Removing bovine leukemia virus-infected animals with high proviral load leads to lower within-herd prevalence and new case reduction.

Autor:	Shrestha S; Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1. Electronic address: sulav.shrestha1@ucalgary.ca., Orsel K; Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1., Droscha C; CentralStar Cooperative Inc., East Lansing, MI 48910., Mijar S; Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1., van der Meer F; Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1.
Jazyk:	angličtina
Zdroj:	Journal of dairy science [J Dairy Sci] 2024 Aug; Vol. 107 (8), pp. 6015-6024. Date of Electronic Publication: 2024 Mar 29.
DOI:	10.3168/jds.2023-24484
Abstrakt:	Bovine leukosis is prevalent in the North American dairy industry, and its effect on animal health and production is widely documented. However, not all bovine leukemia virus (BLV)-infected animals transmit the virus equally. Animals with high proviral loads (HPL) of BLV are associated with higher transmission risks, and therefore, their removal may reduce transmission and eventually within-herd prevalence. We aimed to evaluate the impact of selectively removing HPL cows on the within-herd BLV prevalence and incidence rate of BLV infection in 10 dairy herds. Annual blood or milk samples (or both) were collected from adult cows over 3 yr. Positivity with BLV were determined by ELISA tests, and proviral loads in blood of BLV-positive animals were estimated with BLV SS1 quantitative PCR assays. Herd managers were encouraged to consider the proviral load when making culling decisions and implement BLV control practices. Cows with high proviral load had the highest relative risk of removal, indicating the farmers prioritized HPL cows for culling. The within-herd BLV prevalence decreased significantly in 4 herds, whereas BLV incidence rate decreased in 9 herds. Over the 3 yr, the proviral load demonstrated a relatively stable level, suggesting a single proviral load test in an adult cow may suffice to make culling decisions. (© 2024, The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu