Latitude and seasons influence the prevalence of Theileria orientalis and affect the hematology of non-grazed dairy cows in Korea.

This pilot study aimed to investigate the effects of regional and seasonal variations on the prevalence of Theileria orientalis and the hematological profile of non-grazed dairy cows in Korea. A total of 365 clinically healthy lactating Holstein Friesian cows from 26 dairy farms in 7 provinces that were categorized into northern, central, and southern regions were sampled during the warm period from July to August and the cold period from October to December. The detection of T. orientalis major piroplasm surface protein gene and the hematology non-grazed dairy cows were analyzed using peripheral blood samples. The T. orientalis prevalence was 20.0% (73/365). The prevalence in the southern region was 35.9%, which was significantly higher than that in the central (21.6%) and northern (12.9%) regions (P < 0.05). The prevalence during warm period was higher (43.0%) than that during the cold season (13.5%). The infected cows showed significantly lower erythrocyte counts in the southern region (5.8 ± 0.6 M/µl) and during the warm period (5.8 ± 0.7 M/µl) compared with those in the central and northern regions and during the cold season, which affected the extended RBC parameters, including hematocrit and hemoglobin concentrations. Our findings revealed the prevalence of T. orientalis in Korea, highlighting its high occurrence during warm periods and in certain geographical regions. Climatic factors could contribute to the health and productivity of cattle, as evidenced by the prevalence of T. orientalis and its negative impact on animals.

Age-dependent changes in serum chemistry, mineral concentrations and complete blood cell count parameters in Holstein cattle.

Interpreting laboratory results from large animals is challenging owing to a lack of detailed reference ranges by age, sex, season, and breed. This study determined reference ranges for bovine serum chemistry and complete blood cell count (CBC) according to Holstein milking-cow age. Seventy-two healthy Holstein calves and cows (<1 week to milking age) were grouped: 1 (n = 7, <1 week), 2 (n = 10, 1 month), 3 (n = 13, 3 months), 4 (n = 13, 6 months), 5 (n = 10, 1 year, nulliparous), and 6 (n = 19, milking cows, parous). Fresh blood samples were obtained from the jugular vein between 10:00 and 12:00 AM in the winter; serum chemistry and haematologic profiles were assessed. Serum chemistry and CBC differed significantly by age. Age-related differences were observed for albumin, alkaline phosphatase, creatinine phosphokinase, creatinine, gamma-glutamyl transpeptidase, glucose, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, magnesium, phosphorus, calcium, total bilirubin, total cholesterol, total protein, triglyceride, blood-urea nitrogen, non-esterified fatty acid, and beta-hydroxybutyric acid levels. Age differences in creatinine and C-reactive protein were not noticeable. Among CBC parameters, age-related differences were observed for white-blood-cell, lymphocyte, red-blood-cell, and platelet counts; hemoglobin level; haematocrit; mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular-hemoglobin concentration. Therefore, age-dependent variations should be considered when interpreting cattle laboratory results.