Effect of Arthrospira platensis dietary supplement on growth indices of all female rainbow trout (Oncorhynchus mykiss)

Abstract

Introduction: Iran is one of the largest producers of fish in the world and more than one billion hatched eggs are imported from abroad every year. Given that little is known about the nutritional needs of all rainbow trout (Onchorhynchus mykiss). Algae as an effective substance also delays the absorption of nutrients in the diet and increase the use of carbohydrates and protein, Therefore, the use of this algae in diets leads to increased growth.
Materials & Methods: In an eight-week experiment, the effects of different levels of Arthrospira platensis supplementation on the growth and survival indices of all rainbow trout (Onchorhynchus mykiss) With weight average of 15 ± 0.17 gr were evaluated. A. platensis supplementation was added to the basic diet at levels of 0, 2.5, 5, 7.5 and 10%. The juveniles were fed three times: 8, 12 and 18. At the end of the period, after measuring length and weight, growth indices (feed conversion ratio, specific growth rate and obesity coefficient) and survival were evaluated. SPSS software version 16 was used for data analysis.
Results: The results showed that with the addition of A. platensis, fish growth also increased so that it reached the highest level in 7.5% treatment. Addition of A. platensis to the diet also had a positive effect on the survival rate of juveniles (P<0.05) so that with the increase in algal levels to 10% of the diet, the survival rate increased. Specific growth rate and obesity coefficient of the tested fish had an improving trend with increasing spirulina level (P<0.05). The lowest feed conversion ratio was observed in 7.5% treatment but did not show a significant difference with 10% treatment (P<0.05).
Conclusion: According to the results of the present study, it seems that the best amount of spirulina for all rainbow trout in this study was 7.5%, which showed the highest yield in growth indices.