Effect Of Dietary Lipid(Energy) To Protein Ratios And Lipid Sources On Growth, Physiological Function And Fatty Acid Composion Of Hemibarbus Maculatus

A series of two experiments was conducted to evaluate the effects of feeding different dietary energy to protein ratio and various sources of dietary lipid diets on growth performance,physiological function and fatty acid composition of Hemibarbus maculatus.Experiment 1:Effect of dietary lipid sources on growth,physiological function and fatty acid composion of Hemibarbus maculatusFive experimental diets containing rape oil,soybean oil,peanut oil,lard and rapeseed were fed to triplicate groups of 15 fish with initial mean weights of 17.42g for 61days.The result suggested that final growth performance was better for soybeen oil,peanut oil and lard treatment compared to the rape oil and rapeseed treatment.The experiment also showed us that both C18:2n-6 and C18:3n-3 are dietary essential fatty acids for Hemibarbus maculatus.In fatty acid metabolism, the requirement for C18:2n-6 was much more than the need forC18:3n-3. The containing of five sources of dietary lipid did not affect the quality for human nutrition.Fish fed lard diet retained high deposition of liver lipid in despite of better growth performance.While the feeding of diets containing soybean oil could increase the activitites of T-SOD.And the feeding of diets containing rape oil had the largest effect on the function of liver. The fatty acid composition of the test diets was reflected to a certain extent in the fatty acid composition of body.This phenomenon was also observed in muscle,mesentery and fat in mesentery in this study.For hepatopancreas and serum,the fatty acid composition was not much affected by dietary fatty acid composition. C18:1n-9 was the main fatty acid in muscle and liver lipid.Fish has the ability to convert fatty acids of dietary.This convertion occurred between n-3 and n-6 fatty acids.Experiment 2,Effect of dietary lipid(energy) to protein ratios on growth of Hemibarbus maculatusAn experiment was performed to study the optimum dietary protein level and energy to protein ratio of Hemibarbus maculatus Bleeker.Five crude protein levels(34%,36%,38%,40%,42%) were utilized. Correspondingly, energy to protein ratios were 58.79 KJ/g,53.64 KJ/g,49.75 KJ/g,45.94 KJ/g and 42.55 KJ/g.Fish meal and soybean meal were used as the sourse of protein.Lipid sourse was mixed oil(rape oil:soybean oil 1:1).Each of the experimental diets was fed to triplicate groups of 15 fish with an average individual weight of 3.5g for 77days. The result showed us that with the increasing dietary protein level,the specific growth rate,protein efficiency rates and protein deposit rate and energy retention rate increased too,and feed conversion rate decreased. However,these trends were less marked when the protein level reached 40%.There was no significant difference in survival rate among treatments.Under the condition of this study,maximum specific growth rate(1.58%·day-1),maximum protein efficiency rates(135.94%) and least feed conversion rate(1.72) were achieved at dietary protein level of 42% and 6.85% lipid level,and physiological function of fish was normal.