Effect of dietary Lactobacillus rhamnosus on blood biochemical indices and some digestive enzymes activity in rainbow trout (Oncorhynchus mykiss) fed with aflatoxin B1 infected diet

In the process of production and maintenance of aquaculture diets, there may always be some contamination of feed that aflatoxin B1 is one of the most common and most prominent of these toxins. The purpose of this study was to investigate the effect of Lactobacillus rhamnosus on the improvement of biological conditions of rainbow trout (Oncorhynchus mykiss) fed with aflatoxin B1 contaminated diets. In this experiment, 120# fish with initial weight of 42 ± 4 gr were harvested in 12 fiberglass tanks and fed with 4 different diets (control diet, probiotic diet, aflatoxin diet, and aflatoxin and probiotic mix diet) and after 30-day period of experiment, blood glucose levels in the group fed with aflatoxin B1 significantly increased (P <0.05). Cortisol and alkaline phosphatase enzyme showed the least amount in control diet treatments and probiotic diet. The activity of trypsin in the probiotic diet treatments was significantly higher than other treatments. While the aflatoxin diet reduced the activity of the chymotrypsin enzyme in the gut, adding Lactobacillus rhamnosus to the diet caused a significant increase in the activity of this enzyme. The mortality rate was significantly higher in the treatment of aflatoxin diet than other treatments, but by adding probiotic to diet, it decreased significantly in the treatment of probiotic and aflatoxin diet. In conclusion, the results of this study indicate that probably Lactobacillus rhamnosus probiotic can be used as a diet supplement to reduce the toxic effects of aflatoxin B1 and improve survival in fish, and rainbow trout breeders can use this probiotic in their diet to reduce aflatoxin toxicity.