Comparison of the Prevalence of Bovine Leukemia Virus (BLV) in Holstein and Angus Cattle Breeds From Shandong Province, China.

Bovine leukemia virus (BLV) is widespread globally and causes economic losses in the cattle industry. Shandong Province plays a significant role in China's livestock industry, with an increasing importance in food of Holstein and Angus cattle. However, BLV prevalence in Holstein and Angus breeds in Shandong Province remains unclear. In particular, there are no reports of BLV prevalence of Angus cattle in field surveys worldwide. In this study, 613 samples from six large-scale farms (> 1000 heads per farm) in Binzhou and Weifang cities were screened for BLV antibodies (gp51) using an enzyme-linked immunosorbent assay. The samples included 303 Angus (beef) and 310 Holstein (dairy) cattle. All Angus breeding samples from the three farms were BLV-negative at both the animal- and herd-level prevalences. In contrast, 62 of 310 Holstein cattle (20.0%) from three dairy farms were positive for BLV antibodies. For example, 35/110 (31.8%), 19/100 (19.0%), and 8/100 (8.0%) samples from the D, E, and F farms, respectively, were BLV-positive. Notably, the animal- and herd-level prevalences for Holstein cattle exhibited 20% and 100% positivity, respectively. These findings offer significant insights into the BLV status of Holstein and Angus cattle in Shandong Province, China.