Relationship between gestational age and transabdominal ultrasonographic measurements of fetus and uterus during the 2nd and 3rd trimester of gestation in cows

B-mode ultrasonography and ecobiometric parameters for assessment of embryonic and fetal development in sheep

“…measurable almost throughout the gestational period in sheep (week 4-21). With respect to ruminants, these variables have been reported in cows (Lazim et al, 2016) and mini-goats (Kandiel et al, 2015). There, therefore, were reliable determination coefficients (r² = 97% and 95%, respectively) in the previous study that were similar to that for the HTW in the present study, which was more reliable than that for HTL ( r 2 = 93%) in mini-goats.…”

Establishment of fetal age equations based on ultrasound measurements in cross-bred Holstein cows

“…Trunk measurements can be used throughout the fetal stage until the lower portion of the trunk is beyond the depth of ultrasound field (e.g. using a 3.5 MHz probe at day 140 ) [18][19][20]23]. Eye measurement seems more suitable for estimate late fetal age [21].…”

“…Trunk diameter (TrD), a suitable measurement can be made whether the images are in cross section or longitudinal section, but a cross section may be preferred. TrD measurements may be used throughout the fetal stage as far as the lower portion of the trunk is still in the scanning field [8,[18][19][20]. Eye diameter (ED), by optimally positioning the ultrasound probe, a section which shows the largest diameter of the eye can also be obtained but becomes less precise after day 130 post-breeding [16,21].…”

Estimating fetal age: how accurate is it really?

“…Furthermore, simple correlation coefficients do not provide a means of comparing between measurements as they are affected by factors other than how well fetometry predicts age (Goodwin and Leech 2006). Nevertheless, almost all reports of fetometry and fetal age (from White et al 1985to Lazim et al 2016) have focussed on correlation and regression rather than accuracy. One study (Fitzgerald et al 2015), which claimed to have evaluated ultrasonography as a predictor of gestational age, just reported mean difference between predicted and actual values, with no measure of precision at the individual cow level.…”

“…This is often not appreciated by veterinarians who are used to seeing the association between fetometry and fetal age presented as a simple line graph (e.g. Lazim et al 2016) with no measure of variance included.…”