I have had chickens for about 3 years and everyone who has boughten eggs from me has always said that our yolks were the darkest yellow they had ever seen. This year my chickens stopped laying for a long time. Finally, when they started laying again the yolks seem pale. I am feeding lay mesh pellets and whole wheat berries. Could the wheat cause this? This is the first time I have fed them wheat. I had a bag that got moths in it so had to get rid of it somewhere without wasting it.