Heatwaves cause smaller eggs as chickens suffer from summer fatigue

Extreme heat in Sagamihara City is causing chickens to produce smaller eggs and thinner whites due to heat-induced loss of appetite ^[1].

This phenomenon highlights how climate extremes directly impact food production and the biological stress experienced by livestock. While the physical characteristics of the eggs change, producers emphasize that the nutritional quality remains stable.

Taro Ogawa, representative of the Ogawa Egg Direct Sales Store, manages a facility with approximately 26,000 chickens ^[1]. He said that when chickens are exposed to high temperatures, they eat less and increase their water intake to regulate their body temperature.

This biological response leads to a decrease in egg size, often dropping from a medium size to a small-medium size ^[1]. In addition to the size change, the egg whites can become more watery or runny [1, 2, 3].

Despite these changes in appearance and texture, the taste and freshness of the eggs are not affected [1, 2, 3]. The shift is described as a form of "summer fatigue" in poultry, where the birds prioritize cooling and hydration over nutrient intake [1, 2].

"Chickens eat less when it is hot, so the size can drop from M to MS," Ogawa said ^[1]. He said he wants the summer heat to end quickly, noting that eggs would likely be larger if the temperatures were lower ^[1].

Local producers continue to monitor the birds as temperatures remain high. The impact on egg size serves as a visible indicator of the stress levels within the poultry population during peak summer months ^[1].