There is no way anyone would implant these foetuses, so stories of half human half animal babies are nonsense. In any case, very little of the embryo is animal. They are taking animal eggs and removing the dna and replacing it with human dna, this saves having to use human eggs.

I have to wonder how far this research will take us though, as I think it would be potentially too dangerous to use the derived cells in human therapy, in which case the research done on them might not be applicable.