Pollock Colleen M, Campbell John R, Windeyer M Claire, Rousseau Marjolaine, Waldner Cheryl L
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4 (Pollock, Campbell, Waldner); Faculty of Veterinary Medicine, University of Calgary, 11877 85 Street NW, Calgary, Alberta T3R 1J3 (Windeyer); Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, 3200 Rue Sicotte, Saint-Hyacinthe, Quebec J2S 2M2 (Rousseau).
Can Vet J. 2025 Sep 1;66(9):955-960. eCollection 2025 Sep.
Our objective was to estimate the seroprevalences of 6 serovars in beef calves at or near fall weaning and assess how concentrations of serovar antibody titers in weaning-age calves varied with herd vaccination programs.
Serum was collected from 1922 beef calves from 106 herds in the Canadian Cow-Calf Surveillance Network (C3SN).
A microscopic agglutination test was used to measure antibody titers for serovars Bratislava, Canicola, Grippotyphosa, Hardjo, Icterohaemorrhagiae, and Pomona. Records of vaccine use were available for cows and nursing calves from 94 herds. Generalized estimating equations were used to estimate the associations between serovar antibody titers in weaning-age calves and the number of doses of vaccine administered to cows.
Overall, 90.8% of sampled calves had undetectable (< 50) antibody titers to all tested serovars, whereas 3.2% of sampled calves from 26.4% of participating herds had a positive (≥ 100) titer to 1 or more serovars. The seroprevalences at both the calf and herd levels were higher for the host-adapted serovar Hardjo in western Canada and higher for the non-host-adapted serovars in eastern Canada. The probability of calf serovar Icterohaemorrhagiae titer increasing by 1 doubling dilution was 3.6× (95% CI: 1.7, 7.7) higher in herds that administered 2 doses of vaccine to cows compared to herds that did not vaccinate against this pathogen.
Based on the serological evidence, few weaning-age beef calves across Canada have been exposed to pathogenic bacteria.
我们的目的是估计秋季断奶时或接近秋季断奶时肉牛犊中6种血清型的血清阳性率，并评估断奶龄犊牛血清型抗体滴度浓度如何随牛群疫苗接种计划而变化。
从加拿大奶牛-犊牛监测网络（C3SN）的106个牛群的1922头肉牛犊中采集血清。
采用显微镜凝集试验测量布拉迪斯拉发、犬钩端螺旋体、波摩那型、哈焦型、出血性黄疸型和黄疸出血型血清型的抗体滴度。有94个牛群的母牛和哺乳犊牛的疫苗使用记录。使用广义估计方程来估计断奶龄犊牛血清型抗体滴度与给母牛接种疫苗的剂量数之间的关联。
总体而言，90.8%的采样犊牛对所有测试血清型的抗体滴度检测不到（<50），而来自26.4%参与牛群的3.2%采样犊牛对1种或更多血清型的滴度呈阳性（≥100）。在加拿大西部，宿主适应性血清型哈焦型在犊牛和牛群水平的血清阳性率较高，而在加拿大东部，非宿主适应性血清型的血清阳性率较高。与未针对该病原体进行疫苗接种的牛群相比，给母牛接种2剂疫苗的牛群中，犊牛出血性黄疸型血清型滴度增加1倍稀释度的概率高3.6倍（95%CI：1.7，7.7）。
根据血清学证据，加拿大很少有断奶龄肉牛犊接触过病原菌。
