Weaning decisions is about giving the best feed on the farm to the lambs and giving the ewes time to recover.
Achieve Ag Solutions director, Nathan Scott, said the timing of weaning in all sheep flocks was critical to the future performance of the flock.
He said having lambs healthy and going ahead also gave producers some flexibility when marketing in a challenging year due to COVID-19.
The optimal weaning time was governed by both age and weight, he said.
"Age is a fall-back position but weight is the major factor. The heavier the lambs are the earlier they can be weaned," he said.
"Generally speaking, 14 weeks after the start of lambing is the optimum time for weaning. It's that point when we've got all we can from that ewe and beyond that point she's not providing anything but comfort and worms.
"There is a trade-off in the form of the lure of sucker lambs that keeps lambs on ewes for longer," he said.
Mr Scott said it was an easier decision to make with Merino ewes because at that stage the ewe was "really not contributing anything".
"Once the lambs get beyond 12 weeks of age, the ewe is contributing less than 10 percent of energy requirements of the lamb," he said.
He said in "tight seasons" there were "surprisingly good results" where people had weaned early; but when good seasons returned producers went back to their traditional weaning time.
"The reality is that every year we should be trying to allocate the best feed available to just the lambs and not wasting it on ewes that don't need it," he said.
"But it's not just about the lambs - the ewe needs time to recover as well. Giving her an extra three to four weeks to recover is really important for her and to give her the best chance of performing for us the following year."
He said the biggest problem was people trying to pick when to wean lambs by looking at them.
"When you can see something wrong that's three weeks too late. Too many people use weaning as a reactionary management tool, when it should be a proactive strategy that shouldn't change from one year to the next," he said.
In lamb operations the challenge is when lambs were nearly ready to be marketed as suckers. That often dragged from two weeks to four weeks or six weeks and the lambs were still on the ewe that was eating all the feed, he said.
"The lambs could have been going ahead on better feed and the mums could have been on anything else," he said.
He said the timing of weaning should not change much at all from year to year - good year or bad year.
"In any season we have a portion of the farm offering better feed than the rest of the farm. Beyond that 12 to 14 weeks post lambing the ewe's lactation doesn't warrant the quality of feed she's eating," he said.
"As soon as we split the lambs off the ewes the overall stocking rate falls, just because the ewe stops trying to lactate - even if she's not doing a good job of it."
He said the ewes could go onto lower quality feed and be given time to recover and would perform better the following year.
Mr Scott said the same was true for all sheep operations.
The challenge was high performing composite flocks that were capable of turning off lambs "off mum" at 16 weeks.
Mr Scott said while Merino ewes needed care, their lambs needed to have the best feed on the farm in front of them to "really ramp things up".
"We need to keep those weaners going to thrive and it's all about nutrition," he said.
Mr Scott said that weaning lambs in smaller mobs helped them settle much quicker - finding the leaders, establish a mob dynamic.
A tail develops much quicker in a bigger mob than smaller mobs.
He said that because liveweight was critical for weaning - 45 per cent of the standard reference weight - the heavier the lambs were at weaning the better.
"Sometimes we can't and you need to know that by weighing to be able to put more effort in from that weaning point forwards. You want to track that onwards by weighing a sample of the mob," he said.
Timing weaning to get lambs off ewes before shearing and other management activities was also useful - particularly at the tail end of the season. he said.
"You're just knocking lambs around by having them off feed during those operations, when they could be out just eating while you have a simpler operation of ewes coming though with no lambs at foot."