Breeding Heat-Resilient Cows: Australia’s World-First Genetic Index Leads Global Dairy Innovation

June 22, 2025

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Australia’s dairy industry is making international waves by developing heat-tolerant cows that can withstand rising temperatures — ensuring both animal welfare and consistent milk production despite the challenges of climate change.

For decades, Australian dairy farmers have struggled with significant productivity drops during the sweltering summer months. When temperatures soar above 85°F with humidity levels hitting 80%, dairy cows, much like humans, lose their appetite. According to industry estimates, Australian dairy farmers can see milk yields plummet by 25% to 40% during heatwaves, creating not just financial losses but welfare concerns for the animals themselves.

In response to these challenges, Australian scientists and farmers are turning to cutting-edge genetics. At the center of this breakthrough is the Heat-Tolerance Australian Breeding Value (ABV) — the first of its kind globally — which identifies cows with a natural genetic advantage in coping with heat stress. Developed in 2017, this pioneering index is reshaping breeding strategies across the country and gaining the attention of international dairy markets.

Dr. Thuy Nguyen, the scientist behind the ABV, emphasized that this innovation is not just about profits but about improving the cows’ quality of life. “The history of genetic exploitation in animal agriculture isn’t exactly a textbook on animal welfare: quite the opposite in fact,” Dr. Nguyen told ABC’s Land Line. “But in this case, it improves the animals’ lives because it allows them to tolerate hot and humid conditions more easily.”

Surprisingly, Dr. Nguyen’s team found that the best measurement for heat tolerance wasn’t core body temperature. Instead, they focused on behavioral markers — specifically how cattle’s social dynamics change on hot days. For example, dairy herds on farms like Trevor Parrish’s Kangaroo Valley property become lethargic in the heat, eating little or not at all. They huddle together, unintentionally creating even hotter, more humid microenvironments as they urinate and defecate in the same shaded areas repeatedly.

Parrish, one of the first farmers to adopt the ABV system, described how the genetic index has transformed his breeding choices. When examining potential breeding bulls, Parrish found that some had ABV scores well below 100, indicating poor heat tolerance, while others scored far above 100, making them prime candidates for breeding. “To me it made a lot of sense to have a look into it and try and use bulls that were [more] heat tolerant so it would help the next generation moving forward,” Parrish explained. “I would totally encourage other farmers to use [the ABV]. It’s not getting any cooler.”

The Australian industry’s use of the ABV has now expanded across multiple states, bolstered by strong financial backing and widespread farmer adoption. According to ABC News Australia, this innovation has not only improved local productivity but also sparked international interest. Researchers and dairy farmers in the United States, Italy, and Spain are actively testing the ABV model in their own herds, inspired by Australia’s success.

“The US tested our ABV and found that it works in their conditions so it’s great to see it make waves globally,” Dr. Nguyen noted proudly. This global recognition positions Australia as a leader in dairy innovation, particularly as climate change puts increasing pressure on agricultural industries worldwide.

As heatwaves become more frequent and severe, the ABV offers a promising path forward — one that balances economic resilience with the ethical treatment of animals. Rather than pushing cows beyond their natural limits, Australian farmers are now building herds that are genetically prepared to thrive, ensuring that both animals and farmers are better equipped for a hotter future.