Effects of dietary phospholipids on growth performance and expression of key genes involved in phosphatidylcholine metabolism in larval and juvenile large yellow croaker, Larimichthys crocea

Abstract

The objective of this study was to investigate the effects of dietary phospholipids (PLs) on survival rate, growth performance and expression of key genes related with phosphatidylcholine (PC) metabolism in larval and juvenile large yellow croaker, Larimichthys crocea. Three isonitrogenous and isolipidic diets with graded levels of PLs (2.53%, 6.32% and 12.7%) were randomly allocated to triplicate groups of larvae (initial body weight: 3.86±0.24mg) eight times daily for 30days. Five isonitrogenous and isolipidic diets with graded levels of PLs (1.32%, 3.05%, 5.86%, 7.4% and 9.63%) were randomly allocated to triplicate groups of juveniles (initial body weight: 7.36±0.33g) twice daily to apparent satiation for 60days. Results showed that survival rate and specific growth rate of larvae fed the diet with 2.53% PLs were significantly lower compared with those of larvae in other groups (P<0.05). However, specific growth rate and survival rate were not significantly different among dietary treatments in juveniles. No significant difference was observed in the transcript levels of key genes involved in PC de novo synthesis, including CTP: choline phosphate cytidylyltransferase and phosphatidylethanolamine N-methyltransferase, in both the whole larvae body and the livers of juveniles fed diets with different concentrations of PLs. Although no significant difference was found, the mRNA expression levels of 1, 2-diacylglycerol choline phosphotransferase increased with the increasing levels of dietary PLs in the livers of juveniles, with acyl-CoA: diacylglycerol acyltransferase 2 showing the opposite trend. These results confirmed that the beneficial effects of dietary PLs on survival and growth performance of large yellow croaker were restricted to fish larvae. Dietary PLs might reduce lipid deposition in the liver of juvenile large yellow croaker through utilizing more diacylglycerol for PC synthesis, rather than triglyceride synthesis. Statement of relevanceThe present study was conducted to investigate the effects of dietary phospholipids (PLs) on survival rate, growth performance and expression of key genes related to phosphatidylcholine (PC) biosynthesis in larval and juvenile large yellow croaker, (Larimichthys crocea). The results are reliable and of both theoretical and practical importance. For “theoretical importance”, our study provided the first evidence that dietary PLs might reduce lipid deposition in the liver of juvenile large yellow croaker through utilizing more diacylglycerol for PC synthesis, rather than triglyceride synthesis, which could contribute to better understanding the mechanisms underlying the discrepancy in requirements for phospholipids between larval and juvenile large yellow croaker. For “practical importance”, our study confirmed that the beneficial effects of dietary PLs on growth performance of large yellow croaker were restricted to larvae rather than juveniles (at least 7.36g) and these findings could be applied to reduce the supplementation of PLs in commercial feeds for large yellow croaker, which in turn might reduce the cost of the commercial feeds for large yellow croaker.The work described has not been submitted elsewhere for publication, in whole or in part, and all the authors listed have approved the manuscript that is enclosed. I have read and have abided by the statement of ethical standards for manuscripts submitted to Aquaculture.