Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi 62, Tartu, 51006, Estonia.
Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi 62, Tartu, 51006, Estonia.
Prev Vet Med. 2021 Jul;192:105389. doi: 10.1016/j.prevetmed.2021.105389. Epub 2021 May 27.
Herd culling rates and longevity represent herd health and welfare status as well as farm economic performance. The contribution of endemic circulation of the main cattle pathogens to herd performance has not been previously analysed. The aim of this study was to estimate the herd prevalence of selected endemic bovine pathogens among large commercial dairy herds and to analyse their associations with herd culling rates and longevity. Bulk tank milk (BTM) samples and 10 heifer serum samples were collected from 120 Estonian dairy herds with at least 100 cows, between August 2019 and July 2020. All samples were tested for antibodies against bovine herpesvirus 1 (BHV-1), bovine viral diarrhoea virus (BVDV), bovine respiratory syncytial virus (BRSV), Mycoplasma bovis, Mycobacterium avium spp. paratuberculosis (MAP) and Salmonella Dublin using commercial ELISA. Data on herd size, milk yield, culling rate (CR) and mean age of the culled cows (MAofCC) were collected from the Estonian Livestock Performance Recording Ltd. The apparent herd and animal prevalences were calculated, and linear regression models were used to identify associations between the herd status of six tested pathogens and CR and MAofCC. The herd seroprevalences for antibodies based on BTM and heifer serum sample testing were BHV-1 56.7 % (95 % CI 47.3; 65.7), Mycoplasma bovis 48.3 % (95 % CI 39.1; 57.6), MAP 2.5 % (95 % CI 0.5; 7.1) and S. Dublin 24.2 % (95 % CI 16.8; 32.8) in all tested herds. Excluding vaccinated herds, herds prevalence for BVDV was 27.0 % (95 % CI 19.0; 36.3) and for BRSV 94.7 % (95 % CI 88.1; 98.3). Herd seropositive status for BRSV was associated with lower MAofCC, and herds with BSRV-seropositive youngstock had increased CR. Herds with positive BTM test results for S. Dublin culled cows at an older average age (Coef = 3.79 months, 95 % CI 0.52; 7.07, p = 0.023). MAP-positive herds had somewhat lower herd MAofCC (Coef = -6.18 months, 95 % CI -12.98; 0.63, p = 0.075). There was also a tendency of BVDV-negative herds to have a lower CR than BVDV-positive herds (Coef = -3.03 %, 95 % CI -6.54; 0.49, p = 0.090), and vaccination against BVDV tended to be protective against high CR (Coef = -6.26 %, 95 % CI -12.61; 0.09, p = 0.053 compared to infected herds). This study shows that Estonian large-scale dairy herds are endemically infected with several important cattle pathogens. Most of the studied pathogens influence longevity and culling rates, thus entailing health and economic consequences.
牛群淘汰率和寿命代表着牛群的健康和福利状况以及农场的经济绩效。主要牛病原体的地方性循环对牛群性能的贡献以前没有分析过。本研究的目的是估计大型商业奶牛场中选定的地方性牛病原体的牛群流行率，并分析它们与牛群淘汰率和寿命的关系。在 2019 年 8 月至 2020 年 7 月期间，从至少有 100 头牛的 120 个爱沙尼亚奶牛场中采集了 120 份牛群奶样和 10 份青年牛血清样本。使用商业 ELISA 检测所有样本中牛疱疹病毒 1 (BHV-1)、牛病毒性腹泻病毒 (BVDV)、牛呼吸道合胞体病毒 (BRSV)、牛支原体、牛分枝杆菌副结核分枝杆菌 (MAP) 和都柏林沙门氏菌的抗体。从爱沙尼亚牲畜性能记录有限公司收集了关于牛群规模、产奶量、淘汰率 (CR) 和淘汰牛的平均年龄 (MAofCC) 的数据。计算了明显的牛群和动物流行率，并使用线性回归模型确定了 6 种测试病原体的牛群状况与 CR 和 MAofCC 之间的关系。基于牛群奶样和青年牛血清样本检测的抗体血清流行率为 BHV-1 56.7%(95%CI 47.3%；65.7%)、牛支原体 48.3%(95%CI 39.1%；57.6%)、MAP 2.5%(95%CI 0.5%；7.1%)和 S. Dublin 24.2%(95%CI 16.8%；32.8%)。在所有检测的牛群中，排除了接种疫苗的牛群，BVDV 的牛群流行率为 27.0%(95%CI 19.0%；36.3%)，BRSV 的牛群流行率为 94.7%(95%CI 88.1%；98.3%)。牛群 BRSV 血清阳性与 MAofCC 较低有关，牛群中有 BRSV 血清阳性的青年牛的 CR 较高。牛群奶样中 S. Dublin 阳性的牛淘汰时的平均年龄较大 (Coef = 3.79 个月，95%CI 0.52；7.07，p = 0.023)。MAP 阳性牛群的平均 MAofCC 略低 (Coef = -6.18 个月，95%CI -12.98；0.63，p = 0.075)。BVDV 阴性牛群的 CR 也低于 BVDV 阳性牛群 (Coef = -3.03%，95%CI -6.54%；0.49%，p = 0.090)，BVDV 疫苗接种对高 CR 有保护作用 (Coef = -6.26%，95%CI -12.61%；0.09%，p = 0.053 与感染牛群相比)。本研究表明，爱沙尼亚大型奶牛场受到几种重要牛病原体的地方性感染。大多数研究的病原体影响牛群的寿命和淘汰率，从而对健康和经济产生影响。
