Hematology Reference Intervals for Holstein Cows in Southern China: A Study of 786 Subjects

SIMPLE SUMMARY: The American Society of Veterinary Clinical Pathology guidelines recommend that hematology reference intervals (RIs) should be established based on specific animals in specific regions. However, the information on hematology RIs is still lacking for Chinese dairy cows, which account for a total number of more than 3 million. Thus, the aim of this study is to establish hematology RIs for Chinese dairy cows using a large sample size. After the collection of blood samples from 786 Holstein cows, we generated hematology RIs according to overall animals, different ages, different parities and different lactation stages. Our results provide important hematologic information for both clinicians and researchers to approach the health surveillance of Holstein cows in southern China. ABSTRACT: Hematology RIs help clinicians and researchers determine whether a hematology parameter is abnormal, which plays an important role in animal health surveillance. China is one of the largest dairy producers in the world, with millions of Holstein cows. However, there has been no published data on hematology RIs for dairy cows in China yet. Therefore, the aim of this study is to establish updated and accurate RIs for Holstein cows in southern China. To increase the accuracy of the RIs, we collected blood samples from 786 Holstein cows and analyzed 25 hematologic variables. The RIs for Holstein cows were established using the 95% percentile RIs according to the American Society of Veterinary Clinical Pathology guidelines. The effects of different ages, parities and lactation stages were also checked in this study. The data of 21, 22 and 19 out of 25 hematology parameters were significantly different between different ages, parities and lactation stages, respectively. Furthermore, the hematology RIs of separate subclasses according to different ages, parities and lactation stages were generated. Hematology RIs according to ages and lactation stages, as well as parities and lactation stages, were also assessed. Together, our results confirm that hematology RIs for cows vary by ages, parities and lactation stages. The present study helps to fill the gap in hematology RIs for Holstein cows in southern China, and our data may serve as a very useful tool for monitoring the health and welfare of dairy cattle in China.