Investigation On The Selenium-enriched Condition Of Fish Products In Ankang City And The Effect Of Selenium-enriched Feed On The Selenium Deposition Level In The Onychostoma Macrolepis(bleeker,1871)

Selenium is a necessary trace element in the body and plays an important role in the body's antioxidant defense system.Selenium in fish muscle is a good source of selenium for humans.Ankang City is known as “China Selenium Valley” and is one of the few selenium-enriched areas in China.It also shows that Ankang is the largest selenium-rich area in China.Due to its natural selenium-rich characteristics,Ankang City is rich in selenium resources.The development and selenium-enriched industries have great potential for development.In this study,fish products,aquaculture water and feed samples from different areas of Ankang City were collected and their muscle selenium content was measured to find out the status of selenium in aquatic products in Ankang City.At the same time,different levels of selenium were added to the diet of the Onychostoma macrolepis,and the effects on selenium deposition,growth,body composition and antioxidant capacity of the Onychostoma macrolepis were investigated.Through the above research,it provides a certain reference for the development of selenium-enriched water industry in Ankang City.Experiment 1.Collecting aquaculture fish from many aquaculture companies and cooperatives in Hanyin County,Liushui Town,Qixian County and Zhenping County of Ankang City,as well as wild fish from Wuhu Reservoir,testing fish muscles,aquaculture water bodies and feed selenium The content is to find out the selenium-enriched condition of aquatic products in Ankang area.The test results show that:1.The selenium content of the collected fish samples is between 0.083mgSe/kg-0.34mgSe/kg,and the average selenium content is 0.197mgSe/kg,which is in line with DB61/T556-2012,HB001/T-2013,DB6124.01-The selenium-enriched aquatic product standard defined by 2010 is a selenium-enriched fish.2.There is a difference in selenium content between the same species of fish in different regions,especially the difference in selenium content between wild fish and farmed fish.The selenium content of wild carp and grass carp is significantly higher than that of cultured carp and grass carp.The selenium content in muscles of different species in the same area was significantly different,and the degree of selenium was higher in animal feeding fish than in omnivorous.The selenium content in herbivorous fish was the lowest.4.In the water quality and feed samples,Zhenping County Tianyuan Ecological Breeding Co.,Ltd.,Jixian Green Water Ecological Agriculture Co.,Ltd.and Zhenping County Yinyuan Ecological Resources Protection and Development Co.,Ltd.were tested for three Onychostoma macrolepis breeding enterprises and Han The selenium content in the water body was not detected in the culture water samples of Yinxian Yongfeng Company.This result indicates that the cause of selenium deposition in locally farmed fish is not selenium in water.Experiment 2,using a single factor concentration gradient method,five groups of equal nitrogen(38%)and other lipid(7%)diets were added,and different levels of nano-selenium were added.The selenium contents of the diets in each group were 0.70 mgSe/kg and 1.25 mg,respectively./kg,1.47mgSe/kg,1.57mgSe/kg and 2.08mgSe/kg selenium,choose one-year-old Onychostoma macrolepis(average weight 2.09g)randomly divided into five groups,each group of three replicates,with 200 L circulating water tank Cultured for 60 days.After the end of the culture,the selenium content,growth performance,nutrient components,digestive enzyme activity and antioxidant capacity were measured.The main results are as follows:1.The addition of different levels of selenium in the diet had no significant effect on the selenium content of the Onychostoma macrolepis,indicating that the sedimentation ability of the Onychostoma macrolepis was limited.2.Different levels of selenium in diets had no significant effect on weight gain,specific growth rate,feed coefficient and visceral index of juvenile Onychostoma macrolepis(P>0.05).The crude protein content of the whole fish was increased first and then decreased with the increase of feed selenium level,and the crude protein of whole fish reached the highest in the 1.25mgSe/kg group(P < 0.05).The crude fat content decreased first and then increased,and the crude fat content of the 1.25 mgSe/kg selenium group was the lowest(P < 0.05).The activities of SOD,CAT and GPx in liver tissue increased first and then decreased.Among them,the activity of 1.25mgSe/kg group reached the highest,and the content of MDA decreased first and then increased,and the lowest in 1.25mgSe/kg group..The activity of SOD in muscle tissue decreased first and then increased.The activity of CAT and MDA increased first and then decreased,while the change of GPx activity was not significant.Under the condition of high temperature stress,the activities of antioxidant enzymes such as SOD,CAT and GPx in the liver of juvenile Onychostoma macrolepis increased first and then decreased.The antioxidant level reached the highest when 1.25mgSe/kg selenium was added.Muscle antioxidant enzymes showed the same trend as liver,but antioxidant enzyme activity was highest at 1.47 mgSe/kg(P>0.05).In summary,the species of farmed fish in different areas of Ankang City are selenium-enriched fish,and the selenium content of wild fish is higher than that of cultured species;the addition of different levels of selenium in the diet has no significant effect on the growth performance of the Onychostoma macrolepis,but it can be significant.Affecting the crude protein and crude fat content,when the selenium content in the diet is 1.25mgSe/kg,the crude protein content of the whole fish is the highest and the crude fat content is the lowest;when the selenium level in the diet is 1.25-1.47mgSe/kg,The antioxidant capacity of juvenile Onychostoma macrolepis and the highest antioxidant capacity under high temperature stress.