Ultrasonographic examinations of the ovine fetal growth from day 20 to 50 after mating

Previous studies on embryonic and fetal growth in sheep were mostly transve rsal using animals killed at various stages of gestation. Until now it was difficult to monitor the development of individual embryos/foetuses during pregnancy, especially during the first and second pregnancy month. Real-tim e ultrasound as a non invasive method could be an appropriate method for ex amination of embryonic and early foetal development in sheep. The aim of th is study was to determine the embryonic and foetal development of the crown -rump-length (CRL) in pregnant ewes in relation to the number of fetuses an d/or the breed. Between the 20th and 50th day of pregnancy the embryos/foet uses showed an exponential growth which can be best described by the equati on of the form CRL (mm) = W * exp (k * day of pregnancy). The individual va riability in embryofetal growth is in part due to the number of embryos per sheep and the sheep breed.