Effect Of Different Supplemental Selenium Level On Selenium Content,Related Enzyme Activity And Gene Expression In Tissues Of Broilers

This experiment was conducted to investigate the effect of different selenium level on growth performance,carcass traits,meat quality,plasma and tissue selenium contents and selenium-containing enzyme activity as well as selenium-containing enzyme and selenium-containing protein gene expression of broilers fed a corn-soybean meal diet from 22 to 42 days of age,and screen specific and sensitive indices for evaluating the appropriate level of selenium for broilers fed the corn-soybean meal diet from 22 to 42 days of age,so as to provid scientific basis for adding selenium scientifically and rationally in broiler production and meet accurately the nutritional requirement of selenium for broilers.A total of 380 commercial one-day-old AA male broilers were reared in two stages,all broilers were fed the same corn-soybean meal diet supplemented with normal level of inorganic selenium?containing total Se 0.47 mg/kg?from 1 to 21 days of age.At 22days of age,336 broilers were selected and randomly divided into 6 treatment groups according to body weight and housed in stainless steel cages coated with plastic.Each treatment group consisted of 7 replicate cages?8 chick per cage?in a completely randomly design.These broilers were fed with the corn-soybean meal basal diet without selenium supplementation?control group,0.015 mg Se/kg?and the basal diet supplemented with 0.10,0.20,0.30,0.40 and 0.50 mg/kg of selenium?Na₂SeO₃,reagent-grade?.The trial lasted for 21 days.The results showed that dietary Se level affected thigh muscle shear force and breast muscle L*value,plasma and tissue?liver,kidney,pancreas,breast muscle and thigh muscle?selenium contents and plasma,liver,kidney and pancreas glutathione peroxidase?GPX?,liver and kidney thioredoxin reductase?TR?,kidney iodothyonine deiodinases?ID?activity.Liver and kidney Gpx4,Sepp1,Selu and Selh,renal and pancreas Gpx1,pancreas Id1 mRNA expression levels,and liver,kidney and pancreas GPX4 protein expression level?P<0.04?.As dietary Se level increase,plasma and tissue?liver,kidney,pancreas,breast muscle and thigh muscle?selenium contents and plasma,liver and kidney GPX and liver Gpx4,Selh and kidney Sepp1,Selh mRNA expression level and liver and kidney GPX4 protein expression level showed linear and quadratic responses?P<0.04?,liver Selu mRNA expression level showed quadratic response?P<0.02?.The optimal dietary Se level was0.08 to 0.49 mg/kg obtained from the optimal broken-line,quadratic,or asymptotic line model fitted with all the above indices for broilers fed the corn-soybean meal diet from22 to 42 days of age.In conclusion:?1?Plasma and tissue?liver,kidney,pancreas,breast muscle and thigh muscle?selenium contents and plasma,liver,and kidney GPX and liver Gpx4,Selu,Selh and kidney Sepp1,Selh mRNA expression level and liver and kidney GPX4 protein expression level were specific and sensitive indices for evaluating dietary selenium requirements in broilers from 22 to 42 days of age.?2?The optimal dietary Se level was 0.08 to 0.49 mg/kg obtained from the optimal broken-line,quadratic-curve,or asymptotic-line models fitted with all the above indices for broilers fed the corn-soybean meal diet from 22 to 42 days of age.In order to meet all selenium metabolism needs,the nutritional requirement of Se was 0.49 mg/kg for broilers fed the corn-soybean meal practical diets from 22 to 42 days of age.