Metabolism Of Different Selenium Source In Pigs And Its Role In Maintain The Physiological Function Of Skeletal Muscle

Selenium?Se?is an essential trace element for human and other animal species,and it plays crucial role in redox regulation,immune system,and thyroid hormone metabolism.In view of the unclear metabolism of different selenium sources in pigs and the mechanism of maintaining normal physiological function of skeletal muscle,the following three experiments were conducted.Experiment 1:The effects of different Se sources on growth performance,tissues Se concentrations,meat quality,and selenoprotein expression.In total,108 castrated male pigs were randomly assigned to six treatment groups with six replicates of three per cage.These six treatments received the same basal diet?0.1 mg Se/kg;CON?without any Se supplement,or supplemented with sodium selenite?0.25 mg/kg;SeNa-0.25?,Se-methylselenocysteine?0.25 mg/kg;MeSeCys-0.25?,or selenomethionine?0.25,0.50,and 2.5 mg/kg;SeMet-0.25,SeMet-0.5,SeMet-2.5?for 60 days.Compared with SeNa,organic Se supplements?MeSeCys,SeMet?significantly improved the serum immune function of pigs?P<0.05?;SeMet was more advantages in increasing the tissues Se concentrations than SeNa and MeSeCys?P<0.05?,whereas,MeSeCys was more bioactive in enhancing the selenoprotein gene expression than SeMet and SeNa?P<0.05?.Experiment 2:The effects of different Se source on accumulation of muscle Se concentrations and Se species.We developed a rapid and simultaneous analysis method for seven Se species analysis,which used to determine the muscle total Se and Se species in pigs from the experiment 1.The results shown that the accumulation efficiency of different Se source are:SeMet>MeSeCys and SeNa.A total of three Se speciation?SeMet,SeCys₂,and MeSeCys?was identified in all the treatment groups,and only the SeNa-0.25,SeMet-0.5,and SeMet-2.5 were observed SeUr in the muscle of pigs.SeMet is the primary form?>70%?of Se in muscle,and the percentage of SeCys₂,MeSeCys,and SeUr was relatively low.The results indicated that the accumulation of Se and its chemical form in muscle of pigs was regulated by dietary Se source.Experiment 3:The mechanism of Se deficiency induced skeletal muscle dystrophy in pigs.We established the Se deficiency pigs via feeding the pigs with Se deficiency diet?0.007 mg/kg?or supplemented with SeMet?0.3 mg/kg?for 16 weeks.The results shown that Se deficiency significantly decreased the Se concentrations,selenoprotein genes expression,and the activity of antioxidant enzymes,caused endoplasmic reticulum stress and inflammatory reaction,which led to the muscle dystrophy;meanwhile,Nrf2 pathway and glycolysis was also activated,which attempt to relieve the skeletal muscle dystrophy.In summary,dietary supplementation with different Se sources could significantly affect the Se concentrations and species,and selenoprotein genes expression in pigs.SeMet and MeSeCys have higher bioavailability and bioactivity than SeNa.Dietary Se deficiency induced oxidative stress,endoplasmic reticulum stress and inflammatory response via decreasing the selenoprotein genes expression,and causing skeletal muscle injury in pigs.The results provide data support for the application of different Se sources in pig production and the treatment of Se deficiency related muscle diseases.