Use of rice bran with and without fermentation in the production of the rotifer Brachionus plicatilis

Author: Lídia Sousa Monteiro (Currículo Lattes)
Supervisor: Dr Marcelo Borges Tesser

Abstract

The rotifer Brachionus plicatilis is used as the first food for a wide variety of fish species during their early stages of development. Rotifers are non-selective filters that facilitate their feeding and can provide a high diversity of diets, including microalgae, yeast, and inert foods. The most common foods used to feed rotifers (microalgae and yeast), present problems associated with the cost of production (microalgae) and yeasts that do not have adequate nutritional quality. On the other hand, fermented and non-fermented whole rice bran have high abundance, low cost, high nutritional quality and antioxidant components. Thus, the objective of the present study was to examine the use of fermented and non-fermented whole rice bran as a food source for rotifer production, Brachionus plicatilis. The study was based on three experiments, where the first experiment compared the effect of different concentrations of non-fermented whole rice bran on the rotifer growth rate, four treatments were tested with three replications each: 1) Control (0.7 g yeast / 1,0 x 106 rotifers); 2) 0.5 g non-fermented whole rice/ 1,0 x 106 rotifers); 3) 1 g non-fermented whole rice bran / 1,0 x 106 rotifers; 4) 1.5 g non-fermented whole rice bran / 1,0 x 106 rotifers. The second experiment compared the effect of different concentrations of fermented whole rice bran on the rotifer growth rate, where he tested 4 treatments with three replications each: 1) Control (0.7 g yeast / 1,0 x 106 rotifers); 2) 0.5 g fermented whole rice bran / 1,0 x 106 rotifers); 3) 1 g fermented whole rice bran / 1,0 x 106 rotifers; 4) 1.5 g fermented whole rice bran / 1,0 x 106 rotifers. The third experiment compared the effect of the best concentrations of fermented and non-fermented whole rice bran, as well as the replacement of part of yeast by these brans on the population growth, water quality and antioxidant activities of the rotifer. Five treatments were tested, with three repetitions each: 1) Control (0.7 g yeast / 1,0 x 106 rotifers); 2) 1.5 g non-fermented whole rice bran / 1,0 x 106 rotifers); 3) 1.5 g fermented whole rice bran / 1,0 x 106 rotifers; 4) 0.35g yeast + 0.75g non-fermented whole rice bran / 1,0 x 106 rotifers; 5) 0.35g yeast + 0.75g fermented whole rice bran / 1,0 x 106 rotifers. For each treatment was inoculated in 2L tanks the amount of 400,000 rotifers or 200 rotifers / mL. At the end of the 3o day of creation, the rotifers were washed, population growth determined, and cultivation started again. In addition to the growth parameters, the oxidative stress and water quality parameters were analyzed. Data were analyzed using ANOVA. Therefore, the assumptions of normality and homogeneity of variance were previously observed using the Shapiro-Wilk and Levene tests, respectively. When ANOVA was significant, the means were contrasted by the Newman-Keuls test. All tests were performed at the 5% level. The results of the experiments showed that the rotifers from the treatments with 0.7g yeast, 1.5g fermented whole rice bran, 0.35g yeast with 0.75g non-fermented whole rice bran and 0.35g yeast with 0.75g fermented whole rice bran had higher growth between treatments not differing between you. Brown and fermented rice bran improved environmental quality in cultivation, through the absorption of ammonia from water. No improvement was observed in the antioxidant response of rotifers fed fermented rice bran. The present study demonstrates that 1.5g fermented whole rice bran and substitution of 50% of yeast for fermented or non- fermented whole rice bran can be used to feed rotifers.

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