| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
University of Wisconsin, Madison 53706
Abstract
Two experiments were conducted utilizing ewes to determine the effects of small diameter IUDs on fertility, lengths of estrous cycles and uterine histology. In both experiments, IUDs were inserted bilaterally at day 3 of the estrous cycle (estrus = day 0). The IUDs were single strands of nylon suture (. 3 mm diameter) lying free in the uterine lumen except at a point of attachment near the uterotubal junction. In both experiments, the lengths of the first estrous cycle (cycle in which surgery was performed) and second estrous cycle were determined. All ewes were mated to fertile rams at the estrus beginning the third cycle. In experiment I, ewes which failed to conceive at the first mating were bred to fertile rams at the fourth estrus (no pregnancies occurred), again at the fifth estrus and necropsied 2 or 3 days later. In experiment II, ewes were necropsied 12 days after the first mating with fertile rams.
The results of analysis of variance of the lengths of estrous cycles for experiments I and II showed no significant differences between sham-operated and IUD-treated ewes. Of the 18 sham-operated ewes in experiments I and II, 17 conceived at the first mating with fertile rams. For all 18 IUD-treated ewes in experiments I and II, only one pregnancy resulted from the first mating. The proportion of ewes which became pregnant at the first mating was lower (P<.01 and P<.05 for experiments I and II, respectively) in the IUD-treated groups than in the sham-operated groups. If normal cycle lengths are a reflection of normal luteal function, then the results suggest that IUDs can exert a contraceptive effect in ewes without initiating the uterine luteolytic function. Ten IUD-treated ewes in experiment I failed to conceive at either the first or second mating. Eight ova were recovered from seven of these ewes 2 or 3 days after the third mating. Four ova from three ewes were fertilized. Histological examination of uteri did not reveal any significant differences between sham-operated and IUD-treated ewes for any of the characteristics studied.
1 The author thanks Barbara Spennetta and Thomas Oettiker for assistance in conducting the experiments, and Dr. L. E. Casida for assistance in preparing the manuscript. Research supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison; The Ford Foundation Grant No. 630-0505B, C; and by Public Health Service Training Grant No. 5-T01-8D00104-10 from the National Institute of Child Health and Human Development. This is paper No. 700 from the Department of Meat and Animal Science.
2 Department of Meat and Animal Science.
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
