Effects of Fasting on Fatty Acid Composition of Muscle, Liver, and Abdominal Fat in Channel Catfish Ictalurus punctatus

Channel catfish Zctalurus punetatus were fasted for 20, 40, 60, and 80 d. Proximate and fatty acid composition of liver, abdominal fat, muscle, and viscera were determined. Percentage moisture, protein, and lipid of viscera showed little change during the period of fasting. Percentage protein in muscle decreased ( P < 0.05) after 20 d of fasting from time 0 (control), while percentage lipid increased ( P < 0.05). Fish fasted for 0, 40, 60, and 80 d were not different ( P > 0.05). In the liver, percentage lipid was higher in fish that were not fasted (0 d) than in fish fasted 20, 40, 60, and 80 d ( P < 0.05). while percentage moisture was lower in control fish compared to all other treatments ( P < 0.05). Fatty acid composition of muscle and liver indicated that docosahexaenoic acid (DHA), 22:6(n-3), was conserved in these tissues during fasting, while oleic acid, 18:1(n-9), concentration decreased during fasting. Fatty acid composition of abdominal fat indicated that a high percentage (>50%) of the total lipid was composed of oleic acid and there was little change in levels of individual fatty acids in abdominal fat during 80 d of fasting.