Sheep producers have been advised to consider a range of feed alternatives to maintain the condition of their flock through a long, hot summer.
With harvest winding up early across the Grainbelt, many growers have already put their sheep onto stubbles.
Department of Primary Industries and Regional Development veterinary officer Danny Roberts warned producers stubbles this year may not contain sufficient nutritional value to sustain sheep at condition score 2.5.
Dr Roberts said cereal crops with reduced yields would have less stubble biomass at harvest with insufficient energy and protein to maintain adult sheep.
“Leaf material provides the most nutritious component of the sheep diet when grazing dry cereal stubbles, which comprises only six per cent of the stubble biomass at harvest,” he said.
“The unharvested or split grain on the ground also have a reduced energy and protein content compared with harvested whole seed.
“While many ewes initially gain a small increase in condition during the first week of grazing stubbles, due to intensive selection, growth will subsequently decline due to over-grazing in the area within 600 metres of a watering point.”
Dr Roberts said the key to successfully grazing stubbles was to identify when to start supplementary feeding.
“It is more cost efficient to feed ewes and maintain condition score than it is to try and gain live weight lost by any delays in supplementary feeding,” he said.
“Regular condition scoring of a sample of 25 ewes every four to six weeks will help producers to determine when to start supplementary feeding and at what level to maintain a flock average of above condition score 2.5 through summer.”
Summer thunderstorms can create isolated opportunities to graze weeds and cereal regrowth but Dr Roberts cautioned producers to be mindful of the limitation of the value of this green material.
“Sheep seek out summer weeds and cereal regrowth, which will comprise about 80 per cent of their diet – even when there is as little as 40 kilograms of green material per hectare available in the stubble,” he said.
“For these reasons, it is hard to predict the estimated intake of energy by sheep grazing stubbles for feed budgeting purposes.
“To ensure sheep do not lose condition rapidly, supplementary feeding may be necessary within three weeks after the commencement of grazing the stubble this year.”
Producers are reminded to ensure there is at least 50 per cent ground cover on paddocks to mitigate the risk of wind erosion and more than 70 per cent to stem water erosion.
Water availability and quality is another key consideration when grazing stubbles.
“To prevent sheep from overgrazing around watering points, strategically located chaff heaps may attract sheep to graze beyond the 600 metres around troughs and dams, while moveable watering points may be another option in large paddocks,” Dr Roberts said.
“On hot days during summer adult sheep will require more than 10 litres of water per day but will avoid warm water.”
The department’s Season 2019-20 webpages has been recently updated with an article on Grazing Stubbles and Dry Pasture to assist producers with feed budgeting decisions, alongside links to the Condition Score app.
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