Most Beef Cattle in South America Endure Hundreds to Thousands of Hours of Heat-Related Discomfort Each Year, New Study Finds

A new scientific study has taken a hard, data-driven look at something farmers and animal welfare experts have long suspected: heat stress is a constant reality for beef cattle across much of South America, not just an occasional seasonal problem. For the first time, researchers have measured heat stress not simply as a risk factor, but as the total number of hours cattle actually spend experiencing thermal discomfort over the course of a year.

The research was carried out by scientists from the Welfare Footprint Institute and published in the peer-reviewed journal Animals. It focuses on major beef-producing regions in Brazil, Argentina, Colombia, Paraguay, and Uruguay, countries that together account for a significant share of the global beef supply.

Measuring Heat Stress in Hours, Not Just Temperatures

Instead of asking whether cattle are exposed to high temperatures, the researchers asked a more revealing question: how long do animals actually suffer from heat-related discomfort, and how intense is that experience?

To answer this, the team analyzed five years of climate data from 636 cattle-producing locations across South America. They then applied the Welfare Footprint Framework (WFF), a scientific method designed to translate environmental conditions into cumulative time spent in negative welfare states.

This approach allowed the researchers to estimate not only how often heat stress occurs, but how many hours per year cattle live under moderate, high, or severe thermal stress. The result is a much clearer picture of what heat stress really means for animals on the ground.

Heat Stress Is a Daily Condition, Not a Rare Event

One of the most striking findings of the study is that heat stress is not confined to heat waves or brief summer peaks. In regions classified as having high or extreme thermal risk, cattle experience heat stress on most days of the year.

Across these high-risk areas, individual animals were estimated to spend between 280 and nearly 2,800 hours per year in moderate to intense thermal discomfort. In the most extreme locations, cattle were exposed to stressful heat conditions for more than 300 days annually, averaging over 11 hours per day under conditions that challenge their ability to regulate body temperature.

In practical terms, this means that for many cattle, heat stress is a near-constant part of daily life, rather than an occasional hardship.

What Heat Stress Does to Cattle

At higher intensity levels, heat stress has serious consequences for animal behavior and physiology. According to the study, cattle experiencing sustained thermal discomfort often:

Reduce or stop grazing and ruminating
Remain immobile for long periods to limit heat production
Engage in intense and prolonged panting to try to release excess body heat

These responses are not just short-term coping mechanisms. When heat stress persists day after day, it represents prolonged negative affective states that accumulate over a significant portion of an animal’s life.

Importantly, the study’s estimates are conservative. The researchers measured only the direct experience of thermal discomfort, not the downstream effects such as increased disease risk, reduced fertility, or heat-related mortality, all of which are known to rise under hot conditions.

A New Way to Think About Animal Welfare

This research marks a new application of the Welfare Footprint Framework to a large-scale environmental challenge in animal agriculture. By expressing heat stress in hours of lived discomfort, the framework makes it possible to directly compare heat stress with other major welfare issues, such as hunger, disease, or injury.

Rather than treating heat exposure as an abstract risk, the study makes the welfare cost measurable, comparable, and harder to ignore. It also highlights that climate-related stressors are already shaping animal welfare outcomes today, not just in future climate scenarios.

Shade Makes a Massive Difference

One of the most practical parts of the study is its analysis of shade as a heat mitigation strategy. Using modeling based on real-world production data, the researchers evaluated how effective shade structures could be in reducing heat stress.

The results were clear: effective shade can reduce time spent in the most severe category of thermal discomfort by around 85%. In the hottest regions, this means reducing annual exposure from hundreds of hours to just a few dozen.

Even more interesting is that these welfare gains are not just ethically appealing—they also make economic sense.

Shade Is Not Just Good for Welfare, It Pays Off

The study found that shade structures typically generate net economic returns of US$12–16 per animal, even if they are used only briefly during the finishing phase of production. These gains come from improved feed efficiency and increased weight gain, as cattle are better able to eat, rest, and grow under cooler conditions.

When shade is used throughout the entire production cycle, the researchers expect the economic benefits to be even higher. This makes shade provision one of the most cost-effective animal welfare interventions currently identified for beef cattle in hot climates.

Natural Shade and Environmental Co-Benefits

Beyond artificial shade structures, the study highlights the value of silvopastoral systems, where trees are integrated into grazing lands. These systems provide natural shade while also delivering broader environmental benefits, including:

Increased biodiversity
Improved soil protection
Greater landscape resilience

In feedlot settings, shade-providing infrastructure can also improve the local microclimate without requiring major changes to existing production systems. In this sense, shade stands out as a rare solution that simultaneously advances animal welfare, environmental sustainability, and productivity.

Why This Matters in a Warming World

Heat stress is already one of the most significant challenges facing livestock production globally, and climate change is expected to intensify the problem. Rising temperatures, longer heat seasons, and more frequent extreme heat events all increase the risk to animal welfare and farm productivity.

This study shows that for South American beef cattle, the problem is already severe. Treating heat stress as a marginal management issue is no longer realistic. Instead, the findings suggest it should be considered a central animal welfare and sustainability concern, with clear, actionable solutions available.

A Clear Message for Producers and the Industry

The takeaway from this research is straightforward. Heat stress affects millions of cattle for thousands of hours every year, with serious implications for welfare and productivity. At the same time, practical, affordable solutions already exist, and they often pay for themselves.

By measuring heat stress in lived hours rather than abstract risk categories, the study provides a powerful new lens for understanding animal welfare in hot climates—and a strong case for action.

Research paper:
https://www.mdpi.com/2076-2615/16/2/231