Post-partum ovulation and oestrus in spring-lambing ewes.

Summary. By means of ovarian examination and teasing with vasectomized rams, the intervals to first post-partum ovulation and oestrus were determined in a 23-factorial experiment with twenty-four German Merino ewes which lambed between 28th October and 15th November 1966. First ovulation occurred 32\m=.\1 \m=+-\ 1\m=.\9 (8 to 45) days after lambing. Three, fifteen and six ewes had none, one or more than three silent ovulations respectively, before showing heat after a mean interval from lambing for all ewes of 57\m=.\1\m=+-\4\m=.\5 days. The regression of post-partum interval to ovulation (Y) on ewe's weight 3 days post partum (X) was significant (P<0\m=.\01) ; for ewes weighing 83 to 162 lb, Y = 55\m=.\15-0\m=.\21X. The regression of post-partum interval to oestrus on ewe's weight was not significant, and neither were the effects of treatments, namely, weaning at 3 or 20 days post partum, supplementary feeding of 0 or 1 lb maize grain daily from 3 to 28 days post partum, and joining with vasectomized rams at 3 or 14 days post partum.