I have 5 pekin ducks 1 male and 4 females they started laying here about 2 weeks ago the first day we got 2 eggs, then 1 egg every day since. dh found a soft egg the other day so we gave them oyster shell in with their feed. yesterday evening we found 2 soft shelled eggs and yesterday morning 1 normal. Is this normal for them to lay soft shelled eggs on their first eggs? how can I get more calcium into them.