Yolks are light in color

[Chrismp]

I have eight hens, Three are five years old and five are a year old. They've always had nice, dark yolks to their eggs. For the past month or so, they've started to become very light in color, like a grocery store egg.

Nothing has changed about their diet. They forage on .25 acres in our backyard, get all of our kitchen scraps, and get supplemented with feed (Nutrena, I think). Unless the feed company has changed its ingredients, they are eating the same thing they've always eaten.

Any ideas as to why their yolks have changed?

 

[sbhkma]

Has their production gone down as well? Are they molting? This time of year there's usually less grass & greens for them to eat, which is a major source of that darker color.
If they're anything like mine who free range, they don't eat a whole lot of supplemental feed, so I doubt that's the problem but feed companies are notorious for changing their ingredients w/o any announcement.

 

[Chrismp]

The three older girls are not laying much, the other five are still pretty steady. I'm in NC and it's still summery here, so all the grass is still green. Only one of the older hens is molting.