FETAL GROWTH IN MUSKOXEN DETERMINED BY TRANSABDOMINAL ULTRASONOGRAPHY

A 5 MHz commercial sector scanner was used to monitor 13 muskox pregna ncies and establish normal fetal growth curves. Examinations were carr ied out between 40 and 197 days of gestation and pregnancy could be de tected throughout the period. Early pregnancies were found by scanning lateral to the udder but as pregnancy progressed the fetus was found closer to the dam's umbilicus. Measurements of cranial and abdominal d iameters taken at about two week intervals in seven uncomplicated preg nancies in four cows were used to construct fetal growth curves. These can be reliably used in the reproductive management of muskoxen. In a ddition a series of regressions based on measurements of the fetuses o f muskoxen killed in the Arctic are provided. These allow cranial and abdominal diameters to be related to fetal weight and crown-rump lengt h.