Getting the most from your pasture is an easy but efficient way of increasing farm profitability and productivity. But it can be tricky knowing where to start.
Ruth Wills attends an AHDB meeting to find out...
Improving pasture management by matching livestock to grass availability can bring benefits, optimising outputs both per hectare and per animal says independent consultant Luppo Diepenbroek.
He adds: “Grazed grass is the cheapest feed and produces the highest margin. It has to be managed for better returns.”
But how do farmers go about getting the maximum from their pasture?
Firstly, because grass changes from week to week, Mr Diepenbroek says it is important to measure what is available and then adjust the grazing area accordingly to improve usage.
He adds measuring grass can be done simply by using a sward stick, or more accurately by using a plate meter.
Mr Diepenbroek recommends sheep be turned into a paddock when it has 2,500kg dry matter/ha (1,010kg DM/acre), grazing it down to 1,250kg DM/ha (505kg DM/ acre) before being moved.
With cattle, turnout should be at 2,700-3,000kg DM/ha (1,090-1,215kg DM/acre), grazed down to 1,500kg DM/ha (607kg DM/acre).
However, Mr Diepenbroek says farmers should not always rely on the plate meter.
“If you take a plate meter into a field which has been cut for silage the grass will be quite ridged, so it will be measuring the stem instead of the growing grass, giving a false reading.”
It is also possible to go by leaf stages.
“Rye-grass which is 2,500kg DM/ha will have three leaves and grass really starts motoring when the third leaf is up,” he says.
“If you go beyond the third leaf, the first leaf will die, the stem elongates and then goes to seed. So, to get the most digestible grass you must graze at the three-leaf stage.”
He warns against getting the grass topper out if the seed comes to head during dry periods.
He says: “This will cause the metabolisable energy to drop and if the grass gets stressed by drought, it will go to seed again and so on, so do not ever top when it is dry. If you feel you want to get the topper out, mow instead because it clean cuts the grass instead of shredding it.”
Mr Diepenbroek recommends inputting the grass growth data from every field into a spreadsheet to calculate a grazing rotation, or using a specialist software package which can work out how much the animals should eat and which paddocks to graze next.
He also says it is possible to calculate how much dry matter is needed in total. He says scientists in New Zealand have calculated the stage at which farmers achieve ultimate profitability from the grazing platform.
This is 79kg of animal per tonne of grass produced, so to work out how many tonnes of grass are needed, add up the total weight of the livestock and divide it by 79.
However, only about 80 per cent of grass is actually used, so this must also be accounted for.
MR Diepenbroek advises grazing paddocks with sheep for two or three days.
“If left longer they can overgraze the leys, because the new growth is tastier and has lots of sugar in it. This could mean no leaves are left to sprout and causes sympathetic root death. Eventually the grass’ energy runs out and it will die.”
In contrast, he says short periods of grazing can encourage grass to shoot again, as long as there is greenery left. When the grass is green, sugars are returned to the root and the energy is used to push the grass up and regrow.
HERBAL leys bring benefits in terms of soil structure, nitrogen fixation, drought resistance and season-round yields, as well as protein and mineral content. They are also beneficial to animal health.
Luppo Diepenbroek says: “The reason I like herbal leys is because they reduce worm burden. We do not know exactly how, it could be due to the physical nature of the crop or something in the crop reducing the worm challenge.”
Red and white clover are particularly good for fixing nitrogen in a sward.
A ground cover of 20-30 per cent clover can fix 180kg/ha (73kg/acre) of nitrogen, while 40 per cent clover would fix 240kg/ha (97kg/acre), while 50-60 per cent clover would fix 300kg/ha (121kg/acre).
When compared to the average amount of fertiliser used by sheep and beef farmers – 70kg/ha (28kg/acre) – and 170kg/ha (69kg/acre) on dairy farms – this shows the impact clover can have on the sward.
Earthworms also improve soil structure, so Mr Diepenbroek says it is important to bear in mind drought and cultivations will affect their population. It can take five years to rebuild the worm population, so Mr Diepenbroek encourages minimal cultivations.