1 March 1996

Feed budgeting can realise your full potential

In the first of a series on grazing for profit, we examine how to ration early spring grass to improve performance from cows on grazed pasture. Sue Rider reports

MILK producers keen to maximize use of grazed grass must improve grass budgeting skills. That is the message of Dr Gearoid Stakelum from the Moorepark Dairy Research Centre, Co Cork, Ireland.

He believes feed budgeting is an area in which many dairy farmers are falling down. "Most producers are not achieving potential performance from their cows on grazed pasture," says Dr Stakelum. "High yields a cow are being achieved on many units. But all too often success comes from feeding concentrates in place of grass." The aim must be to get more grass into cows rather than costly feeds. That depends on good grazing management. And feed budgeting will add precision to those skills.

"Feed budgeting of grazed grass involves assessing yields of grass at regular intervals. For example, how much grass is immediately ahead of the cows, and how much was just behind the cows." And such measurements are important to anticipate surpluses and deficits.

"Producers keen to feed cows properly at pasture must be able to judge how much pasture is available for grazing in this way and how much was eaten in a particular paddock. Go out and fetch your own cows for milking. That will enable you to monitor the grass situation on the farm," he adds.

Stocking rates

Long-term grass budgeting decisions determine stocking rate, N-input, and conservation management. Short-term budgeting is all about offering the herd enough grass each day, says Dr Stakelum.

This depends on cow size and genetic potential for milk production (see Table 1). On average, daily herd needs are about 16-18kg DM a cow – to a maximum of 20kg DM a cow. An extra 0.4-0.5kg DM a day is needed for each extra 1kg of milk that is produced.

Daily grass allowance is the useable grass in a paddock divided by the number of cows grazing that paddock, then divided by the number of days the herd stays in the paddock (see Table 2). When allowance is too low, the paddock will be grazed out too well. Daily allowance is reduced, intakes fall and the amount of grass left behind after grazing also falls. But it is also important to avoid offering too much grass for undergrazing reduces grass quality.

The key is to offer the cows just enough to allow them to eat enough and leave the paddock clean. When cows are offered 19-20kg of grass DM above 4cm (1.6in), under very good grazing conditions, they can eat 17-18kg DM daily, says Dr Stakelum. He advises allowing cows to eat down to a post-grazing height of 6cm (2.4in) in the paddock from April to mid-June.

This post-grazing sward height should be monitored closely to achieve the correct daily allowance.

In late April/May/June when grass growth rates are high it is crucial to stop grass getting ahead of demand and running to seed.

Dr Stakelum suggests that while a 6cm post-grazing height is recommended from April to June, post-grazing heights should be relaxed to 7-8cm (2.75-3in) from mid-June onwards.


&#8226 Do you know your paddock areas?

&#8226 How often do you walk your paddock?

&#8226 Can you match lifts or drops in bulk tank reading to pasture use?

&#8226 When you allocate grass by subdividing a paddock, do you relate the post-grazing yield and height to the new area allocated and the pre-grazing yield on that area?

&#8226 Could you estimate herd intake in a paddock?

&#8226 Could you make an assessment of when its necessary to feed supplements?

&#8226 Who goes for the cows?


Table 2: How to

calculate daily grass intake based on yield assessments

1) Pre-grazing yield

= 3500kg DM/ha

(to ground level)

2) Post-grazing yield

= 2000kg DM/ha

(to ground level)

3) Paddock size

= 0.8ha (2 acres)

4) Time in the paddock

= 2 days (4 grazings)

5) Herd size

= 40 cows

Then intake a cow

a day can be calculated as

(1-2) x 3 ÷ 4 x 5

eg 3500-2000 x 0.809

÷ 2 x 40 = 15.2kg DM


Table 1: Feed demand (kg DM/day) for different categories of cows.

Average lactationTotal lactation yield

weight (kg)4000 l7000 &#8226

45012.818.0

50013.618.8

55014.519.6

60015.320.5

65016.121.3

Can you judge how much pasture is available for grazing and how much was eaten in a particular paddock?