Cattle farming is a cornerstone of global agriculture – it provides essential resources such as dairy products and meat. However, farmers face a major challenge: the occurrence of cattle abortion.

The loss of unborn calves causes significant losses in animal production. In South Africa, this loss has not been quantified, but in California, USA, for example; the cost of a lost bovine foetus amounted to US$1,900 per foetus in 2016. In Argentina in the early 2000s, the annual estimated cost was US$165 million. These losses not only impact the economic viability of farms but also raise concerns about herd health.

Several factors can contribute to the loss of the developing calf; these include infectious disease, genetic abnormalities, toxicity, and nutrition. Determining the cause of abortion in cattle is important for implementing effective preventative measures. This, however, can often be challenging with a global success rate of 30-40%.

Too often abortions are investigated without determining the actual cause. Traditional methods to diagnose cattle abortions often involve post-mortem examinations and laboratory testing such as serology or isolation/culturing of the organisms. These methods are prone to environmental contamination, are costly, and involve lengthy waiting periods.

Polymerase Chain Reaction (PCR) assays that can rapidly detect abortion-causing pathogens such as bacteria and viruses have partly overcome some of the challenges of traditional diagnostic methods. This is a laboratory technique used to provide rapid, simple, and sensitive detection of bacterial genes. These assays, however, are currently limited to testing each suspected pathogen individually.

Emerging PCR techniques such as multiplex PCR or real-time PCR, allow multiple pathogens to be detected at once. However, even these advanced methods can only identify a small number of pathogens simultaneously. This is because each target pathogen requires a unique fluorescent dye, which limits how many can be tested at once due to a limited number of available dyes.

XMap

Diagnostic advancements

Advancements that we are exploring at the University of Pretoria's Faculty of Veterinary Science, particularly with Luminex xMap technology, are opening new doors for diagnosing cattle abortions more quickly and accurately.

This cutting-edge technology tackles some major limitations of traditional diagnostic methods by using tiny magnetic beads, each dyed with two different colours. By adjusting the concentration of these dyes, the xMap machine can distinguish between up to 500 unique beads.

This is where it becomes powerful: each bead can be labelled with a molecule that detects a specific pathogen. This means scientists can load the system with beads for up to 500 different pathogens, allowing for a “multiplex” setup that tests all these at once. In just one test, xMap technology could screen for all known infectious causes of bovine abortion, delivering results quickly and efficiently.

This advancement could be a game-changer, allowing for rapid, large-scale testing that would improve disease management in cattle and help prevent outbreaks by detecting multiple pathogens simultaneously.
Thanks to funding from the Red Meat Industry Services, the Faculty of Veterinary Science at UP is exploring the capabilities of xMap technology. We are developing a multiplex system for the simultaneous detection of several abortive agents of importance in South Africa.

These include Brucella spp., Listeria spp., infectious bovine rhinotracheitis (IBR), and bovine viral diarrhoea virus (BVDV).

Latest findings

Early laboratory testing of this new approach shows promising results. In lab trials, the technology successfully detected known samples of Brucella abortus, Listeria monocytogenes, and bovine alphaherpesvirus 1 (BoHV-1) – all pathogens that can cause cattle abortions.

We have also determined the optimal conditions for attaching the labelled beads to each pathogen, a key step that ensures accurate detection.

As further validation of this method for real-world field samples continues, the potential benefits are clear: the ability to detect multiple pathogens at once not only speeds up the diagnostic process but also increases the chances of identifying the exact cause of the abortion. This advancement could lead to faster, more informed decisions, leading to quicker responses and more effective prevention strategies.

As these technologies continue to evolve and as new insights emerge from these advanced diagnostic methods, farmers can expect more efficient tools for swift and accurate identification of the causes of abortion in their herds.

Dr Angelika Loots holds a PhD in Veterinary Tropical Diseases and is a Postdoctoral Fellow at the University of Pretoria. Professor Melvyn Quan is a researcher and associate professor at the university’s Department of Veterinary Tropical Diseases.