Samenvatting

Good reproduction is key for successful dairyfarming. Detection of estrus is the first step in getting acow pregnant. Visual detection of estrus is a challengingjob, to aid the farmer, estrus detection tools (EDT), suchas pedometers, neck mounted collars to measure activityand pressure sensing devices to measure standing estrus,have been developed. EDT have proven useful inpractical dairy farming, however, studies from the lastfive years reveal a great variation in sensitivity,specificity and positive predictive values. In research,the standard that is used to define a true estrus periodcan affect the performance of the EDT underinvestigation. Cow factors that can affect performanceof EDT are number of ovulation after calving, milkproduction, lactation number, body condition score andlameness. The second step in getting a cow pregnant isinsemination at the correct time. With EDT it is easierto determine optimal insemination time, which is 12 to24 h before ovulation. The optimal time interval inwhich to inseminate seems to be about 5 to 17 h after anincrease in activity as measured by pedometers or neckmounted collars. Novel measurements, such asrumination time, eating time, lying behavior, ultra-wideband technology to measure mounting and standing-tobe-mounted behavior and infrared thermography tomeasure temperature are being studied to further aidestrus detection.