Analysis of the growth and biochemical composition of the rotifer Brachionus plicatilis (Müller 1786), fed with biomass of Spirulina subsalsa Oersted ex Gomont, 1892

Abstract

The rotifer Brachionus plicatilis is commonly used as a diet in the culture of fish larvae and invertebrates. In this study, the growth and biochemical composition of this rotifer, fed with the biomass of Spirulina subsalsa, were evaluated to verify if said food provides the necessary nutrients for its culture. The cultures started with a density of 100 rot/mL and were fed 1.5 mg/L/day of S. subsalsa biomass disintegrated in seawater, using fresh cultures of Tetraselmis chuii (1.5 mg/L/day) as a control. for 10 days. Fecundity (number of eggs/female) and population density of rotifers were quantified. At the end of the trial, the rotifers were harvested and kept at -20 °C until the time of biochemical analyses. The population density at the end of the trial showed significant differences between the diets (P< 0.05), with T. chuii reaching the highest population density (255±5 rot/mL), and 210±10 rot/mL with S. subsalsa. Productivity was higher (15,500±500 rot/L/day) when T. chuii was used as food, and 11,000±1000 rot/L/day when using S. subsalsa. The highest growth rate was obtained with T. chuii (0.12±0.00026 rot/day) and fecundity (1.47±0.15 eggs/female), compared to 0.10±0.0057 rot/ day and 0.83±0.06 eggs/female obtained with S. subsalsa. Protein values ​​varied between 27-35%, carbohydrates between 9-12%, and lipids between 16-25%, with no significant difference between diets. This study showed that the biomasses obtained with S. subsalsa showed acceptable contents of biochemical components, to be used as an alternative diet for the cultivation of the rotifer B. plicatilis, and in this way guarantee a good product of high nutritional quality in aquaculture industries.