My birds have suddenly (last few days) started laying very pale, almost white eggs. They also seem to be smaller than they were before. The breeds are Red sex link, Black sex link, and Rhode Island Red. They have free access to oyster shell. The last two bags of feed have been Purina Layena pellets. Before that, I had been feeding them layer pellets from a company called A.L. Gilbert - a smallish (smaller than Purina anyway ) feed supplier in California. The birds are about 1 year old. Nobody seems to be molting. Any ideas?