Grazing extension probe
LOWER lamb prices and financial returns from sheep enterprises have caused Irish researchers to examine ways of extending the grazing season to cut winter feed costs.
Costs of making silage and indoor feeding must be cut, says Sean Flanagan, principal Teagasc sheep production officer and farms director at Knockbeg Sheep Unit, Carlow, Co Carlow, Ireland.
"This continues our policy on cutting sheep management costs. Silage making involves clamping and machinery, and indoor feeding requires labour and trough feeding – both are labour and machinery intensive."
Therefore, Teagasc researchers have been looking to extend grazing to all year round, maximising grazed grass in ewe diets.
Practically, this means lower stocking rates, down to 10 ewes/ha (4/acre). But in some ways extended grazing management flies in the face of good grass management, says Dr Flanagan.
"Nitrogen application could produce grass at an embarrassing level and because of lower stocking rates there are not enough mouths to eat it." And when grass growth outstrips demand, there is no point in conserving any excess because theres no need for it, he says.
Sheep graze paddocks which are split by an electric fence. This is moved every day to give ewes their allocated grass allowance on a New Zealand daily shift system.
Ewes require 1.3kg dry matter each a day, he says. "We know a ewe in mid-pregnancy will maintain herself on 1kg DM a day of good-quality grass, but because sheep do not eat all the grass on the ground we allow 1.3kg DM."
Total all year grazing is yet to be achieved at Knockbeg, but last year grazing continued into January.
"We shut up 4.35ha of grass in early September which was allowed to accumulate during October and November. Ewes were turned on to this on Dec 3, with 2.64kg DM/ha on offer."
There are 202 March and April lambing Belclare x Cheviot ewes in the extended grazing flock. Their mid-pregnancy liveweight is 70kg and a feed budget is prepared on this basis.
"Each day the flock requires 263kg DM of grass. We predicted we had 38 days supply from the feed wedge shut up in September."
The area in fact supplied 37 days of grazing and the ewes came in weighing the same and in good condition at a score of 3.4, he adds.
To ensure the budget in maintained a Flexinet electric fence divides paddocks and an area supplying ewes with their need for a days grazing is calculated. This usually means shifting the Flexinet 10m (32ft) a day.
A back fence is used to prevent ewes going back on what they have already grazed. "Grass can then recover immediately, because it can become poached. It is critical ewes are not allowed back onto that area if the damage is not going to be more permanent."
To extend grazing further into winter, grazing allowances a day will increase as pregnancy progresses and introducing supplementary concentrate feeding will have to be considered, says Dr Flanagan.
During the grazing season the perennial ryegrass permanent pastures are monitored every week so a feed budget can be updated.
Grazing days are calculated by using a platemeter and assessing available grass by eye – eyeballing – which Dr Flanagan says improves with experience.
"Sward height is not always a good indicator of grass availability as some pastures can be open and give a lower supply of grass DM."
• Cuts machinery costs.
• Feed budget needed.
• Build up feed wedge.