I truly don't know my husband bought them at a local veterinarian. They are white and meat birds that is all I know.  I researched holistic medicine for chickens on the internet and found numerous sites that said use colloidal silver in hollistic veterinarian sites. I use colloidal silver on my horses with excellent success so gave the sick chicken on drop of it this morning.  It said 4 times a day and I will also add to the other chickens water. Costa Rica is plagued by parasites so one needs to be vigilant here.  Add when I was growing up on a farm in Canada we had hens and roosters the hens looked after their chicks.  This is a whole other experience for me.  My worry is I am getting far to attached to these chickens for my own good,lol.  I found information on one of the forums about Chicken poop and from what I can see its poop looks normal.  It is eating and drinking just cannot walk, it crawls!  plus not growing feathers as most of the other birds the same age.  I have figured out I have a lot to learn about Chickens!  Also, I started giving it oregano a few days ago in its feed and that seems to have picked up its appetite substantially. I have also been adding to the other chickens feed. What I don't know is how much colloidal silver to put in their drinking water. The other issue I find here is that all the food available has a lot of corn in it and I am not a lover of corn we never fed corn to our chickens when I was growing up my dad made his own ground chicken feed from oats, barley and I am not sure what other grains.  I do not think wheat but could be wrong. Our chickens were always really healthy and they free ranged as I am doing with mine during the day they are out in a big fenced in area with lots of grass, tree's for shade.