The relationship in the response of ovaries of superovulated heifers

THERIOGENOLOGY THE RELA'l!IONSHIP IN TH.ERESFONSE OF OVARIES GFSUPEROVULATEDHEXFERLS J. Saunande and D. Chupin I.N.R.A.Station de Physiolcgiede la Reproduction 373SO Nouzilly, France In the cow, the right ovary is known to be more active than the left. This study was undertaken to see whether this is also true after superovulation. Our purpose was also to look for a regulatorymechanism ovaries which could control the response to exoxenousgonadotrophin. Cyclic heifers (38)of the Friesian breed were sunerovulntedon one or more (up to 18) occasions with the same treatment: 2000 I.U.PM,% on day 10 and 1 mg Estrumate on day 12 (day 0 = day of estrus). The ovulation rate was measured by counting the number of corpora lutea by endoscopy. As the cow may have up to two ovulationsspontaneously,we cons;dered only the response of animals with at least three ovulations on one ovary, in order to be sure that we studied the effect of PYSG. Within this constraint,241 observationswere taken into account. The mean ovulation rate of each ovary was not different: right ovary, 5.32 + 0.24; left ovary, 5.27 + 0.25 (mean + s.e.m.). The correlation &efficient in the response of ovarigs was highly significant(1eo.58;P
JANUARY 1982VOL. 17 NO. 1

107