Influence of dietary L-selenomethionine exposure on growth and survival of juvenile Huso huso

The influence of different levels of dietary selenium in juvenile Huso huso was investigated in an 8 week growth trial. The present study was conducted at the International Sturgeon Research Institute with the objective to determine the effects of dietary selenium on growth, survival and whole body proximate composition. Six experimental diets were prepared by adding dietary concentrations of 0, 5, 10, 20, 40 and 80 mu g g(-1) diet selenium in the form of L-selenomethionine (SeMet) resulting in dietary concentrations of 1.26, 2.44, 3.01, 5.37, 11.56 and 20.26 mu g Se g(-1) diet on a dry weight basis. Juvenile H. huso with a mean weight of 3.5 +/- 2.0 g and mean total length of 8.5 +/- 2.5 cm were obtained from the Shahid Marjani hatchery and acclimated to formulated diets for 20 days, after which the fish were divided into six experimental groups and moved to 18, 500-L tanks with 13 fish per tank in a completely randomized design and fed diets supplemented with selenium. Three replicates were used for each experimental group. A one way ANOVA and the correlations analysis were used to determine the relationship between the data at 95% confidence interval by SPSS software for windows (ver. 14.0) and the means were compared using the Duncan's Multiple Range Test. After 8 weeks mean survival rate was 75 +/- 9% across all groups. Comparison of results showed that although good growth was observed in all groups, H. huso in experimental groups 4 and 5 fed above 11 mu g Se g(-1) diet showed faster and higher growth rates. No significant differences were observed among the hematological parameters studied. Selenium accumulated in all tissues studied in a dose dependent manner with highest levels observed in the liver. Results obtained showed that selenium had no histopathological effects on the tissues studied. It is evident from the results of this study that dietary concentrations of selenium between 11.56 and 20.26 mu g Se g(-1) diet can be considered the threshold dietary concentrations for suitable growth in juvenile H. huso. Further research is required to study the interactive effects of Se with other chemical and physical stressors in order to establish suitable supplementary levels of selenium to increase immune response and disease resistance in H. huso.