If the 'rare free' chick was a salmon Favorolles, I have received two from them and the second has nothing but issues. Pasty butt for two weeks followed by an eye infection at about *one week that still isn't cleared up. All the breeds I have received from McMurray have been strong but I have...
What other symptoms do they have? If it isn't pasty butt it could be failure to thrive which is a result of bad breeding in most cases. Especially loosing as many as you have! I lost six chicks from an order of 25 once, all due to failure to thrive, all chicks were smaller than their sisters...
I would probably give the little ones a bath if it gets any worse. It doesn't look like it is to dangerous levels but it is more than I would like to see.
My technique is to use a bath in warm water (use a little tupperware type container) and fill it to butt level with nice, hot water. Try...