Stabel Judith R, Goff Jesse P
USDA-ARS, National Animal Disease Center, Bacterial Diseases of Livestock Research Unit, Ames, IA 50010, USA.
J Vet Diagn Invest. 2004 Sep;16(5):412-20. doi: 10.1177/104063870401600507.
This study was designed to evaluate if the immunosuppression typically observed during the immediate periparturient period (3 weeks before and after calving) in dairy cows influences the effectiveness of diagnostic tests for the detection of Johne's disease; and, if providing additional energy to the cows during this period would minimize any immunosuppressive effects. Twelve dairy cows naturally infected with Mycobacterium paratuberculosis were fitted with rumen cannulas in late gestation and assigned to treatment groups: control, n = 6; or stuffed, n = 6. Cows in the control group were allowed to consume feed ad libitum. Cows assigned to the stuffed treatment group were also fed ad libitum but received additional total mixed ration by manually stuffing their rumens with refused feed to maintain a dry matter intake of 2% body weight/day before calving and 2.5% body weight/day after calving. Parturition had a significant impact on immune function with significant reductions in M. paratuberculosis-specific antibodies detected in the serum and milk regardless of treatment group. Similarly, in vitro immunoglobulin production was decreased at calving for both treatment groups. In addition, stuffing cows modulated cell-mediated immune function by reducing antigen-specific lymphocyte proliferation and interferon-gamma production after calving. Shedding of M. paratuberculosis in the milk was apparent in 58% (7/12) of cows after parturition with no difference noted between control and stuffed animals. Parturition had no major effect on fecal shedding of cows regardless of treatment. These data suggest that parturition had a significant effect on immune function parameters including diagnostic tests for paratuberculosis. Furthermore, providing additional energy to cows with Johne's disease did not preclude immunosuppressive effects during the periparturient period.
本研究旨在评估奶牛围产期（产犊前后3周）通常观察到的免疫抑制是否会影响用于检测副结核病诊断试验的有效性；以及在此期间给奶牛额外补充能量是否能将任何免疫抑制作用降至最低。12头自然感染副结核分枝杆菌的奶牛在妊娠后期安装了瘤胃瘘管，并被分配到治疗组：对照组，n = 6；或补饲组，n = 6。对照组的奶牛可自由采食。分配到补饲治疗组的奶牛也可自由采食，但通过人工向瘤胃中填入废弃饲料来额外给予全混合日粮，以使产犊前干物质摄入量维持在体重的2%/天，产犊后维持在体重的2.5%/天。无论治疗组如何，分娩对免疫功能都有显著影响，血清和乳汁中检测到的副结核分枝杆菌特异性抗体显著减少。同样，两个治疗组在产犊时体外免疫球蛋白产量均下降。此外，补饲奶牛通过降低产犊后抗原特异性淋巴细胞增殖和干扰素-γ产生来调节细胞介导的免疫功能。58%（7/12）的奶牛在分娩后乳汁中有明显的副结核分枝杆菌排出，对照组和补饲组动物之间未发现差异。无论治疗如何，分娩对奶牛粪便排出均无重大影响。这些数据表明，分娩对包括副结核病诊断试验在内的免疫功能参数有显著影响。此外，给患有副结核病的奶牛额外补充能量并不能防止围产期的免疫抑制作用。
