8Senger P L, Becker W C,Davidge S T et al.Influence of corneal insemination on conception in dairy cattle [J]. J.Anim. Sci, 1988, 66.3010-3016.
9Perkins J R, Olds D, Seath DM. A study of 1000 bovine genitalia[J]. J. Dairy Sci, 1954, 37: 1 158-1 163.
10Dalton J C, Nadir S, Bame JH et al. Effect of a deep uterine insemination on sperm atozoal accessibility to the ovum in cattle: a competitive insemination study [J]. Theriogenology, 1999, 5 1: 888-890.
