How long should I isolate a breed to make sure their babies are of that kind?

[Madhava]

Hi!
I have 2 breeds of chickens: Lavender Orpingtons and Black Marans.
They all commingle together as a big family. Each of the breeds have a rooster so I have 2 roosters total.
I'd like to know how long do I need to isolate one breed to make sure that the fertile eggs are of that specific breed.
For example, how long do I have to isolate my Black Marans hens with their rooster in order to make sure the fertile eggs they lay are not a mix Black Marans/Lavender Orpingtons?

There was a time when I only had a rooster and I gave him away... The hens kept laying fertile eggs long after... so I'm puzzled as to how long the eggs inside these hens remain fertile from whatever rooster they mate with.

I hope I'm clear with my question. It's kind of like a mind bending question. Thanks !!!

 

[wamtazlady]

I have always thought the answer was 2 weeks. Then I read where some eggs can still be fertile for 4 weeks. To be sure I would say to wait 5 or 6 weeks before being sure to get eggs fertilized by only your selected rooster.

 

[JacinLarkwell]

30 days is a good rule. 14 days resulted in 4 half siblings when I had a broody hatch those eggs out (mama was the only brown layer so I knew they were hers

 

[allenw]

I never waited more then a week and only had a couple of crossed chicks once. That was my results others may vary. Birds have some strange abilities when it comes to fertilizing their eggs.

If your going to hatch one time I would wait longer, if doing multiple hatches I would start sooner.

 

[3KillerBs]

I have 4 black pullets to prove that my friend's separation of her breeds for 3 weeks before setting eggs didn't work entirely.

In her flock only the Lavender Orpington rooster over the SLW hens could have produced black.

 

[Madhava]

Thank you guys! Insightful. I think I'll go 5 weeks just to make sure. I really don't want to have mix breed chicks. Mahalo!