Effect of dietary choline levels on growth performance, lipid deposition and metabolism in juvenile yellow catfish Pelteobagrus fulvidraco.

The present experiment was conducted to determine the effect and mechanism of dietary choline levels on growth performance and lipid deposition of yellow catfish Pelteobagrus fulvidraco. Dietary choline was included at three levels of 239.2 (control (without extra choline addition), 1156.4 and 2273.6mg choline per kg diet, respectively) and fed to yellow catfish (mean initial weight: 3.45±0.02g mean±standard errors of mean (SEM)) for 8weeks. Fish fed the diet containing 1156.4mgkg-1 choline showed the higher weight gain (WG), specific growth rate (SGR) and feed intake (FI), but the lower feed conversion rate (FCR), than those in control and highest choline group. Hepatosomatic index (HSI) and hepatic lipid content declined with increasing dietary choline levels. Muscle lipid content was the lowest for fish fed adequate choline diets and showed no significant difference between other two groups. Choline contents in liver and muscle increased with increasing dietary choline levels. Dietary choline levels significantly influenced mRNA levels of genes involved in lipid homeostasis in muscle and liver, such as CTP:phosphocholine cytidylyltransferase a (CCTa), phosphatidylethanolamine N-methyl-transferase (PEMT), microsomal triglyceride transfer protein (MTP), apolipoprotein b (APOBb), apolipoprotein E (ApoE) and lipoprotein lipase (LPL), and effects of dietary choline levels on lipid deposition and metabolism were tissue-specific. Different responses of these genes at the mRNA levels partially explained the profiles of lipid deposition in liver and muscle for fish fed different choline diets. To our knowledge, this is the first to explore the effect of dietary choline level on mRNA expression of these genes, which provides new insights into choline nutrition in fish.