I would definitely not recommend Chicken or any kind of bird/mammal meat as food for amphibians.
Lean meat is high in protein, but low in essential minerals like calcium that they need to grow and stay healthy, it is also hard for them to digest and can pollute the water very quickly if uneaten.
In my opinion the best and easiest food for Axolotls is Pellets or earthworms. You can easily find high quality Axolotl pellets on ebay, but any sinking pellets for carnivorous fish from the petstore are perfectly adequate.
Hope this helps!