Researches On Feeding Behavior And Dietary Protein Requirement Of Sea Cucumber Apostichopus Iaponicus (selenka)

In recent years, with the rapid development of sea cucumber culture, the nutritionresearch was far behind of the requirement of this industry. In this paper, as the shortageof nutrition and artificial feed situation for sea cucumber, we studied the feedingpreference of varied macroalgea powder diet, effects of different seaweed diets anddietary protein content on growth, energy budget, digestibility on sea cucumber, andoptimum processing technology of artificial feed. This study can provide theoryparameters for nutrition standards and contribute to the development of artificial feed.The main results are as follows:1. Macro-algae powder and sea mud were mixed together to study the feeding behaviorof sea cucumber. Six diets containing Sargassum thunbergii, Sargassum polycystum,Zostera marina, Ulva lactuca, fresh Laminaria japonica and boiled L. japonica wereprovided to the sea cucumber. Based on the smell sense, through the attractiveexperiment, we found that Ulva lactuca and fresh Laminaria japonica diets were moreattractive for sea cucumber than others. Based on the taste or touch sense, through patchexperiment, sea cucumbers showed clear preferences for fresh L. japonica and boiled L.japonica diets over the other diets and these two diets made up about54.7%of theentire intake.2. Six diets containing Sargassum thunbergii, Sargassum polycystum, Zostera marina,Ulva lactuca, fresh Laminaria japonica and boiled L. japonica were provided to the seacucumber to study growth performance, apparent digestibility coefficients, andammonia-nitrogen production of A. japonicus. Sea cucumbers grew faster when fed theU. lactuca or L. japonica diet than when fed the S. thunbergii or S. polycystum diet. The ingestion rate was much higher when fed the U. lactuca, L. japonica, Z. marina, orboiled L. japonica diet than when fed the S. thunbergii or S. polycystum diet. Theapparent digestibility coefficients of the test diets ranged from9.63%to15.84%.Ammonia-nitrogen production was much lower in A. japonicus fed the U. lactuca or L.japonica diet compared to the other seaweed diets. The lysozyme activity was higherwhen feed U. lactuca and boiled L. japonica diet.3. A set of six experimental diets with5%,10%,15%,20%,25%and30%proteincontent was formulated to study the effect of dietary protein on growth performance,digestibility, energy budget and water quality of white and black sea cucumber. As theincrease of dietary protein content, the SGR of white sea cucumber decreased, however,the SGR of black sea cucumber increased at first and then declined. The SGR of blacksea cucumber was much higher and the FCR was much lower than the white seacucumber. The digestibility of dry matter, protein and energy showed a positivecorrection with dietary protein level. The growth energy ratio and feces energy ratiodecreased and excretion and respiration energy ratio increased as the dietary proteinlevels increased. Ammonia excretion of whit sea cucumber was much higher than blacksea cucumber. Regression analysis revealed a strong linear relationship between thedietary protein level and the SGR of black sea cucumber. The formulation indicates thatwhen dietary protein content was10.7%the SGR of black sea cucumber reach thehighest level.4. A set of six experimental diets with5%,10%,15%,20%,25%and30%proteincontent was formulated to study the effect of dietary protein on digestive enzyme,immunity index and metabolism of white and black sea cucumber. As the increase ofdietary protein levels, the protease enzyme activity increased at first and then decreased,and reaches the highest level when dietary protein content was19.7%. The amylaseactivity of black sea cucumber was higher than that of white sea cucumber. The SODactivity and LZM activity of black sea cucumber were much higher than white seacucumber. Ammonia excretion was increased at first and then decreased as the increaseof dietary protein content. The ammonia excretion was higher for black sea cucumberthan for white sea cucumber, however, the oxygen consumption was lower for black sea cucumber than for white sea cucumber. The GPT activity and γ－GT activity showedpositive correction as the dietary protein increase. The GPT activity and γ－GT activitywere higher in black sea cucumber than in white sea cucumber.5. In this study, growth performance, energy budget, water quality and immunity of thesea cucumber fed diets produced using four different processing methods (extrudedpellet diet, cold-bonded pellet diet, flake diet, and mash diet) were quantified to identifythe optimal feed type for culturing of this species. Sea cucumbers grew faster (0.96), thefeed conversion ratio was much lower, and immunity indicators were higher when fedthe extruded pellet diet compared to the other diets. The lysozyme activity anddigestibility for dry matter of sea cucumbers fed the extruded pellet diet was higher thanother groups. When animals were fed the mash diet, the ammonia-nitrogen,productionwere higher than in animals fed the other diets. These results indicate that the extrudedpellet diet is the optimum feed type for use in the culture of A. japonicus.