Growth of the early bovine fetus.

Testing for bovine hereditary syndactyly used artificial insemination, superovulation, and embryo transfer. Thirty-two suspect bulls and 9 suspect cows were mated with 10 syndactyly cows and two syndactylous bulls, respectively. 209 embryos were recovered and one, two, or three embryos was/were transfered into each recipient cow and 56 to 77 days after transfer, 174 fetuses were recovered. There was a significant relationship between amniotic fluid weights from the left uterine horn, fetal weights from right and left uterine horns, and fetal sex, side of corpus luteum, and number of embryo implants. Fetal membrane weights, amniotic fluid weights, fetal weights, and crown-rump lengths increased significantly with fetal age, but recipient cow weight had no significant effect. Survival data from single, double, and triple embryo implants indicated that it was most profitable under these test conditions to implant two embryos per recipient cow, one in each uterine horn.