8 August 1997

SET STOCKING AVOIDS GRAZING CONSTRAINTS

Not all grassland farms can exploit rotational grazing effectively. Jonathan Riley reports from the Worcs-based host farm of a High Genetic Merit Initiative open day

LOW summer grass growth and low labour availability mean that buffer feeding and set stocking are the preferred option for dairy producers Robert and Linda Tarver.

Their 95ha (235-acre) Hayes Farm, Bishampton, supports 92 pedigree Holstein Friesian cows and is a Dalgety and Holstein Friesian Society high genetic merit initiative monitor farm.

Milked three times a day, the herd averages 9921 litres from a 60/40 maize and grass silage mix. This is offered with brewers grains, molasses and up to 11kg of concentrates fed to yield.

"The annual rainfall is only 21in and in summer grass growth stops. To sustain milk yields, we have to feed a maize silage buffer one hour before each milking," explained Mr Tarver.

"The buffer is high in energy and complements the high protein levels in grass."

Speaking at a farm open day, Northern Ireland-based researcher Sinclair Mayne, of the Agricultural Research Institute, Hillsborough, said that the drop in milk price meant dairy producers had to maximise grass use to cut costs.

He said that rotational grazing offered the chance to improve grass intakes and reduce reliance on conserved feed and concentrates.

High quality sward

But at the Tarvers the set stocking policy has created a high quality, dense sward of an optimum set stocking height of 4cm (1.6in) to 5cm (2in).

"Unlike rotational grazing, set stocked swards are grazed continually and light is able to penetrate to the sward base. This promotes tillering and ensures that the cows are always grazing young leaves which results in a highly digestible feed of about 78D-80D," explained Dr Mayne.

"But the disadvantage of set stocking – particularly for high yielders – is that the cow does not consume as much grass a bite because the grass is shorter. She then has to work harder to achieve intakes needed to support yields. However, on units such as this – where the grass growth period is so limited – any extra returns gained may not offset the investment in fencing and labour needed to support rotational grazing," said Dr Mayne.

At Hayes Farm labour comprises of only Mr and Mrs Tarver and one part-time worker. The set stocked regime, therefore, helps to reduce the workload.

Instead Dr Mayne suggested grass use could be improved by extending the grazing season beyond the first week in September when cows are housed at Hayes Farm.

"As the youngstock and heifers have been kept at grass successfully until December it may be possible to leave milkers out for a further 30 days," said Dr Mayne.

He calculated that as grass is a third of the cost of silage this would cut feed costs by £18 a cow.

But Mr and Mrs Tarver explained that the grey marl soil was prone to poaching and that grazing on wet days reduced intakes and hence milk yields.

Robert and Linda Tarvers high yielding pedigree herd is set-stocked. Researcher Sinclair Mayne agrees that this type of grazing management promotes tillering.

GRAZING CONSTRAINTS

&#8226 Low summer rainfall.

&#8226 Grey marl soil prone to poaching.

&#8226 Low labour availability.

HERD FACTS

&#8226 Calving index 369 days.

&#8226 Calving interval 70 days.

&#8226 Margin over purchased feeds £2056 a cow.

&#8226 Margin over concentrates 21.2p/litre.