Performing Department
(N/A)
Non Technical Summary
Increased global temperatures threaten food security and animal welfare in the United States. Heat stress is common in dairy cows and reduces the volume and quality of milk they produce and increases the incidence of disease that affects animal welfare, costing the US dairy industry up to $1.5 billion per year. We need to understand how heat stress affects the cows immune system so we can better protect animals from disease which will improve animal welfare and also increase productivity and profitability of dairy cows in the United States. When we complete these studies, we will have a clearer understanding of a cows immune system and the impact of heat stress. This knowledge will allow us to develop strategies to combat the negative consequences of heat stress, improve the health, welfare and productivity of cattle, thereby maintaining food security of the United Sates dairy sector.
Animal Health Component
100%
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Increased global temperatures threaten food security and animal welfare. Heat stress decreases the productive value of dairy cows costing the US dairy industry up to $1.5 billion/year. The effects of heat stress on production are well established; however, the impacts on cow health and welfare have gone largely uninvestigated. We have demonstrated that prepartum heat stress during the dry period increases the incidence and severity of uterine disease (metritis), while pathogen abundance of the reproductive tract is not altered even when cows are provided heat abatement after calving. It is not known why prepartum heat stress increase uterine disease later. The overall goal of these studies is to determine how prepartum heat stress compromises immune resilience that results in disease - the capacity of cellular tissues to resist and/or tolerate pathogens. We hypothesize that environmental heat stress increases susceptibility to disease by reducing host immune resilience. Addressing this gap in knowledge will increase our understanding of how heat stress impacts immune function and improve dairy cow productivity and animal health in the face of climate change.Objectives:1. Evaluate the impact of prepartum heat-stress on development and severity of metritis.2. Determine the impacts of prepartum heat stress on cellular immune function.3. Demonstrate the impact of heat stress on disease susceptibility.These studies will allow us to determine the mechanisms of heat stress-mediated immune dysfunction and lead to the develop of management, pharmacological or clinical interventions that reduce the impact of heat stress on dairy cow health.
Project Methods
The overall goal of these studies is to determine how prepartum heat stress compromises immune resilience that results in disease - the capacity of cellular tissues to resist and/or tolerate pathogens. To address this overall goal we will use a combination of in vivo, whole animal experiments and targeted in vitro experimentation.To evaluate the impact of prepartum heat-stress on development and severity of metritis, we will adopt a heat stress model in dairy cows by which we remove heat abatement infrastructure (fans and water soakers) to reduce the evaporative cooling of cows. This model will allow is to evaluate the natural progression of disease in cows that are cooled or exposed to heat stress. Sampling of these animals and applying single cell RNA sequencing will allow us to identify very specific cellular changes occurring in animals under heat stress conditions that facilitates the development of disease.To determine the impacts of prepartum heat stress on cellular immune function we will combine the application of whole animal heat stress with in vitro cell culture manipulations of cells. These experiments will allow us to increase our understanding of the detailed mechanisms by which cells of the reproductive tract respond to infections, and how heat stress can mediate an altered response that leads to the development or increased susceptibility to disease.Finally, using a complex whole animal heats stress model combined with experimentally induced disease we will demonstrate the impact of heat stress on disease susceptibility. In these experiments we will apply heat stress to cows and then induce uterine disease with "high" or "low" doses of pathogen to examine the manner in which heat stress increases susceptibility to disease.Collectively, addressing these gaps in knowledge will increase our understanding of how heat stress impacts immune function and improve dairy cow productivity and animal health in the face of climate change.