Impact of <i>Bacillus coagulans</i> ATCC7050 supplementation on growth, gut microbiota, and immunity in <i>rainbow trout</i> exposed to pretilachlor

This study investigates the effects of <i>Bacillus coagulans</i> ATCC7050 probiotic supplementation on the growth performance, immune function, antioxidant activity, and liver health of rainbow trout (<i>Oncorhynchus mykiss</i>) exposed to the herbicide pretilachlor. Over 30 days, the fish were fed diets supplemented with <i>B. coagulans</i> (1 × 10⁶ or 1 × 10⁸ CFU/g) and/or 12.5% pretilachlor. Probiotic supplementation significantly enhanced growth parameters and reduced the feed conversion ratio, whereas herbicide exposure had the opposite effect (<i>p</i> = 0.000). Immune responses, including lysozyme activity and total immunoglobulin levels, were improved by probiotic treatment but suppressed by pretilachlor exposure (<i>p</i> = 0.001). Additionally, the probiotic increased antioxidant enzyme activity and reduced markers of oxidative stress. Liver function indicators elevated due to herbicide exposure were mitigated by <i>B. coagulans</i> supplementation (<i>p</i> = 0.028). These findings underscore the potential of <i>B. coagulans</i> to counteract herbicide-induced toxicity, supporting fish health and promoting more sustainable aquaculture practices.