Precision dairy technologies (PDT) are becoming more accessible and are therefore becoming more common on commercial dairy farms and in dairy research. Prior to any use of PDT, one should understand the precision, accuracy and bias of the device by a validations studies before interpreting the behavior measurements. Thus, the objective of the first section of my thesis is to validate ruminating, feeding and resting measurements of a behavior monitoring collar used in the second section. Precision dairy technology is used in heat stress studies to compare behavior of cows exposed to different heat stress treatments or abatement strategies. Heat stress is an important issue to research because it negatively affects cow behavior, physiology, and therefore production in lactating dairy cows. The objective of the second section is to assess the ability of a free choice soaker to reduce heat stress measured utilizing PDT and compare use of a free choice to a soaker in addition to one of the two treatments 1) no mandatory soakings, or 2) two mandatory soakings.

Animal welfare, reproduction, and milk production can be negatively affected when dairy cattle experience heat stress. Dairy cows in southern latitudes spend nearly 4 to 6 months in a state of heat stress. Animal health professionals and dairy producers use changes in physiological responses and behavioral patterns of cows as a tool for identifying poor health and welfare in periods of heat stress. The objectives of this study were to monitor the effects of heat stress on grazing dairy cows provided with shade or sprinklers by comparing various physiological indices of heat stress, and to, design and utilize a heat stress scoring system to evaluate heat stress severity on grazing dairy cows with access to shade and sprinklers. Finally, the results were used to predict the accuracy of the scoring system with machine learning methods. The findings from this study provide a new tool to assess heat stress in dairy cows.

The objective of this thesis was to determine how pregnant, lactating Holstein cows on pasture interact with shade and sprinklers when offered a choice or no-choice between methods. Authors hypothesized that cows would use shade more then sprinklers, but sprinklers would be more effective at cooling cows. Additionally, authors predicted cows using shade more would have decreased lying bouts and steps and an increase in time lying, compared to cows choosing sprinkler. Results indicate cows will use both methods when offered alone or together. However, cows will choose to be exposed or in shade at lower temperature humidity index values, but as the heat load increases, cows will shift to using sprinkler just as much as shade, and decrease overall time exposed. Overall, sprinklers were more effective at reducing vaginal temperature in heat stressed cows on pasture. Cows in shade had decreased lying bouts and steps, and increased time lying.