作者单位:Univ Montreal, Fac Vet Med, Ctr Rech Reprod & Fertilite, 3200 Rue Sicotte, St Hyacinthe, PQ J2S 7C6[1]Univ Sao Paulo, Sch Anim & Food Sci, Dept Vet, Pirassununga, SP, Brazil[2]Univ Sao Paulo, Sch Vet Med & Anim Sci, Dept Surg, Sao Paulo, SP, Brazil[3]