The Effects Of Dietary Supplement Of Arachidonic Acid On Ovary Development And Nutritional Quality Of Swimming Crab, Portunus Trituberculatus

By the individuals culture technique and biochemical analysis,to investigate the effects of purified diet (group A), fresh foods(Octopus variabilis and Sinonovacula constricta, group B) and mixed diets (purified diets and fresh foods, group C) on the survival, growth performance and biochemical composition of juvenile swimming crab Portunus trituberculatus (initial mean wet weight was0.5g);To investigate the effects of ARA on the ovary development and tissue biochemical composition of swimming crab, four formulated isolipidic and isonitrogenous diets,which contain different ARA levels (0.06%,0.24%,0.36%,0.6%) by the supplement of semi-purified fish oil,were made to feed the crab during the reproductive cycle,while the fresh clam were chosen as a control diet;Then another one experiment was conducted to evalute the nutruional quality of the crab fed with the different ARA diets on the basis of the above two experiments.The results are as followings:1. Effects of purified diet, fresh foods and mixed diets on the survival, growth performance and biochemical composition of juvenile swimming crab, Portunus trituberculatus(1) The survival of juvenile swimming crab were ranged from70%to80%, and no significant effects caused by survival were observed among each three groups(P>0.05).(2) There were no significant difference on the WGR (weight gain ratio), molting period, SGR(specific growth rate) and FCR (feed conversion ratio) of juvenile swimming crab between group A and B(P>0.05). The second molting cycle and FCR of group C was significant shorter and FCR was significant lower than the other two groups(P<0.05), however, SGR of group C was significant higher than the group A and group B(P<0.05).(3) Each dietary had showed a significant effect on the Hepatosomatic Index(HSI),and its protein and lipid contents(P<0.05). The HSI and the lipid content of group A were significant higher(P<0.05), however, the protein content was significant lower than the other two groups(P<0.05).(4) With regard to the fatty acid composition,the saturated fatty acids and mono-unsaturated fatty acids of hepatopancreas and body from group A were significant higher than the other two groups(P<0.05), and the poly-unsaturated fatty acids and highly unsaturated fatty acids were significant lower than the other two groups(P<0.05). In conclusion, juvenile swimming crab fed our purified diets could achieve good growth performance, which lay a solid foundation for the further study on the nutrition requirments for this crab species.2. The effects of dietary supplement of ARA on ovary development and tissue biochemical composition of swimming crab, Portunus trituberculatus.(1) No significant difference was observed in the HSI and GSI among the all five diets(P>0.05),the GSI of the control is significant higher the other four ARA diets.(2) Mositure,total lipid content,crude protein and total carbohydrate were all not affected by the dietary supplement of ARA in heptopancreas and ovary. With an increase of ARA in the diets,an insignificant decrease of moisture was found in both heptopancreas and ovary(P>0.05).The total lipid content of heptopancreas of the crab of control diet was significant higher than the other four diets(P<0.05),however,the moisture was opposite.As for the lipid class,there was no significance of difference among the four formulated diets(P>0.05).The content of TG(Triacyglycerol) of heptopancreas was significant lower than the other four diets(P<0.05),while the content of PL(Phospholipids),CHO(Cholesterol) and FFA(Free fatty acids) were significant higher than other diets(P<0.05).Due to the formulation of diet1,content of TG of hep topancreas was significant higher than any other groups(P<0.05).The ARA levels did not affect the lipid class of the ovary among all groups.(3) The fatty acid composition of heptopancreas and ovary both significantly had a positive relationship with the fatty acid composition of each diets(P<0.05).The fatty acid compositon of the food could be reflected significantly throuth the fatty acid composition of the heptopancreas of Portumts trituberculatus,which had been strongly affirmed in crustacean.While,the fatty acid composition of the ovary could show the fatty acid requirement of the crab,form which we also conclude that DHA(Docosahexaenoic Acid) is of great importance of Portunus trituberculatus.And the insignificant decrease of EPA(Eicosapentaenoic Acid) was also observed while the content of ARA was increasing among the four diets groups.The effects of dietary supplement of ARA on ovary development were not significant (P>0.05),so the dietary supplement of0.06%-0.24%(wet weight of diets%) was recommended here.The high level ARA may lead to the albinism of Portunus trituberculatus.3. The effects of dietary supplement of ARA on nutritional quality of swimming crab, Portunus trituberculatus.(1) Mositure,total lipid content,crude protein and total carbohydrate were all not affected by the dietary supplement of ARA in muscle(P>0.05).The moisture of muscle of the control was significant lower than the other four diets (P<0.05),and no significant difference was observed among each ARA diets.Highest level of PL(P<0.05) and lowest FFA&CHO(P>0.05) were detected in the muscle of control diet compared with the four formulated diets.(2) The fatty acid composition of diets have greatly influenced the fatty acid composition of the muscle(p<0.05),however,with the increasing of ARA levels in the diets,the content of ARA showed a insignificant positive relationship(P>0.05).The muscle of crab of control diet had a better fatty acid ratio because of its highest n-3/n-6PUFAs(P<0.05). (3) The amino acid composition in both ovary and muscle did not show a significant difference(P>0.05),from which we could conclude that the swimming crab fed our diets could achieve a normal level of amino acid of main edible part.The content of collegan and heat soluble collegan were all showed a highest level in the muscle of contol diet,which mean our diets still need to be improved.In conclusion,the Portunus trituberculatus fed our diets could achieve a good ovary development,the ARA in the diets have a positive effect during the early ovary development.The fatty acid composition of heptopancreas of ovary were significantly affected by the diets.The ARA content of different diets showed no significant difference in the nutritional quality of meat,while the collagen of control was significant higher than the other diets group.