I have 6 hens who will be 1 yr old in April, 5 Dominiques and 1 Road Island Red, no roosters. They've been laying eggs regularly since last September. Their egg output increased during winter months since I "extended" their daylight time with artificial light on a timer over their run. I have noticed repeatedly streaks of blood inside an egg, mostly on the yolk or between the yolk and white. It happens occasionally, not every day. Again, there are no roosters so the eggs are not fertilized and there are no other signs of an embryo. My feeling is that it is nothing serious. I am not a professional farmer or poultry raiser nor an avian biologist. It moderately bothers my wife. Anything I should be concerned about? Thanks.