[Early ultrasonic diagnosis of twins after insemination and contralateral embryo transfer in cattle and the results of calving].

In order to test the efficacy of ultrasonic diagnosis of early twin pregnancy, 20 dairy cows were inseminated, and 4-8 days later a seven-day old embryo was additionally transferred into the uterine horn contralateral to the site of ovulation. Sixteen of 20 cows became pregnant (80%). In 7 of 16 animals a twin pregnancy resulted (44%). Out of eight single pregnancies five (62.5%) followed insemination, and three (37.5%) followed egg transfer. Sixteen pregnant animals were examined ultrasonically. In 7 cases it was possible to estimate a twin pregnancy on the 41st day. This diagnosis was verified on parturition. The ultrasonically diagnosed side of pregnant horn in the singles was correct in 7 of 8 cases, identified by the genetical different origin of the offspring from artificial insemination or egg transfer.