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Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in beef cattle. Common management practices in addition to BRD have been shown previously to cause inflammation. The objectives of this study were: (1) characterize the inflammatory profiles as indicated by haptoglobin concentrations, over a receiving period in high-risk cattle; (2) evaluate the impact of on-arrival metaphylactic antimicrobial therapy on inflammatory profiles in high risk cattle; and (3) examine the relationship between inflammatory profile and BRD morbidity and mortality in high risk cattle. This 70 d trial was repeated over two years. A total of 160 black/black white face crossbred heifers were acquired from local auction markets and randomly assigned at arrival to treatment groups. Heifers were purchased by an order buyer from auction barns. At arrival, heifers were randomly assigned to either receive tulathromycin (Draxxin, META, n = 40) or not (NO META, n = 40) upon arrival. Each group was housed on a 10-acre pasture planted in annual ryegrass where they were offered complete commercial supplemental feed (14% CP) and free choice (both Purina Animal Nutrition, Nashville, TN) mineral and were observed daily for clinical signs of BRD. Cattle were weighed and blood was collected every seven days from d0 to d20, and again on d70. Haptoglobin concentrations were determined using ELISA. Effects of treatment and morbidity on haptoglobin concentration were tested using the MIXED procedure of SAS. Overall morbidity was 28.5%. Initial body weight (227 kg META, 229 kg NO META, P > 0.10) did not differ between the two treatment groups. However, final body weight differed between treatment groups (294 kg META, 289kg NO META). Haptoglobin concentrations remained elevated over time for all groups (P = 0.03). Metaphylaxis did not affect haptoglobin concentration (P > 0.10). There was a significant increase in BRD cases from day 0 to 20 (P = 0.00). Morbidity (BRD vs no BRD) did not impact haptoglobin concentrations. Overall, metaphylaxis did not affect haptoglobin levels or BRD incidence. [ABSTRACT FROM AUTHOR]