Donna,
A blood spot in an egg doesn't have anything to do with whether it is fertile or not. I found this:
Egg with blood spots inside
This is usually the result of blood escaping from the ovarian follicle and becoming embedded in the albumen. It can sometimes be the result of shock or stress and normally rights itself. There is some evidence that there is a hereditary tendency for this condition, so avoid breeding from such a hen.
Here is what I found about fertile eggs:
Fertile eggs
If hens are running with a cock the chances are that they will be laying fertile eggs. These should not be offered for sale for they cause offence to many consumers. Registered producers are required by the egg marketing regulations to produce eggs with, ‘a yolk that is free of foreign bodies’.
There is considerable misconception about this subject, with people making varied claims such as: ‘hens lay better when there is a cock with them’, and ‘fertile eggs are more healthy and nutritious’. In fact, the opposite is the case with both claims. With the former, there is a greater risk of disease transference, as well as physical damage to hens from the male’s spurs. With the latter, there is a greater risk of disease-transference into the egg.
Traditionally, breeding flocks and laying flocks were kept quite separate, as they still are with free-range flocks today. If you have your hens running with a cock and don’t object to eating fertile eggs, that is of course your own business, but selling them to others should be avoided.
