Muskens J, Swart W A J M, Berends I M G A, Van Schaik G, Lam T J G M
Tijdschr Diergeneeskd. 2008 Jul 1;133(13):562-5.
The effect of BVD v-free certification of BVD v-infected dairy herds on udder health was determined, by comparing parameters of udder health in 319 cases and 629 controls. Cases were dairy herds that originally had at least one BVD V antigen-positive animal but which subsequently became BVD v-free and maintained this certified status for at least 2 years. Controls had an unknown BVD V status. Each case was matched with two controls by region and herd size. The three udder health parameters were bulk-milk somatic cell count (scc), the proportion of cows with a high scc, and the proportion of cows with a high scc after previously having a normal scc (these cows were considered to have a new intramammary infection). Udder health was better in the cases in the 2 years preceding the BVD V-free period than in the controls. BVD V-free status was not associated with bulk-milk scc or the proportion of cows with a high scc but was associated with occurrence of a new intramammary infection:fewer case cows had a new intramammary infection than control cows (difference 0.6%; P < 0.05).
通过比较319个病例和629个对照的乳房健康参数，确定了对感染牛病毒性腹泻病毒（BVDV）的奶牛群进行BVDV无感染认证对乳房健康的影响。病例是最初至少有一头BVDV抗原阳性动物，但随后成为无BVDV感染并保持该认证状态至少2年的奶牛群。对照的BVDV状态未知。每个病例按地区和牛群规模与两个对照进行匹配。三个乳房健康参数分别是原料奶体细胞计数（SCC）、SCC高的奶牛比例，以及之前SCC正常后SCC高的奶牛比例（这些奶牛被认为发生了新的乳房内感染）。在无BVDV感染期前的2年里，病例组的乳房健康状况优于对照组。无BVDV感染状态与原料奶SCC或SCC高的奶牛比例无关，但与新的乳房内感染的发生有关：病例组奶牛发生新的乳房内感染的数量少于对照组奶牛（差异0.6%；P<0.05）。
