FETAL HEART-RATE AND REAL-TIME ULTRASONIC FETOMETRY FOR DETERMINATIONOF FETAL AGE IN SHEEP

Fetal heart rate was repeatedly measured in 84 ewes of different breed s during gestation. The Doppler system (83 measurements) and the real- time M-Mode ultrasound system (221 measurements) were used. Furthermor e the following fetometric parameters were ascertained in 13 pregnant ewes sonographically once a week: crown-rump-length, width of the head , inter-eye distance, heigth of the lateral thorax in the region of th e cardial septum and caudal of the sternum, as well as the diameter of the thorax and abdomen in each case latero-lateral and ventro-dorsal. The following influencing factors were tested by means of group regre ssion analyses and multiple regression analysis. days before parturiti on, method of examination, litter size and later birth weight of lams, and heart rate, breeds and diseases of the ewes. A significant regres sion exists between the days before parturition (d. b. p.) and fetal h eart rate (fhr). y (fhr) = 139 + 0,94 x (d, b. p.); r = 0,781 p <0,001 ; n = 304. No significant influence was proved for the birth weight, l itter size, maternal heart rate, method of examination, breed and heal th state of the ewes on the fetal heart rate. All fetometric parameter s were significantly correlated with the days before paturition. This regression was most evident for the measured value of the ventro-dorsa l abdomen (abd. vd., mm): y (abd. vd) = 114,2-0,966 x (d. b. p.); r = -0,958; p <0,001, n = 128. The litter size influenced the regression w ith a significance of p <0,05. The fetometry is more appropriate for t he determination of gestational age and the prediction of parturiton t han the measurement of the fetal heart rate.