France's June heatwave killed hundreds of thousands of laying hens, threatening egg supply
In one of the oldest buildings on his free-range organic farm near Redon in northwest France, Erwann Etrillard lost 1,000 laying hens during the second half of June—a quarter of his flock. The building, lacking mechanical ventilation and misting systems, became a death trap as temperatures soared.
"It was so hot that the hens suffocated,"Etrillard explained. The high temperatures arrived early in the morning, precisely at laying time, creating intense stress among the birds.
"They stayed inside, huddled together in the nesting boxes, looking for a safe spot."
The devastation at Etrillard's farm was part of a broader catastrophe affecting poultry operations across France. According to the Comité national pour la promotion de l'œuf (CNPO), between 500,000 and 700,000 hens—representing 1.5% to 2% of the national flock—died during the June heatwave. The same weather event claimed more than 2,700 human lives nationwide, with daily high temperatures averaging 36.9°C across France, shattering the previous June record by 2.4°C.
Brittany particularly vulnerable
"The consequences were more severe in regions less accustomed to high temperatures and less prepared for them, such as Brittany or Pays de la Loire,"said Alice Richard, director of the CNPO. These two regions account for 66% of French poultry production, making France the largest egg producer in the European Union with 15.4 billion eggs produced in 2024.
Brittany has historically been spared the worst of France's heatwaves, particularly along its western coast. However, all four departments in the region were placed under orange heat wave alerts from May 26-28, marking what Météo France described as an unprecedented and historic heatwave episode for the area. Emergency room visits and medical calls for heat-related issues in Brittany from June 21-27 reached levels not seen since the monitoring system was established, with people aged 75 and older among the hardest hit.
The rapid temperature increase proved particularly deadly for the birds. Laying hens thrive in a thermoneutral zone between 18-22°C, but when air temperatures approach 37.8°C, their core body temperatures rise to lethal levels without adequate cooling measures. The speed of the temperature spike was critical—acute heat stress can result in mortality rates exceeding 95% within just five hours, far more devastating than gradual temperature increases.
Infrastructure gaps exposed
The crisis exposed significant gaps in farm infrastructure. While EU regulations require high-density poultry holdings to be equipped with ventilation, heating and cooling systems to maintain appropriate temperature and humidity levels, many older farm buildings lack these modern protections. Organic farms, which represent approximately 13.7% of French egg production, often operate facilities without the mechanical systems that might have prevented the mass die-offs.
"These heatwaves are likely to happen again, so significant investments are needed to ensure the entire country is equipped to face them,"Richard emphasized. The mortality depends heavily on how well farms are adapted to extreme heat—a reality that will require substantial capital outlays in a sector already under pressure.
The timing could not be worse for the French egg industry. Consumption grew by 5.2% in early 2024 while production growth stagnated at less than 1%, prompting the industry to launch a €300 million investment plan to build over 300 new sheds by 2030. The loss of hundreds of thousands of laying hens further strains an already tight supply situation, raising concerns about egg availability and prices in the months ahead.
