## 3 Results
Cows were classed as still pregnant after receiving a false alert by their physical appearance [21; 22], and also after sighting their newborn calf at least seven days after the false alert was received. There was one Brand 2 collar that was broken and removed from analysis. Both brands performed similarly for true (\(p\) = 0.258) and false (\(p\) = 0.51) birth alerts, but Brand 2 showed lower missed birth alerts compared to Brand 1 (\(p\) = 0.013; Table 3). However, 75 % (three out of four) of Brand 1's missed alerts occurred due to calving happening within the one-week calibration period after implant. The Brand 2 birth alert system had slightly better accuracy and over two-fold better sensitivity, but lower specificity compared to the Brand 1 system (Table 3). Only 37% of all VIT were retrieved from the paddock during Trial 1. No calving difficulties such as dystoca were observed over the trial periods. In Trial 1, seven of the 19 calves (36%) went missing and their dams returned to the yards without a calf at weaning time. None of these calves had confirmed death sightings. In trial 2, 2 of the 10 calves (20%) were confirmed dead and necropsy samples taken. Necropsy samples showed that one calf's death was caused by septicemia and the other was a suspected dog attack. In Trial 2, there were no true birth alerts, five false alerts and five missed alerts (Table 3). In addition, two VIT were expelled early (24 and 28 days after insertion), and therefore, reinserted 61 and 70 days before true calving time. Subsequently, one was expelled prematurely again, 10 days prior to true calving. The VIT were expelled on average 35.82 \(\pm\) 40.65 days before calving. Three calves were found with their respective mothers before the birth alert was received from the software (false negatives). Eight out of 10 VITs were retrieved. The mean distance travelled by collared cows during the calving period, defined as 30 days each side of the calving date, was similar between trials (Table 2). The day from calving affected distance travelled by cows in both trials (\(p\) < 0.05) with animals travelling further on days \(-\)3, \(-\)9, \(-\)20, 15, and 26 compared to calving day and day 1 in Trial 1 (\(p\) < 0.05; Figure 2a), and travelling further on day -2 compared to the calving day in Trial 2 (\(p\) < 0.05; Figure 2). The average daily activity on the X-axis of the accelerometers was affected by the day from calving in both trials (\(p\) > 0.05; Figure 3). However, the average activity of the Y-axis was affected by the day from calving in Trial 2 (\(p\) < 0.05), but not in Trial 1 (\(p\) = 0.24; Figure 3). The average distance travelled within the first hour after a true birth alert in Trial 1 was 158 m, with only two animals having a distance greater than 7 m in the hour after the expelled alert was registered by the collar (Table 2). Of the eight true birth alerts in Trial 1, the distance cows travelled between the registration of the alert on the collar and the notification email was 0 m in six out of eight cases. In the other two alerts, the cows travelled 680 m and 750 m, respectively. This distance could not be calculated for Trial 2 as there were no true birth alerts. The Pearson correlation coefficient