I just treated one of my hens with antibiotics and can't eat her eggs for a couple weeks so I want to be able to tell if an egg is hers. What is the best way to do this? I've seen food coloring applied to the vent as one recommendation. How long does that last?
Food coloring sort-of works.
I have put food coloring in some hens' vents and gotten eggs smeared with that color, sometimes for up to a week.
But I have also put food coloring in hens' vents and failed to get colored eggs. (If every hen laid, and no egg had color, I knew it wasn't working right!) I don't know what the difference was, because sometimes it was the very same hens, same food coloring, and (I thought) put on the same way.
If you get food coloring on the feathers around her vent, she can accidentally spread it to other eggs in the same nest. (If one hen has blue food coloring, but three eggs have blue smears... I've had it happen after a hen wiggled at the wrong moment when I tried to drip the food coloring in the right place.)
If you want to try the food coloring, keep her in the cage until you get at least one egg that clearly shows the food coloring, to make sure it worked.
Keep her in a cage until she lays. Then let her out with the girls, gather her off the roost at night, and back in the cage - until she lays. Thing is you don't want to make a mistake with this, you want to know, and know you know her egg.
^ If you want to be really sure about the eggs, this sounds like the best method. It gives her some time out of the cage, but lets you be completely sure which eggs are hers. Once she lays her egg for the day, you can be pretty sure she won't lay another one that day.
