Effect of nanoliposomes coated with astaxanthin on growth performance indices and feed product efficiency of rainbow trout (Oncorhynchus mykiss)

The present study investigated the effect of nanoliposome-coated astaxanthin (NA) in the diet on growth indices of rainbow trout. A total of 375 fish with an average initial weight of 31.00±2.00 g were divided into five treatments including 0 (control), 25, 50, 75 and 100 mg kg-1 NA. Each treatment had three replications and each replication contained 25 pieces of fish that were randomly stored in 15 tanks with capacity of 200 liter and fed with food related to the same treatment for 60 days. The results showed that the highest percentage of weight gain (225.22±13.80) was related to the treatment of 75 mg kg-1 NA and the lowest (194.57±12.88) was related to the treatment of 100 mg kg-1 NA. Also, the highest daily growth rate (%) with 2.51±0.10 g d-1 was from the treatment of 75 mg kg-1 NA, which was significantly higher than the amount in the control (p <0.05). The highest rate of food efficiency was from the treatment of 75 mg kg-1 NA. The finding of the present study indicated that 83.61 mg NA has the best effect on the growth of rainbow trout and is recommended for culturing of this fish.