Effects of Dietary Protein and Lipid Levels on Growth Performance and Body Composition of Chinese Sucker( Myxocyprinus Asiaticus)

A 3×3 factorial design was adopted in this experiment to investigate the effects of dietary protein and lipid levels on growth performance and body composition of Chinese sucker( Myxocyprinus Asiaticus),in order to determine the optimum dietary protein and lipid levels of Chinese sucker. Nine experimental diets were prepared with three protein levels( 35%,40% and 45%) and three lipid levels( 6%,8% and 10%),and Chinese sucker with the average body weight of( 16. 40 ± 0. 02) g were fed the 9 kinds of diets for 8 weeks.Each diet was randomly fed three cement pool,and each cement pool had 30 fish. The results showed that weight gain rate( W GR),specific growth rate( SGR),feed conversion ratio( FCR) and protein efficiency ratio( PER) were significantly influenced by both dietary protein and lipid levels( P 0. 05),but there were no interactions between dietary protein and lipid levels existed for above indices( P 0.05). The W GR,SGR and PER in 35% protein group were significantly lower than those in 40% and 45% protein groups( P 0.05),but the FCR had an opposite trend of changing. The W GR and SGR in 6% lipid group were significantly lower than those in 8% and 10% lipid groups( P 0.05),and the FCR in 6% and 8% lipid groups was significantly higher than that in 10% lipid group( P 0. 05),but the PER had an opposite trend with FCR. Crude protein and crude lipid contents in whole-body improved significantly( P 0. 05) as protein level increased from 35%to 40%. Contrary to moisture content,crude lipid content in whole-body increased with increasing lipid level.Dietary protein level had significant influences on valine,isoleucine,histidine,glutamic acid,essential amino acids and total amino acid contents in whole-body( P 0.05),and dietary protein level had a significant influence on whole-body arginine content only( P 0.05). Both dietary protein and lipid levels had little influence on the whole-body fatty acid composition of Chinese sucker,only C14 ∶ 0 and C18 ∶ 0 contents in whole-body were changed to some extent. The results indicate that the optimum dietary protein and lipid levels of Chinese sucker are 40% and 6% to 8%,respectively.