| The marine pearl industry in china has being in shrinking,due to the pearl with poor quality that including small size,thin bead layer,defects and so on.In China,most of the marine pearl was being produced from Pinctada fucata martensii,and it is difficult to meet the standard at jewelry grade,and be accepted by international jewelry market.The large-size pearls industry is developing fast,for their value and production,and it is important and necessary way to revitalize the pearl industry in China with sustainable development.Winged pearl oyster Pteria penguin is one of the species in large-size marine pearl oyster,which has the potential to produce large-size pearl.The P.penguin farming activity in China is very underdevelopment,with high mortality rate and low retention rate.It is due to the scientific planning and guidance lacking,higher labor cost,environment pollution,extreme climate change and so on.In recent years,farming in sea is often affected by cooler climate,rainfall and typhoon,and result in economic losses.Industrial farming mode can reduce or avoid the above risks and disadvantages,where many key technologies need to be considered.For bivalves farming,high-quality food selection for using in farming activity is one of the key factors.In this study,we have attempted to explore the feasibility of using spray-dried microalgae as daily food in P.penguin juvenile industrial farming and developed industrial farming methods and technology.To our knowledge,the findings in present study can provide some information on rearing protocols and management of P.penguin industrial farming mode.1.The spray-dried microalgae powder(Isochrysis spp.and Platymonas spp.)were in eutrophic,and can promise the high survival rate in industrial farming for P.penguin juvenile.The crude protein contents were 50.6±2.18% and 47.7±1.64% respectively in Isochrysis spp.and Platymonas spp.powder,significantly higher than groups(p < 0.05).The contents of essential amino acids in Isochrysis spp.and Platymonas spp.powder were41.55% and 40.5% respectively,significantly higher than groups(p<0.05).With the same farming condition,the highest survival rate was observed in Isochrysis spp.and Platymonas spp power group,that 93.33±3.85% and 95±3.34% respectively without significant difference(p > 0.05).2.Using spray-dried microalgae powder,can enhance the digestive ability of P.penguin juvenile.The better digestive enzyme activity was observed in Isochrysis spp.and Platymonas spp powder group,where the lipase activity were 82.57±5.27 U/g prot and30.39±2.38 U/g prot respectively,significantly higher than other groups.3.Using spray-dried microalgae powder,can enhance the antioxidant capacity of P.penguin juvenile.The superoxide dismutase(SOD)activity in mantle and visceral mass were more obvious.The SOD activity in mantle were 221.11±11.92,466.94±12.76,290.72±13.79,150.39±10.86 U/g prot respectively in Isochrysis,Platymonas,Chlorella spp and diatom powder group,while 281.53±11.73,436.12±14.87,214.98±10.39,134.29±9.14 U/g prot were observed in visceral mass respectively,significantly higher than fresh microalgae groups(p < 0.05).4.Using spray-dried microalgae powder,can change the intestinal microbial community of P.penguin juvenile,with higher alpha diversity metrics and abundant phylum changing.The relative abundance of Bacteroidetes in Isochrysis spp and diatom powder group were 37.34±6.16% and 45.88±4.23% respectively,significantly higher than other groups,while the relative abundance of Actinobacteria in Isochrysis spp.and Platymonas spp.powder group(6.09±2.15% and 4.37±1.21% respectively)significantly higher than other groups(p < 0.05).The relative abundance of Bacteroidetes and vibrios were observed in spray-dried microalgae powder groups. |
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