Enzymatic, Immunological, Biochemical, and Antioxidative Responses of the Rainbow Trout to Dietary p-Coumaric Acid upon Exposure to Ronstar Herbicide

The use of herbicides has risen considerably in order to increase agricultural production, and Ronstar® is one of the popular organochlorine herbicides with oxadiazon as its active component. This herbicide has a wide range of effects on fish, including physiological, genetic, neurological, and hemato-immunological impacts. In the current study, p-Coumaric acid (P-CA) was used as a feed additive for its potential benefits in rainbow trout (Oncorhynchus mykiss) exposed to Ronstar using hematological, immunological, and biochemical analyses. The fish (16.02 ± 0.27 g) was divided into eight treatments as follows: C (negative control), P1, P2, and P3 (0.5, 1, and 1.5 g P-CA/kg, respectively, with no toxin), R1, P1R1, P2R1, and P3R1 (12.5% Ronstar toxin with 0, 0.5, 1, and 1.5 g P-CA/kg, respectively), each with a replicate of three. According to the two-way ANOVA test (P < 0.05), the overall trend of changes were growth, antioxidant enzyme activity (superoxide dismutase, catalase, glutathione peroxidase), and malondialdehyde level, humoral immune system (total immunoglobulin levels (total Ig)), lysozyme, complement 3 (C3), complement 4 (C4), ACH₅₀, serum nitroblue tetrazolium, and myeloperoxid. The only parameters that were unaffected by P-CA were globulin, albumin, and cortisol; however, Ronstar had negative effects on all three of these measures as well. It was found that the positive effects of dietary P-CA may ameliorate the negative effects of Ronstar in rainbow trout in a dose-dependent manner, with the best performance for the treatment P-CA + Ronstar. However, it is crucial to evaluate the mitigating effects of dietary P-CA against Ronstar on some vital organs of rainbow trout, especially the liver, at histological levels in future studies.