Fig 1.
A) Crown-rump length (CRL). This is measured from the most anterior point of the calvarium with the neck flexed 90° to the spine until the most caudal part of the thigh (tuber ischiadicum), fetus aged 145 days. B) Measurement of the head length (HL) from philtrum nasi to the most caudal point of the head. The measurement is done in the dorsal longitudinal midline as indicated in C). The most caudal point varies among fetuses. In younger fetuses, it is more ventral than in late term fetuses, where the intercornual protuberance becomes the most caudal point. Fetus aged 134 days. C) Measurement of the head width (HW) as the largest distance between the zygomatic arches. The site of measuring HL is also indicated. Same fetus as in B). A-C: bar = 5 cm.
Table 1.
Fetal variables recorded at post mortem examination of Holstein fetuses.
Fig 2.
Relation between fetal age, crown-rump length, head width and head length.
Scatter plots illustrating the distributions and relations of the fetal age with crown-rump length (CRL) in cm (pink), head width in cm (red), head length in cm (green and body weight (BW) (blue) The points illustrate the observations, while the lines are illustrations of linear models fitted CRL, head-width and head-length, whereas a 5-degree polynomial model was fitted the BW. Notice that the Y-axis values are either in mm or cm depending on the parameter analyzed.
Fig 3.
Sequence in the development of fetal morphological characteristics.
Fetal morphological characteristics illustrated by the range of 95% of the observations within each group of categorical variables for 247 Holstein fetuses. For the lower (left) group, the 95% is from minimum to the 95-percentile. For the upper (right) group, the 95% cover the 5th percentile to maximum, and for the remaining groups covers the 2.5- to 97.5-percentile range.
Table 2.
Coefficients of variation (R2) for quantitative and morphological variables prediction of fetal age in Holstein cattle based on examination of 274 fetuses.
Table 3.
Multivariable models for coat, eyelid opening and quantitative variables (Model 1, left) and teeth variables and quantitative variables (Model 2, right) for prediction of fetal age (days) in 274 Holstein fetuses.