Effects Of Flow Rate On Growth,Nonspecific Immunity And Fatty Acid Composition In Juvenile Phoxinus Lagowskii Dybowskii

The effects of flow rate on growth,antioxidant capacity,non-specific immunity and fatty acid composition.in juvenile Phoxinus lagowskii Dybowskii were investigated to determine the optimal flow rate in fishery production practice,which provide a theoretical basis for the healthy breeding of circulating water in P.lagowskii.The main research contents are as follows:1.Effects of different flow rates on fish growth,non-specific immunity and fatty acid compositionTaking P.lagowskii with an initial body weight of 2.21 ± 0.01 g as the test object,four flow groups(control 0cm/s,experimental group 2cm/s,5cm/s,and 8cm/s)were set up to conduct water flow training tests,4 h/d.After 7 weeks of breeding,the effects of flow rate on the growth,body index,visceral whole fish body nutrients,digestion,non-specific immunity and fatty acid composition of P.lagowskii were measured.The test results showed that the mass increase rate and specific growth rate of P.lagowskii increased first and then decreased with the increase of the flow rate,and the survival rate of each group was 100%,in which the mass of the 5 cm/s flow rate group increased.The rate and specific growth rate were significantly higher than the other groups,and the differences between other groups were significant.Different flow rates had no significant effect on the plumpness of P.lagowskii.Both the visceral and hepatic ratios decreased first and then increased,and the liver-to-body ratio in the 5 cm/s flow rate group was significantly higher than in the other groups.The crude protein content increased with the increase of flow velocity,while the crude fat showed a downward trend,but the difference between the groups was not significant.The crude protein content was highest at the 8 cm/s flow rate group,while the crude fat content was the lowest.The feed rate and feed coefficient were highest in the 5cm/s flow rate group,and the protein efficiency was the lowest.The feed coefficient in the 8cm/s flow rate group was significantly lower than the other groups;the amylase activity and lipase activity of P.lagowskii in the 5cm/s flow rate group reached the highest.Different flow rates had no significant effect on total antioxidant capacity,superoxide dismutase activity,and malondialdehyde content in P.lagowskii(P> 0.05).The total antioxidant capacity of the liver and the activity of superoxide dismutase reached the highest in the 5 cm/s flow rate group.The MDA content in the flow rate group was lower than that in the control group.The catalase activity in the 5cm/s flow rate group was significantly higher than in the other groups(P <0.05).The activity of alkaline phosphatase in the 5cm/s flow rate group was significantly higher than that in the other groups(P<0.05),and the acid phosphatase activity also showed a trend of first increase and then decrease,but the difference was not significant(P>0.05).Overall,the non-specific immunoenzyme activity was highest in the 5 cm/s flow rate group.The SFA content in the flow rate group was lower than the control group,the MUFA content flow rate group was also lower than the control group,and the PUFA content flow rate group was higher than the control group.The ARA content increased first and then decreased.The content of the 2cm/s and 5cm/s flow groups was significantly higher than the control group and the 8cm/s flow group(p <0.05).The EPA content and flow group were higher than the control group,but the difference was not significant(P> 0.05);DHA content increased with the increase of flow rate,and the 8cm/s flow rate group was significantly higher than the control group(p <0.05).In summary,the content of polyunsaturated fatty acids in the flow rate group was higher than that in the control group.2.Effects of different water exercise time on the growth,non-specific immunity and fatty acid composition of P.lagowskiiTaking P.lagowskii as the test object,a static water control group and three test groups with different flow time were set up,and the flow rate of each group was 2cm/s,which was divided into three groups according to different flow time: test group 4h/d,8h /d,20h/d,to study the effects of different water flow time on the growth,body index,visceral whole fish nutrient composition,digestion,non-specific immunity and fatty acid composition.Determine the most suitable water flow time for P.lagowskii at 2cm/s.In this test,the total antioxidant capacity of the liver of P.lagowskii reached the highest activity at the 8h/d flow rate group;the activity of superoxide dismutase reached the highest at the 4h/d flow rate group;The activity of catalase was significantly higher in the 8h/d flow rate group than in the other groups(P <0.05);the alkaline phosphatase and acid phosphatase activities in the 8h/d flow rate group were significantly higher than those in the other groups.Under the condition of flow rate of 2cm/s,the MUFA content of P.lagowskii was the highest in the control group,while the PUFA content reached the highest in the 8h/d flow rate group,while the ARA,EPA,DHA content reached the highest in the 20h/d flow rate group.In summary,the polyunsaturated fatty acid content of the flow rate group is higher than that of the control group,and the polyunsaturated fatty acid content of the 8h/d flow rate group reaches the highest.3.Effect of different flow rates on fatty acid composition of P.lagowskiiIn this experiment,P.lagowskii were used as the research object.Through two weeks of experiments,analyze the effects of different flow rates on the nutrient composition of the whole fish body of viscera in hungry P.lagowskii,and the fatty acid content of liver and visceral fish.Effects of changes in body nutrition and fatty acid content on meat quality of P.lagowskii.The terminal body mass of P.lagowskii in the starved state decreased with the increase of flow velocity.The terminal body mass of the 8 cm/s flow rate group was significantly lower than the other groups,and the survival rate of each group was 100%.The 2cm/s and 5cm/s flow rate groups were significantly lower than the control group and the 8cm/s flow rate group.The 5cm/s flow rate group had the lowest visceral body ratio,and the liver-body ratio was lower than the control group.There was no significant effect on water,crude fat and crude ash.The crude protein content showed a decreasing trend.The 8cm/s flow rate group was significantly lower than the other groups.The crude fat content showed a downward trend with increasing flow rate,but the differences between the groups were not obvious.(P>0.05).There were no significant differences in the contents of SFA,MUFA,and PUFA in the liver and whole fish of P.lagowskii between starvation groups in this experiment.Liver and whole fish MUFA content was highest in the 8cm/s flow rate group,liver PUFA content was the highest in the control group,and 5cm/s flow rate group was the lowest,while whole fish PUFA content was just the opposite,and PUFA content was the highest in the 5cm/s flow rate group.Liver ARA,EPA,and DHA contents were significantly higher in the 2 cm/s flow rate group,while whole fish ARA,EPA,and DHA contents were highest in the 2 cm/s flow rate group.In summary,with the increase of flow velocity,the energy consumption of fish body is on the rise,but when starved,the fish consumes liver and fish fatty acids with different rules.