Vaginal temperature before calving assessed with wireless vaginal temperature sensor in dairy and beef cattle

We evaluated the daily and hourly vaginal temperature changes and the relationships between the dams' breed and parity by using a commercially available vaginal temperature sensor in 72 Holstein (Hol) calvings and 101 Japanese Black (JB) calvings. Vaginal temperature sensors inserted 7–10 days before the expected calving day sounded two alerts: when the temperature fell below the threshold (Alert 1), and when the sensor reached the ambient temperature after falling out of the dam's vagina with the rupture of the allantoic sac (Alert 2). The durations from Alert 1 to Alert 2 (Time 1) and from Alert 2 to delivery (Time 2) were calculated. Only Time 1 in the Hol group tended to be affected by parity and parity × calf body weight. In the JB group, none of the factors examined affected Time 1 or Time 2. The alert detection rates did not differ by parity in either breed or by the temperature threshold in Hol. However, the Hol group's alert detection rate was significantly lower than the JB group's (p