Dietary supplementation with fermented plant meal enhances growth, antioxidant capacity and expression of TOR signaling pathway genes in gibel carp (Carassius auratus gibelio var. CAS V)

Abstract

Abstract This study assessed the nutritional potential of supplementing the practical diets for gibel carp (Carassius auratus gibelio var. CAS V) with a blend of fermented plant meal. The fermented plant meal (FPM) comprised mixed fermentation of rapeseed meal (RM), sprayed corn husk (SCH), rice bran (RB), palm meal (PM) and soybean meal (SM) in the proportion of 30:25:25:15:5. Four experimental diets were including a basal diet (the control diet, Con) and three FPM diets (supplementing 3 g, 5 g and 8 g FPM per 100 g diet in the basal diet, FPM3, FPM5 and FPM8, respectively). Each diet was randomly allotted to triplicate fish tanks where each tank had 25 fish weighing 28.00 ± 0.02 g. Fish from each group were fed twice per day until apparent satiation for 60 days. From the results, gibel carp from the FPM5 group had significantly higher feed efficiency and specific growth rate despite having significantly lower feeding rate than the control group. Fish from FPM5 group had significantly higher hepatosomatic index and viscera somatic index than those from FPM3 group. Meanwhile, serum antioxidants (including aspartate aminotransferase, catalase, glutathione peroxidase, superoxide dismutase and malondialdehyde) and intestinal digestive enzymes (including chymotrypsin, trypsin and amylase) of fish increased proportionately to amount of FPM in the diet. Fish fed on FPM5 diet had significantly higher expression of TOR and IGF-1 in the liver than those fed on the control diet. Further, supplemented with 8% of FPM significantly increased the relative mRNA abundance of hepatopancreas GH and S6K1. These results reveal that moderate level of dietary FPM significantly enhanced growth performance, antioxidant capacity, digestive enzymes activities and the expression of TOR signaling pathway genes of juvenile gibel carp, and dietary supplementation of 5% FPM is recommended for the juveniles base on the performance of growth and antioxidant properties.