SPLITTING OF PORCINE EMBRYOS AT THE 4-CELL OR MORULA STAGE

Porcine embryos obtained from estrus-induced prepuberal gilts were split at the 4-cell and morula stage. The in vitro development of the demi-embryos was compared with that of intact control embryos. The intact control embryos developed according to expectation. The in vitro survival of the demi-embryos was inferior to that of the respective controls. The splitting of 4-cell embryos was easier to accomplish and more efficient than the splitting of morulae. The in vitro development of the 4-cell embryos was also slightly better, although this difference was not significant. In vitro development of demi-embryos originating from morulae split at room temperature was slightly although nonsignificantly inferior to that of demi-embryos from morulae split on a warming stage at 37 degrees C. Between 14 and 18 demi-embryos were transferred to synchronous recipient gilts after 24 to 48 h of culture. Of 3 gilts receiving split 4-cell embryos, 1 gilt aborted 2 normal fetuses on Day 90 of pregnancy and 1 carried a single piglet to term. Of the 4 gilts receiving split morulae, 1 gilt had 4 normal and 3 degenerated fetuses upon slaughter on Day 35 of pregnancy.