Effect of partial replacement of fish oil with vegetable oil on muscle and liver total lipid and fatty acid of larvae Larmichthys crocea

Abstract:

A 50-day feeding trial was conducted to investigate the effect of partial replacement of fish oil with vegetable oil on growth, muscle and liver total lipid and fatty acid of larvae Larmichthys crocea(initial weight 0.65g±0.11g).Six isonitrogenous and isoenergetic experimental diets were formulated.The control feed(Group A) was formulated with 6% fish oil, whereas the other 5 experimental diets were formulated by replacing the fish oil with 16.67% rapeseed oil(Group B),33.33% rapeseed oil(Group C),50% rapeseed oil(Group D),66.67% rapeseed oil(Group E), and 66.67% blended vegetable oil(Group F,palm oil:perillaoil:rapeseed oil=3.6:2.5:1),respectively. Results showed that these replacements(Group B,C,D,E and F) did not significantly influence the final weight, weight gain, specific growth rate compared with Group A; the survival rate of Group C, D and E was lower than Group A;the feed coefficient had no significant difference among the six experimental groups.Partial replacement of fish oil with vegetable oil significantly influenced the content of muscle protein, and Group A had the lowest content of muscle protein(58.9%±0.41%); ash had no significant difference among the six experimental groups. Though there was no significantly influence on the content of total lipid on muscle and liver among six experiment groups, the composition fatty acids was significant influenced. With the increasing replacment by rapeseed oil, the contents of 18:3n3 in muscle and the contents of 18:1,18:2n6,18:3n3 in liver were significantly increased, whereas the contents of EPA and DHA were significantly decreased. Compared with the same level of rapeseed replaced group, the contents of EPA,DHA in muscle and the contents of 18:3n3 in liver in blended vegetable oil group were significantly increased, whereas the contents of EPA and DHA in liver were significantly decreased. This study suggested that replacing 66.67% fish oil with rapeseed oil or with blended vegetable oil fed larvae Larmichthys crocea for 6weeks did not influence its growth, but reduced its nutritional value of fatty acid.