A good egg
We have Marans chickens bought last spring from the local French market. They’ve laid beautiful dark-brown eggs but then, after the moult and a short resting time before beginning to lay again, one of them is now occasionally producing an egg much lighter in colour than the rest. Is there any reason for this? Malcolm Curtis
Although it is known that it is definitely related to genetics, the breed does not alone guarantee a consistent supply of continually dark brown eggs. For instance, a male bird could hatch from a dark brown egg but may not have the genes to father pullets that produce dark brown eggs (it seems to be accepted by most that the father is the determining factor for the colour of eggs in the next generation) but that is obviously not the reason in your case.
Egg shell colour is ‘polygenic’, meaning that there are a multiple of genes that affect the end result. The particular pigment that is responsible for creating a brown eggshell in the oviduct is a hemoglobin porphyrin – in effect, a blood product. A hen that lays a single dark chocolate coloured egg and then reverts to those of a paler pigment, most likely does so due to an abnormality in glandular secretions as the egg passes through the oviduct. But, as you’ve noticed, it doesn’t necessarily happen with every egg laid.
Incidentally, the spelling of Marans is always with an ‘s’ on the end – irrespective of whether talking of single or plural.
Marans eggs stand out in the crowd!