| A study was conducted to evaluate the effects of dietary carbohydrate-to-lipid m(CHO).m(L), carbohydrate sources and lipid sources on the growth performance, metabolism and feed utilization of juvenile Chinese sucker (Myxocyprinus asiaticus).On this basis, it deduced the appropriate proportion of carbohydrate and lipid, superior carbohydrate source and lipid source for juvenile Chinese sucker.1. Effects of dietary carbohydrate to lipid levels on growth performance and carbohydrate metabolism of juvenile chinese suckerTotal360Chinese sucker(Myxocyprinus asiaticus), with average initial body mass of (4.01±0.02)g were randomly divided into6treatments with3replicates (20fish per barrel). Six isonitrogenous (crude protein41%) and isoenergetic (16KJ/g) diets were formulated to contain with graded levels ofm(CHO):m(L)(0.29,0.81,1.58,2.88,5.46and13.22). Each treatment was fed a diet to investigate the effects of dietary carbohydrate-to-lipid m(CHO):m(L) on growth performance, feed utilization and carbohydrate metabolism enzymes activities of juvenile Chinese sucker. The results showed that, weight gain rate and specific growth rate increased first and then decreased with the increasing dietary m(CHO):m(L), reached to the highest in fish fed diets with m(CHO):m(L) of5.46, which was significantly higher than those of fish fed other diets (P<0.05), while feed coefficient rates showed converse trend; The crude lipid content in whole-body and muscle of fish decreased with the increasing dietary m(CHO):/m(L) significantly (P<0.05), while hepatic crude lipid first decreased and then increased, and reached to the lowest in fish fed diets with m(CHO):m(L) of2.88; Hepatic triglycercide concentrations increased significantly with the increasing dietary m(CHO):m(L)(P<0.05), while activities of aspartate aminotransferase and alanine aminotransferase first increased and then decreased, and reached to the peak with dietary m(CHO):m(L) of2.88; Hepatic pyruvate kinas activities increased significantly with the increasing dietary m(CHO):m(L) (P<0.05), while phosphoenolpyruvate carboxykinase showed converse trend. No significant difference was observed in activities of hepatic hexokinase and glucose-6-phosphatase among dietary treatments (P>0.05); Based on broken-line regression analysis of specific growth rate against dietary/m(CHO):m(L), a m(CHO):m(L) of4.65was proved to be optimal for the growth of juvenile Chinese sucker.2. Effect of carbohydrate sources on growth performance, body composition and carbohydrate metabolism of juvenile Chinese SuckerThe experiment was conducted to evaluate the effects of dietary carbohydrate sources on the growth performance, feed utilization, body composition, carbohydrate metabolism enzymes activities of juvenile Chinese sucker (Myxocyprinus asiaticus). The initial weight of the Chinese sucker was (8.39±0.04) g.5sonitrogenous (crude protein41%) and isoenergetic (17KJ/g) diets were formulated respectively with28%of glucose, sucrose, dextrin, corn starch or gelatinized corn starch. The results showed that the weight gain rate, specific growth rate and protein efficiency ratio reached highest in the gelatinized corn starch treatment, and they were significantly higher than those of glucose and sucrose dietary treatment (P<0.05); Feed efficiency of fish fed the gelatinized corn starch diet and corn starch diet were significantly higher than those fed other dietary (P<0.05); The concentration of liver glycogen in fish of glucose group and dextrin group were significantly higher than other3groups (P<0.05);The crude lipid content of liver and whole-body in fish of glucose group were significantly higher than those fed other dietary (P<0.05); Liver triglycercide in fish of glucose group and sucrose group were significantly higher than other3groups (P<0.05), but no significant difference was found in total cholesterol and glucose concentration in liver of fish fed all dietary(P>0.05); Activities of hepatic pyruvate kinase and phosphoenolpyruvate carboxykinase in fish of sucrose group were significantly higher than those of dextrin group (P>0.05); No significant difference was observed in the activities of hepatic hexokinase and glucose-6-phosphatase among dietary treatments (P>0.05). In conclusion, the present study suggested that complex carbohydrate, such as gelatinized corn starch, seemed better for the growth and feed utilization of juvenile Chinese sucker as carbohydrate source compared to monosaccharide and disaccharide diets.3. Effect of dietary lipid sources on growth performance, body composition, fatty acids composition of juvenile Chinese SuckerA feeding experiment was conducted to investigate the effects of different lipid sources in diets on growth performance, body composition, lipid metabolism, antioxidant ability and fatty acid composition of juvenile Chinese sucker (Myxocyprinus asiaticus). The initial weight of the Chinese sucker was (3.63±0.03) g.7sonitrogenous (crude protein41%) and isoenergetic (17KJ/g) diets were formulated with8%of either fish oil (FO), soybean oil (SO), pork lard(PL), palm oil (PO), peanut oil (PNO), linseed oil (LO) and beef tallow (BT), respectively. The results showed as follows:the highest weight gain rate and specific growth rate was found in SO group, and the lowest in PL, BT groups, there were significant difference in those indicators between them (P<0.05); No significant difference was observed in WGR and SGR among FO, PO, PNO, LO groups (P>0.05); There was no significant difference in efficiency ratio among all groups (P>0.05); The crude protein content in whole-body of fish in the SO group significantly higher than those of fish in the PL and PO groups, the crude protein in muscle and hepatic of fish in the FO group were the highest, while its crude lipid content was significantly lower than those of fish fed other diets (P<0.05); Hepatic triglyceride and total cholesterol concentration of fish in the SO and LO groups were significantly lower than those of fish fed other diets (P<O.05); SOD activitie showed a order of SO> LO> SO> PNO> PO> PL> BT, and no significant difference was observed in LO, SO, PNO and PO groups; Fatty acid composition of muscle and hepatic in fish generally reflected the composition of the diet. These results suggested that Chinese sucker had ability to desaturate and elongate18:2n-6and18:3n-3to highly unsaturated fatty acid. In conclusion, SO, PO and PNO were good alternative lipid sources for Chinese sucker, and SO was the best lipid source. |
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