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Anyone yet to be convinced about the benefits of rotational grazing of beef cattle, perhaps should take note of the figures presented at the GrassCheck event held on an outfarm owned by Wayne Acheson in Sandholes, Cookstown, last week.
A 17.3ha block (42.7 acres) has carried 120 steers since April and delivered average liveweight gains of 1kg/day, with no meal fed.
Cattle were initially turned out in early April, weighing an average of 383kg. Wet weather meant they were re-housed until the end of the month, but since then conditions have been good, and on 13 August the cattle averaged 511kg. Some of the heaviest cattle are now over 600kg, and will soon be housed for a quick finish. That will allow remaining lighter cattle to stay out into the autumn.
The aim is simple – to get as much weight put on from grass as possible. Figures presented by Dr Elizabeth Earle from AgriSearch put the cost of each kg of grass dry matter (DM) at 6p, compared with 12p for a kg of silage DM and 27p for a kg of concentrate DM.
A rotational grazing system was put in place on the Acheson farm eight years ago and has been refined since then, with steers now split into three batches. Each batch is grazed across eight individual paddocks, each approximately two acres in size. Cattle usually spend three days in each paddock, so it is a 21-day rotation.
As there is no access to mains electricity, the system is powered using battery fencers. The cost to set up the fences and drinkers comes to around to £45 to £50 per acre. Given that Wayne estimates grass output is now virtually double what it was before, it is a quick return on the investment.
Barriers
When setting up a paddock grazing system, the advice from Elizabeth Earle is to use a farm map to work out the best layout options.
“Try to keep each paddock reasonably square. If you have a long rectangle shape, cattle tend to do more damage in wet weather going up and down a fence,” said Earle.
One of the main issues when setting up paddocks is giving cattle access to water. On the Acheson farm, each drinker can service four paddocks. Water pipes don’t need to be buried and many farmers just run the pipe over the top of the ground, just underneath the fence.
The other issue is to work out the size of each paddock. In practice it is probably a matter of setting up some temporary fences, and refining the system over time, before putting any permanent infrastructure in place. A more scientific approach is to work out stock demand and use opening and closing grass covers to calculate the required size of each paddock. A spring-calving cow with a calf at foot requires 17kg of grass DM per day, so a group of 20 cows plus calves will eat 1,020kg DM over a three-day period. If going into covers of 3,000kg DM/ha (around 10cm) and grazing down to 1,600kg DM/ha (around 4cm), that means there is 1,400kg DM/ha available. To meet the requirement of the group for three days, a 0.73ha paddock is required.
Fertiliser
On the Acheson farm, paddocks either receive one bag of CAN/acre, or approximately 2,000 gallons of slurry per acre, after each grazing.
Measuring grass
Grazing blocks on the farm are measured weekly, and by mid-August a total of 6.8t DM/ha had been grown. That is slightly behind the average of 23 beef farms in the GrassCheck project, which stands at 7t DM/ha, but still around twice what is thought to be grown on typical beef and sheep farms across NI.
However, the land at Sandholes is dry and growth slowed significantly during June and July.
“Last year we were taking out paddocks left, right and centre, for bales. But this year we have only been able to take out four paddocks for silage. Growth has been steady for most of the year. It was difficult in mid-July, but exceptionally good since then,” said Andrew Clarke, who helps manage the Acheson farm.
He pointed out that one of the main benefits of grass measuring is that it helps to identify under-performing swards. The poorest-performing paddock this year will be reseeded next spring.
Regular measuring also allows a farmer to assess whether supply is in line with demand. For one of the groups, demand has recently moved ahead of supply, so 12 steers will soon be removed from this group and housed for finishing.
Slaughter
The aim is to house cattle at 550kg to 600kg, and have them slaughtered within 100 days at 680kg. For continental types the finishing diet consists of 4kg maize, 2kg barley, 1kg soya hulls, 1kg distillers, 0.5kg straw and 15kg of grass silage.
For Angus and Friesian types, the grass silage allocation is increased to 25kg, at the expense of concentrate.
Single variety used to reseed
Key to maintaining a high stocking rate and good animal performance at grass is to reseed worn out pastures.
The target on the farm at Sandholes is to reseed every eight years, but rather than use a typical grass seed mix, a single perennial ryegrass variety, AberGain, has been sown, along with clover, in recent years.
According to Wayne Acheson, the decision to go with a single ryegrass variety came after he saw how it was performing on a local dairy farm.
Given that AberGain is one of the top performing varieties on the Teagasc Pasture Profit Index, it is hard to argue with his decision, but as pointed out by Dr Debbie McConnell from AFBI, using a single variety might not suit everyone.
“By using a mix, you are spreading the risk – for example, if one variety doesn’t perform as well at a certain time of the year, the others might compensate. Our research suggests that there can be an overall yield improvement by using a mix, but it depends on the varieties used,” she said.
The other issue with AberGain is that it is a tetraploid, rather than a diploid. Tetraploids generally grow taller and more aggressively than diploids, and animal intake (and therefore animal performance) may be higher. But they tend to be more open, making them unsuitable for heavy land and prone to poaching.
They might also be less persistent when compared with diploid varieties. Most mixes generally try to balance the various strengths and weaknesses, by containing a combination of both diploid and tetraploid varieties.
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