Balancing Progress and Heritage: Marathon Wagyu’s Data-Driven Breeding Journey
On the fertile soils of what is known as the Central Highlands of Queensland near Emerald, the McCosker family has been raising food and fibre for nearly seven decades.
Their story begins in 1929, when the family purchased Codenwarra, by the mid 1990s, the baton had passed to the third generation. Michael and Susan McCosker purchased their own property, Marathon, in 1996, building a reputation for award-winning cotton while also expanding their cattle interests. Twenty years later, they added the neighbouring property, Lake Nash, transforming its old abattoir infrastructure into a backgrounding and artificial insemination hub for a growing Wagyu herd.
That pioneering spirit lives on, underpinned by irrigated cropping of cotton, wheat, chickpeas, and sorghum. Crops feed into the cattle program, and cattle fertilise the cropping, a circular model of stewardship and sustainability.
What began as a mixed enterprise of sheep, Herefords, and crops has grown into Marathon Wagyu, a business that now provides industry leading genetics to Wagyu producers across the globe. At its core is a philosophy that blends deep respect for heritage with a sharp eye on the future.
Pioneers of Fullblood Wagyu
The McCoskers became pioneers of the Australian Wagyu industry in 1997 when John and Robin McCosker made the purchase of their first fullblood bulls to establish the Codenwarra Wagyu herd. Three years later, they expanded again with fullblood embryos and the Codenwarra Stud was established. It was an audacious move in an era when Wagyu markets were still emerging.
“John and Robin were ahead of their time,” explains Laine Thomson, who married into the family and now drives the Wagyu program. “They saw the potential of Wagyu long before it became mainstream, and they built a program known for big-framed maternal cows suited to northern conditions.”
In 2022, Michael and Susan, together with Michael’s sister Debra Postle, purchased Codenwarra and amalgamated its herd into their own. The Marathon and Codenwarra amalgamation brought together some of Australia’s leading genetics for maternal growth and carcase traits for balanced progeny.
Balancing Heritage with Vision
At the heart of Marathon Wagyu’s program is a commitment to protect the maternal growth traits that defined the early herd, while harnessing technology to refine carcase performance and consistency.
“Our vision is to keep building on what the McCosker herd was known for, growthy, maternal cows, while ensuring the next generation also delivers on carcase weight and marbling,” says Laine Thomson.
With around 1,200 breeders and a fully integrated farming model, the enterprise now represents one of Australia’s most structured Wagyu breeding programs, providing elite genetics to producers worldwide.
Data-Driven Decisions
While heritage provides the foundation, data drives the future. Since 2018, Marathon Wagyu has been benchmarking carcase performance using an MIJ camera, a decision that transformed their understanding of the herd.
The camera has allowed Marathon Wagyu to capture precise carcase images and marbling scores on every steer processed, a game-changing shift after years of operating with little feedback.
“In the old days, most of our steers went to AACo, and once they were gone, we never saw them again,” recalls Laine. “We had maternal records, but no idea how our carcases stacked up. Buying our own MIJ camera was about taking back control of that information.”
With support from the Australian Wagyu Association and their “meat ninja” technical officer, Marathon Wagyu began collecting a complete dataset of carcase performance. Every kill was recorded, benchmarked, and compared across cohorts.
“It gave us a baseline, a reality check,” Laine says. “From there, we could start making real decisions. Which sires were delivering? Which cows should be retained? Were we trending in the right direction with marbling and carcass weight? Suddenly we weren’t guessing anymore.”
The results have been encouraging. Over successive cohorts, average marbling has climbed from the high 7s to consistently above 8.3, all while maintaining the maternal base. “We could have chased a quick fix with a high-marbling sire, but we wanted sustainable progress,” Laine explains. “The MIJ data shows we’ve done that, every year, we’re nudging ahead.”
The camera has also guided reproductive decisions. High-performing carcases are flagged for replication through AI and ET, while underperforming lines are gradually culled. “You can’t recreate the perfect animal, but you can tip the odds in your favour,” Laine says. “The MIJ gives us the evidence to do that.”
For Marathon Wagyu, the camera is not just a piece of equipment, it’s a cornerstone of transparency. “We advocate for data integrity and sharing results. Having our own MIJ means we know exactly what we’re producing, and we can stand behind it when we talk to other breeders, buyers, or customers.”
Harnessing MateSel for Balanced Progress
A key part of that improvement has been the adoption of MateSel, a genetic tool that optimises mating allocations.
