Climate change impacts on milk and egg quality: summary
- Rising temperatures can reduce milk protein and fat content
- European heatwaves caused measurable milk quality declines during 2026
- Heat-stressed hens may produce thinner shells and altered yolks
- Consumer demand remains largely unaffected despite temporary quality changes
- Adaptation mitigates impacts, but extreme heat still poses risks
While the impact of climate change on crops gets a lot of the attention, increasing temperatures can also affect livestock.
Yields and quality of products such as milk and eggs are often affected by hot weather, and extreme heat can even cause animal deaths. As climate change increases temperatures, this risk becomes greater.
How much does this actually impact the egg and dairy industries?
Milk quality is lower
Milk from heat-stressed animals often has a lower protein and fat content, according to the UN’s Food and Agriculture Organisation (FAO) and the World Meteorological Organization (WMO).
This impact of heat on milk quality was seen during the intensive heatwaves that hit Europe earlier this year.
“In the days and weeks of the summer 2026 heatwaves, the decrease of the solid content in milk was at a detectable size,” confirms Alexander Anton, secretary general of the European Whey Processors Association and European Dairy Association.
Nevertheless, since this was for a limited time period, he says, the impact on the dairy industry was “rather negligible”. General trends see the solid content of milk – content of proteins, fats, carbohydrates and minerals – increasing rather than decreasing in both Europe and the US.
Even during the heatwave, he says, variations in nutritional quality were “in the normal ranges”. The impact of heatwaves did not affect the overall demand for milk.
Natural fat and protein content varies for many other reasons alongside heat, he points out, including herd, feed and farm management, cow breed and season.
Egg quality
Heat-stressed chickens can also produce eggs with thinner shells and altered yolk quality, according to the FAO and WMO.
The term ‘altered yolk quality’ refers to “changes in the physical characteristics of the yolk, such as its consistency, colour, size or structural integrity. Heat stress can affect the physiology of laying hens and, in turn, influence how nutrients are deposited in the egg”, explains Monika Tothova, senior economist at the FAO.
Thinner shells can create issues during transport, handling and storage, increasing the risk of breakage.
Nevertheless, Tothova cautions against overstating the issue. “There is evidence that shell quality can deteriorate during periods of heat stress, but this does not mean that large shares of eggs suddenly become unsuitable for marketing.”
The outcome depends on how severe the heat is, the production system and the measures in place to mitigate these effects.
While thinner shells can affect the efficiency of production, Tothova points out, they have little impact on consumer demand.
Adaptation has its limits
Of course, while climate change makes global temperatures rise, heat stress for animals is not a new phenomenon, says Tothova.
“Producers in many parts of the world contend with elevated temperatures every year, and some degree of seasonal variation in productivity is already factored into production decisions and management practices.”
Because of this, much of the supply chain is already prepared. “Large-scale operations often employ mitigation measures such as improved ventilation, cooling systems and, in some cases, climate-controlled facilities.”
However, adaptation has its limits, and sometimes heat stress can be too much. In the recent European heatwave, poultry losses were reported.
As a result of heatwaves, some producers have faced lower productivity and higher mortality rates and cooling costs. Nevertheless, these impacts can be partly offset by higher production in less affected areas.
The impact of heat on milk and egg quality and yields has not, at this point, been profound. Yet industry must be aware that heat can, and often does, influence the output of its animals.
