The in vitro exposure to bovine rhinotracheitis virus of zona pellucida-micromanipulated bovine embryos with the zona pellucida damaged or removed.

One hundred and eighty-five embryos were collected from 29 superovulated donors 6 to 8 d post estrus. The zona pellucida (ZP) of these embryos was either cracked, removed mechanically or removed with acidified Tyrode's solution, or left intact. Forty-eight of 103 (47%) ZP-cracked and ZP-free embryos, exposed for 24 h to infectious bovine rhinotracheitis virus (IBRV), survived. No significant difference was found in the embryonic survival of the ZP-cracked embryos exposed to IBRV and control embryos not exposed to IBRV. However, there was a significant (P < 0.001) difference in the survival of ZP-free embryos exposed to IBRV and ZP-free embryos not exposed to IBRV (30% vs 80%).