Evaluation of the iVET ® birth monitoring system in primiparous dairy heifers.

The objective was to validate the iVET® birth monitoring system and to determine if it reduced fetal death in primiparous dairy heifers over a 1-y interval. There were 359 pregnant heifers enrolled; 167 heifers in the iVET® group were monitored electronically and the remaining 192 (controls) were monitored visually for onset of Stage 2 labor, according to routine farm management. In addition, as a reference, all heifers were observed throughout the study by two independent investigators. Calves born dead or that died within 24 h after birth were defined as stillborn. The interval from appearance of the chorioallantoic sac to recognition of onset of calving in the control group averaged 21 min longer than the iVET® signal (p = 0.0001) and rate of fetal death was numerically lower in the iVET® group (8.9%) than in the control group (10.4%, p = 0.65). Interestingly, dystocia occurred more often in the iVET® group (58.3%) than in the control group (40.9%, p = 0.001). The iVET® system detected onset of Stage 2 labor earlier than conventional monitoring by farm staff. However, the device was lacking in several aspects and should be improved before its use in primiparous heifers can be recommended.