US animal behaviourist and scientist Dr Temple Grandin has flagged significant welfare and environmental challenges posed by the growing size of North American beef cattle, driven by genetics favouring larger frames.

In her essay for the US industry magazine Meat and Poultry, Dr Grandin detailed the scale of the issue, revealing that the average carcass weight of fed cattle in the US had increased by 17.2 kg (38 lbs) between June 2023 and June 2024. "Today’s fed cattle in the US are getting bigger and bigger," she explained, and this presents both logistical and economic problems for the beef industry.

Dr Grandin highlighted three major concerns with these larger animals:

-Back bruising: Taller cattle are more likely to suffer back bruising when they exit the bottom deck of semi-trailers, despite trailers being modified to increase clearance. This issue is becoming increasingly prevalent as carcass sizes grow.

-Handling facility limitations: Many of the existing cattle handling facilities, particularly those with 76 cm (30-inch) chutes, were designed for smaller cattle. As the animals grow in size and girth, they no longer fit comfortably through these standard facilities. This is particularly problematic for the heaviest animals, where chute width becomes a constraint.

-Feeding economics: The largest steers have correspondingly large sisters, which pose significant economic challenges on grassland ranches, especially during winter. "Each huge steer has a huge sister who will be too expensive to feed in the winter on grassland ranches," Dr Grandin noted, underlining the sustainability trade-offs that come with maintaining large animals on arid rangelands.

While Dr Grandin acknowledged that larger animals contribute to greater meat production efficiency—producing more pounds of high-quality beef from fewer animals—she pointed out that this comes at a cost. Ranchers face the risk of financial losses if they attempt to feed oversized cattle on limited natural resources, especially during harsh winter months.

Historical Trends in US Cattle Carcass Weights

The trend towards larger carcass weights is not new. Dr Grandin noted that the average weight of steer carcasses in the US has been increasing by approximately 1.8kg annually over the past 60 years. In the 1960s, a typical steer carcass weighed around 300 kg, today, that figure exceeds 409kgs. This steady rise has transformed the US beef industry, introducing both opportunities and new challenges.

The shift towards larger cattle began in the early 1970s, when smaller Herefords and Angus breeds, once the mainstay of US beef production, were gradually replaced by crossbreeding with larger European breeds like Charolais. While this breeding strategy improved meat yields, it has now led to other complications, particularly the size of cuts, with ribeye steaks sometimes being too large to fit standard plates.

Australian plan to cut carcase size

These challenges are also present in Australia's 28.8m head of cattle. To combat this some breeders have begun moderating frame sizes. Australia’s technical committee chairman, Rick Greenup, for the hybrid breed Santa Gertrudis, explained that breeders had once pursued larger frame scores, with some cattle scoring as high as nine or 10. However, the industry has now shifted towards more moderate frame scores of seven or eight, balancing body size with other production traits such as fertility and feed efficiency.

This moderation has provided producers with greater flexibility. “A Santa Gertrudis animal with a moderate frame score gives producers the ability to raise quality, early-maturing feeder steers that finish well and meet Meat Standards Australia (MSA) compliance,” Greenup said.

Processing and Infrastructure Challenges

The shift towards larger animals has had a profound impact on processing facilities. A 2023 report by the Australian Meat Processor Corporation (AMPC) highlighted that heavier carcasses require retrofitting in processing plants, which increases costs significantly. For example, a trade-weight carcass that once filled ten standard cartons of beef may now be a custom-kill Wagyu carcass weighing 450-500 kg, filling more than 20 cartons. The larger bodies also increase the demands on processing workers, many of whom come from smaller-framed backgrounds.

The AMPC report also noted that processing rates are affected by carcass size. Smaller carcasses, with their lighter body weights, slow down processing speeds—plants may only achieve 65 head per hour. In contrast, larger animals can be processed at a faster rate of 75 head per hour, improving overall efficiency. Furthermore, boning larger carcasses results in higher meat yields per animal: a large carcass can produce 14,280 kg of beef per hour, compared to 14,000 kg from smaller animals, representing a tangible productivity gain.

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Are We Repeating Past Mistakes?

Dr Grandin concluded her essay with a warning, reflecting on the history of cattle breeding. “The question I wish to ask is: Are we repeating old mistakes?” she wrote, suggesting that while the industry has gained significant efficiencies through genetic selection for larger animals, it must carefully balance these gains against the costs—both in animal welfare and sustainability.

By integrating more of the technical data, including figures on carcass weights, frame scores, and processing yields, this piece underscores the complex trade-offs involved in managing the growth of cattle size within the global beef industry.

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