Optimal Contents Of Dietary Protein,Lipid And Starch For Furong Crucian Carp (Cyprinus Carpio Var. Furong Carp♀×C.Carpio Red Crucian Carp (?))

Four growth trials were conducted to determine the effects of dietary protein, lipid and starch levels on growth and feed utilization of Furong crucian carp(Cyprinus carpio var. Furong carp (?)×C. carpio red crucian carp (?)).Body composition, hematological parameters and digestive enzyme activities were also determined to investigate the mechanism for the utilization of the nutrients by the fish.Results are showed as follows:1. In Trial 1, fish meal and casein were used as main protein source, equal mixture of fish oil and soybean oil was used as dietary lipid source and corn starch was used as carbohydrates to formulate seven isolipid (8%) and isoenergetic (17MJ/kg) experimental diets containing different protein levels (25%-43%), which was used to feed juvenile Furong crucian carp (7.67±0.66 g). The experimental duration was 64 days. The results showed that:with the increasing of dietary protein levels, weight gain increased with dietary protein up to 40% and then decreased (P<0.05). Feed efficiency increased, with dietary protein and that in 37% treatment group was the highest (P<0.05). Plasma triglyceride concentration declined with dietary protein levels increased (P<0.05). Plasma total cholesterol concentration had no difference between groups (P>0.05). Midintestine typsin activities was significantly increased with dietary protein levels (P<0.05), while chymotrypsin activities had no significant difference between treatments (P>0.05). Glutamic-pyruvic transaminase activities in liver decreased firstly and then raised with dietary protein levels,34% treatment group was the lowest (P<0.05). Glutamic oxalacetic transaminase activities and hepatic glycogen content were not affected by dietary protein levels (P>0.05). Broken-line of SGR estimated that protein requirements for maxmum growth was about 41.35% for juvenile Furong crucian carp.2. In Tiral 2, a 61-day growth trial was conducted to investigate the optimal dietary starch level for juvenile Furong crucian carp of (8.94±0.59) g. Fish meal and casein were used as main protein sources and mixture of fish oil and soybean oil (1:1) was used as dietary lipid source to formulate seven isonitrogenous (35%) and isolipid (8%) experimental diets containing different corn starch levels (6%,12%,18%, 24%,30%,36% and 42%). The results showed that weight gain, specific growth rate and feed efficiency increased first and then tended to be stable with dietary corn starch (P<0.05), while there were no significant differences between those fed with 18%-42% dietary corn starch (P>0.05). Protein retention efficiency increased with increasing dietary corn starch (P<2.05) and those of the fish fed with 30% and 42% dietary corn starch were higher than those fed with 6% and 12% dietary corn starch (P<0.05). Fish plasma glucose concentration had no difference between groups (P>0.05). Plasma triglyceride concentration increased with dietary corn starch (P<0.05). Plasma total cholesterol concentration were significantly higher in 30% dietary corn starch group (P<0.05). Intestine amylase activities and muscle glycogen content significantly increased with dietary corn starch (P<0.05). Hepatic glycogen content was significantly higher in the fish fed with 36% corn starch (P<0.05). Broken-line analysis based on specific growth rate (SGR) showed that the optimal dietary starch level was about 27.47% for juvenile Furong crucian carp.3. In Trial 3, fish meal and casein were used as main protein source, corn starch was used as carbohydrates source, equal mixture of fish oil and soybean oil was used as dietary lipid source and to formulate seven isonitrogenous (35%) experimental diets at various lipid levels (0%-21%), which was used to feed juvenile Furong crucian carp (8.86±0.59 g). The experimental duration was 61 days. The results showed that: weight gain, feed efficiency and specific growth rate were not affected by dietary lipid levels (P>0.05), while vales were the highest in 14% treatment group, considered from the aspects of growth and feed utilization, the optimal dietary lipid level for juvenile Furong crucian carp was 14%. Plasma triglyceride concentration was lowest in 0% treatment group and plasma total cholesterol concentration decreased as dietary lipid raised (P<0.05). MDA concentration and SOD activities in plasma and liver were not affected by dietary lipid levels (P>0.05). Intestine amylase activities had no difference with dietary lipid increased (P<0.05).4. In Trial 4, fish meal and casein were used as main protein source, corn starch was used as carbohydrates source, equal mixture of fish oil and soybean oil was used as dietary lipid source and to formulate seven isonitrogenous (35%) experimental diets at various lipid levels (3%-21%), used to feed medium-size Furong crucian carp (55.5±0.05 g). The experimental duration was 64 days. The results showed that: weight gain and specific growth rate increased with dietary lipid up to 18% and then decreased (P<0.05). Feed efficiency was the highest in 6% group, each group had no difference (P>0.05). Plasma triglyceride concentration and total cholesterol concentration were also not affected by dietary lipid levels (P>0.05). With dietary lipid, MDA content increased up to 12% and then decreased in liver (P<0.05), SOD activities increased (P<0.05). Midintestine lipase activities increased with dietary lipid and reached the highest value in 18% treatment group (P<0.05). Considered from the aspects of growth, the optimal dietary lipid level for medium-size Furong crucian carp was 18%.