Dietary lipid-induced changes in antioxidant status, lipid metabolism and flesh quality of juvenile rice flower carp (Cyprinus carpio)

Lipids are necessary nutrients for fish and play an important role in growth and metabolism. This study analyzed the effects of dietary lipid levels on growth performance, flesh quality, antioxidant status, and lipid metabolism of juvenile rice flower carp (Cyprinus carpio). The results showed that the weight gain rate and specific growth rate increased initially and then decreased with increasing dietary lipid levels, which 5.82 % dietary lipid level had the best growth in rice flower carp. Dietary lipid levels also affect the nutrition and quality of fish flesh. With the increase of dietary lipid levels, the hardness, adhesiveness, springiness, gumminess and chewiness of muscle showed a trend of increase and then decrease. Moreover, there are similar changes in the activity of antioxidant enzymes in the muscle, and the content of ROS and MDA was significantly higher than other levels at 11.80 % dietary lipid level. The expression of Nrf2 mRNA and some downstream antioxidant enzyme genes was the contrary. Furthermore, the content of TG, TC, and LDL-C in serum and liver increased with increasing dietary lipid levels. Meanwhile, it was observed that the lipid accumulation increased in the liver. The mRNA expression of ATGL and CPT1 genes associated with lipid metabolism in liver increased firstly and then decreased, the expression of FASN, PPARγ, and SREBP1 gradually increased, and reached its maximum at 11.8 % dietary lipid level. The above results showed that the growth performance of juvenile rice flower carp was optimal when the dietary lipid level of 5.82 %, and the nutrition and quality of fish flesh also has good effects. However, the dietary lipid level of 11.80 % inhibited the weight gain and induced oxidative stress and lipid metabolism disorders of rice flower carp, which can affect their flesh quality and health.