A Comparative Study On Utilization Of Lecithin And Fish Oil Of Pearl Gentian(♀Epinephelus Fuscoguttatus×♂Epinephelus Lanceolatu) And Epinephelus Coioides Larvae

A comparative study on utilization of lecithin and fish oil of pearl gentian and Epinephelus coioides larvae was undertaken, which included three main aspects:1. Influences of different dietary soybean lecithin/fish oil ratios on survival, growth performance, feed utilization and histology in juvenile grouper E.coioides. In this experiment four micro-diets that supplemented different soybean lecithin/fish oil ratio:0%/22%-diet1,5%/17%-diet2,10%/12%-diet3and15%/7%-diet4, were fed to40-day after-hatching grouper larvae. Each experiment diet was distributed in triplicate tanks. Survival, feed efficiency, growth performance and intestine histology for grouper juvenile were monitored after a40-day growth trial. Results showed that different dietary SL/FO ratio significantly affected grouper juvenile’s growth and survival (p≤0.05). Weight gain (WG) in diet3(10%/8%, SL/FO) and diet4(15/7, SL/FO) was significantly higher than that of value in diet1(0%/22%, SL/FO). Whole body lipid content of dietl (0%/22%, SL/FO) was significantly lower than that of value in other diets (p≤0.05), but whole body protein content of dietl (0%/22%, SL/FO) was significantly higher than the value in other diets (p<0.05). There were no significant differences in the value of feed efficiency (FE), hepatosomatic index (HSI), viscerosomatic index (VSI) and condition factor (CF), specific growth rate (SGR), protein efficiency ratio (PER), and final body weight (FBW). Increasing of dietary soybean lecithin/fish oil (SL/FO) ratio would reduce lipid droplets in intestine enterocytes of grouper juvenile. In conclusion, high dietary soybean lecithin/fish oil ratio (such as15%/7%) was needed for grouper microdiets during their juvenile stages.2. Influences of different soy lecithin levels on growth, feed utilization, phospholipase activity and histology in pearl gentian larvae. In this experiment, four kinds of diets that contain1%,5%,9%,13%soy lecithin were fed to40-day after-hatching grouper juvenile. Each experiment diet was distributed in triplicate pools. Survival, feed efficiency, growth performance and intestine histology for grouper juvenile were monitored after a40-day growth trial. Results showed that the diet4group has a significantly higher survival rate than the other three groups (p≤0.05). The Hepatosomatic index increased with the increasing of the amount of feed soy lecithin supplemented, and similarly, the intraperitoneal fat also increased with the soy lecithin level rising, and the difference was significant (p≤0.05). Feed efficiency and protein efficiency had no significant differences (p>0.05)(Table4), but had a rising trend with the feed lecithin content increasing among all dietary treatments. Lipid content and protein content had significant different among these four experiment diets (p≤0.05). With elevated levels of feed lecithin, pearl gentian larvaes’ intestinal lipid droplets generated quantitive corresponding change in diet3. The activity of lecithin in the intestinal digestive enzymes (phospholipase) was similar except lipase C. The liver histological phospholipase activity did not exhibit a correlation among the four diets. Therefore, although the lecithin has a positive effect on growth and development of pearl gentian was improved, the effect was almost reflected in the organ development, not the growth..3. Influences of different fish oil levels on growth, feed utilization, phospholipase activity and histology in pearl gentian larvaes. In this experiment, four kinds of diets that contain1%,5%,9%,13%fish oil were fed to40-day after-hatching grouper juvenile. Each experiment diet was distributed in triplicate pools. Survival, feed efficiency, growth performance and intestine histology for grouper juvenile were monitored after a40-day growth trial. Results showed that, increasing of the supplement of dietary fish oil has a positive effect on pearl gentian fish larvae’s growth, and also on the development of organs development. The amount of fish oil supplementation should be controlled, because a high level of fish oil supplementation will lead to excessive fat deposition in the intestinal epithelium, and will reduce the concentrate of phospholipase C.