Stock Handling & Animal Welfare

Lamb mortality is on the animal activist agenda

Terry Sim, March 22, 2024


ANIMAL welfare body FOUR PAWS is focussing on lamb mortality in Australia as an industry-funded study concludes high temperatures during critical periods could result in 2.1 million fewer lambs annually, costing sheep farmers an estimated $97 million each year.

As part of its investigation into lamb mortality, FOUR PAWS has highlighted footage it found on the Farm Transparency Project’ website and images, of ewes with lambs and dead lambs in paddocks.

FOUR PAWS said in Australia, the world’s leading wool producer, lamb mortality rates surpass the global average (9-20percent) by up to 10pc and in some cases reaching even 70pc, resulting in an estimated ten million lamb deaths every year.

In a briefing paper, the global animal welfare organisation FOUR PAWS has also highlighted how breeding less wrinkled sheep has the potential to tackle multiple welfare issues including mortality rates, flystrike and mulesing, and advocates for urgent action to protect lambs.

FOUR PAWS ‘end mulesing’ campaign head Rebecca Picallo Gil said every year, millions of lambs silently starve and freeze to death in Australia.

“This needless suffering occurs on an unimaginable scale. It’s simply heart-breaking and an issue that can and must be solved,” she said.

“For an Australian sheep, the biggest hurdle is not to die within the first three days after being born.

“This is where over 80 percent of lamb deaths are reported.”

She said studies also show that lamb mothers are at high risk. Due to birthing difficulties alone, it is estimated that nearly 300,000 ewes die every year in Australia.

Ms Picallo Gil said globally, “live lamb cutting” (mulesing) takes the lead as one of the most invasive routine mutilations conducted on farmed animals, “a mutilation that contributes to the overall high rates of lamb mortality across Australia.”

“These latest images are hard to witness, and the certainty of live lamb cutting (mulesing) after this ordeal makes it even harder to bear,” she said.

“But thankfully there is hope, with growers reporting that the use of good genetics along with adequate animal husbandry practices, can help to tackle both high lamb mortality rates and reduce the need for live lamb cutting.

“For the welfare of lambs and their mothers, and for the sustainability of the industry, it is high time for a change.”

Temperatures above 32 degrees could cause significant losses

Researchers from the University of Adelaide and South Australian Research Development Institute found that high temperatures during critical periods of the reproductive cycle of sheep result in 2.1 million fewer lambs produced in Australia each year.

The work funded by Meat & Livestock Australia found that days above 32°C during the week of mating caused the significant loss of potential lambs.

An MLA spokesperson said the project was based on previous research and modelling of existing and future climate scenarios, with no animal work.

“The wording is important in that the 2.1 million lost lambs represents lost potential at (mostly at the oocyte stage) not lamb mortality at birth; noting that almost all lambs are born in the cooler months when heat stress is less of an issue,” the spokesperson said.

The study was published in Nature Food and found annual losses of potential lambs would increase to 2.5 million if median global warming increased by 1°C, and 3.3 million if it increased by 3°C.

“This modelling is important as it demonstrates that heat events threaten the sustainability of sheep production, both within Australia and globally,” study leader University of Adelaide Associate Professor William van Wettere said.

Not only does heat stress decrease the number of lambs born, but it can also reduce lamb birthweight by between 0.6-1.4kg, the study found.

“If the effects of birthweight are accounted for, economic losses could increase to $168 million under our current climate, and $203 million and $278 million for the 1°C and 3°C temperature scenarios, respectively,” Associate Professor van Wettere said.

The complex research underlying this paper was informed by climate data and modelling conducted by the University’s Professor Seth Westra and Dr Sam Culley, and with contributions from Dr Kathy Gatford of the School of Medicine.

Associate Professor van Wettere said researchers have identified readily available strategies to improve thermoregulation and improve sheep fertility during summer.

The work is underpinned by multiple years of animal heat stress trials conducted at SARDI’s Turretfield Research Centre in Rosedale and our Roseworthy campus, he said.

The collaborative research was conducted by SARDI’s Dr Alice Weaver and Dr Alyce Swinbourne, as well as a large group of early-career University of Adelaide researchers.

