Although this is distasteful,and something to be turned off by,I don't think it does the chicks any harm.
They were probably dipped in harmless vegetable dye,it will grow out as the feathers develop.
Indeed the noted English eccenric(and composer) Geral,Lord Berners in the 1930' and 40's had a awhole flock of colour dyed doves at his home in Farrigdon.Oxon.
Indeed the National Trust,who own his house,and are not known for being silly,repeat the operation each Easter.
Have a look at them here:~
http://www.petticoated.com/faringdondoves.jpg