31 January 1997


To maximise intakes from grazed grass, some producers should be planning to turnout as early as late February.

Jonathan Riley reports

MILK producers should aim to provide 55% of the cows ration as grazed grass.

This is the view of New Zealand dairy consultant Paul Bird who estimates that grass currently accounts for only 40% of the UK dairy cows diet. But he explains that grass can provide 11MJ/kg dry matter at a cost of 2p to 4p a kg compared with silage costs of 8p to 10p a kg DM.

"Concentrates cost 16p to 18p/kg DM and with every extra kg of early grass consumed one less kg of concentrates is used," says Mr Bird. "By increasing grass use from 40% to 55%, feed costs could be cut by £100 a cow a year."

All grassland should, therefore, be seen as a grazing opportunity at the start of the season and not as silage ground, says Mr Bird.

He suggests that every effort should be made to get cattle grazing as soon as sufficient grass is available because as well as feed costs, labour costs and disease treatments were cut after turnout.

"The key concept is that of grass as a feed block so that it is easier to match cow intakes – measured as kg DM – with feed available. Once you can measure grass in kg DM it becomes more obvious when cattle should be moved on and when grass is starting to grow away from them," he says.

He recommends walking fields at least once a week to assess how much grass is available, and that once there is 2000kg to 3000kg grass DM available it should be safe to turn out. In many areas this could be as early as late February. But most producers hold back because they are concerned about turning cows out in wet weather, says Mr Bird.

"However, when cows are out for only one to four hours a day, land damage is minimal because when hungry a cow will not walk around but will graze. And in four hours a cow can harvest about 7kg DM, equivalent to a dry cows full daily feed requirement or a third to a half of a milking cows daily ration."

He advises that to ensure consumption is good at grass, in-parlour concentrates could be cut by 30% by, for example, 6kg to 4kg so that cows are still hungry once they have walked to the fields.

"Damage to swards should be reduced by improved access and paddock design. Many UK farms have a central track with a number of narrow fields extending off to each side.

Square-shaped paddocks

"This means that to get to the far end of the field, the cows trample across much of the herbage and a system of square-shaped paddocks would help to reduce poaching.

"With a herd size of about 120 cows Mr Bird recommends creating between 20 to 25 paddocks with electric fences comprising only a single strand of wire for older stock.

"These paddocks should be sited inside and outside of a ring road of tracks between 2m and 4m wide," he says.n

New Zealand grass consultant Paul Bird recommends walking fields at least once a week to assess grass availability. Grass cover can be measured using a rising plate meter.

How to calculate grass intake as % of total intake

As the percentage of grazed grass in the cows diet increases farm profits will tend to increase. Fill in the boxes below to calculate the percentage of grazed grass in your cows diet.

Calculation sheet

Dry matter (DM) for Maintenance

5.3 x cow weight = kg DM for maintenance

5.3 x kg = kg DM (A)

Dry matter (DM) for Milk Production

2 x production a cow a year = kg DM for milk production

2 x gal = kg DM (B)

Total annual dry matter intake a cow = (A) + (B) = kg DM

Less Silage DM a cow

(kg silage x 0.2 = kg silage DM) = kg DM

Less Concentrate DM a cow

(kg concentrate x 0.85 = kg concentrate DM) = kg DM

Equals Grass DM Intake a cow = kg DM

Divide grass intake by total intake

Grass Intake as a % of Total Intake = %

Aim for 75 to 80%

See more