| The one year old Misgurnus anguillicaudatus cohort juvenile[body weight(14.23± 1.92)g,body length(104.9± 16.57)cm]was used as experimental objects under the condition of water temperature(28±0.2)0C,pH 7.68±0.05,DO(7.58±0.02)mg/L.The 1200 experimental objects were ranked in descending order according to their weights,and were divided into five groups according to 5%?19.9%?50.1%?20.1%and 4.9%.Then the morphological characteristic and related physiological functions of Misgurnus anguillicaudatus cohort juvenile with different weight-gaining performance were studied(1)Morphological differences showed that all the traits measured showed A>B>C>D>E(P<0.05)among the 57 morphological traits in the study.The 11/27 morphology ratio indexes showed significant differences among all experimental groups(P<0.05),and their values were A>B>C>D>E.Principal component analysis was carried out with the morphology ratio indexes,and the variances of the main components with 4 eigenvalues greater than 1 were extracted.The contribution rate was 90.78%,and PC1 had the largest variance contribution rate,reaching 46.75%which was much larger than the sum of the other principal components.The A experimental group was defined as the fast growing group,while the groups of B,C,D and E were normal group.The progressive elimination method was used,and C7?C12?C12?C16 which contributed a lot to the discrimination,were selected to establish Fisher classification function equations.The discrimination accuracy P1 and P2 of the fast growing group were 96.67%and 100%respectively;the discrimination accuracy P1 and P2 of the normal group were 100%and 99.17%respectively,and comprehensive discriminant accuracy was 99.3%(2)The texture of the back muscle:the measured values of hardness,elasticity,chewiness and resilience showed significant difference(p<0.05),except for the B group and the C group.There were significant differences in the adhesiveness of each group(p<0.05).(3)Differences in respiration and excretion:There was significant difference in suffocation point among the other groups(P<0.05),except for group B and C;The oxygen consumption rate of each experimental group showed a monotonous upward trend during the period 18:00-22:00 and 22:00-02:00,and the all values were A<B<C<D<E,showing significant differences among the other groups(P<0.05),except for the group D and E at 18:00-22:00.The ammonia excretion rate of each group increased in each time period,and all values were A<B<C<D<E(P<0.05),showing significant difference.(4)Differences in digestive enzyme activities:the pepsin activity of experimental group B and C showed no difference,bu there were significant differences among the other groups(P<0.05),but trypsin activity of liver and intestine,lipase activity of liver and amylase activity of intestine were significantly different in each group(P<0.05),and they incremented with the decrease of weight-gaining performance.(5)The difference of antioxidant enzymes and ATPase activity:There was significant difference in SOD activity of liver among all groups(P<0.05).The SOD activity of gill had significant difference among the other groups(P<0.05),except for group C and D.The SOD activity of liver decreased with the increase of weight-gaining performance,while SOD activity of gill was opposite.The CAT and POD activity of liver and gill showed a decreasing trend with the increase of weight-gaining performance.There were significant differences among other groups(P<0.05),except for gill's CAT activity of group B and C and liver's POD activity of group A and B.The activity of Na+/K+-ATPase in liver was not significantly different among group B,A and C,and Ca2+/Mg2+-ATPase activity showed no significant difference between group A and B,while there were significant differences among the other groups(P<0.05). |
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