Know your grazing and silage needs

19 March 1999

Scarce cover not always bad thing

DONT be too concerned if pasture cover is lower than it usually is in April, New Zealand consultant Paul Bird told the Cumbria workshop.

"Its a good thing; it means you have grazed more grass and eaten less silage."

Mr Bird said producers had to achieve the right balance between when to start grazing and when they expected to complete the first grazing round.

"Thats why a whole farm grazing plan is important. Paddocks may not always have 2500kg DM/ha. If you start grazing when cover is low, calculations suggest that you should graze larger areas which would mean finishing the first round too soon.

"Thats not good. The first round must finish in mid-April; thats more important in the long run than feeding cows fully on pasture early in the season," he said.

He advised producers not to fall into the trap of allocating too much ground for first cut silage. Paddocks carrying 3000kg DM/ha are often set-aside for silage but if too much land is taken out for silage there could be a shortage of grazing before aftermaths are ready. "When in doubt, cut less silage," said Mr Bird.

May to June grass management should aim to maintain grass cover at 2200-2300kg DM/ha, grazing to 1600-1800kg DM/ha to give a good compromise between high intakes and maintaining grass quality.

Magic day in

Could you make better use of grass this year and help cut

feeding costs in tour dairy herd? Jeremy Hunt reports from

a workshop aiming to help producers do just that

DAIRY farmers following the New Zealand principles of grass management should set their sights on magic day – the day when pasture is growing faster than it is being eaten.

It occurs on most UK farms during April and by that time all paddocks should have been grazed once by the dairy herd.

At a Dairy Profit Workshop in Cumbria last week, producers were urged to recognise the importance of spring grassland management, its impact on year-round grass production and ultimate effect on herd profits.

"Your skill in managing pasture in the spring determines profits for the year. The aim is to graze the maximum amount of grass in the early part of the year," New Zealand grassland consultant Carol Gibson told producers.

To calculate magic day it was essential that producers knew their stocking rate, intake a cow in kg DM/day and pasture growth rate. Multiplying stocking rate and daily intake will give daily grass demand:

&#8226 Stocking rate x intake = feed demand in kg DM/ha.

&#8226 2.5 cows/ha x 16kg DM/cow = 40 kg DM/ha demand a day.

Taking this example, Miss Gibson explained that magic day would be the day when growth rates reach 40kg DM/ha/day on a consistent basis. "For most areas in the UK this will be around mid-April; later in colder areas and early April in mild areas.

"Obviously the higher the stocking rate the later magic day will be on any farm, all other things being equal," she said.

Farmers attending the workshop, organised by the British Grassland Society, were advised to aim for turn out when pasture cover was 2000kg DM/ha – about 7cm (2.8 in) of grass growth as measured by a sward stick.

Turning the herd out for just a couple of hours at the start of the season when they could be using a daily intake of fresh grass is better than keeping cows inside for longer,"said Miss Gibson.

"As cows are turned out for longer they should be given a fresh area every day or at least every other day and a backfence should be used to protect re-growth."

Aim to graze pastures down to 1600-1700kg DM/ha (5-6cm) to encourage tillering and ensure good pasture quality when the grass is grazed or cut for silage, she advised.

"You should never be feeding silage at the same time as you are saving grass for silage. It does not make sense," said Miss Gibson.

She advised measuring grass cover over entire farms every week. The level of cover will fall to about 1800-1900kg DM/ha in April.

"If it drops too rapidly early in the season reduce the area allocated. Dont allocate more pasture early in the season; feed more concentrates if necessary and remember that there must only be one grazing round before magic day."

Miss Gibson advised mastering an understanding of the grass wedge. This is a way of describing grass heights in different paddocks and is an important feature of rotational grazing, indicating the amount of grazing available.

As a guide cows turned out by day in early spring will need about 1ha/100 cows (2.5 acres/100 cows) every day – assuming a ground cover of 2500kg DM/ha on the paddock being grazed. Paddocks should be taken down to 1700kg DM/ha. According to Miss Gibson, 1ha (2.5 acres) is enough to provide 100 cows with a daily intake of 8kg DM.


Know your grazing and silage needs

MATCHING growth and demand is the key to efficient grass management and it can be achieved by measuring grass growth and linking that to the farms grazing area.

West Sussex dairy farmer Christian Fox said this enabled the amount of grass (kg DM/ha) being produced by the farm each day to be equated to the daily requirement (kg DM) of the cows.

"Farmers usually adopt two totally different attitudes to calculating grazing requirements and silage needs.

"The amount of silage in the clamp is calculated in dry matter terms. When equated to the herds requirements its possible to work out if it will be enough and whether other feeds may be necessary to supplement the diet.

"No one makes silage then hangs a plastic sheet in front of the clamp and says they will just keep feeding it until it runs out, but thats exactly the attitude many farmers have to grazing," said Mr Fox.

Turning out in the spring, waiting to see what happens to grass, and then making silage when there is too much to graze is an inefficient way of managing grass.

"You need to know how much you require, how much youve got and how best to feed it," said Mr Fox.

For ease of calculation Mr Fox measures his entire farm every 10 days enabling him to work out the growth (kg DM/ha) of each paddock and the average for the farm. This figure can then be compared to cows demand.

"When average growth a day is 20kg DM/ha and I have one cow a hectare demanding 10kg each of grazed grass, I have 10kg more than I need which is a good position to be in.

"If we did the same set of figures for July and I have a demand over the farm of 40kg DM/ha of dry matter a cow and yet I am only growing 30kg DM/ha I know I am eating more grass than I am growing.

"But I wont suddenly find that I have got no grass left. I am ahead of the situation. The average farm cover figure combined with cow intake of grass is the main tool for successful grass management and enables a feed wedge to be created as the basic concept of the system," said Mr Fox.

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