Ploeger H W, Kloosterman A, Rietveld F W, Berghen P, Hilderson H, Hollanders W
Department of Animal Husbandry, Agricultural University, Wageningen, Netherlands.
Vet Parasitol. 1994 Dec;55(4):287-315. doi: 10.1016/0304-4017(94)90071-x.
In two experiments groups of calves were exposed to different levels and patterns of infection with Ostertagia spp. and Cooperia spp. The experimental design simulated the stereotypic pattern of herbage infestation, including a normal or a delayed midsummer increase, under conditions of set-stocking. The purpose of the experiments was to investigate the accuracy of egg counts, pepsinogen and gastrin values and antibody titres as estimators of the level of exposure to infection. Faecal egg counts significantly reflected levels of exposure during the first half of the simulated grazing season. Antibody titres and pepsinogen values reflected levels of exposure best during August and September, partly depending on the pattern and range of levels of exposure. Antibody titres against Cooperia spp. were particularly useful when levels of exposure to gastrointestinal nematode infection were low. Gastrin values were elevated only at high levels of exposure, which caused large weight gain reductions, in the later part of the simulated first grazing season. It is suggested that antibody titres and pepsinogen values can be used for prognostic diagnosis, indicating whether or not control measures should be taken. Both estimators of infection correlated significantly with the realised weight gain at the end of the simulated grazing season. Egg counts in the second month after the initial infection (turnout) also may be of significant value to support decisions concerning control measures. Comparisons with data from field trials and experiments conducted by others under various conditions suggested that the conclusions of the present experiments are also valid under field conditions. Furthermore, the results supported the conclusions drawn from previous field work, that levels of exposure are often very low on commercial farms in the Netherlands.
在两项实验中，将犊牛分组，使其接触不同水平和模式的奥斯特他属线虫和古柏属线虫感染。实验设计模拟了在围栏放牧条件下牧草感染的刻板模式，包括正常或延迟的仲夏期感染增加。实验目的是研究虫卵计数、胃蛋白酶原和胃泌素值以及抗体滴度作为感染暴露水平估计指标的准确性。在模拟放牧季节的前半段，粪便虫卵计数能显著反映感染暴露水平。抗体滴度和胃蛋白酶原值在8月和9月能最好地反映感染暴露水平，部分取决于感染暴露的模式和水平范围。当胃肠道线虫感染暴露水平较低时，针对古柏属线虫的抗体滴度特别有用。仅在模拟第一个放牧季节后期，当感染暴露水平较高且导致体重增加大幅减少时，胃泌素值才会升高。建议抗体滴度和胃蛋白酶原值可用于预后诊断，指示是否应采取控制措施。这两种感染估计指标均与模拟放牧季节结束时的实际体重增加显著相关。初次感染（放牧开始）后第二个月的虫卵计数对于支持控制措施的决策也可能具有重要价值。与其他在各种条件下进行的田间试验和实验数据的比较表明，本实验的结论在田间条件下同样有效。此外，结果支持了先前田间工作得出的结论，即在荷兰的商业农场中，感染暴露水平通常非常低。
