Question: why do some chickens lay brown eggs and some white?
Answer: The answer is quite simple — egg color depends on the breed of the chicken. For example, White Leghorn chickens lay white-shelled eggs, while Plymouth Rocks and Rhode Island Reds lay brown-shelled eggs ( 1 , 2 ). ... It's the same pigment that sometimes gives bruises a blue-green color ( 4 , 5 ).