Studies On The Effects Of Different Diets On The Growth, Body Composition, Non-specific Immunity And Digestive Enzymes Activities Of Sea Cucumber, Apostichopus Japonicus

Apostichopus japonicus (Selenka) belongs to Echinodermata: Holothuroidea: Apostichopus,a epibenthic deposit-feeding species inhabiting the Pacific Northwest from35°N to at least44°N. And it is believed to have aphrodisiac and curative properties. As a sea cucumber specieswith the highest economic value, A. japonicus is considered to be the top of the traditionaleight seafood delicacies. So in recent years, it has long been exploited as an importantaquaculture species in the coastal zones of northern China.As one of the main component of formulated feed for A. japonicus, macroalgae plays animportant role in sea cucumber culture industry. The demand for macroalgaes, such asSargassum thunbergii, Sargassum polycystum and Zostera marina, had increased rapidly tomeet the growing of sea cucumber culture industry over the last two decades. However, thesupply of powered S. thunbergii and fish meal obtained from the natural environment had beendeclining due to overexploitation and pollution. Combined with the development ofnon-standard sea cucumber feed market, the study about the special feed of A. japonicus seemsto have entered a bottleneck period. It has become the decisive factor for the development ofsea cucumber seedling and culture industry. Therefore, finding optimal substitutes for thesealgaes is one of the crucial issues to be solved in the study of sea cucumber feed. Plant proteinhas attracted the attention of the researchers for its low price and stable supply of the market.A series of laboratory experiments were conducted to investigate the growth, bodycomposition, immune enzymes activities and digestive enzymes activities of A. japonicus fedon different diets. Through the reasonable collocation between different components, we wantto find the new varieties of feed ingredients to promote the healthy growth of A. japonicus. Itprovided some references for the production of special formulated feed and getting the mostsuitable feed formulation of sea cucumber.Experiment mainly been divided into the following three parts.The results are as follows:1. Effects of Adding Alfalfa Meal in Diets on the Growth, Body Composition and ImmuneEnzymes Activities of Juvenile Sea CucumberTo determine the appropriate proportion of alfalfa (Medicago Sativa) in the diet ofjuvenile sea cucumber, effects of five diets containing0(A0),5%(A1),10%(A2),15%(A3) and20%(A4) M.sativa meal on the growth, body composition and immune enzymes activities ofjuvenile sea cucumbers (3.16±0.66g) were tested. The results showed that:(1) sea cucumbersin group A2showed the best special growth rate (SGR)(0.73%d-1) and feed conversion ratio(FCR).(2) Compared with group A1, sea cucumbers in group A2contented significantly morecrude protein (52.10%)(P＜0.05).(3) The activity of CAT in group A4(142.28U/ml) wassignificantly higher than those in group A0、A1and A2(P＜0.05). The activity of SOD ingroup A3(136.58U/ml) was significantly higher than that in group A0(P＜0.05). Seacucumbers in group A3contented significantly more LSZ (1.92μg/ml) than those in group A0、A1and A2(P＜0.05). These above results suggested that the optimum proportion of M. Sativain diet for A. japonicus should be10%. 2. Effects of Substituting Myriophyllum spicatum L. for Sargassum thunbergii in Diets onthe Growth,Body Composition and Digestive Enzymes Activities of Juvenile SeaCucumberIn this study, growth performance, body composition and digestive enzymes activities ofjuvenile sea cucumbers (1.66±0.61g) fed five diets containing0(A0),15%(A1),30%(A2),45%(A3) and60%(A4) M. spicatum meal were quantified to identify the effect of substitutingM. spicatum L. for S. thunbergii in the diet. The results showed that:(1) the special growth rate(SGR) and growth rate (GR) of sea cucumbers in group A4were significantly higher than thosein other groups. And sea cucumbers in group A4showed the best surviving rate (SR)(97.78%).(2) Compared with groupA0, A1and A2, sea cucumbers in group A4contented significantlymore crude protein (50.92%)(P＜0.05).(3) The activity of amylase in group A3(0.83U/g pro)was significantly higher than those in group A0、A1and A2(P＜0.05). The activity of proteasein group A4(1.62U/g pro) was significantly higher than those in other groups (P＜0.05). Theresults of this study indicate that the M. spicatum L. has wide raw material source, low priceand better effect than the S. thunbergii. It turns out that M. spicatum L. is a low-cost substitutefor Sargassum thunbergii in the diet of A. japonicus.3. Effects of Adding Chlorella sp Meal in Diets on the Growth Performance and BodyComposition of Juvenile Sea CucumberTo determine the appropriate proportion of Chlorella sp in the diet of juvenile seacucumber, effects of five diets containing0(A0),2%(A1),4%(A2),6%(A3) and8%(A4)Chlorella sp meal on the growth and body composition of juvenile sea cucumbers (0.97±0.28g)were tested. The results showed that:(1) the special growth rate (SGR) and growth rate (GR)of sea cucumbers in group A3were significantly higher than that in group A4.(2) body lengthof sea cucumbers in group A3was significantly longer than that in group A0and A4(P＜0.05).(3) Compared with group A0, A1and A4, sea cucumbers in group A3contented significantlymore crude protein (48.04%)(P＜0.05). These above results suggested that the optimumproportion of Chlorella sp in diet for A. japonicus should be6%.