Fig. 8
Association between pairwise eruption of incisor teeth (I) 1–3, canine teeth (CT) and probability of fetal age exceeding the gestation length (G90) threshold of 250 days, i.e., 278 days—10%, where 278 is the overall median gestation length for Holstein cattle. Gestation length data are based on the data presented in Table 1. A jitter has been used to separate the graphs for ease of readability. The error bars illustrate the 95% confidence interval. It would often be the case that 1 would correspond to I1, 2 to I2, 3 to I3 and 4 to CT, as this is the most common sequence of eruption (see text), but when using the figure to determine fetal age, it is important to assess the number of pairwise tooth eruptions without regard to their anatomical order. The figure can be used to predict the probability that a Holstein fetus with a given pairwise sequence of eruption of the I1–3 and CT will exceed the G90 threshold based on a median GL of 278 days. For example, if a fetus has an eruption of I1–3, the probability of the fetus exceeding G90 is around 0.86 (95% CI 0.72–0.99) based on the median, and 0.71 (95% CI 0.53–0.88) based on the 99.5th percentile