49 Hematological and physiological changes observed in commercial stocker operation during early management

Abstract

Abstract Dynamic physiological parameters’ change in recently received stocker calves may indicate disease onset or further progression. Our objective was to capture changes in rectal temperature and blood chemistry to determine relationships between these responses, castration status, and time after arrival at a commercial farm. Forty newly weaned steers of variable breed and body weight were received from order buyer on February 13, 2020 to a commercial stocker farm in Crossville. Calves were monitored for 4 wks; blood samples and rectal temperature were collected at day 0, 7, 14, and 21. All calves were either freshly (FC) (n = 27) or previously castrated (PC) (n = 13). Complete blood count (CBC) was analyzed on each sampling day using Hematology Analyzer, and the correlation between body temperature and CBC parameters was assessed using CORR procedure in SAS 9.4. To test if FC group differed from PC with CBC value changes, mixed model analysis of variance was performed (Proc GLIMMIX) with day as repeated measure (α = 0.05). Rectal temperature was significantly negatively correlated with red blood cells (RBC) (r = -0.33, P = 0.03) and hemoglobin (HGB) (r = -0.37, P = 0.01) on day 21. A castration by day interaction (P = 0.04) was found for white blood cell (WBC). Significant differences were found in between FC and PC groups for WBC on day 0 (10.59 and 14.23, respectively) and 14 (12.04 and 15.80, respectively). Significantly lower RBC, HGB, and Mean Corpuscle Volume (MCV) were found in FC; however, they had increased Mean Corpuscle Hemoglobin (MCH) and platelet (PLT) counts (P < 0.05). In addition, there were day effects on mean WBC, MCH, PLT, and Mean Corpuscular Hemoglobin Concentration (MCHC) (P < 0.001). While previous health history of stocker cattle remains unknown, there are definite differences in hematology and physiology at arrival and over time, which may increase risk for illness in this stage of production.