Determination of Crude Fat in Fish Feeds

Abstract Traditional solvent extraction procedures have yielded crude fat values lower than anticipated, on the basis of fat contents of composing ingredients, in extrusion processed fish feeds but provided reasonable values in steam pelleted feeds. Acid hydrolysis before solvent extraction increased the crude fat values in extrusion processed fish feeds by two and one-half times. Acid hydrolysis pretreatment offered no advantage over solvent (ether) extraction alone for crude fat determination in steam pelleted fish feeds, fishmeal, catfish waste meal, or yellow corn meal. Acid hydrolysis pretreatment doubled the yield of crude fat in commercial, solvent-extracted soybean meal.