![Department of Primary Industries research officer Gordon Refshauge said identifying cause of death was important when it came to managing lamb survival. Department of Primary Industries research officer Gordon Refshauge said identifying cause of death was important when it came to managing lamb survival.](/images/transform/v1/crop/frm/213266301/0b68f182-46f6-419c-902b-d2abd911c507.jpg/r0_744_3987_2921_w1200_h678_fmax.jpg)
Sheep producers have been encouraged to better understand the cause of death in lambs as a way to improve survival going forward.
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Department of Primary Industries research officer Gordon Refshauge said producers often incorrectly focused on extreme cold or predation, however the most common cause of lamb mortality was dystocia, followed by starvation.
Mr Refshauge gave a presentation as part of the annual MerinoLink conference held in Bathurst recently.
He said carrying out thorough autopsies to establish patterns in lamb mortality would help producers identify how to improve survival rates.
Having accurate data would also help the industry target research and development that focused on the primary causes of lamb mortality, he said.
"The (autopsy) method you use will change the result that you get," he said.
"If you were to pick up dead lambs and only look in their stomachs - that's all you did, you ignored every other sign - you'll put 70 to 90 per cent of the dead lambs in the starvation category.
"But that would ignore important information like dystocia or they died during birth and had never walked and never breathed.
"If a lamb dies from starvation, it has to have lived long enough to have starved to death.
"The signs that we pick up in an autopsy pool these things together."
A critical point was establishing the time of death in relation to the time of birth, he said.
It was important to determine whether the lamb died before or during the birth, or immediately afterwards as opposed to days later.
Having an accurate time of death would help producers decide the cause, he said.
"I say dystocia is the most prevalent cause of death, and if you were to try and manage that you would have a number of genetic options, like birth weight management, thinking about avoiding very high birth weight or very low birth weight sires," he said.
The longer it took to give birth, the longer a lamb was forced to go without oxygen that could lead to injuries to the brain, he said.
Lambs with brain injuries were then less likely to feed and were more likely to struggle to maintain body temperature.
As well as selecting for adequate birthing rates, producers should also consider udder soundness, he said.
Research from the University of New England had indicated the lambs born to ewes with unsound udders were 1.5 times more likely to die than those born to ewes with sound udders.
Those born to unsound udders were also 4.6 times more likely to die of starvation.
"Tidying up udders isn't that hard to do, you'll improve lamb survival but you'll also improve weaning weights," Mr Refshauge said.
He also recommended producers gave ewes a second chance when it came to joining.
There were a lot of environmental factors that contributed to the success rate and giving ewes a second chance improved the accuracy of selection, he said.
Other factors to consider when it came to lamb survival included managing body condition and nutrition, shelter, and dam and sire selection.
"If I was only allowed one of those tools, I would be wetting and drying ewes at marking," he said.
Results from a recent survey involving 57 producers found about one third were not wetting and drying their ewes, he said.
"That data is gold," he said.
"If you want to improve lamb survival, that's the data you want to go and get.
"Pregnancy scanning, identification of pregnancy status and litter size, isn't going to help your rearing ability."
There were opportunities for further research and development into selecting for lamb vigour, he said, which he believed was more relevant than maternal behaviour.
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