The effect of different levels of dietary microalgae chlorella (Chlorella vulgaris) and brewer’s yeast (Saccharomyces cerevisiae) on growth performance, digestive enzymes and intestine microbiota in sterlet (Acipenser ruthenus) juvenile

The aim of the present study is to investigate the effect of microalgae (Chlorella vulgaris) and brewer’s yeast (Saccharomyces cerevisiae) on growth performance, digestive enzymes activity and intestinal microbiota in sterlet juveniles (Acipenser ruthenus). Total number of 315 sterlet juveniles (24.5 ± 0.2g) were divided into 7 treatments and were fed with a basal diet containing different amounts of Chlorella and yeast during 8 weeks. Treatments 1 to 7 were fed with a basal diet supplemented with no chlorella and yeast (control), 1% yeast, 0.5% yeast, 3% Chlorella, 5% Chlorella, a combination of 0.5% yeast and 5% Chlorella and a combination of 0.5% yeast and 5% Chlorella, respectively. At the end of trial, growth factors, digestive enzymes and total number of intestinal bacteria were measured. The results showed that the addition of yeast and Chlorella to the fish diet improved growth performance, increased the secretion of digestive enzymes and also increased the number of intestinal bacteria compared to the control (p<0.05). The best growth performance was observed in treatments 5 (5% Chlorella) and then treatments 6 and 7 (combination of Chlorella and yeast) so that the highest amount of body weight gain, average daily growth, specific growth rate, and the lowest feed conversion ratio were observed in treatments 5, 6 and 7 (p<0.05). No significant difference was seen in the survival rate between treatments (p>0.05). The results showed that supplementing the diet of sterlet juveniles with microalgae and brewer’s yeast as well as their combination significantly improve the growth performance, secretion of digestive enzymes and intestinal bacterial flora.