| In this paper, the average weight of 70 g blunt snout bream(Megalobrama amblycephala) was treated as the research object using the Peru fish meal, casein as protein source. Different lecithin, cholesterol, EPA and DHA levels of feed were prepared, and thereby to investigate dietary lecithin, cholesterol, EPA and DHA requirement for blunt snout bream in the same formula system.This article study was set up three parts:Part 1: Six experimental diets were formulated to supply the graded levels of soy lecithin(containing lecithin 1.48, 3.12, 5.79, 8.35, 10.03, 13.13 g/kg of diet, respectively). A total of 480 healthy blunt snout bream with an average body weight of(70.5±1.4) g were randomly divided into 6 groups with 4 replicates per group and 20 fish per replicate. The specific growth rate(SGR) was significantly higher in 13.13 g/kg group compared to the control group(P<0.05). Compared with the control group, the final body weight(FBW) in the 5.79, 13.13 g/kg groups was increased by 9.61% and 10.76%, respectively. The lipid retention ratio(LRE) of supplemental lecithin was significantly higher than the control. Different levels of lecithin inclusion did not affect survival, feed conversion ratio(FCR), protein efficiency ratio(PER), protein retention ratio(PRR), fatness or hepatosomatic index. The body fat content and the abdominal fat of diets supplemented group were significantly higher than the control group(P<0.05) and the lipid in the muscle was significantly higher when added level 5.79 g/kg or more. In contrast, the lipid in the hepatopancreas of the fish fed the graded levels of lecithin was lower than the control diet, except that of the level of 8.35g/kg. The cholesterol, high density lipoprotein cholesterol(HDL-C) and low density lipoprotein cholesterol(LDL-C) concentrations in the serum was increasing with the raising of the lecithin content. Based on the broken line model analysis of the SGR and FCR data indicated that the optimum recommended dietary lecithin requirement for juvenile blunt snout bream was 0.024~0.025g/100 g of body weight /d.Part 2: Six experimental diets were formulated to supply the graded levels of cholesterol(containing cholesterol 0, 4.81, 9.90, 14.49, 19.87, 24.91 g/kg of diet, respectively). A total of 480 healthy blunt snout bream with an average body weight of(70.5±1.4) g were randomly divided into 6 groups with 4 replicates per group and 20 fish per replicate. After 40 d outdoor pond aquaculture, the results showed that: ①The viscera index and hepatosomatic index of supplemental cholesterol was significantly higher than the control(P<0.05). Different levels of cholesterol addition did not affect the growth performance, condition factor(CF) and survival rate(P>0.05). ② As supplemental cholesterol to rise, the lipid in the whole fish, muscle, abdominal adipose and hepatopancreas increased at first and then decreased. Compared with the control group, crude fat of cholesterol-added group was significantly higher(P<0.05). ③The cholesterol, high density lipoprotein cholesterol(HDL-C) and low density lipoprotein cholesterol(LDL-C) concentrations in the serum was significantly higher than the control(P <0.05). In contrast, the cholinesterase, triglyceride and HDL-C /LDL-C ratio was lower than the control(P <0.05). Cholesterol added or not had no significant effect on total bile acid content and the activity of aspartate aminotransferase(AST) and alanine aminotransferase(ALT) in the serum(P>0.05). The results showed that cholesterol added or not had not effect on the growth performance, survival, hepatopanereas function and health of blunt snout bream, but the fat absorption, transport and deposition had been affected to some extent under the experimental conditions.Part 3: According to aquaculture compound feed industry standard design formula of blunt snout bream, eight experimental diets were formulated to supply the graded levels of Guangdong fish oil and Zhejiang fish oil,(diet containing EPA/DHA(g/kg), group 1(2.01/3.05), group 2(10.52/15.35), group 3(10.61/15.68), group 4(9.74/14.41), group 5(9.77/14.27), group 6(9.69/14.34), group 7(8.83/13.07), group 8(9.20/13.20), respectively). A total of 640 healthy blunt snout bream with an average body weight of(70.3±1.8) g were randomly divided into 8 groups with 4 replicates per group and 20 fish per replicate. After 40 d outdoor pond aquaculture, the results showed that: ①The feed conversion ratio(FCR) of group7,8 was significantly higher than other groups(P<0.05) and the specific growth rate(SGR) of group 5 was highest. Among the groups, the survival rate, the end of average weight, condition factor(CF) and viscera index were no significant differences(P>0.05). ②The crude fat of hepatopancreas from experimental groups was significantly higher compared with the control group while the crude protein content lower(P<0.05). ③Significant correlation was found between unsaturated fatty acids content in whole fish, muscle, hepatopancreas, abdominal adipose and the EPA/DHA content of diets by correlation regression analysis(P<0.05). ④The EPA/DHA content of diets influenced serum biochemical indexes to a certain extent. Based on the specific growth rate and feed conversion ratio, the regression analysis showed that: the optimum recommended dietary EPA requirement for juvenile blunt snout bream was 0.050~0.051 g/(100g·d), and the optimum recommended dietary DHA requirement for juvenile blunt snout bream was 0.074~0.075 g /(100g·d). |
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