I have a gallon ice cream tub I have filled with eggshells to give the chickens soon.My chickens have done the same thing every couple of months they'll lay an odd one and then it will go back to normal laying. Its most likely fine just make sure you are giving them plenty of food, treats, and some type of calcium like crushed up ouster shells and believe it or not you can actually feed them there own shells with the yoke or without it. Whenever your cooking instead of throwing the shells away, give them to your chickens. They are using alot of their calcium to make their eggs. If you crush it up and mix it in their feed it will help them with their eggs a lot so its less common that will happen. I wish you luck!
Those aren't veins. That's the odd shell pattern. Yes, there's 5 cockerels that share the coop, she's been laying fertile eggs for awhile without a hiccup.Also do you have any roosters? This might have been caused by a first time laying fertile eggs type of deal. The egg in the picture looks like it has vains in the egg which probably means it's fertile. If you don't have a rooster do you think maybe someone elses rooster might have come into your yard and then left?
The layer mash we feed has oyster shell in it, so I will add egg shell too. I'll post if she lays another odd egg.Oh ok then just try to see how she does when she lays another one and see if it's better and just go with the first thing i said about the calcium. Hope she does better!