Abstract
Wildfires burn millions of hectares of land worldwide annually and experts predict the size and intensity of wildfires to continue to increase. Large wildfires expose millions of people and animals to particulates and other hazardous pollutants in smoke. Significant associations between exposure to wildfire particulate matter and many negative health effects, such as respiratory and cardiovascular diseases, infertility, and mortality, have been reported in humans. However, health and production issues related to exposure to wildfire particulates in dairy cattle have not been thoroughly researched despite potential for increased susceptibility of cattle to respiratory disease and alternate exposure routes beyond inhalation. Holstein multiparous dry (n=11), multiparous lactating (n=6), primiparous lactating (n=7), and pre-weaned Holstein heifer calves (n=4) were followed for the duration of the Pacific Northwest fire season (July-September). Blood samples were taken before, during, and after a week-long smoke event, and assayed for blood chemistry (K+, Cl-, CO2), innate immune cells (neutrophils, WBC, RBC, hemoglobin, hematocrit, monocytes, basophils, eosinophils, and lymphocytes), blood metabolites (NEFA, BHB, glucose), inflammatory markers (haptoglobin, serum amyloid A), and gene expression of IL-6, IL-8, TNF, IFN, and NF-. For primiparous lactating cows, there was a significant positive relationship with platelet count (P=0.0002). There was also a significant negative PM X THI interaction on RBC, hemoglobin, hematocrit, neutrophils, and monocytes (All P<0.01). Multiparous lactating cows had a significant negative PM x THI interaction for RBC, hemoglobin, hematocrit, and platelets (All P<0.04), and a significant positive PM x THI interaction for blood sodium (P=0.01), and potassium(P=0.02). Multiparous lactating cows also had a significant downregulation of TNF (P=0.0004) and NF- (P=0.02), and significant upregulation of IFN (P=0.003) during high wildfire-derived PM relative to baseline before the wildfire event. Multiparous dry cows had a significant negative relationship with PM for blood chloride (P=0.01) and NEFA concentration (P<0.0001), and a significant positive association between PM and eosinophils (P<0.003), and haptoglobin (P<0.0001). Our results demonstrate a significant response to PM in blood composition, blood chemistry, and gene expression for multiple physiological stage groups.