Effects of different dietary selenium sources (selenomethionine and selenite) on growth performance, haematocirt and some blood parameters on rainbow trout (Oncorhynchus mykiss)

Subject Areas : Marine Biology

H.  Rajabiestrabadi ¹ (Dep. Of Fisheries, Islamic Azad University, North Tehran Branch)
H.  Emadi ² (Dep. Of Fisheries, Islamic Azad University, North Tehran Branch)
M. R.  Imanpoor ³ (Dep. of Fisheries, Faculty of Fisheries and Environment, Gorgan University of Agricultural Sciences and Natural Resources)

Received: 2012-02-27 Accepted : 2012-07-22 Published : 2012-09-20

Keywords: growth, Rainbow trout, selenomethionine, selenite, haematocirt,

Abstract :

This study was aimed to determine the role of selenomethionine and selenite on the growth, haematocirt and some blood parameters of rainbow trout (Oncorhynchus mykiss). A twelve-week feeding trial was undertaken with seven experimental dietary treatments based on a common commercial trout grower diet (FFT2, Chineh,  Tehran, Iran) supplemented with various levels of selenomethionine or selenite.. Rainbow trout (mean weight 22 ±2.5 g) were acquired, acclimated to a 21 tank recirculation (300 l) at a density of 30 fish per tank. All fish in each tank were weighed at t=0 and were fed three times daily at 8:00, 14:00 and 20:00 with each feed. Daily feeding rate was about fed 3% body weight per day. No significant difference was observed in survival rate, FCR and SGR due to the inclusion of selenium in fish diets (P >0.05). Weight gain of rainbow trout increased significantly with the increase of selenium level in the tested diets. The higher weight gain (464.0±60.2 g) was obtained when fish fed on 8 mg kg-1 selenomethionin diet, while the lowest one (390.0±36.5 g) was obtained at the control group. There were significant decreases (P < 0.05) in WBC of 4 mg kg-1 selenomethionine and 8 mg kg-1 selenite with the control and also there were significant decreases (P < 0.05) in RBCs of 2 mg kg-1 selenomethionine with the control. Physiological parameters(haematocirt, hemoglobin, Differential cell count, MCV, MCH and MCHC) were not affected by Se supplementation (P >0.05).