Sense of Sensors: monitoring behavior of dairy cows

This thesis describes the daily time budgets of dairy cows and how these time budgets are affected by rising environmental temperatures. Further, associations between sensor based behavioral variables during an extended transition period and two major health issues, reduced fertility and lameness, were presented. In chapter 2, two types of complete time budgets are shown: the lactational time budget averaged per month over the course of lactation and the daily time budget with behavioral patterns over 24h. A main finding was the difference in time budgets between first parity cows and older cows before and after entering the milking herd. These findings showed that first parity cows have to adapt from the pre- to post-partum period, similar to a transition period. Introducing cows in the lactational herd led to major changes in daily behavioral patterns, potentially reflecting the effects of accomplishing the hierarchical order. This effect on daily behavioral patterns was largest in primiparous cows, indicating that these animals may be better housed in a separate group. The main finding from the daily time budget indicates that dairy cows are diurnal animals which eat, stand and walk during the day and lie down and ruminate during the night. For both types of time budgets, the behavioral patterns were quite comparable between farms. Thus, this is what high producing cows in free stalls with or without pasture access do in the Netherlands. These behavioral profiles can be used as a benchmark for comparable dairy farming systems. For other types of systems, e.g. seasonal breeding, full grazing, organic farming or tie stall housing, specific benchmarks should be studied. In chapter 3, associations between daily time budgets and the daily Temperature Humidity Index (THI) and daily temperature were analyzed. Strikingly, behavioral adaptation increased with increasing THI and temperature, and was already present at the relatively low THI values and temperatures commonly found in the mild summers in the Netherlands. This adaptation was noticeable from a mean temperature of 12°C or a mean THI of 56 when dairy cows started spending less time lying, eating and walking, and spent more time standing. Chapter 4 describes associations between eating time in the transition period and the interval between calving and first service. Besides differences between primiparous and multiparous cows, lower eating time in week 4 before calving and week 3 after calving was associated with a prolonged interval between calving and first insemination. In chapter 5, associations between body condition score, locomotion score, and sensor-based time budgets during the dry period and early lactation were studied. The percentage of lame cows increased over the course of the scoring moments and was overall very high. There was a clear association between lameness and daily time budgets as well as with the expected loss of body condition in early lactation