| Bluntnose black bream(Megalobrama amblycephala), belongs to Osteichthyes, Cypriniformes, Carp, Bream subfamily, is an important economic herbivorous fish, is one of China’s major freshwater aquaculture species, because of its wide feeding habits, low cost, fast growth rate, high survival rate with high-quality meat and tastes delicious. They are good herbivorous fish species across the country, and breed more cost-effective good in recent years.414same size breams were random selected to be divided into six groups, one group was control group, feeding the basal diet conteining8%fish meal, the other five groups were the test groups, feeding0.75%,1.5%,3%,6%,9.5%algae powder to corresponding alternate8.25%(T8.25),16.75%(T16.75),33.25%(T33.25),66.625%(T66.63) and100%(T100) fish meal of the basal diet, with each group3replicates, and each box23tails, which were cultured in aquarium with automatic temperature control culturing system with recycling water for65days. After that, indicators of fish weight gain, hepatosomatic, dry matter digestibility, blood biochemical and immune parameters, liver and immune indicators were measured, to discuss the growth and immune effects of different algae powder diets on Bluntnose black bream.1. Effect of the diets with different levels of fish meal alternated on the growth and blood parameters of Bluntnose black breamIn the culture environment under the same conditions, the breams were fed different feed for65d, the fish growth gene express level the weight gain, specific growth rate, feed conversion, protein efficiency, hepatosomatic, viserosomatic and fullness coefficient indexes were measured. The fish growth gene express level of group T16.75and T33.25were significantly higher than the other groups, and group T100were significantly lower than the other groups; The weight gain, specific growth rate and protein efficiency of the group T33.25were significantly higher than control group(P<0.05), the different of these indicators between group T16.75and control group were not significant(P>0.05), but a clear upward trend, these indicators of group T66.63and group T100were lower than other groups; the feed conversion of group T33.25was significantly lower than the other groups(P<0.05), and group T66.63and group T100were higher than other groups; The hepatosomatic, viserosomatic and fullness coefficient indexes were no significant differences among these groups(P>0.05), the results showed alternating16.75%fish meal will promote the growth of breams, while the high replacement ratios(group T66.63and group T100) would inhibit the growth of breams.With the amount of fish meal substitute increasing, breams plasma total protein and albumin levels had a certain upward trend, group T100plasma total protein and albumin were significantly higher(P<0.05) than other groups; blood glucose levels did not change significantly among these groups(P>0.05); blood total cholesterol and triglycerides had a decreasing trend; total cholesterol and triglyceride levels of group T100were lower than the other groups, indicating that algae powder had a certain control on the blood triglycerides and total cholesterol of breams.2. Effect of the diets with different levels of fish meal alternated on whole-body fish and muscle nutrition composition of Bluntnose black breamAt the end of the experiment, the rude protein, crude fat and ash content of total dry matter and the moisture content in muscle and whole-body fish were not significantly different(P>0.05). The results showed the diets with different levels of algae powder had no significant effect on nutrients of whole-body fish and muscle.The muscle essential amino acid content was not significant different among these groups(P>0.05), there were significant differences among non-essential amino acids: serine(ser), glycine(gly) and cystine(cys-s) in each group(P<0.05), the ser in group T16.75was significantly higher than the control group, and the differences among the other groups were not significant; the gly in group T66.63was significantly higher than the control group, group T8.25and group T100(P<0.05); and the differences among the other groups were not significant(P>0.05); the cys-s in all experimental groups was significantly higher than the control group(P<0.05). There were significant differences among essential amino acids:lysine(lys), methionine(met) and valine(val) in whole-body fish(P<0.05):the lys in group T16.75was significantly higher than the control group and group T8.25(P<0.05); the met in group T16.75was significantly higher than the group T100(P<0.05), group T16.75was significantly higher than the group T100(P<0.05); the val in the other experimental groups was not significant different(P>0.05), the whole-body fish non-essential amino acid content was not significant different among these groups(P>0.05). There were great relevance between feed amino acids composition and muscles and whole-body fish amino acids composition in each experimental. The results showed that the feed with different algae powder content would change part of the amino acid composition of the whole-body fish and muscle, but there were still big relevances between feed amino acids composition and muscles and whole-body fish amino acids composition.3. Effect of the diets with different levels of fish meal alternated on digestibility and digestive enzyme activities of Bluntnose black breamThere were no significant differences in digestibility of dry matter and protein among these group(P>0.05), the digestibility of lipid in group T100was significantly higher than control group and7.5%algae powder group(P<0.05).There were significant differences in the digestibilities of essential amino acids(met) and non-essential amino acids(cys-s and glu)(P<0.05):the digestibilities of met in group T16.75and group T33.25were significantly higher than group T100(P<0.05); the digestibility of glu in group T66.63was significantly higher than that in the group T33.25(P<0.05), with the other experimental groups no significant difference(P>0.05); the digestibility of cys-s in group T100was significantly lower than other experimental groups(P<0.05), the digestibilities of other amino acids were no significant difference among these experimental groups(P>0.05).The liver trypsin activity of the control group was significantly higher than the group T66.63and group T100(P<0.05); the chyme trypsin activity of group T16.75was significantly higher than group T100(P<0.05); there were not significantly different on intestinal trypsin activities among the experimental groups(P>0.05).There were not significantly different on amylase activities of the liver, intestine and chime(P>0.05). But the activities of the amylase chyme in the other groups were lower than the control group. The activities of trypsin and amylase followed by hepatopancreas <intestine<chyme chime.There were significantly different on the lipase activities of the chyme(P<0.05), the lipase activity of group T100was significantly higher than other experimental groups (P<0.05).4. Effect of the diets with different levels of fish meal alternated on stress, plasma and hepatic immune parameters of Bluntnose black breamThe plasma aspartate aminotransferase(AST) in the group T16.75was significantly lower than group T66.63and group T100(P<0.05); the plasma alkaline phosphatase(AKP) activities in the group T16.75and group T33.25were significantly higher than the group T100(P<0.05).The globulin(ALB) in the control group was significantly lower than group T100(P<0.05); C4in the group T16.75, group T33.25, group T66.63, group T100were significantly higher than the control group(P<0.05); C3in each experimental group was not significant different(P>0.05).The malondialdehyde(MDA) content in the group T100was significantly higher than control group, group T8.25, group T16.75, group T33.25(P<0.05), the MDA content in the group T66.63was significantly higher than group T8.25, group T16.75(P<0.05); the serum anti-superoxide anion(ASAFR) showed no significant differences among the experimental groups(P>0.05); the peroxides(POD) in the control group, group T8.25, group T16.75, group T33.25were significantly higher than group T66.63and group T100(P<0.05); the total antioxidant capacity(T-AOC) of the control group,0.75%algae powder group, group T16.75, group T33.25was significantly higher than group T100(P<0.05); there were no significant differences on superoxide dismutase(SOD) in all experimental groups(P>0.05).The plasma cortisol hormones showed no significant differences among the experimental groups(P>0.05), the HSP70expression levels increased significantly with replacement ratio increasing.The appropriate alternate proportion of fish meal with algae powder will increase immunity ability of Bluntnose black bream. |
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