EARLY EMBRYONIC DEATH AND SUBSEQUENT CYCLE LENGTH IN THE EWE

Publisher Website
Google Scholar
Abstract
Injections of colchicine into the lumen of the uterus of the ewe have been employed to cause timed embryonic deaths between Day 5 and Day 19 after ovulation. The length of oestrous cycles following embryonic death has then been studied, Control ewes had a mean cycle length of 17. 44[plus or minus]1.06 days, and the cycle length of ewes treated on Days 5,7,9 and 11 did not differ significantly from the controls. Ewes treated on Day 13 had a mean cycle length of 19.75[plus or minus]0.90 days, a highly significant increase over the controls. Embryonic death on Days 15 and 19 caused mean extensions of the cycle length of approximately 8 and 18 days respectively, but with wide individual variation. The results are discussed in relation to the maintenance and regression of the corpus luteum in the presence of embryonic substance. The findings indicate that in the field, embryonic death occurring on or before Day 11 is unlikely to be distinguished from fertilization failure.