I have been incubating my own chickens eggs for a few months. My first two hatches did very well, total of 17 chicks from 19 eggs. The hatch I have now, and the last I had, were both failures. The last had a fully formed chick (only one egg), moving on day 18, with no pip. This one has 2 eggs, both of which look like quitters, around day 12-14. I read up on this, and a lot of things point to poor nutrition? I feed all my chickens chick starter, and they free range all day. There are no illnesses, and they seem very healthy. I was wondering, since it seems like many things causing mid to late embryo death are linked to vitamin defficiency, should I supplement my birds with vitamins?