Effects of dietary Pediocuccus pentosaceus and/or ferulic acid on performance, digestive enzymes, blood biochemistry, and growth-related genes expression in rainbow trout (Oncorhynchus mykiss)

This study investigated the effects of dietary Pediocuccus pentosaceus (PP) and/or ferulic acid (FA) on the performance, digestive enzymes, and growth-related genes expression in rainbow trout (Oncorhynchus mykiss). Fish (94.30 ± 1.77 g) were fed on the control diet (T0), 10⁸ CFU/g of PP probiotic (T1), 100 mg/kg of FA (T2), and a combination of PP and FA (T3) for 8 weeks. The present results indicated that rainbow trout fed with PP and/or FA showed better final weight, weight gain, and feed conversion ratio than the control group (P < 0.05). The activities of trypsin and chymotrypsin were higher in T2 and T3 than in the control group (P < 0.05). Meanwhile activities protease and alpha-amylase were highest in T2, lipase activity was highest in T3. Compared to the control group, total protein, total antioxidant activity, and cholesterol levels were significantly (P < 0.05) higher in T2 and T3 with no significant (P > 0.05) differences between them. Supplemented diets with FA and/or PP decreased markedly (P < 0.05) triglycerides levels and its lowest levels were obtained in T2 and T3 with no significant (P > 0.05) differences between them. The relative expression levels of GHRL and GHr genes were significantly higher in the treatments fed with FA and/or PP (T1 – T3) than those in the control group (P < 0.05). Highest upregulation of IGF-1, and IGF-II gens were detected in T2 and T3 with no significant (P > 0.05) differences between them. In conclusion, it was shown that both dietary supplements have the potential role to enhance the performance, digestive enzymes, and growth related-genes expression in rainbow trout. Feeding fish on FA-enriched diets showed superior enhancements than that fed on the PP diet only.