Effects Of The Alternate Use Of Foods On Feeding, Molting, Lipid Composition Of Portunus Trituberculatus

1. Effects of the Alternate Use of Foods on Feeding and Molting of JuvenilePortunus trituberculatusThe four diets in the experiment were: Clam Foot (CF)—the foot of clam(Ruditapes philippinarum), Fish Flesh (FF)—the flesh of little yellow croaker(Pseudosciaena polyactis), Oyster Skirt (OS)—the skirt of Pacific oyster (Crassostreagigas), Shrimp Flesh (SF)—the flesh of a small size shrimp (Trachypenaeuscurvirostris).Six models of alternant diets (CF+FF, CF+SF, CF+OS, FF+SF, FF+OSand SF+OS) and four models of single diets (CF, FF, OS and SF) were designed toinvestigate their effects on the feeding,growth and molt of Portunus trituberculatus.The daily feeding rates of CF, SF and CF+SF were significantly higher than the othertreatments.The variation trends of daily consumption of OS and FF were not regularwhereas alternately feeding with CF or SF obtained regular trends. The shrimps inCF+SF grew fastest and the shrimps in FF+SF、CF+SF and CF+OS treatmentsobtained higher food conversion efficiencies than others. The molting process fromⅣ stage to Ⅴ stage presented significantly differences between every treatment.CF+SF and CF+FF was the best treatment separately in terms of molting cycle andthe most high frequency of molting rate per day.The results above suggest that feedingalternately had positive effects on feeding,growth and molting of Portunustrituberculatus.The causes of MDS were discussed.2. Effects of the Alternate Use of Foods on Lipid Composition of JuvenilePortunus trituberculatusFour natural foods which were clam foot (CF), fish flesh (FF), oyster skirt (OS), and (SF) were chosen and fed juvenile Portunus trituberculatus in the way ofsingle-food diets of CF, FF, OS, and SF respectively and alternant use of two diets(CF+FF, CF+OS, CF+SF, FF+OS, FF+SF, and OS+SF) once of each two days. Theresults showed that alternate use of clam foot and shrimp flesh was the highest interms of weight gain rate. The diets of single-food clam foot and alternate use of clamfoot with fish flesh and clam foot with shrimp flesh showed effects on improvingmolting synchrony and survival of juvenile Portunus trituberculatus.Content ofphospholipid in SF,CF,CF+FF,CF+SF,and CF+OS was higher than othertreatments.Highest phospholipid and cholesterol content was found in Crabs fedshrimp flesh.Higher EPA and DHA content was found in crabs fed clam foot.3. Effects of the Alternate Use of Two Nature Food on Lipid Compositionof Portunus trituberculatusTwo natural foods which were clam foot (CF), and fish flesh (FF) were chosenand fed Portunus trituberculatus in the way of single-food diets of CF, and FFrespectively and alternant use of the two foods.Female and male crabs accountedrespectively for half in every treatment. Effects of the alternate use of the two naturefood on lipid and fatty acids composition were investigated.The results showed thatthe content of triglycerides(TG) was highest in hepatopancreas.The treatment thatobtained highest total lipid content in hepatopancreas was CF+FF.Highest TG contentand lowest phospholipid(PL) content in hepatopancreas were found in crabs fed FF.PLwas the primary lipid in muscle,and the highest PL content was found in treatmentalternately fed CF and FF. monounsaturated fatty acids were dominating inhepatopancreas,while polyunsaturated fatty acids were primary in muscles.Thecontent of fatty acids in the same tissue was not varied considerably in differenttreatments.