Improving the welfare of dairy cows and calves: The importance of the environment

The objective of this dissertation was to address animal welfare as a continuous state as it pertains to dairy cattle and their environment. Chapter 1 reviews the concept of animal welfare and how to assess it scientifically, based on the three critical components of welfare proposed by animal welfare scientists: 1) the animal's health and biological functioning, 2) the affective state of the animal, and 3) the animal's ability to display innate behavior. Chapter 2 thoroughly reviews the literature pertaining to Chapters 3, 4, 5, and 6, beginning with the welfare of the dairy calf in utero, continuing through the pre-weaning phase for young heifer calves in relation to the benefits of social companionship, and concluding with the importance of the environment to the welfare of the mature dairy cow. Chapter 3 acknowledges that animal welfare science thus far has primarily considered the homeostatic challenges production animals may encounter after birth; however, it emphasizes that the prenatal period is also of critical importance to mammalian species, as this period of development may significantly influence and predetermine the capability of offspring to respond and adapt to their future environment. Chapter 3 specifically investigates the prenatal period in relation to maternal social stress experienced by overstocking the feeding area for multiparous cows during late gestation and how this may affect the postnatal growth of the offspring. The results of this first experiment indicate that the experimental conditions of overstocking imposed did not compromise the postnatal growth of the offspring through weaning. Chapter 4 continues to examine the effect of pair housing on the behavior and performance of Jersey heifer calves during the milk-feeding phase; the majority of studies have been conducted with Holstein calves, and it is currently unknown if Jersey calves behave the same as Holstein calves when pair-housed. Calves housed in pairs performed better than calves housed individually, especially during the weaning period. However, cross-sucking behavior was prevalent, as calves were fed milk via bucket. Future research should aim to reduce cross-sucking behavior within the Jersey breed through alternative feeding systems or environmental enrichment. Lastly, Chapters 5 and 6 examine the effect of overstocking the feed bunk during the dry period on dairy cow metabolic health, stress, productivity, and indicators of cow temperament. Although the overstocking conditions imposed did not compromise metabolic health or productivity, overstocking the feed bunk made cows less approachable by an approaching experimenter.