[Real-time ultrasonographic pregnancy diagnosis (B-mode) in sheep. 3. Determination of the number of embryos and fetuses].

Transrectal ultrasound examination was performed once in 1159 German Mutton Merino ewes in a standing position using a 5.0 MHz linear array transducer (group 1), 505 German Mutton Merino ewes were restrained in dorsal recumbency while scanned transrectally using a 7.5 MHz probe (group 2). Referring to actual number of lambs born the prepartal prediction of fetal number was correct in 71.8% (group 1) and 78.6% (group 2) of the ewes from days 17 to 69 p.c. The highest accuracy for determining fetal number (89.1%) was in group 1 at days 35 to 46 of gestation. In group 2 the accuracy was more consistent over the whole period of examinations and reached over 80% from as early as 29 days p.c. As litter size increased, examinations in both groups became increasingly inaccurate in determining correct litter size. A subdivision of living, underdeveloped and dead embryos or foetuses was possible by the presence or the absence of a heartbeat and the crown-rump-length of the embryos or foetuses. The percentage of ewes with embryonic or fetal loss is given.