شاخص هاي تغذيه و رشد در ماهي قزل آلاي رنگين كمان (Oncorhynchus mykiss) طي دوره هاي مختلف محروميت غذايي و غذا دهي مجدد

Feeding and growth efficiency indices of rainbow trout Oncorhynchus my kiss) during deprivation and re-feeding periods

We studied effects of different feeding deprivation periods on the growth and feed utilization indices of rainbow trout. The study lasted for eight weeks. Four treatments with three replicates including a control group without feed deprivation and treatments 1, 2 and 3 with 1, 2 and 3 week(s) of feed deprivation, respectively, were set up. Fish were fed ad lib for five weeks from week four up to the end of week eight, twice daily. The initial weight was (44.01±0.19g ±S.E). At the end of the deprivation period (day 21 of the experiment), starved fish including treatments 1 (46.96±2.74g), 2 (46.04±1.21g) and 3 (41.04±0.22g) had significantly lower weights (P<0.05) than the control group (64.00±5.60g). At the end of week eight, treatments 1 (93.00±3.95g), 2 (83.06±3.87g) and 3 (93.85±5.60g) and the control group (82.87±9.53g) showed no significant differences in the final body weight (P>0.05, weight after starvation as covariate). From day 21 to day 33, treatments 2 (3.11±0.09% BW/day) and 3 (3.13±0.14% BW/day) had significantly higher feed intakes than the control group (1.77±0.29) and treatment 1 (2.60±0.08) (P<0.05, weight after starvation as covariate). Meanwhile, there were no significant differences in FCR in the given period among the treatments. From day 33 to 55, FI and FCR were similar among the treatments (P>0.05). PER and PPV but not LPV for fish with starvation were higher in value, but did not differ statistically (P>0.05). Different body components were not significantly different among the treatments at the end of the starvation period (P>0.05). Results indicated that the rainbow trout with average weight of 44.01±0.19g could tolerate the starvation and could finally compensate for the final body weight.