| Two growth trials were designed to investigate the effects of dietary peotein and lipid levels on growth,body composition,plasma biochemical indices and digestive enzyme activities of juvenile Fang zheng Caucian carp.The results are presented as follow:Trial 1The research on dietary protein requirement of juvenile Fang zheng Caucian carp.Fish meal,blood meal,soybean meal and pea protein meal were used as main protein source and fish oil was as lipid source to formulate six isolipid and isoenergetic experimental diets containing 30.18%,33.13%,36.16%,39.34%,42.32% and 45.46% crude protein.A total of 540 juvenile Fang zheng Caucian carp with the average initial weight(3.10±0.01)g were randomly divided into eighteen aquaria and 30 juvenile Fang zheng Caucian carp per aquarium,which were fed for 56 days.The results indicated that with the increasing of dietary protein levels,weight gain rate,specific growth rate,feed efficiency and protein efficiency ratio increased up to 36.16% group and then decreased(P < 0.05),there was no significant difference on feed efficiency among 36.16%,33.13% and39.34% group(P > 0.05),and there was no significant difference on protein efficiency ratio between 36.16% group and 33.13% group(P>0.05).The hepatic glutamic-pyruvic transaminase activity with dietary protein levels increased up to 36.16% group and then decreased(P< 0.05),which was no significant difference in 36.16% group and 39.34% group(P> 0.05).The hepatic total cholesterol and triglyceride content in 30.18% group were significantly higher than those in other groups except 33.13% group(P< 0.05).Intestinal trypsin activity of fish in 36.16% group was significantly higher than in 45.46% group(P < 0.05).Based on the quadratic regression analysis,the optimal dietary protein requirement for Fang zheng Caucian carp is 35.29% to37.07% under this experimental condition.Trial 2A 56 days trial was carried out to ensure the dietary lipid requirement of juvenile Fang zheng Caucian carp.Fish meal,blood meal,soybean meal and pea protein meal were used as main protein source and fish oil was as lipid source to formulate five isonitrogenous diets containing3.91%,5.99%,8.12%,10.01% and 12.30% crude lipid(EE).A total of 525 juvenile Fang zhengCaucian carp with the initial weight(23.30±0.08)g were randomly divided into fifteen aquaria and35 juvenile Fang zheng Caucian carp per aquarium.The results indicated that with the dietary lipid level increasing,the weight gain rate,specific growth rate,feed efficiency and protein efficiency ratio of fish in 8.12% group were significantly higher than other groups(P < 0.05).The feed conversion ratio decreased up to 8.12% group and then increased(P<0.05).The whole body crude lipid(EE)content increased(P<0.05),which was no significant difference between 12.30% group and 10.01% group(P>0.05).The plasma glutamic-oxalacetic transaminase activity increased with dietary lipid levels up to 10.01% group(P < 0.05),the glutamic-pyruvic transaminase activity increased with dietary lipid levels up to 12.30% group(P < 0.05).The plasma total protein,globulin,total cholesterol and triglyceride content of fish in 3.91% group were significantly higher than other groups(P<0.05).The plasma lysozyme activity increased with dietary lipid levels(P<0.05).The hepatic catalase,superoxide dismutase,total antioxidant capacity,glutamic-oxalacetic transaminase and glutamic-pyruvic transaminase increased up to 8.12% group and then decreased(P<0.05).Malate dehydrogenase increased with dietary lipid levels(P<0.05).Intestinal trypsin and lipase activities of fish in 8.12% group were significantly higher than other groups(P<0.05).Based on the quadratic regression analysis,the optimal dietary lipid requirement of juvenile Fang zheng Caucian carp is 7.10% to 7.56% under this experimental condition.In conclusion,the dietary protein requirement for juvenile Fang zheng Caucian carp is35.29% to 37.07%,the dietary lipid requirement for juvenile Fang zheng Caucian carp is 7.10% to7.56%. |
