Effects of three feed attractants on the growth, biochemical indicators, lipid metabolism and appetite of Chinese perch (Siniperca chuatsi)

This study aims to investigate the effects of three feed attractants on the growth performance, body composition, biochemical indicators, liver histology, lipid metabolism and appetite of Chinese perch (Siniperca chuatsi). An eight-week feeding trial was conducted using four diets, including a basal diet of 51% fish meal without attractant (control), with 5% stickwater (SW), 5% squid paste (SP) and a 5% mixture of SW and SP a ratio of 1:2 (Mix), respectively. The results demonstrated that SW diet significantly increased the weight gain rate and feed intake (P < 0.05), while resulted in the lowest crude lipid content of whole fish and liver in Chinese perch. Dietary attractants also significantly affected the contents of serum albumin (ALB), glucose (GLU), total cholesterol (CHO), triglyceride (TG) and low-density lipoprotein (LDLC), as well as the activities of aspartate transaminase (AST) and alanine transaminase (ALT). Compared with the control diet, the SW diet significantly increased the serum superoxide dismutase (SOD) and catalase (CAT) activities (P < 0.05), while obviously decreased the activity of malondialdehyde (MDA) (P < 0.05). In addition, dietary SW significantly increased the expression of neuropeptide Y (npy) and agouti-related protein (agrp) while significantly decreased that of cocaine- and amphetamine-regulated gene (cart) and pro-opiomelanocortin (pomc) gene in the brain. As for the peripheral appetite, dietary SW reduced the expression of leptin A, while significantly increased that of ghrelin. Gene expression analysis revealed that dietary SW reduced liver lipid accumulation probably by inhibiting the lipid synthesis related gene (fas) and inducing the lipid oxidation-related gene (cpt-1).) In general, our results indicated that the supplementation of 5% SW can improve the growth performance, increase the expression of appetite-promoting genes and antioxidant capacity, and reduce liver lipid accumulation in Chinese perch.