compared with £70/t DM for grass silage. "The more we can get cows to harvest grass for us, reducing reliance on silage, the lower our costs."

Cows peaked at maintenance plus 20 litres off grass in early season. "The trick is to maintain that performance for as long as possible. That means getting more grass into them and we cant do that with set stocking," he explained. "The system restricts production off grass – once we increase yields I expect rotational grazing to have the edge." The technique would ensure more grass was in front of the cows. "We wont increase performance by having cows ranging over fields to find the grass." He also intended to run a leader follower grazing system – and topping only when absolutely nessessary in early season – to clean up behind the high yielders and maintain sward quality throughout the grazing season.

Getting more from grass would also mean greater emphasis on grass budgeting. "We must be more precise about rationing cows at grass. We talk about intake of kilos of dry matter in winter. I would find it easier if I knew what grazing cows were eating as well. Tools – such as plate meters – can help us determine how much grass is in front of cows," he said.

This was particularly important with high merit cows. "They must have plenty of grass in front of them because they are programmed to produce milk and will loose condition before they loose milk production," he warned. When well managed there was little difference in welfare terms between high and low output systems. But taking high genetic merit cows down the low input route was potentially the riskier strategy – with less room for manoeuvre, he conceded.

SACs Johnny Bax…set stocking restricts production off grass.