[1] TSAKMAKIDIS I A,LYMBEROPOULOS A G,KHALIFA T A A.Relationship between sperm quality traits and field-fertility of porcine semen[J].Journal of Veterinary Science,2010,11(2):151-154.
[2] BROEKHUIJSE M L W J,ŠOŠTARIC E,FEITSMA H,et al.The value of microscopic semen motility assessment at collection for a commercial artificial insemination center,a retrospective study on factors explaining variation in pig fertility[J].Theriogenology,2012,77(7):1466-1479.e3.
[3] BEUTLER E,BLAISDELL R K.Iron enzymes in iron deficiency.Ⅱ.Catalase in human erythrocytes[J].The Journal of Clinical Investigation,1958,37(6):833-835.
[4] BANSAL A K.Manganese:a potent antioxidant in semen[J].Iranian Journal of Applied Animal Science,2013,3(2):217-221.
[5] ARREDONDO M,NÚÑEZ M T.Iron and copper metabolism[J].Molecular Aspects of Medicine,2005,26(4/5):313-327.
[6] LETELIER M E,SÁNCHEZ-JOFRÉ S,PEREDO-SILVA L,et al.Mechanisms underlying iron and copper ions toxicity in biological systems:pro-oxidant activity and protein-binding effects[J].Chemico-Biological Interactions,2010,188(1):220-227.
[7] WADI S A,AHMAD G.Effects of lead on the male reproductive system in mice[J].Journal of Toxicology and Environmental Health:Part A-Current Issues,1999,56(7):513-521.
[8] MONSEFI M,ALAEE S,MORADSHAHI A,et al.Cadmium-induced infertility in male mice[J].Environmental Toxicology,2010,25(1):94-102.
[9] PANT N,KUMAR G,UPADHYAY A D,et al.Correlation between lead and cadmium concentration and semen quality[J].Andrologia,2015,47(8):887-891.
[10] LI C L,ZHAO K,ZHANG H P,et al.Lead exposure reduces sperm quality and DNA integrity in mice[J].Environmental Toxicology,2018,33(5):594-602.
[11] TVRDÁ E,KÑAZICKÁ Z,LUKÁCOVÁ J,et al.The impact of lead and cadmium on selected motility,prooxidant and antioxidant parameters of bovine seminal plasma and spermatozoa[J].Journal of Environmental Science and Health:Part A-Toxic/Hazardous Substances and Environmental Engineering,2013,48(10):1292-1300.
[12] WANG C,LI J L,WEI H K,et al.Effects of feeding regimen on weight gain,semen characteristics,libido,and lameness in 170-to 250-kilogram Duroc boars[J].Journal of Animal Science,2016,94(11):4666-4676.
[13] SMITAL J,DE SOUSA L L,MOHSEN A.Differences among breeds and manifestation of heterosis in AI boar sperm output[J].Animal Reproduction Science,2004,80(1/2):121-130.
[14] WOLF J,SMITAL J.Quantification of factors affecting semen traits in artificial insemination boars from animal model analyses[J].Journal of Animal Science,2009,87(5):1620-1627.

[15] BEORLEGUI N,CETICA P,TRINCHERO G,et al.Comparative study of functional and biochemical parameters in frozen bovine sperm[J].Andrologia,1997,29(1):37-42.
[16] KOZINK D M,ESTIENNE M J,HARPER A F,et al.Effects of dietary
L-carnitine supplementation on semen characteristics in boars[J].Theriogenology,2004,61(7/8):1247-1258.
[17] SHIPLEY C F.Breeding soundness examination of the boar[J].Journal of Swine Health and Production,1999,7(3):117-120.
[18] AGUIAR G F M,BATISTA B L,RODRIGUES J L,et al.Determination of trace elements in bovine semen samples by inductively coupled plasma mass spectrometry and data mining techniques for identification of bovine class[J].Journal of Dairy Science,2012,95(12):7066-7073.

[19] URIU-ADAMS J Y,KEEN C L.Copper,oxidative stress,and human health[J].Molecular Aspects of Medicine,2005,26(4/5):268-298.
[20] MASSÁNYI P,TRANDZIK J,NAD P,et al.Concentration of copper,iron,zinc,cadmium,lead,and nickel in bull and ram semen and relation to the occurrence of pathological spermatozoa[J].Journal of Environmental Science and Health:Part A-Toxic/Hazardous Substances and Environmental Engineering,2004,39(11/12):3005-3014.
[21] LIEU P T,HEISKALA M,PETERSON P A,et al.The roles of iron in health and disease[J].Molecular Aspects of Medicine,2001,22(1/2):1-87.
[22] KASPERCZYK A,DOBRAKOWSKI M,CZUBA Z P,et al.Influence of iron on sperm motility and selected oxidative stress parameters in fertile males-a pilot study[J].Annals of Agricultural and Environmental Medicine,2016,23(2):292-296.

[23] WU Y H,LAI W,LIU Z H,et al.Serum and seminal plasma element concentrations in relation to semen quality in Duroc boars[J].Biological Trace Element Research,2019,189(1):85-94.

[24] WU Y H,GUO L L,LIU Z H,et al.Microelements in seminal and serum plasma are associated with fresh semen quality in Yorkshire boars[J].Theriogenology,2019,132:88-94.
[25] FRY R S,SPEARS J W,LLOYD K E,et al.Effect of dietary copper and breed on gene products involved in copper acquisition,distribution,and use in Angus and Simmental cows and fetuses[J].Journal of Animal Science,2013,91(2):861-871.

[26] TCHOUNWOU P B,YEDJOU C G,PATLOLLA A K,et al.Heavy metal toxicity and the environment[M]//LUCH A.Molecular,Clinical and Environmental Toxicology.Basel,Switzerland:Springer,2012:133-164.
[27] SOKOL R Z,WANG S,WAN Y J Y,et al.Long-term,low-dose lead exposure alters the gonadotropin-releasing hormone system in the male rat[J].Environmental Health Perspectives,2002,110(9):871-874.

[28] GOMES M,GONÇALVES A,ROCHA E,et al.Effect of
in vitro exposure to lead chloride on semen quality and sperm DNA fragmentation[J].Zygote,2015,23(3):384-393.

[29] LAWTON L J,DONALDSON W E.Lead-induced tissue fatty acid alterations and lipid peroxidation[J].Biological Trace Element Research,1991,28(2):83-97.

[30] TAHA E A,SAYED S K,GHANDOUR N M,et al.Correlation between seminal lead and cadmium and seminal parameters in idiopathic oligoasthenozoospermic males[J].Central European Journal of Urology,2013,66(1):84-92.
[31] BONDE J P,JOFFE M,APOSTOLI P,et al.Sperm count and chromatin structure in men exposed to inorganic lead:lowest adverse effect levels[J].Occupational and Environmental Medicine,2002,59(4):234-242.

[32] CHENG C Y,MRUK D D.The blood-testis barrier and its implications for male contraception[J].Pharmacological Reviews,2012,64(1):16-64.

[33] MENDIOLA J,MORENO J M,ROCA M,et al.Relationships between heavy metal concentrations in three different body fluids and male reproductive parameters:a pilot study[J].Environmental Health,2011,10(1):6.
[34] PARÍZEK J,ZÁHOR Z.Effect of cadmium salts on testicular tissue[J].Nature,1956,177(4518):1036.