Research challenges thinking on lamb survival

New research is underway to help boost lamb survival in Australian sheep flocks by better understanding the underlying causes of dystocia, or difficulty in lambing, one of the costliest conditions for sheep producers. 

The project is researching the impact duration of lambing has on ewes and lambs, to help better inform future control efforts such as treatments.

It is one of 10 projects to be funded by the Strategic Partnership for Animal Welfare Research, Development and Adoption (RD&A). The Partnership is a collaboration between Meat & Livestock Australia (MLA), through MLA Donor Company (MDC), and some of the country’s leading research bodies to undertake ground-breaking projects focused on animal welfare.

MLA Program Manager Health Welfare & Biosecurity, Dr Johann Schröder, said neonatal lamb loss has been identified by MLA as one of the top five conditions or diseases compromising sheep profitability, and is estimated to cost the industry in excess of $219 million annually.

The four-year project is being led by Dr Sabine Schmoelzl, CSIRO Armidale, who says it will help establish a better understanding of why lambs don’t survive or why ewes fail to raise the lambs.

“Dystocia is defined as ‘prolonged lambing’ or any reason a labour doesn’t progress, including when a ewe is running out of energy and just can’t handle it anymore,” Dr Schmoelzl said.

“We believe dystocia contributes to more than half of all neonatal lamb mortality, which is the single highest cause of financial loss in the sheep industry.

“This project is developing a completely new research tool to help define what affects the duration of lambing. We want to be able to answer the question – how can we prevent prolonged lambing by various treatments or through genetics?

“Natural selection of the fittest lambs, or genetic selection of ewes which are successfully rearing lambs, is an attractive concept, and important to keep in mind. Relying on it alone, even with good management, has nevertheless not achieved solving the issue of lamb mortality altogether, and that is why we are developing this new tool.”

Now in its second year, the project has already collected data on 400 ewes during lambing. The ewes comprise Merino ewes of different ages, crossed to either Merino or Border Leicester sires.

The project’s in-field research involves using on-animal sensor technology - with ewes wearing sensor collars - combined with blood testing to identify biomarkers that relate to difficult lambing.

“We bring ewes in groups of 20 at a time into smaller paddocks to allow them to display normal behaviours during lambing,” Dr Schmoelzl said.

“Being able to keep watch on lambing ewes on scale and out in paddock conditions rather than a small number of intensely monitored animals will make a big difference.

“We deploy the sensors and have cameras in the paddocks with day and night vision. The video streams are collected and whenever a lamb is born we use that footage to observe the behaviours of the ewe and match it with the data that the sensors collect.

“We also have a blood analyser that can be used pen-side to collect blood parameters from the ewes and lambs after birth. We want to find out if can we find biomarkers to measure the metabolic status of the ewe that relates to having undergone a difficult labour.”

Dr Schmoelzl said the research is building on evidence and years of data sourced largely from the Sheep CRC’s Information Nucleus Flock.

“Over four years, every lamb that was found dead in that flock was analysed in an autopsy and they also looked at brain damage. From these data it was quite clear that in at least half of all lambs that died, there were signs of birth related injury and that means birth trauma. It’s quite important to understand what are the underlying reasons when lambs are abandoned by ewes,” Dr Schmoelzl said.

“We think these lambs may get abandoned because they had some birth-related injury. This may mean they were not behaving properly, were a bit slow or couldn’t bleat properly, and the mum couldn’t form the necessary ewe-lamb bond. Also, if there was a difficult labour, then the ewe will also have had trauma and is probably exhausted and unable to immediately bond with that lamb.

“It’s basically moving away from saying some ewes are bad mothers, to saying that some ewes have a poor lambing event, and they will overcome that if they are given a chance.”