The effect of using synbiotics containing button mushroom (Agaricus bisporus) extract in combination with two species of lactic acid bacteria on digestive enzyme activities, body composition, growth and intestinal microbial flora in zebrafish (Danio rerio)

This study aimed to investigate the effect of two species of Lactobacillus probiotics (Lactobacillus acidophilus and Lactobacillus bulgaricus) and button mushroom (Agaricus bisporus) extract singular and combined on digestive enzyme activities, body composition, survival, growth and microbial flora in Zebrafish (Danio rerio). For this purpose, 7 experimental diets were evaluated in 3 replications. One-month-old aged zebrafish (D. rerio) (75.9±1 mg) were fed with experimental diets including: diet without probiotics and prebiotic as the control diet (diet 1), diet with 1% button mushroom extract as prebiotic (diet 2), diet with 107 CFU g-1 Lactobacillus acidophilus as probiotic (diet 3), diet with 107 CFU g-1  Lactobacillus bulgaricus  as probiotic (diet 4), diet with 107 CFU g-1  Lactobacillus acidophilus in combination with 1% button mushroom extract as synbiotic1 (diet 5), diet with 107 CFU g-1  Lactobacillus bulgaricus in combination with 1% button mushroom extract as synbiotic2 (diet 6) and diet with 107 CFU g-1  Lactobacillus acidophilus, 107 CFU g-1  Lactobacillus bulgaricus and 1% button mushroom extract as synbiotic3 (diet 7) for 60 days. At the end of the experiment, Sampling was performed randomly to evaluate those mentioned factors. The results showed that the highest growth rate, specific growth rate and the lowest feed conversion ratio were observed in the synbiotic treatments, which were significantly different from the control group (P <0.05). However, there was no significant difference in the survival rate of all treatments with the control group (P <0.05). Also, the highest activity of digestive enzymes was observed in the group which fed with diet 7, which was significantly different from other treatments and control group (P <0.05). In addition, the highest amount of protein was observed in the treatment which fed with diet 7, which was significantly different from control group (P <0.05). However, this difference in fat, ash content and body moisture between control group and other treatments was not significant (P <0.05). The total number of intestinal microbial flora bacteria and lactic acid bacteria that was examined at the end of the period was significantly different from the control group in all treatments (P <0.05). But, there was no significant difference between all treatments with the control group 10 days after stopping feeding with the experimental diets (P <0.05). According to the results, feeding with synbiotics containing these probiotics in combination with button mushroom extract as a prebiotic had a positive effect on growth performance and digestive enzymes in Zebrafish (D.rerio), therefore, it can be recommended as a functional synbiotic in zebrafish (D. rerio) farming.