Terminology for intervals, proportions and patterns derived from individual-cow sensor records in dairy reproduction and herd health: definitions and prior use

Automated monitoring systems record activity, rumination throughout the day, as well as milk yield, milk components and conductivity for every cow at every milking. Several patterns and metrics shown by these biosensor records lack standard names, which makes them difficult to cite, measure and compare across studies. This technical note defines seven terms and proposes a measurement for each. Actionable Alert Proportion (AAP) is the proportion of cows flagged by a monitoring system for which an intervention is taken. Physiological Waiting Period (PWP) is the interval from calving to the earliest days in milk (DIM) at which physiologic normalcy is achieved, defined by maximized conception risk within a herd; as opposed to the voluntary waiting period (VWP), which is a management decision, the PWP is a biological interval. First Heat, first Insemination and first Pregnancy (FHIP) are three intervals measured from calving: to the first detected estrus, to first insemination and to conception, and they help provide a quick overview of reproductive health of the entire herd. Gapsynch is a reproductive program in which cows are inseminated based on natural estrus detected by activity monitors and hormonal synchronization is applied only to cows with no increases in activity, to fill the gaps left by missing heats. Lullspan is the number of days without estrus-level activity after calving, or between two heats (normally around 18-25 days). Sentinel Cyclicity Proportion (SCP) is the proportion of do-not-breed (DNB) cows that show regular inter-estrus intervals, which reflects the natural cyclicity of the herd not exposed to hormonal intervention and can therefore flag environmental, nutritional or disease problems in the herd. Isoyield Divergence describes cows that reach equivalent lactational yield through lactation curves of different shape, with diverging disease, conception and culling risk. For each term, the note documents prior use by the author in conference presentations, webinars, proceedings as well as lay articles from 2002 to 2026.