Complete blood count changes according to age and parity in pregnant Hanwoo beef cows one month before delivery

Previous studies have been conducted on age- and parity-related complete blood count (CBC) changes in adult dairy cows. This study aimed to confirm these changes in beef cows. Blood samples collected one month before parturition from 434 clinically healthy, pregnant Hanwoo beef cows were analysed. Fourteen haematological parameters were measured using a Hemavet 950. The average CBC parameter values of four age groups (≤36, 37-72, 73-108, and ≥109 months) and four parity groups (parity 0, 1, 2-4, and ≥5) were compared. Ten parameters differed across the age groups (P < 0.05). Ten parameters also differed across the parity groups (P < 0.05). The CBC results of the pregnant cows differed for only one parameter when they were stratified by the sex of the calf confirmed after delivery and for two parameters based on the birth weight of the calf. Our results confirm that the CBC reference intervals in beef cows can be affected by age and parity. Additionally, these results emphasise the need to establish reference intervals for age- and parity-based subclasses of beef cattle to increase the accuracy of CBC.