Effect of probiotic Bacillus sp. on growth performance and some of hematological parameters and biochemical factors of blood serum in rainbow trout larvae (Oncorhynchus mykiss Walbaum, 1792) reared at different stocking density

Document Type : Research Paper

Authors

1 Fisheries Group, Faculty of Agriculture and Natural Resources, University of Gonbad kavous, Golestan, Iran

2 Associate Professor Fishery Science, Faculty of Agriculture and Natural Resources, Gonbad Kavous University, Golestan, Iran

3 Department of Chemistry, Faculty of Sciences, Golestan University, Gorgan, Golestan, Iran

Abstract

In the present study the effects of five- strain probiotic blend (Bacillus spp.) with concentration 1×108 CFU/ liter against stress responses, due to expose to high stocking density (30, 45, 60 and 75 larvae per 10 liters of water) on Oncorhynchus mykiss larvae were investigated in triplicates. The growth factors and hematological parameters were recorded as well. The larvae with the mean weight of 0.235±0.08g introduced in each experimental unite and fed the experimental diets and reared for a 45- day period. At the end of the experiment, the maximum growth and feeding rates were obtained in the treatment with a density of 60 fish larvae per 10 liters (fed from a diet supplemented with Bacillus) and the minimum rate significantly obtained in the treatment with a density of 45 larvae per 10 liters compared to other experimental treatments (p < 0.05). However, there were no significant differences among treatments containing 30, 60 and 75 larvae per 10 liters of water (p>0.05). The results of hematology indices, WBC, RBC, Ht, Hb, MCV, MCH and MCHC increased significantly with an increase in the density of fish larvae among the experimental treatments and their highest levels were obtained in treatment with a density of 75 fish per 10 liters. The serum glucose levels increased significantly while the fish density increased and it was higher in 60 and 75 fish per 10 liters treatments compared to 30 and 45 fish in 10 liters densities. Overall, the findings of this study showed that despite the effects of fish density, the use of probiotic bacilli also affecting on some growth, nutritional and blood indices.

Keywords

Journal of Fisheries
Volume 73, Issue 3
September 2020
Pages 431-440

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