SHEEP producers have been reminded of the benefits of weaning lambs at 14 weeks after the start of lambing to optimise growth rates and pasture use.
Pasture food on offer (FOO) levels have been low across much of the agricultural region this season, placing pressure on feed costs and supplies.
Department of Primary Industries and Regional Development (DPIRD) veterinary officer Danny Roberts said there were many advantages from weaning 12 to 14 weeks after the start of lambing.
Dr Roberts said the improved rate of survival from weaning could be considerable.
“Weaning at no later than 14 weeks after the start of lambing ensures there are no impediments to achieving the highest growth rate before pastures start to flower,” Dr Roberts said.
“The ultimate goal is to capture as much liveweight before pasture senescence to improve performance over summer.”
Weaning allows lambs to be given selenium and cobalt before the spring flush and preferentially graze clover-dominated pastures to ensure maximum growth rates.
Producers also have greater flock management flexibility after weaning, enabling ewes to be fed maintenance rations, placed on paddocks with less FOO, or sold or agisted.
Dr Roberts said weaning at 12 to 14 weeks also helped to minimise the risk of worms in lambs, which could lead to reduced growth rates, scouring and fly strike.
“Lambs have no immunity to worms, and weaning removes lambs from paddocks that may have been contaminated with worms by their mothers,” he said.
“Ideally, lambs would be weaned onto a paddock with a lower worm burden to reduce the risk of scouring and reduced growth rates after being given an effective drench.
“Recent research has demonstrated lamb growth rates above 240 grams per head per day results in weaners being more resilient to winter worms.”
Ewes also benefit from weaning, as they have more time to regain condition before joining.
“Ewes need sufficient time and FOO to regain condition, as they need to reach condition score 3 by joining to achieve good reproductive rates,” Dr Roberts said.
DPIRD recommends lambs be weaned onto paddocks with access to good quality water and FOO levels of more than 1500kg/ha to maximise their intake of energy.
Where this is not available, supplementary feeding should undertaken.
If lambs are to receive supplementary feeding, they should be trained to eat lupin or cereal grain or pellets, while still with their mothers.
This period of ‘imprinting’ is important to ensure weaners are conditioned to the feed and won’t have negative growth rates in the two to three weeks after weaning.
On weaning day, it is important that lambs receive a second vaccination for clostridial diseases and cheesy gland.
Dr Roberts said while there had been interest in weaning earlier, he cautioned producers to do so carefully.
“The smallest lamb should weigh more than 10kg at weaning,” he said.