effects of short terms starvation periods on body composition in rainbow trout (oncorhynchus mykiss)

in aquaculture, fishes might experience periods of food deprivation during pre-harvesting, transporting and sorting. in during starvation, some fish utilize muscle protein as a major energy source and some fish utilize primarily lipids. with respect to vital role of starvation periods on body composition, the current study was carried out for one month in autumn 2010 at research farm of isfahan university of technology. after adaptation for three week to experimental conditions, 120 experimental fish, with initial body weight of 39±2.73 g were randomly distributed in twelve 100 l fiberglass tanks and were subjected to 4 different feeding regimes: c, control (fed four times daily); d1 (5 days starvation); d2 (7 days starvation) and d3 (10 days starvation). at the end of starvation periods, samples for the analyses of body composition (protein, lipid, moisture and ash) was collected. the results indicated that different starvation periods did not affect moisture, protein and lipid values between the treatments and the control group (p> 0.05). ash value varied significantly (p < 0/05) between the control and the fish starved for 7 and 10 days. also, ash value in the fish starved for 5 and 7 days were significantly lower (p< 0.05) than the fish starved for 10 days. it could be conclude that during occurrence unpredictable stress such as transporting and sorting, food deprivation could be appropriate method for reducing metabolism in this species, with respect to body composition of rainbow trout were not significantly affected by short-term starvation.