اثر مکمل ال کارنیتین بر فراسنج ههای خونی و رشد ماهی قز لآلای رنگی نکمان(Oncorhynchus mykiss)

In order to study the effects of L-carnitine on performance and some blood biochemical parameters of rainbow trout, the present experiment was conducted with 144 fish (130±5 g) for 8 weeks. In a completely randomized design, the experimental fish were divided into 9 groups with 3 treatments and 3 replicates and 16 fish in each group. Levels of L-carnitine supplements were 0 (control), 1 and 2 g per kg of diet. Results indicated that specific growth rate (SGR), total body weight, weight gain and protein efficiency ratio (PER) were significantly increased by 1g/kg L-carnitine supplements (P<0.05). L-Carnitine also improved feed conversion ratio (FCR) of fish. Crude protein of fish fillet was increased, but its crude fat was reduced at 1g/kg L-carnitine treatment. Similarly, cholesterol, total protein, albumin and globulin of fish blood serum were significantly (P<0.05) increased by the same levels of L-carnitine in the diet, however, blood glucose level remained unchanged. L-Carnitine reduced visceral fat index and increased hepatosomatic index. In conclusion, the results of the present study indicated that the addition of 1g L-carnitine per kg of diet could improve the performance of rainbow trout at grower stage.