My ducks eat locally milled layer feed, when they bother to eat feed, which isn't much now that the grass is growing and the bugs are active. They are molting, so from the five girls i am only getting an egg a day. But the shells seem soft, and are often cracked at collection time. Is this a calcium shortage or a molting thing? If they need extra calcium, how can I best work it in to their foraging lifestyle choices?