Rates of neonatal lamb mortality across the nation have been shown to cost the sheep industry $540 million a year according to a study carried out by Meat and Livestock Australia in 2015.
That breaks down to be a flock average of $43,000.
Dr Tom Graham, Coolac Vet, along with Sarah Heffernan, Zoetis and Elders Wagga Wagga, recently conducted a field day, with lamb mortality rates being the main topic.
Dr Graham said one of the biggest factors of lamb mortality was the birthweight of the lamb, with more than 80 per cent of losses occurring within the first 48 hours of life.
"Twin deaths are twice as high as single lamb deaths in the same flock," he said.
"Gordon Refshauge found that twin lambs were most likely to die of starvation or birth injury, while single lambs were most likely to be still born or die from dystocia."
A study conducted by NSW Department of Primary Industries research officer Dr Refshauge categorised the cause of death of 3198 newborn lambs less than five days old throughout NSW in 2015.
The study showed that 25 per cent of deaths were due to mismothering, 21pc stillborn, 18pc due to birth injury, 10pc death in utero-prematurity, while 9pc was due to dystocia, 7pc predation and 5pc due to cold exposure and the remaining 6pc was a combination of misadventure, infection or undiagnosed.
Steps for producers
So what can producers do to reduce the lamb mortality rates?
Dr Graham encouraged producers to set aside time to perform an autopsy, as generally there were multiple tasks being carried out on the farm during lambing.
"Get in there with your knife and cut them open, it's the only way to learn to do it," he said.
"In general, as a rule if you can't see things with your own eyes, they're not going to see it in the lab.
"Don't be afraid to end up with no diagnoses.
"You might get to the end of the process, you haven't achieved nothing, you don't have a diagnosis but you've crossed off brain swelling and a bunch of other things.
"That's actually a very good start."
Autopsies can be performed in the paddock and can quickly identify basic factors about the history of the lamb - has it drunk? Has it breathed? Has it walked?
One guide for producers to run through when carrying out paddock autopsies, is the post mortem worksheet from the Agriculture and Horticulture Development Board, which is a step-by-step list to help determine the cause of death.
When first assessing the lamb a large indicator is to look at its feet and see if there is any wear of the soft sole of the feet.
This will indicate if the lamb had the chance to walk at all.
Another factor was if there was meconium present [the brown/yellow staining seen on the lambs], which is only present in difficult births, which can also cause swelling of the head.
When moving onto the inside of the lamb, then look for any bruising that may be apparent due to pressure around the lamb, including from another sibling in the womb if it was a multiple, trying to compete to be the first born.
"Lambs we tend to roll over on their back and then run the knife down the mid-line of the animals," Dr Graham said.
In the case of dystocia, these symptoms of a swollen head and bruising would potentially be enough to say the cause of death, but if that's not the case then the next step is important.
When looking at the kidneys, brown fat is one thing to be looking for which essentially covers the kidneys and is used up within the first few hours of the lamb's life as an energy source.
It is found around the kidneys and the heart.
"If the brown fat is gone it means that the lamb has probably been a few hours old (before it died)," Dr Graham said.
"You won't see that in a sheep that is a day old, they come out and burn that really fast."
Another quick assessment is if the lamb has taken a breath or not. This can be done by placing the lungs in water.
If the lungs float then the lamb has taken a breath, but if the lung sinks to the bottom of the bucket then it indicates the animal never took a breath.
By opening the intestines producers can get an understanding of whether the lamb has taken a drink or not, based on whether milk was present or not.
Producers are encouraged to always consult with their veterinarian when opting to perform autopsies on animals to get advice on the cause of death.
Once cause is known
Once the cause of death is determined then procedures can be put into place to reduce the mortality rates within an operation.
Flock size management and separating twin bearing ewes from single scanned ewes can help with mismothering, especially if for instance, managing multiple scanned ewes in mobs of 200 as opposed to 400 head.
Supplementary peri-parturient nutrition (the period leading into and immediately post lambing) has shown to double the colostrum production.
This can be done by feeding grains ahead of lambing, which allows the lamb the best chance at survival.
Selecting for maternal traits within a flock is also an option, because chances are if the ewe abandons her lamb she will repeat it in the future, he said.
One underutilised option producers could use to identify these ewes was a wet and dry test.
Dr Graham said work in 2014 carried out by the University of New England's Dr Rachelle Hergenhan also showed ewes would generally stay at a lambing site for six hours, with Merinos between 1.3 and 3.5 hours.
