IN-VITRO PRODUCTION OF BELGIAN BLUE CATTLE EMBRYOS - SOME DATA ON THE RISK OF VIRAL-INFECTIONS

Since bovine embryo production in vitro has become possible, sanitary precautions must be taken while transferring such embryos. In a large field trial, in vitro produced Belgian Blue embryos were transferred to dairy cattle recipients housed on four different farms. Blood samples of oocyte and oviduct donor cattle were screened for the prevalence of BVD-virus and for BHV1-antibodies. Also follicular fluid, maturation medium, oviduct medium and medium with degenerated embryos were screened for the presence of common bovine viral infectious agents. 95.6% of the oocyte donors showed high virus antibody titers against BHV1. None of them were viraemic for BVD-virus. Of the 96 sampled fluids, 4.1% was positive for non-cytopathic BVD-virus. The probable source of infection was the serum used for in vitro embryo culture. No other viruses were found. Pregnancy and calving rates did not differ between BVD-virus infected and BVD-virus free groups. Three calves, born after transfer of an embryo out of a BVD-virus infected group, were BVD-negative at six months of age.