Why are eggshells thin in summer?

The main component of eggshell is calcium carbonate, and there are many reasons that affect the formation of eggshell. Environmental temperature, season, nutrition, and lack of calcium or vitamin D in food will make eggshells thinner. Calcium ions that form eggshells are mainly provided by blood. When the ambient temperature is high in summer, the food intake of chickens decreases, and the calcium ion content in chickens decreases. High temperature will also reduce the concentration of carbonic acid in the blood, and the eggshell will become thinner.