“You start with the question: do you back the data? For us, yes absolutely,” Laine says. “MateSel gives us the ability to set clear objectives and stick to them: keep maternal growth, manage inbreeding below 12%, and still push forward with carcase improvements.”
The program allows Marathon Wagyu to run multiple mating “scenarios” each year. These include dedicated heifer runs with low-birthweight sires, AI and ET runs targeting genetic gain, and saleable female runs that identify the top-performing cows to retain in the herd. The software even highlights which bulls to retire and which younger sires deserve greater use, creating a long-term framework for herd renewal.
“The beauty of it is consistency,” Laine explains. “You’re not getting one calf that’s way above the rest and another that’s disappointing. Instead, you get a really even line right across the drop. Phenotypically they match, and genomically they’re progressing each year. That’s the sign of a good herd.”
But Laine is quick to emphasise that technology is only part of the equation. “MateSel doesn’t know what a bull looks like. You can have the best EBVs in the world, but if the animal’s weak in structure, you just don’t use him. That’s where the breeder’s eye still matters.”
Outcross Genetics and Industry Collaboration
Marathon Wagyu’s pursuit of genetic progress extends beyond its own paddocks. The herd is both a sire nominator and contributor to the Australian Wagyu Association’s Progeny Test Program (PTP), a collaborative initiative designed to validate sires and accelerate breed-wide genetic improvement.
“We saw it as a chance to introduce outcross genetics and test them in our environment,” Laine says. “A bull might look great in one program, but until you see how he performs in the north, you don’t really know. The PTP gives us that insight, while also helping the industry as a whole.”
One standout example is their heavily used sire, P11. “He’s what we call our ‘super sire’, he combines growth, carcase weight and fine, highly marbled carcases,” Laine explains. “MateSel now wants to retire him because the next generation is testing even stronger. As much as it’s hard to see him go, that’s a good problem to have. It means the system is working.”
Participating in the PTP also strengthens accuracy of EBVs across the herd. By placing sires into different environments and collecting large volumes of carcase and performance data, accuracy lifts from 60–70% into the 90s. “That gives you real confidence,” Laine says. “If you’re going to build a herd around certain sires, you need to know exactly what they’re delivering. The PTP makes that possible.”
For Laine, being part of the PTP is about more than Marathon Wagyu. “We’ve always believed in transparency and sharing data. The Wagyu gene pool isn’t that big, if we all progress together, everyone benefits. The PTP is one way we can contribute back to the breed that’s given our family so much.”
Investing in Infrastructure and AgTech
Marathon Wagyu’s appetite for innovation goes beyond genetics. The family has invested in single-sire mating paddocks, water storage expansion, and agtech like FarmBot water monitoring and crop monitoring platform DataFarming.
“Managing 50 cows to one bull instead of 100 to three has been a game-changer,” Laine says. “FarmBot was another one of those investments where you think, why didn’t we do this sooner?”
Every investment is measured against a simple benchmark: will it deliver a return in both performance and sustainability?
Looking Ahead
Having built their herd from 350 to 1,200 breeders, Marathon Wagyu is now shifting gears. The next phase is less about herd expansion and more about targeted genetic refinement.
“We’ll always protect our maternal strength, but now we’re focusing more on traits like eye muscle area and carcass refinement,” Thomson explains. “I also think Wagyu will have a much bigger role in the broader beef industry, we’re already seeing F1 bulls used commercially in the north to lift fertility.”
Building on its cornerstone of family, Marathon Wagyu sees environmental stewardship as fundamental to a sustainable future. Best-practice management underpins both the cropping and cattle enterprises, while cutting-edge reproductive technologies, elite genetics, and full traceability ensure every animal is backed by robust data. Just as importantly, Marathon Wagyu champions transparency and integrity, recognising that shared information and accountability will drive the industry forward together.
What excites Thomson most, however, isn’t just the numbers or the genetics, it’s the people. “There’s nothing better than getting a call from someone who bought a bull from us, telling me how well his calves are doing. For us, it’s not just a transaction. We want those genetics to work for people, to move the whole industry forward.”
A Heritage of Stewardship, A Future of Opportunity
From the bold vision of the McCosker brothers to the data-driven strategies of today, Marathon Wagyu is a story of continuity and change, a herd shaped by tradition but sharpened by science.
“Wagyu has so much opportunity ahead,” Laine reflects. “If we keep making smart decisions about genetics, about diversity, about sustainability, the future is bright. For us, for the industry, and for the people who believe in what this breed can do.”
First published in Wagyu Update Magazine Vol 93 – Spring 2025