A survey on effect of different concentrations of Lactobacillus casei on serum antioxidative defense status and biochemical parameters of rainbow trout exposed to foodborne lead toxicity

This study was aimed to investigate the effects of different concentrations of Lactobacillus casei on some serum biochemicals and antioxidant factors in rainbow trout exposed to foodborne lead toxicity. For this purpose, 375 juvenile fish (15±4.6g) were randomly divided into five groups in three replications. Group 1, 2 and 3 were respectively fed with a diet containing 5×106, 5×107 and 5×108 CFU/g Lactobacillus casei throughout the experiment. Group 4 (negative control) was fed with a basal diet (no probiotic and lead) during all experiment period. Group 5 (positive control) was fed with the basal diet for 45 days and was subsequently fed with diets containing 500 µg/kg lead nitrate similar to the probiotic groups for 21 days. Blood sampling was performed to measure the parameters on days of 0, 45, 52, 59, and 66. The results showed that LDH, cholesterol and triglyceride levels were significantly reduced in most probiotic treatments after probiotic consumption for 45 days compared to a negative control group (P<0.05). After exposure to lead, serum ALP and LDH values in group 2 were significantly lower than group 5 (P<0.05). In group 2, GSH enzyme levels significantly increased compared to group 5 on day 52 (P<0.05). The findings of this study showed that supplementing the diet with Lactobacillus casei in rainbow trout can be effective in preventing the chronic effects of lead poisoning by improving the biochemical and antioxidant indices. It seems that level of 5×107 CFU/g of probiotic bacteria had an ameliorative effect on improving of the biomarkers.