Hematological analysis of the Korean native cattle (Hanwoo) according to the period and method of grazing

Blood tests have been used to develop treatment plans, such as disease diagnosis, treatment effect, and prognosis determination in livestock. The present study examined changes in the blood count, including RBCs, WBCs, and platelets, before and after grazing among the Korean native cattle grazing from spring to autumn. The study compared the blood count of livestock group (A, n=34) that returned from the rangeland to cowshed every evening and livestock group (B, n=21) that were not returned from the rangeland to cowshed every evening during the grazing period. Hematological parameters such as RBC, hemoglobin, hematocrit, MCV, and WBC, neutrophil, eosinophil, monocyte, and lymphocyte were determined using a blood cell analyzer. Livestock group (A) showed significant differences in the values of RBC, MCV, MCHC, WBC, EOS, and LYM. Livestock group (B) showed significant differences in the values of RBC, Hb, HCT, MCV, MCH, PLT, NEU, and BAS. In particular, the RBC count decreased after grazing when compared with that before grazing. Compared with that before grazing, low RBC count was maintained from the first to fifth month of grazing. The WBC count increased from the fourth month of grazing, whereas the EOS count increased from the second month of grazing. These results suggest that the values of RBC and WBC vary before and after grazing, and also with the grazing period. Furthermore, it is necessary to develop a detailed feeding management based on these values of blood analysis for livestock that are raised continuously in the rangeland.