Department for Farm Animals and Veterinary Public Health, University Clinic for Ruminants, University of Veterinary Medicine Vienna, Veterinaerplatz 1, Vienna, 1210, Austria.
Bioinformatics and Biostatistics Plattform, University of Veterinary Medicine Vienna, Veterinaerplatz 1, Vienna, 1210, Austria.
Acta Vet Scand. 2023 Sep 28;65(1):43. doi: 10.1186/s13028-023-00707-9.
As calves are born without circulating immunoglobulin G (IgG) they depend on transfer of passive immunity via colostrum within the first hours of life. If calves are not sufficiently supplied with high qualitative colostrum they suffer from Failure of Transfer of Passive Immunity (FTPI). The objectives of this study were to evaluate a calf-side point-of-care test to detect calves with FTPI and to evaluate the cut-offs for a positive test result. Two hundred fifty calves from 11 dairy farms (born between September 2021 and September 2022) were included, whereof 23 were excluded due to incomplete data. Twelve to 16 h post partum the farmers carried out a point-of-care test (FASTest® IgG bovine, Megacor, Austria) using a whole blood sample. Between the 3rd and the 6th day of age, all calves were physically examined and blood samples were collected to carry out further point-of-care tests using whole blood supernatant and plasma and for measuring the Brix values in serum and plasma. Brix values in serum were used as reference for the evaluation of the point-of-care test between the 3rd and the 6th day of age, as radial immunodiffusion assays could not be conducted simultaneously.
Brix values were not normally distributed (median at 8.6% and 9.3% in serum and plasma). In this study, the cut-off values for the point-of-care tests using whole blood supernatant and plasma were at 8.3% Brix in serum. FASTest® IgG bovine shows high sensitivities of 90% and 84% and specificities of 70% and 72% for whole blood supernatant and plasma.
Of the 227 investigated calves, 39.7% showed Brix values of < 8.4% (cut-off for FTPI) which indicates an urgent need to improve colostrum management. The results of the study suggest that the FASTest® IgG bovine is a suitable on-farm method to assess FTPI in whole blood supernatant and plasma of calves between the 3rd and the 6th day of age. However, the results also show that FASTest® IgG bovine is not adequate to test for FTPI using whole blood at 12 to 16 h post partum.
由于小牛出生时没有循环免疫球蛋白 G（IgG），它们依赖于在生命的头几个小时内通过初乳进行被动免疫转移。如果小牛没有充分获得高质量的初乳，它们就会患上被动免疫转移失败（FTPI）。本研究的目的是评估一种小牛床边即时检测（POCT）方法来检测 FTPI 小牛，并评估阳性检测结果的截止值。250 头小牛来自 11 个奶牛场（2021 年 9 月至 2022 年 9 月出生），其中 23 头因数据不完整而被排除。产后 12 至 16 小时，农民使用全血样本进行 POCT（FASTest® IgG 牛，Megacor，奥地利）。在第 3 至第 6 天，所有小牛都进行了体格检查，并采集了血液样本，以使用全血上清液和血浆进行进一步的 POCT，并测量血清和血浆中的 Brix 值。血清中的 Brix 值被用作第 3 至第 6 天评估 POCT 的参考，因为不能同时进行放射免疫扩散测定。
Brix 值呈非正态分布（血清中中位数为 8.6%和 9.3%，血浆中中位数为 8.6%和 9.3%）。在本研究中，使用全血上清液和血浆的 POCT 的截止值为血清中 8.3%Brix。FASTest® IgG 牛对全血上清液和血浆的敏感性分别为 90%和 84%，特异性分别为 70%和 72%。
在所调查的 227 头小牛中，39.7%的小牛 Brix 值<8.4%（FTPI 截止值），这表明急需改善初乳管理。研究结果表明，FASTest® IgG 牛是一种在第 3 至第 6 天评估小牛全血上清液和血浆中 FTPI 的合适的农场方法。然而，结果还表明，FASTest® IgG 牛在产后 12 至 16 小时使用全血进行 FTPI 检测是不够的。
