Hi Everyone! One of my female ducks is about 4 years old. For the past couple of months she is laying incredibly soft eggs, the shell is literally like tissue paper. I have tried oyster shells in her food but she absolutely hates it when I add it in. Is there any other suggestions on what she could be lacking in her diet? I thought maybe just with the lack of sunlight over the winter was contributing, we did have a really cold winter this year so she was in her indoor pen more than usual but she has had ample sun the last month. Help!