All the previous replys sound about right (low calcium diet) but you said you just recieved them could be the birds had some rough handling which may take a little time to sort its self out plus they are young and only starting to ovulate which also takes time to get up to speed with the rest of...
Its a pitty the pictures are not of the whole bird,
Males tend to have a faster feathering growth rate especially on the shackle and flight and tail feathers these all look like hens.