| Part 1 A 8-week feeding trial was conducted to determine the effects of partial substitute for fish meal by krill meal on growth performance, body composition and serum biochemical parameters of juvenile starry flouder.The basal diet was formulated using fish meal, wheat gluten, fermented soybean meal as the main protein and fish oil as the lipid source respectively. Six isocaloric and isonitrogenous diets were formulated to contain graded proportion of replacing fish meal by krill meal: 0%(R0), 15%(R15), 30%(R30), 45%(R45), 60%(R60), 75%(R75). Results showed that: 1)Weight gain rate(WGR) and specific growth rate(SGR) were significantly decreased when the replacement fish meal proportion was more than 30%(P<0.05). Replacement fish meal with krill meal significantly elevated apparent digestibility coefficient of dry matter and crude protein(P<0.05).However,there is no statistical differences in daily feed intake(DFI), feed conversion ratio(FCR), condition factor(CF) and hepatosomatic index(HSI)(P>0.05). 2)No significant difference was found in the content of moisture, crude protein,crude lipid, ash and essential amino acids contents of whole body(P>0.05). With the increasing of krill meal subsititution proportion for fish meal, the crude lipid content in dorsal muscle decreased, and R75 group showed significantly higher than R0 group(P<0.05). Alanine, proline and non essential amino acid of whole body in R75 group were significantly higer than those in R0 group(P<0.05). 3) Replacement fish meal with krill meal s ignificantly decreased content of albumin(ALB) and alkaline phosphatase(ALP)(P<0.05). No significant differences were found in the content of total protein(TP) and total cholesterol(TCHO)(P>0.05). 4) Fluoride contents of dorsal muscle in fish fed all diets were below the detectable amount, and its content in vertebral bone significantly increased with the subsititution proportion increasing(P<0.05). In conclusion, based on the results of growth performence, body composition and serum biochemical parameters of juven ile starry flouder, krill meal can replace of 15% fish meal without any adverse effects.Part 2 Six isonitrogenous and isoenergetic diets, in which fish meal protein was replaced by hydrolyzed krill meal in the following proportions: 0%(R0), 10%(R10), 20%(R20), 30%(R30), 40%(R40), 50%(R50), was formulated to investigate the effects of partial substitute for fish meal by hydrolyzed krill meal on growth performance,feed utilization and body composition of pearl gentian grouper(♀Epinephelus fuscoguttatus×♂Epinephelus lanceolatu). 360 pearl gentian groupers with initial weight(57.80±0.28)g were randomly divided into 6 groups with 3 replicates per group and 20 fish per replicate.The experiment lasted for 8 weeks. The results showed as follows : 1)with the increas ing of hydrolyzed krill meal subsititution proportion for fish meal, the weight gain rate, specific growth rate and feed intake rate first increased and then decreased, and R30 group showed significantly higher than R0 group(P<0.05); the apparent digestibility coefficient of dry matter of the groups which substitution percentages are more than 20% are significantly higer than R0 group(P<0.05); the feed conversion ratio, condition factor, protein efficiency ratio, apparent digestibility coefficient of protein and hepatosomatic index of all substitution groups were not significantly different with R0 group(P>0.05). 2) No significant differences were found in moisture, crude protein, crude lipid and ash contents of substitution groups from those of R0 group(P>0.05). In dorsal muscle, crude protein content in R30 group was significantly higher than R0 group(P<0.05), and moisture, crude lipid and ash contents in all substitution groups showed no significant differences(P>0.05). In the conditions of this study, hydrolyzed krill meal can replace less than 40% fish meal in grouper diet,and the most suitable replcement ratio of fish meal protein by hydrolyzed krill meal was 30% based on the results of growth performance, body composition.Part 3 The aim of the experiment was to determine the effects of partial substitute for fish meal by hydrolyzed krill meal on serum biochemical parameters and antioxidant capacity of pearl gentian grouper. Six isonitrogenous and isoenergetic diets with graded levels(0%, 10%, 20%,30%,40%,50%) of substituting for fish meal by hydrolyzed krill meal were each fed to triplicate groups of pearl gentian grouper(mean initial weight 57.80±0.28g) for 8 weeks. Results showed that: 1) No significant differences were found in serum aspertate aminotransferase, alanine aminotransferase,total pritein, albumin, alkaline phosphate, triacyglycerol content among all groups(P>0.05). The content of blood urea nitrogen in R30 group was significant lower than R0 group(P<0.05); The contents of cholesterol in substitution groups except R10 were significant higher than R0 group(P<0.05). 2) Replacement fish meal with hydrolyzed krill meal significantly elevated activity of glutathione peroxidase activity in serum and liver and serum superoxide dismutase(P<0.05) while s ignificantly reduced malondialdehyde contents of serum and liver(P<0.05). 3) Fluoride contents of dorsal muscle in fish fed all diets were below the detectable amount, and its content in vertebral bone increased with the subsititution proportion increasing. 4)With the replacement of hydrolyzed krill meal, pepsin activities significantly increased, and trypsin and lipase activities of the intestine showed no significantly different.In this experiment, partial substitution for fish meal by hydrolyzed krill meal could effectively improve the antioxidant capacity of pearl gentian grouper and pepsin activities, and has no significantly influence on fluoride contents of dorsal muscle. |
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