Practical uses of ultrasound in early pregnancy in cattle.

Using a 'real-time' ultrasound scanner with a 3.5 MHz rectal transducer, a herd of 80 Friesian cows were scanned at weekly intervals during early pregnancy to assess the accuracy of pregnancy diagnosis, and the accuracy of twin detection. The growing fetuses were also measured to determine the relationship between crown-rump length and age. The accuracy of detection of pregnancy was inversely proportional to the age of the cow (r -0.967), the accuracy of detection of twinning was 100 per cent and there was strong correlation between fetal crown-rump length and age (r 0.98).