Study On Dietary Protein And Lipid Requirement Of Polyodon Spathula

This study researched the effects of dietary protein and lipid levels on growth,body composition,and healthy status of paddlefish(Polyodon Spathula).The results of the study were as follows:From the first experiment,we discovered that the weight gain,specific growth rate of the experimental fish gradually increased with the increase of dietary protein levels from 35.44% to 42.05%.The protein efficiency ratio did not change significantly when protein level increased from 35.44% and 42.05%,however,it significantly decreased when protein level reached 45.30%.Based on second-order polynomial regression analysis of weight gain,the recommended dietary protein level for paddlefish diet was 40.67%.The body composition of the experimental fish did not change significantly in response to the varied dietary protein levels.Intestinal trypsin and lipase activity of paddlefish peaked in protein level of 42.05%,while no significant difference was observed in intestinal α-amylase.The highest superoxide dismutase activity of the paddlefish was observed in 37.20% group,and the activity of catalase significantly increased when protein levels reached 39.19% compared to the 35.44% group.In the second one,with the increase of lipid level in feed,weight gain,protein efficiency and condition of paddlefish factor all showed a trend of first rising and decreasing,and regression analysis determined that when the specific growth rate reached the maximum,the feed lipid level was 7.88%,and when the protein efficiency ratio reached the maximum,the feed lipid level was 9.46% The crude lipid content of muscle and liver increased with the increase of feed lipid level(P<0.05),3.01% groups of total fish and muscle crude protein level were the lowest(P<0.05),and the level of feed lipid was too high to affect muscle protein level.Some fatty acid composition in the muscle of the paddlefish was related to the fatty acid in the feed,with the increase of the feed fat level,the ratio of n-6 PUFA in the muscle and liver was higher,the n-3/n-6 PUFA was lower,the SFA(C14:0,C16:0,C18:0)in the liver decreased with the increase of the feed fat level;MUFA(C16:1,C18:1n-9)were first ascending,then decreased.7.14% groups of intestinal protein enzyme activity were significantly higher than 9.35%,Amylase was more stable when lipid level reached 7.14%,and no significant difference between trypsin and lipase.The concentration of serum total protein,albumin and globulin increased with the increase of lipid level,the total serum cholesterol and high density cholesterol concentration in 3.01% group were significantly lower than that in 11.64% Group(P<0.05),and alanine aminotransferase and aspartate aminotransferase were not affected by dietary lipid level.The level of dietary lipid was too high,the activity of superoxide dismutase,catalase and glutathione peroxidase decrease significantly,and there was no significant difference in glutathione and malondialdehyde content.Based on second-order polynomial regression analysis of the activity of superoxide dismutase in serum,when the it reached the maximum,the feed lipid level was 9.69%.The above results showed that the appropriate protein level in the feed of paddlefish feed was 39.19%-42.05%,and lipid level was 7.88%-9.69%.We recommended that the protein level was 40.67%,and the lipid level was 7.88%.