Dietary medicinal herbs improve growth performance, fatty acid utilization, and stress recovery of Japanese flounder

Some effects of dietary medicinal herbs mixture (HM), Massa medicata fermentata, Crataegi fructus, Artemisia capillaries, and Cnidium officinale, in the proportions 2:2:1:1 were identified in juvenile Japanese flounder Paralichthys olivaceus. In an 8-week feeding trial, fish were fed with 0.1, 0.3, 0.5, and 1.0% HM in a moist diet composed of horse mackerel and an artificial diet in equal parts. Fish fed the diets with 0.3, 0.5, and 1.0% HM showed higher weight gain and feed efficiency than fish in 0.1 and 0% HM feed groups. No significant differences were found in survival, feed intake, final carcass proximate composition, hemoglobin and hematocrit levels, plasma total cholesterol level, and alanine aminotransferase activity among the dietary treatments. Fish fed with 0.3, 0.5, and 1.0% HM showed higher total carcass unsaturated fatty acid content and docosahexaenoic acid (22:6n-3) level, and plasma high density lipoprotein-cholesterol level, but lower carcass saturated fatty acid content and plasma aspartate aminotrasferase activities than the control group. Moreover, a 10-min air exposure test with five times repeat, and an anesthesia test for 2 min with 200 p.p.m. 2-phenoxyethanol, also revealed lower mortality and lower recovery time in 0.3, 0.5, and 1.0% HM groups than the control group at the end of the trial. These results indicate that the medicinal herb mixture is useful to improve growth, fatty acid utilization, and stress recovery in the Japanese flounder.