Effects of Dietary Soybean Oil Replacement by Silkworm, Bombyx mori L., Chrysalis Oil on Growth Performance, Tissue Fatty Acid Composition, and Health Status of Juvenile Jian Carp, Cyprinus carpio var. Jian

Five triplicate groups containing 15 Jian carp (33.51 +/- 1.91g) were fed five isonitrogenous (30%) and isolipidic (8%) diets, with an increase in silkworm chrysalis oil (SCO) to replace soybean oil (SO) at 0 (SO), 25 (SCO25), 50 (SCO50), 75 (SCO75), or 100% (SCO100) levels for 59d. Results showed that the SCO50 and SCO75 groups presented higher thermal growth coefficients than the SO and SCO100 groups and lower feed conversion ratios than the SCO100 group (P<0.05). Moreover, the 50% SCO-supplemented level decreased hepatopancreas lipid content and increased muscle crude protein content (P<0.05). Meanwhile, -linolenic acid, n-3 polyunsaturated fatty acid (PUFA) content, and n-3/n-6 PUFA ratio increased in the hepatopancreas, and intraperitoneal fat and muscle as the replacement of SO increased (P<0.05). No significant differences of the serum biochemical indices and hepatopancreatic malondialdehyde content were found among groups (P>0.05), but hepatopancreatic superoxide dismutase activities in the SCO25 and SCO50 groups were significantly higher than those in the other groups (P<0.05). There was no significant difference in muscularis coat thickness, fold height, and fold width in the mid-intestine (P>0.05). Overall, up to 50 or 75% replacement of SO by SCO in the diet of Jian carp could improve growth performance without affecting the health status of the fish.