Background: Hanwoo cattle, an indigenous Korean breed, have become economically significant due to genetic improvements and large-scale farming. As individual cow value increases, understanding their unique physiology across different life stages is crucial for optimal health management. This retrospective study aimed to investigate serum biochemistry differences among non-pregnant, pregnant, and fattening female Hanwoo cattle and establish breed-specific reference intervals (RIs) for accurate health assessment, utilizing data obtained from routine veterinary care. Methods: Blood samples were collected from female Hanwoo cattle, categorized as pregnant (n = 12), non-pregnant (n = 25), and fattening (n = 11). Eighteen serum biochemical parameters were analyzed and descriptive statistics were calculated for each group. The new RIs in different reproductive status of female Hanwoo were established using the Reference Value Advisor program. Results: Significant differences based on reproductive status were identified in blood urea nitrogen (BUN), γ-glutamyl transferase (GGT), triglyceride (TG), glucose (GLU), and creatinine (CRE) levels. BUN, GGT, and TG levels were significantly higher in fattening cattle compared to pregnant and non-pregnant cows. GLU levels increased progressively across pregnant, non-pregnant, and fattening groups, while CRE levels were significantly higher in pregnant cows. Based on values of biochemical parameters, new RI were suggested for sixteen biochemical parameters, encompassing all three reproductive stages. Conclusions: This study established new RIs for female Hanwoo cattle across nonpregnant, pregnant, and fattening stages, providing a more accurate basis for health assessment and management. These findings will contribute to improved individual cow management, supporting genetic improvement efforts, and enhancing overall herd health in female Hanwoo cattle.

Because multiple ovulation embryo transfer (MOET) in cattle includes several benefits such as wide spreading of genetically superior offspring for long distance, this biotechnological method has been widely applied to Hanwoo. When the recipients are not stayed close after embryo recovery from donor, the embryos are moved to other farms via several vehicles (car, train, and airplane). However, air travel induces lesser oxygen level, increased vibration, lower air pressure, higher noise, and increased exposure of cosmic radiation to living things than ground level. It was still unknown that fresh embryos obtained from multiple ovulation of Hanwoo could maintain their fertility after being transported via air plane, the present case report introduced a clinical case of MOET in Hanwoo after shipping fresh embryos via air transportation. The donor was multi-ovulated via follicle-stimulating hormone series of injection, which was followed by a gonadotrophin-releasing hormone injection and artificial insemination twice. The embryos were recovered by the uterine flushing, packed in ministraws, transported to recipients for 6 h including 1 h air flight, and then transferred to the synchronized recipients. During pregnancy diagnosis of early gestation period, 5 of 7 recipients (71.4%) presented no heat signs and showed fetal sacs with fluid under transrectal ultrasonography. After normal gestation period, all recipients naturally delivered healthy calves (male n = 2 and female n = 3) without abortion, stillbirth, and premature birth. The present case report indicated that transportation of fresh embryos for MOET via domestic flight in Korea did not affect to their fertility.