8Bari F, Khalid M, Haresign W, et al. Factors affecting the survival of sheep embryos after transfer within a MOET program. Theriogenology,2003,59:1265～1275.
9Donaldson L E. Matching of embryo stages and grades with recipient oestrus synchrony in bovine embryo trnsfer. Vet Rec, 1985,117:489～491.
10Hasler J F, Mccauley A D, Latrop W, et al. Effect of donor-embryo-recipient interactions on pregnancy rate in a large scale bovine embryo transfer program. Theriogenology, 1987,27:139～168.
