A NEW DRY DIET WITH ALTERNATIVE OIL SOURCES FOR PACIFIC SALMON

Abstract

ABSTRACTA dry diet utilizing two oil sources that are less expensive and easier to obtain than marine fish oils was developed and found acceptable to salmon.Chinook salmon fry (initial wt = 0.5 g) were fed the dry diet with either cod liver oil, linseed oil, or a linseed oil‐tallow mixture as the dietary oil source. A commercial moist pellet and a commercial dry pellet were also fed. Growth and feed conversions were monitored throughout the 12‐week experiment and the proximate composition of the fish were determined at the end of the experiment along with the fatty acid compositions of the diets and total body lipids of the fish.Fish fed the experimental dry diets were significantly larger than those on the moist pellets. The commercial dry pellet was discontinued after six weeks due to poor growth. Among groups of fish fed the dry diet, those given the formulation containing cod liver oil were slightly heavier than those receiving either the linseed oil or linseed oil plus tallow formulations. Feed conversion was similar among fish fed the experimental dry diets and lower than the feed conversion of fish given the moist pellets.Fish receiving the moist pellets had less carcass fat and more carcass protein than did fish on the experimental dry diets. The difference reflected the level of protein in the diets. The fatty acid composition of the total body lipids varied with the fatty acid composition of the diets.