help! odd looking yolk

[harbourhens]

Dear all,

My girls are looking and acting fine but are producing eggs with a stringy bit coming from the yolk... It looks to me like excess yolk membrane. Can anyone tell me what it is? is it serious? What's caused it and treatment?

Tryed to attach an image but thats not working.

 

[harbourhens]

BTW they are hybrids, and they eat standard layer pellets, I use verm x in their Feed every month, they don't have a lot of greens as they are on the same patch.. But I have recently started giving the vitamins

 

[harbourhens]