I worked with Marans for awhile and my original line for 3 years started back in 2008. I believed it was a good line but every time I would point out common flaws and ask what others were seeing and what they did to improve the quality and they told me that my flock was junk and that I need to cull everything I had and start over. I didn't do that but in the 4th year I did get stock from some of these people that claimed that they didn't have flaws. Guess what? They were full of shit. I worked with stock from 7 different breeders and I only found one that I like half as much as my original line. Quality in Marans is not automatic. It's a difficult breed. Some of the problems that I saw were:
1) small eggs
2) hens that laid fewer than 160 eggs in their first year of production
3) pullets that didn't start laying until they were more than 8 months old
4) black coppers with white undercoats
5) black coppers with white tipped feathers with more than one inch of positive white (i.e. wing feathers, tail feathers, shank feathers)
6) Black Coppers that were carrying extended black, wheaten, eB and other recessive color flaws
7) high tails
8) narrowbodies
9) weak hocks
10) heart problems in males
11) curved backs
12) upward sloping backs
13) short backs, etc... and guess, what?
The biggest criticisms was always egg color. My flock would start laying a nice #5 to #6 but would lighten up to as much as a number 3 after laying 5 eggs a week for 3-4 months. Others tried to reduce the number of eggs their hens laid to one day on one day off so the color wouldn't fade as fast and most claimed their egg color never faded, but ALL seven lines we worked with (even the ones that swore up and down that egg color never faded) but they did. The hens that only laid 3 eggs a week would take twice as long to fade color.
Since they were laying half as many eggs but anything that can lay at least 4 eggs a week in their first year of production was useless to me and a cull. People don't like that word but cull doesn't always mean kill it just means that they are taken out of the breeding pen. Others claimed that their eggs were a #8, #9, or even one person swore up and down that they were getting a #10. When I questioned them on that informing them that the Marans Scale only went up to a #9 this person told me I was told by others that the eggs were a #10. So...it should be too surprising that of the 7 lines I got that most started out laying a #4-#5 eggs. The ever best lines I found would get about 6 out of 8 hens laying a #5 and about one out of 8 hens laying a #6 and about one out of eight laying a #7. I kept probably 100 Marans hens to laying age and only ever had one hen that laid a #8 consistently at the beginning of her laying cycle. We breed her for three years and every year at the beginning of the season she would pop out about 4 #8's then her color would fade to a #7, then a #6. She laid 5-6 eggs a week (and they were XL to Jumbo) and most of the laying cycle they would hold a #5-#6. I would have to go through 1000 hens to find another hen like that. There are many variables and it takes a long time, alot of chicken feed and So Marans Quality is something that requires a lot of hard work. It requires line breed and lot of culling. Crossing the Marans to other breeds ruins them. I know a man that spent 5 years trying to regain the dark egg color in his Marans after an outcross and was never able to get it so he culled his flock and started over too. A color that is created by outcrossed to other breeds like the Orpington would probably require about 20 years of line breeding to get back to the quality that the line had before it was crossed. So think carefully if your goals are to maintain the birds to SOP.