Feather meal as a dietary protein source during parr-smolt transformation in fall chinook salmon

Juvenile fall chinook salmon (Oncorhynchus tshawytscha) were fed variations of the U.S. Fish and Wildlife Service practical production Abernathy diet for 20 weeks. Feather meal was substituted at levels of 0, 5, and 15% for portions of the fish meal in the diet. Weight gains and condition factors of the fish did not differ at the end of the experiment. Gill ATPase activity began increasing after 16 weeks of feeding (mid-May) and was highest in the fish fed the diet with 15% feather meal. Plasma thyroxine levels peaked before the increase in ATPase; fish fed diets with no feather meal maintained higher levels after peaking than did the other two diet groups. Regulation of plasma sodium levels after a seawater challenge was best in May. Starvation for 1–3 weeks adversely affected ATPase, thyroxine, plasma sodium regulation, and condition factor.