Effect of Harim-CLH, a chicken liver hydrolysate, as an enhancer of diet-palatability in Anguilla japonica culture

This study evaluated the effects of Harim-CLH, a chicken liver hydrolysate manufactured from Harim, Korea, on the palatability, growth performance, and physiological responses of Anguilla japonica eels. Eels were fed either a control diet (CTL) or an experimental diet (CLH-1), in which 1% of fishmeal in the CTL was replaced with Harim-CLH, for eight weeks. We assessed growth performance by measuring weight gain rate (WGR) and total feed intake (TFI); feed efficiency (FE) was also recorded. Biological indices (condition Index and hepatosomatic Index), non-specific immune responses (lysozyme and phagocytic activities), and plasma biochemical factors (glutamate oxaloacetate transaminase, high-density lipoprotein cholesterol, total protein, alkaline phosphatase, triglycerides, glucose, and total cholesterol) were analyzed. The CLH-1 group exhibited a significant increase in WGR and TFI, while FE did not show significant differences. There were no significant changes in the liver weight index, non-specific immune responses, or blood biochemical factors. Attractancy to the CLH-1 diet was lower than CTL, but not significantly, whereas palatability was significantly higher. Next-generation sequencing analysis of brain, intestine, and liver tissues revealed no gene expression differences in the brain but identified variations in non-coding RNA and genes with unknown functions in the intestine and liver. This study highlights the potential of Harim-CLH to enhance growth and feed palatability in aquaculture diets without adverse effects on health indices.