"At that stage the birds are only around 14 to 16 months old. So we go in and pay for them, per hen."
Kelly says once they rescue the chickens from the battery farms the pair bring them back to her house and conduct health checks.
"We go through all the hens and cut their claws, de-mite them, and make sure they're okay."
Fiona, who owns animal rescue business Mana Rescue, says some of the hens have skin infections as their feathers have all fallen out.
"We separate all the sick ones out so the infection doesn't spread and I take those ones home with me. It's sad. The first thing they do when you release them is flop on their side and put their wings up to the sun. They have never felt the sun before."
"We rehabilitate them, feed them up on good food, and give them a special tonic and lots of water and sunshine that they're not used to having. Once they're better we go through the process of trying to find good homes for them."
Kelly says they keep the hens for around two weeks, as they have to train them how to do things that other hens do.
"The first day we get them, I'm out there three or four times that day showing them where their coop is because if it's raining they won't know how to get away from the rain.
"They don't know how to scratch, or how to eat off the ground. They're very institutionalised."
With limited space and funds Fiona says the pair struggle with leaving so many hens behind at each rescue.
"It's awful pulling out 50 and having to turn your back on another 1600, but you just have to focus on what's in front of you and know that you are making their lives better. We hope as word gets around, we can gather some funding so we can rescue more of them."
To find out more about how to help save the hens, contact Kelly on 021 212 4788 or (07) 332 5551.