We let all our chickens free range. The yolks are deep orange and much better tasting than commercial layer houses where the chickens eat pelletized feed and stay under lights 24 hours a day just to lay them selves out in about 12 months.
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Unfortunately this is only one of several incorrect statements in this thread. Laying hens are never, ever, on 24 hours a day lighting. They would stop laying. Most housed birds are on about 16 hours on and 8 off. It is a legal requirement in most of the world for adult stock to have a minimum dark period of 7 hours in 24. Some folks have experimented with 8 on and 8 off. Only possible if the house is light proof. I am not convinced it produces more eggs.
I have kept commercial flocks of laying hens in several countries over the last 60 years so speak from a wee bit of experience. Whenever possible, including on my previous farm in the North of Scotland where eggs were my sole source of income, I have free ranged the hens. The yolk colour is purely due to the feed consumed. I had sufficient numbers that the feed mill made my feed to order. There is a yolk colour indicator that Roche used to make. I understand they stopped production soon after the turn of the century. This indicator was coloured strips of plastic numbered from 1 to 15 if I remember correctly, 1 being very anaemic looking and the top end verging on blood red. In Inverness and further north they only wanted eggs with a yolk colour right at the top end. My feed was made to provide that colour. Maize (corn in the US) will give a good yellow colour, but not the reddish tints that many people look for. Marigold petals and some other plants will help, but food colouring materials are what is needed to move the colour towards the red end. Some green feeds will give a greenish tint to the white, and sometimes an "off" smell. The age of the hen that laid the egg has a great deal to do with the consistency of the white part, known as the albumen. A young hen will produce an egg with a tight albumen if the egg is broken into a pan, whilst the older the hen becomes, the more the albumen will tend to spread. The weather also is involved. In really hot temperatueres when the hen drinks more, the albumen tends to become thinner. This can happen in housed flocks if the ventilation is not sufficient to keep the temperature down.
As already pointed out, blood spots have nothing to do with whether the egg is fertile or not. In fact, a bloodspot is not wanted in a hatching egg.
Cockerels are not necessary for egg production, and they are never used in commercial flocks. Cockerels are *** machines on legs and will, as Gary Fowler says, rape the hens until they cause physical damage. A hen with no feathers due to treading has been treated most cruelly, and I would not want to be the owner of such birds. Almost every female in the animal kingdom produces eggs on a regular basis up to a certain age. Ask your wife/girlfriend. Hens have been bred to produce more frequently than most species.
I do not know what the regulations are regarding when eggs are deemed to be past their "use by" date, but in much of the world it is 28 days after laying. They will keep much longer than that if not subjected to high temperatures. A cool pantry is ideal, despite instruction that they should be refrigerated. In Europe that is a stupid suggestion, because the producer is banned from refrigerating the eggs, as is the retailer, yet the consumer is recommended to keep them in the fridge.