EFFECT OF UNI LATERAL HYSTERECTOMY AND OVARI ECTOMY ON PUBERTY, UTERINE SIZE AND EMBRYO DEVELOPMENT IN SWINE

Eighty crossbred gilts were assigned randomly to treatments: 1) removal of an ovary and ipsilateral uterine horn (UHO) at 130 d of age and removal of the remaining ovary and uterine horn 12 d post-puberty; 2) UHO at 130 d of age, mated and reproductive tracts recovered when slaughtered at 30 d of gestation; 3) UHO 12 d post-puberty, mated and slaughtered at 30 d of gestation and 4) unoperated controls that were mated and slaughtered at 30 d of gestation. Age of puberty was not affected by treatments. Gilts in treatment 1 had a mean ovulation rate at the pubertal estrus comparable to gilts in treatment 3. But, gilts in treatments 2 and 3 had 16% fewer (P\u3c.01) corpora lutea at 30 d of gestation than control gilts. Length and weight of the remaining uterine horn at 12 d post-puberty for gilts treated at 130 d of age were similar to the averages of gilts left intact. Gilts with one uterine horn had 2.2 fewer live embryos at 30 d of gestation than control gilts (P\u3c.01). But, the proportion of corpora lutea represented by live embryos did not differ significantly among treatments. Gilts with one uterine horn had 1.1 fewer live embryos (P\u3c.15) after adjustment for number of corpora lutea, less uterine space occupied by each embryo (P\u3c.O1) and less total placental membrane per embryo (P\u3c.05) than control gilts. Mean length of the remaining uterine horn was less for treatment 2 than for treatment 3 (P\u3c.01), but time of UHO did not affect measurements of placental membranes and embryos. Number of corpora lutea and measures of uterine size explained from 25 to 67% of the variation within treatments in number of live embryos