Assessment of blood L-lactate concentration (LAC) as point-of-care (POC) biomarkers is turning into a typical procedure for different diagnostic purposes in the food animal industry. The purpose of our study was to figure out whether blood LAC measured by a hand held lactate analyzer with different variables could be utilized to anticipate the event of bovine respiratory disease (BRD) in feedlot cattle. Moreover, assess the blood LAC stability over different time point in clinically healthy feedlot cattle. Blood sample was collected at entry during processing (n=104) and at initial diagnosis of BRD (n=24). In addition, clinically healthy pen matched controls calves (n=24) were sampled at the same time of pulling diseased calves for determination of blood LAC using a handheld portable lactate analyzer. In a separate study, selected clinically healthy calves (n=9) were sampled and blood LAC stability at the different time point (0, 30, 60, 90 and 120 minute) was assessed. Logistic regression model revealed blood LAC during initial processing was significantly associated with odds of becoming a BRD case in calves revealing lung score 2. Moreover, blood LAC was significantly different (P=0.02) between clinically healthy and those calves that developed BRD and was significantly correlated (P>0.01) within the different time points. Our results demonstrated that analyzing blood LAC at initial diagnosis of BRD together with other clinical variable might help in the treatment decision. Therefore, further investigation should be designed to correlate blood LAC measurements for prediction of BRD clinical outcomes.

Key words: Bovine respiratory disease, Feedlot calves, Handheld analyzer, L- lactate