| Scylla spp.has the characteristics of rapid growth,delicious taste and high nutritional value,which is deeply loved by consumers in East and Southeast Asia.Among them,Scylla paramamosain accounted for more than 90% of the total production.In China,the culture of S.paramamosain mainly depends on the natural wild seedlings,which has a negative impact on the coastal biological resources.On the other hand,pond culture is the main mode of production of S.paramamosain,but this mode is relatively extensive,which leads to serious cannibalism of S.paramamosain and low yield per mu,which restricts the further development of S.paramamosain culture.One of the ways to solve the above problems is the industrial breeding and breeding of S.paramamosain.But at present,the survival rate of S.paramamosain is low,and the technology of seedling cultivation and large-scale industrial intermediate cultivation is not mature.Therefore,this study carried out the research on the color optimization of industrial large-scale seedling culture and transportation tank of S.paramamosain,and provided some technical guidance for the cultivation and transportation of large-scale seedling of S.paramamosain.1.The effect of culture tank color on growth performance and carapace color of juvenile S.paramamosainIn order to study the effect of tank color on the growth of juvenile S.paramamosain,six tank colors(red,yellow,green,blue,black and white)were evaluated in a 46 day culture experiment.The results showed that the survival rate of juvenile S.paramamosain cultured under yellow,blue and black background was higher(> 63%),followed by green and white(50%),and red(36.67%);the specific growth rate of juvenile S.paramamosain cultured under yellow and blue background was also significantly higher than other treatment groups(P<0.05).The color of the tank also significantly affected the color of the juvenile S.paramamosain carapace,and the body color of the juvenile S.paramamosain gradually approached the color of the tank.The L* value(brightness)of black group was the lowest(17.73±1.88),and that of white group was the highest(44.99±3.45)(P<0.05);the +a*value of red group was higher(-2.83±0.64);the +b* value of yellow group was higher(14.57±2.04).The linear regression equation showed that the contribution of tank color to L*,a*,b* values of juvenile mud crab’s carapace color was 80.17%,41.28%,19.13% respectively.2.The effect of tank color on stress response,antioxidant capacity and energy metabolism enzyme activities of juvenile S.paramamosainIn terms of stress,the levels of cortisol in red and yellow groups were significantly higher than those in blue,black and white groups(P<0.05).The content of malondialdehyde in red group was significantly higher than that in other treatment groups(P<0.05),and the levels of superoxide dismutase(SOD)and catalase(CAT)in yellow group were significantly higher than those in other treatment groups(P<0.05).The content of hexokinase(HK)in blue group was significantly lower than that in other treatment groups(P<0.05).The results showed that the yellow and blue background could improve the survival rate and growth rate of juvenile S.paramamosain,but compared with the yellow group,the blue background had lower stress on juvenile S.paramamosain,so the blue background was more suitable for the intermediate cultivation of juvenile S.paramamosain.3.The effects of tank color and shelter on cortisol level of juvenile S.paramamosainTransportation may cause stress to S.paramamosain,resulting in a decrease in the survival rate of subsequent breeding,and the color and shelter of the culture tank may affect the stress response of S.paramamosain during transportation.In this study,three experiments were conducted to study the effects of tank color(black and yellow)and shelter(with or without shelter)on the cortisol in the juvenile S.paramamosain after and during transportation.The results showed that the cortisol level of S.paramamosain cultured in black tanks in the early stage was significantly lower than that of the mud crabs cultured in yellow containers(P<0.05).During transportation,the black tank can also reduce the cortisol peak(P<0.05).Both in black and yellow tanks,the presence of shelter can reduce the peak and duration of the cortisol response of juvenile S.paramamosain.The results of the threefactor analysis of variance showed that the color of the tank,the setting of the shelter and the transportation time all had a significant effect on the level of cortisol(P<0.05).Therefore,by setting a reasonable tank color and shelter,the stress response of the juvenile S.paramamosain during transportation can be alleviated. |
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