Fine - what about cows? How many cows are bulls? Then there is the steer who is no longer a bull. Chickens or hens are female. Without a rooster, there is no laying hen. There can be no egg without the chicken and no chicken without the rooster. When all of the animals were brought to Adam, there no single one of them found suitable. Kind after kind - it is a law of genetics. For breeding, the word ***** is used for a female but the word dog is a male. If you are talking about breeding as is implied with the chicken or the egg, then we are looking for a rooster and that is what is missing in the puzzle. What was missing in the puzzle for Adam but the female.