Date of Award
Master of Science (MS)
Susan D. Eicher
Committee Member 1
With the increase in global climate change and the population growth driving the high demand for additional food production, heat stress (HS) is a major concern in the livestock industry across all species. Animals experience HS when exposed to high environmental temperatures outside their thermal neutral zone. The level of the effects can vary due to the length and intensity of HS to which the animal is exposed to. In experiment one, laying hens with access to cooled perches during HS had a lower heterophil to lymphocyte ratio compared to the control hens after 4 h of acute heat stress, indicating cooled perches as a method to alleviate the effects of HS on laying hen immunity. In the second experiment, HS on dams during late gestation had detrimental effects on biomarkers of the calf's innate immunity, including an increase in neutrophils, lower plasma proteins, and greater toll-like receptor 4 in calves born to HS dams. In conclusion, HS greatly impacts many different species and poses a wide threat on the health and wellbeing of animals due to the global climate changes and increased demands on the livestock industry. Thermally cooled perches, as a method to improve hen immunity during HS, has allowed additional knowledge for creating a long-term strategy to alleviate HS in laying hens. The changes found in neonatal immunity after exposure to late gestational prenatal HS has potentially opened other avenues of research to better understand the effects of prenatal HS on the offspring of livestock.
Strong, Rebecca Ann, "The Effects Of Heat Stress On Immunity In Laying Hens And Dairy Cattle" (2014). Open Access Theses. 383.