Wet carcass syndrome (WCS) is a perplexing condition that significantly impacts the quality of sheep carcasses post-slaughter. The syndrome manifests itself after the slaughtering process, making it difficult to detect and prevent while the animal is alive.

This condition poses considerable economic challenges to the sheep farming industry, particularly in South Africa, where it has been a persistent issue since the 1980s.

Bhaveni B Kooverjee, a doctoral candidate at the Agricultural Research Council (ARC) researching WCS, and Dr Pranisha Soma, a researcher at the ARC, shed light on this complex syndrome, delving into the clinical signs, potential physiological and biochemical markers, impact on carcass processing, recent research findings and the economic implications of WCS.

“WCS is a condition that is only found in sheep and appears after slaughter. Prior to slaughter, the animal appears normal and unaffected. However, after the 24-hour cooling period, the carcass appears to have a sticky, slimy layer coating the entire outer layer of the carcass,” explains Kooverjee.

This condition makes the carcasses difficult to handle and its appearance affects its marketability.

Physiological and biochemical markers

Detecting WCS before slaughter is a significant challenge.

“WCS appears post-slaughter; there are no symptoms prior that we can use as identifying markers to say that this animal will be susceptible to WCS. It appears at the carcass stage,” notes Kooverjee.
This absence of early markers complicates efforts to manage and prevent the syndrome effectively.

The presence of a slimy layer on the carcass significantly hampers processing.

“The carcass, as it goes through the processes in the abattoir, becomes very difficult for the abattoir people to cut and clean because it’s so slippery. The tools even slip off, posing a challenge for the abattoir workers working on the carcass,” explains Kooverjee.

Furthermore, because the carcass is wet, it creates a favourable environment for micro-organisms, reducing the shelf life of the carcass and posing a risk to human consumption. Such carcasses are condemned by health inspectors as unfit for human consumption, she adds.

Emerging diagnostic technologies

Despite the current lack of diagnostic technologies for early detection, hope is on the horizon. Kooverjee’s research aims to identify potential genetic mechanisms underlying WCS.

“At the moment, there isn’t any diagnostic technology. However, my current study is aimed at identifying the genetic mechanism for this condition, particularly any possible gene/s responsible for activating the slimy liquid that coats the carcass, either through activation or dysregulation of genes,” she states.

This genetic focus could pave the way for future diagnostic and preventative measures.
Initial observations linked WCS predominantly to Dorper crossbreeds, but recent findings suggest a broader susceptibility.

“Previously, this condition was only found in the Dorper and Dorper crossbreeds. However, the current project has now identified that it’s found in almost all sheep breeds. This raises the question of whether it’s related to sheep genetics in general and not just breed-specific genetics,” says Kooverjee.

This broader genetic predisposition requires further investigation.

Soma provides additional insights into the genetic aspects of WCS.

“A study in 2017 identified several candidate gene markers linked to WCS, implying that genetics plays a role in the etiology of this condition. This aspect is currently being investigated further by the ARC. The ultimate aim is to develop a genetic test for the syndrome,” she explains.

While there are no concrete treatments or preventative measures currently, ongoing studies hold promise.

“There were previous suggestions in terms of handling animals prior to slaughter, such as providing sheep with enough water to calm down before going straight from transport into the abattoir. However, there hasn’t been any concrete evidence showing that these measures positively prevent WCS,” notes Kooverjee.

The focus remains on genetic research to develop more effective solutions.

Economic impact

The economic implications of WCS are profound. “In South Africa, a study done in 2011 and 2012 found that approximately R27 million was lost due to WCS in 2010,” says Kooverjee.

She adds that information supplied by the National Animal Health Disease Information System estimated that out of the 1,3 million sheep slaughtered in the Northern Cape in 2018, 19 782 carcasses were affected by WCS. This resulted in an estimated loss of R29 million.

Soma adds: “According to the Food Safety Agency Abattoir report, 2 476 carcasses were condemned due to WCS between 2019 and 2023. The cumulative losses over the past 30 years amount to approximately R600 million.”

Key challenges and knowledge gaps 

One of the major challenges in understanding WCS is its post-slaughter manifestation.

“As this condition appears post-slaughter, there’s nothing that we can use to identify it when the animal is healthy and fine,” explains Kooverjee.

Previous studies have tried to induce the condition in animals without success. Factors like drinking too much water prior to slaughter, transport distances, allergies, and washing carcasses using high-pressure systems have all been explored, but none of them could be linked to WCS.

“The current way forward is to interrogate the condition at the genomic level. Previously, two DNA markers have been associated with this condition, but we need more information from various breeds. Over the past two years, we’ve collected over 200 affected samples, and with the use of whole genome sequence techniques, we will be able to further interrogate those regions where these markers were identified,” says Kooverjee.

Soma adds that understanding the interaction between genetics and environmental factors is crucial.

“Heat stress or environmental stress could play a role in activating the genes responsible for WCS. Our research aims to investigate these potential triggers in depth,” she says.

Both experts agree that WCS poses significant challenges for the South African sheep industry, affecting both the economic viability of farming operations and the quality of sheep products. The potential for mitigating its impact becomes increasingly promising, offering hope for the sheep farming industry in South Africa.

Email Bhaveni B Kooverjee at [email protected], or Dr Pranisha Soma at [email protected].