| In this experiment,the effects of selenomethionine(SM)and yeast selenium(Selenium-enriched yeast,SY)on production rates,egg quality,serum biochemical indexes,selenium deposition distribution pattern,and selenoprotein gene expression of Taihang chickens in the late egg-laying stage were investigated.In the experiment,54054-week-old late-laying Taihang chickens with similar egg production rate and good health condition were randomly divided into 9 groups with 6 replicates in each group and10 chickens in each replicate.The control group was fed the basal diet and the experimental groups A1,A2,A3 and A4 were supplemented with 0.15 mg/kg,0.30 mg/kg,0.45 mg/kg and 0.60 mg/kg of SY(as selenium)in the basal diet,respectively.Groups B1,B2,B3 and B4 were supplemented with 0.15 mg/kg,0.30 mg/kg,0.45 mg/kg and0.60 mg/kg of SM(as selenium)in the basal diet,respectively.The pre-feeding period was 7 d and the test period was 63 d.The results of the study are as follows.1.Experimental group A2 significantly increased egg production rate and qualified egg rate(P < 0.05),significantly increased protein height and Hastelloy units,improved egg shape index,and enhanced egg shell thickness(P < 0.05)in late laying Taihang chic kens.Test group B2 significantly improved egg production rate and reduced feed-to-egg ratio(P < 0.05),highly significantly increased protein height and Hutchinson units(P <0.01),and significantly improved egg shape index and enhanced egg shell thickness(P< 0.05)in late laying Taihang chickens.2.Both SY and SM groups significantly increased immunoglobulin A(Ig A),immu noglobulin M(Ig M),and immunoglobulin G(Ig G)levels in late laying Taihang chicken s(P < 0.01);significantly increased total protein(TP)and albumin(ALB)levels in late l aying Taihang chickens(P < 0.01),and significantly decreased triglyceride(TG)levels(P < 0.01);significantly increased serum glutathione peroxidase(GSH-Px),total antioxi dant capacity(T-AOC),and total superoxide dismutase(T-SOD)activities(P < 0.01),an d significantly decreased malondialdehyde(MDA)activity(P < 0.01);significantly incr eased egg GSH-Px activity,T-SOD activity,and T-AOC activity(P < 0.01),and decreas ed MDA activity(P < 0.01).3.each test group of SY could improve the selenium content of eggs,serum and all tissues of Taihang chickens in the late laying stage(P < 0.05),except for oviduct and leg muscle,test group A4 had the highest selenium deposition in eggs,serum and all tissue s;each test group of SM could improve the selenium content of eggs,serum and all tissu es(P < 0.01),and the selenium content increased with the increase of selenium level,tes t group B4 had the highest selenium deposition.The distribution pattern of selenium dep osition by SM in vivo showed the same trend: liver > kidney > spleen > fallopian tube >ovary > leg muscle > pectoral muscle > serum,and the deposition effect of SM was bett er than that of SY,and the highest selenium deposition was found in the group of 0.60 m g/kg SM.4.Compared with the control group,there was a highly significant increase(P < 0.05)in the expression of tissue selenoprotein genes GPX1,GPX4,SELENOU and SELE NOP m RNA in both test A2 and B2 groups.The liver selenoprotein genes GPX1,GPX4,SELENOU and SELENOP,pectoral muscle selenoprotein genes GPX1,GPX4,and SEL ENOP and leg muscle selenoprotein genes GPX4,SELENOU and SELENOP m RNA ex pressions were higher and had better antioxidant effects in test group B2 compared with test group A2.In conclusion,the addition of selenomethionine to the diet can improve the egg production rate,reduce the feed-to-egg ratio and improve the egg quality of Taihang chickens,and also improve the serum immunity and biochemistry,enhance the antioxidant function of serum and eggs,which can significantly increase the egg and tissue selenium deposition,improve the expression of tissue selenoprotein gene and enhance the antioxidant function of the body.In a comprehensive analysis,the addition of 0.30 mg/kg selenomethionine was more effective. |
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