The Effect of Bovine Leukosis Virus Infection on the Proportion Among Bovine Leukocyte Populations in the Hemogram of Cows

Abstract

The effects of Bovine Leukosis Virus (BLV) infection on the proportion among bovine leukocyte populations in blood (WBC) was investigated using differential staining and a CBC profile. Previous research has indicated that total WBC count and total lymphocyte are impacted by BLV infection. However, few studies have included neutrophils, basophils, and monocytes. Eighty Angus cows (51 positive and 29 negative) were bled by jugular venipuncture into 7 ml EDTA treated vaccutainer tubes on October 2, 2007. Cows had previously tested positive for the presence of BLV and were retested by ELISA on the day blood samples were taken. The analysis of variance was generated using PROC GLM (SAS Inst., Inc. Cary, NC), the model included presence or absence of BLV infection and sex. Least-squares means were calculated and separated using pair-wise ttests (PDIFF option). There was no impact of sex on any of the parameters used in this study and thus the bulls were eliminated from the data set. Total white blood cell count and total eosinophils were greater (P \u3c 0.09 and 0.005) in the cows that tested positive for BLV. Proportions of lymphocytes were greater (P = 0.11) for uninfected cows compared to infected cows. However, there were no differences in total counts or proportions of neutrophils, basophils, or monocytes and there was no difference detected for the neutrophil:lymphocyte ratio. This study supported previous research in its findings that BLV infection has an impact on total white blood cell counts and lymphocytes