Two of my chickens are getting on in years. This last cold snap has been hard on my rooster, Peter. He is at least 7 years old, possibly older. He has slowed down a lot. His comb is fading. He walks slower, sleeps longer and is no longer fertile. His favorite hen and constant companion, Eggatha, is also 7 or older. She has started laying shell less or thin shelled eggs, dispite good food and free choice oyster shell. Yesterday, she laid two eggs at once. Both were thin shelled, and one was filthy. I think one egg didn't come out on time and was pushed out by the second egg. Is there anything special that can be done for older chickens to help them along a bit? It will be a sad day when I finally lose them.