Why do Eggs Get Smaller During the Winter?

 

You may have noticed that eggs tend to be smaller during the winter versus spring and summer, where they can be quite big. Typically, if you buy conventional eggs there won't be much variation from one egg to the other because they are produced in a controlled-environment setting. On the other hand, eggs from pastured farms can vary in size, shape, and color. These differences arise because of the difference in the environments the eggs were produced in. 

Similar to the reason why egg production is lower in the winter, the same applies to egg size. Since chickens need approximately 16 hours of daylight to be fully productive, anything less than that starts to lower egg production. When temperature is factored into the equation, egg numbers also drop because chickens would rather keep their body temperature up than be cold and produce eggs. Compounding the two defining factors of winter (cold, short days), smaller eggs become more prevalent because less calories are being put toward making big eggs, and are instead focused on body temperature regulation. 

Then, when spring comes along with its mild temperatures and longer days, with lots of intense sunlight, egg production is at its highest! It's during spring that roughly 90%-96% of a flock lays eggs on a given day, which is about the height of the modern chicken's efficiency. Even old chickens still manage to lay a few eggs during the spring, which can be quite amazing for a 5 year old chicken.