Anyone know how much your average hybrid layer would weigh?

[Blackpuddingbertha]

I know they're all different and some breeds lighter / heavier than others but anyone have a clue on a general weight? I need to get some invermectin from the vet to treat for lice (tried everything else) and he wants to know what they weigh so he can work out the dose! Besides boxing them up and sticking them on the kitchen scales which will be traumatic for all involved I'm not sure how to do it!

Also, has anyone used invermectin and know what the egg withdrawal period should be? He was saying 28 days but I'm sure I've read 7 days.

I've answered my own question as we bit the bullet and weighed one before treating them. Just in case anyone else is interested, one of my middle-sized ones weighed just under 2.5 kg. so we estimated the biggest to be about 3kg and the skinny ones about 2kg.

Withdrawal period is 7 days but I've got to treat them once a week for 3weeks. So no eggs for three weeks! This better work as I've run out of options (& it cost £43 for the invermectin)...