FERMENTED RAPESEED MEAL ON APPARENT DIGESTIBILITY, LIVER AND INTESTINAL HEALTH OF YELLOW CATFISH (TACHYSURUS FULVIDRACO)

In order to investigate the effects of fermented rapeseed meal on apparent digestibility, liver and intestinal health of yellow catfish (Tachysurus fulvidraco), the experiment utilized yellow catfish as the research object. Three groups were established, namely the Control (reference diet group), URSM (unfermented rapeseed meal group) and FRSM (fermented rapeseed meal group) respectively. The feeding experiment lasted for 7 weeks. The results showed that the weight gain rate (WGR) of the FRSM group were significantly higher than those of the USRM group (P<0.05), while the feed conversion ratio (FCR) and hepatosomatic index (HSI) were significantly lower than those of the URSM group (P<0.05). Compared with unfermented rapeseed meal materials, the apparent digestibility of dry matter, crude protein, crude fat and gross energy of the fermented rapeseed meal materials were all increased. The relative area of hepatic vacuoles in URSM group was significantly higher than that in control group and FRSM group (P<0.05). There was no significant difference in the villi width of yellow catfish among the three groups (P>0.05), while the villi height of the FRSM group was significantly higher than that in the URSM group (P<0.05). The FRSM diets reduced the upregulation of mRNA expression of liver pro-inflammatory factor-related genes (tnf-α, tnf-β, il-1β and il-6) and intestinal tnf-α and il-6 induced by rapeseed meal. In addition, the FRSM diets alleviated the downregulation of liver anti-inflammatory factors il-10 and intestinal il-10 and tgf-β induced by unfermented rapeseed meal. Compared with the control group, the URSM diets significantly increased the Malondialdehyde (MDA) content (P<0.05), decreased the total antioxidant capacity (P<0.05), and induced oxidative stress in the liver and intestine. the FRSM diets alleviated the oxidative damage caused by rapeseed meal of liver and intestine of yellow catfish. The detection of apoptosis-related genes showed that the URSM diets up-regulated the expression levels of pro-apoptotic genes (bax, p53, caspase3, caspase9 and mdm2) in the liver and intestine of yellow catfish, but down-regulated the expression levels of bcl2 mRNA expression (P<0.05) compared with the control group. Therefore, the FRSM diets improved the pro-apoptotic phenomenon caused by unfermented rapeseed meal. This study shows that fermented rapeseed meal added to the diet can reduce the inflammatory response, oxidative damage and cell apoptosis in the liver and intestine of yellow catfish caused by unfermented rapeseed meal, thereby improving the liver and intestinal healthy of yellow catfish. This study provides a basis for in-depth exploration of the effect of fermented rapeseed meal on the improvement of liver and intestinal health of fish, and it holds significant implications for the application of fermented rapeseed meal in fish production.