Susceptibility of Theileria sergenti Infection in Holstein Cattle Compared to Korean Native Cattle on Cheju Island

Abstract

Equal　numbers　of　grazing Holstein, Korean native and crossbreed cattle on Cheju island (South Korea), totaling 195 were examined for Theileria sergenti infection and parasitemia levels by microscopic examination of Giemsa-stained blood smears and the polymerase chain reaction (PCR). Comparatively the positive rates of T.sergenti infection as well as the parasitemia levels were higher in Holstein cattle than both the Korean native and crossbreed cattle. Positive rates and parasitemia of Holstein cows increased continuously during the grazing period. These results suggest that Holstein cattle showed more sensitive to T. sergenti infection than the Korean native cattle and crossbreed cattle.