“Working alongside the SA Drought Resilience Adoption and Innovation Hub and Farming Systems Groups, validation of these outcomes is taking place within commercial flocks across South Australia,” Associate Professor van Wettere said.

“An integral component of this project is also the work of SARDI’s Drs Dane Thomas and Peter Hayman, who developed a tool that producers can use to understand and quantify the impact of heat stress on fertility of their flock.”

The researchers are now investigating whether selectively breeding animals that thermoregulate more effectively can improve the climate resilience of sheep flocks, and how sheep thermoregulation and behaviour affect fertility during periods of heat.

“We are interested to know whether sheep who seek shade or those who are more active during periods of heat are impacted differently,” Associate Professor van Wettere said.

“Ultimately, we seek to provide sheep farmers with strategies which they can easily implement to safeguard their enterprise from the impacts of current and future climate,” he said.

South Australian sheep producer Jane Kellock participated in the study and has already implemented some of its findings.

“The use of melatonin to mitigate the impacts of heat has increased our reproduction rates, and just being aware of the heat sensitivity of animals and some of the different things that you can do to help with that,” she said.

“It’s really important that we support these research projects and make sure that some of them are done on farms so that we know it’s practical and logistically viable to do these things.”

What does the industry say about lamb mortality?

Australian Sheep Sustainability Framework manager Courtney Nelson said the framework is not aware of any comprehensive or verifiable sources of data on lamb mortality in the Australian sheep industry, other than any information that may be collected for individual business purposes.

For this reason, the framework’s metric for lamb survival is the percentage of producers pregnancy scanning ewes for litter size, she said.

“In the 2023 Annual Report, this was 29pc and collected through the 2022 National Sheep Producer survey, also noting this was the first time this metric was reported in the SSF.

“We continue to evaluate our reporting, and the sources of data we utilise on a regular basis as part of best practice sustainability reporting,” she said.

When asked what status lamb mortality/survival is accorded under the framework, she said:

“Along with what is noted above, we continue to evaluate our reporting, and the sources of data we utilise, on a regular basis as part of best practice sustainability reporting.”

Ms Nelson said pregnancy scanning of ewes for litter size enables producers to differentially manage ewes and tailor nutrition to increase birthweight, weaning rates, and ultimately lamb survival.

“For this reason, we consider pregnancy scanning for litter size a good proxy for lamb survival.”

A simple Google search tells a different story

A simple Google search found that according to a 2013 review ‘Lamb survival in Australian flocks’ by Hinch G.N., Brien F. ‘, average lamb mortality rates of 10pc for single-born lambs and 30pc for twin-born lambs are common in Australia, but mortality can be up to 70pc.

An Agriculture Victoria report published in 2019 and funded by AWI ‘Improving lamb survival by optimising lambing density and mob size’ said that lamb mortalities represent a major source of reproductive wastage and are estimated to cost the Australian sheep industry more than $1B each year. Improving reproductive performance is therefore a high priority for Australian Wool Innovation and MLA (funders of the sustainability framework) to sustain the national ewe flock and meet domestic and export demand for wool and sheep meat, the report said.

The report said the National Sheep Reproduction Strategy estimated that improving the survival of single lambs by 5pc and twin lambs by 20pc would improve farm profit across the industry by $100M and $350M per annum.

“Participation in Lifetime Ewe Management has improved marking percentage by approximately 10pc amongst adopters or 2pc across the national flock.

“It is estimated that about half of these gains have been achieved from improving lamb survival,” the report said.

“However, it is evident that additional strategies that will appeal to a much larger proportion of sheep producers are needed to improve marking rates by 5pc or more over the next 5 years.”

In the SSF Annual Report 2023, AWI’s project manager for reproduction and nutrition, Emmah Goldsmith said every year, the Australian sheep industry loses $850 million due to peri-natal mortality.

In arguing for more pregnancy scanning in flocks, Ms Goldsmith said increasing the number of ewes that are differentially managed and fed to their optimal nutritional profile will certainly improve lamb survival rates.


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