18 Influence of Pregnant Cattle Grazing Endophyte-Infected Tall Fescue on Innate Immune Response of Male Offspring

Abstract The objective was to evaluate the influence of dams grazing endophyte-infected tall, toxic, fescue (E+) during gestation on innate immune response male offspring an endotoxin challenge. Crossbred pregnant multiparous cows (n = 36) bred Red Angus sires were housed in replicated E+ or novel endophyte-infected, non-toxic, (NE+) pastures before breeding and through length gestation. After parturition, calves moved a common bermudagrass pasture until weaned. From this calf-crop, subset post-weaned steers (E+ n 8; NE+ 8) selected for lipopolysaccharide (LPS) Steers (302 ± 36 d age; 261 62 kg body weight) fitted with jugular vein catheters >7 h sampling. Blood collected every 30 min starting 2 (Pre-LPS) 9 following (Post-LPS) LPS administration (0.5 µg/kg weight). Sickness behavior score (SBS), cortisol, glucose analyzed min. Complete blood count (CBC) rectal temperature (RT) hourly. Peak concentration, time at peak baseline, return area under curve (AUC) evaluated cortisol glucose. Cortisol determined by radioimmunoassay hexokinase colorimetric assay, respectively. CBC data using Hemavet hemocytology analyzer. Pre-LPS Post-LPS glucose, SBS, RT, MIXED procedure SAS specific repeated measures treatment, time, interaction as fixed effects dam sire breed random effect. AUC treatment effect There RT (P < 0.05). monocyte lower relative hematocrit increased SBS As expected, WBC, neutrophil count, lymphocyte percentage, eosinophils RBC, platelets changed over percentage decreased eosinophil Preliminary results suggest altered toxic