Abstract：
This study evaluated the reproductive, productive and financial consequences of chronic Trypanosoma vivax infection in a dairy cattle herd located in a region without the cyclic vector during two years. Animals were categorized as either positive (chronically infected) or negative for T. vivax antibodies using a commercial rapid test. Additionally, serum samples from cows were analyzed for the presence of anti-Neospora caninum antibodies. Pregnancy diagnoses were performed through rectal palpation and ultrasonography after 30, 60 and every 21 days until the 144th day of pregnancy. If an abortion occurred in the final trimester, serology and cPCR were performed on calves for T. vivax and N. caninum. The breeding period, calving interval and pregnancy losses were recorded. The milk production of each animal during the 305 days of lactation was measured, and the annual financial impact of milk production was calculated using a revenue minus feed cost (RMFC) indicator. Out of 177 cows, 71.75 % were chronically infected, and 13.50 % were T. vivax-negative. No correlation (p = 0.8854) of co-infection between T. vivax and N. caninum was observed. Negative cows required fewer (p≤0.05) artificial inseminations than chronically infected ones. T. vivax was not significantly associated (p = 0.7893) with pregnancy loss up to 81 days of pregnancy. Cows chronically infected by T. vivax had 4-fold greater chance (p = 0.0280) of experiencing pregnancy loss between 82 and 144 days of gestation. Eighteen cows aborted, two were positive for T. vivax antibodies, and one for N. caninum antibodies. The calves were negative for T. vivax and N. caninum. Chronically infected cows and negative cows for T. vivax that experienced pregnancy loss (82-144 days of pregnancy) had a longer (p≤0.05) breeding period to become pregnant, and consequently a longer calving interval compared to cows that maintained pregnancy. The difference (p≤0.05) in milk production was evident when pregnancy loss occurred between 82 and 144 days of gestation in cows chronically infected by T. vivax. The RMFC indicated a negative impact of 38.2 % on the farm\'s annual milk revenue due to the presence of chronically infected cows.
摘要：
这项研究评估了生殖，在两年内，位于没有循环媒介的地区的奶牛群中，慢性间日锥虫感染的生产和财务后果。使用商业快速测试将动物分类为阳性(慢性感染)或阴性。此外,分析来自奶牛的血清样品中是否存在抗犬新孢子虫抗体。妊娠诊断通过直肠触诊和超声检查在30、60和每21天进行，直到妊娠第144天。如果流产发生在最后三个月，对小牛进行了血清学和cPCR检测。繁殖期,记录产卵间隔和妊娠损失。测量每只动物在哺乳305天期间的产奶量,牛奶生产的年度财务影响是使用收入减去饲料成本(RMFC)指标计算的。在177头牛中，71.75%是慢性感染,13.50%为间日疟原虫阴性。未观察到间日疟原虫和犬奈瑟氏球菌之间共感染的相关性(p=0.8854)。阴性母牛比慢性感染的母牛需要更少的人工授精（p≤0.05）。间日疟原虫在妊娠81天内与妊娠丢失没有显着相关（p=0.7893）。慢性感染间日疟原虫的奶牛在妊娠82至144天之间经历妊娠丢失的机会大4倍(p=0.0280)。18头牛流产,其中两人的间日疟原虫抗体呈阳性,还有一种是针对犬奈瑟菌抗体的。小牛对间日疟原虫和犬硝虫呈阴性。长期感染的母牛和间日疟原虫阴性的母牛经历了怀孕损失（怀孕82-144天），有一个更长的（p≤0.05）繁殖期怀孕，因此，与保持怀孕的母牛相比，产卵间隔更长。在慢性感染间日疟原虫的奶牛的妊娠82至144天之间发生妊娠损失时，产奶量的差异（p≤0.05）是明显的。RMFC指出，由于存在慢性感染的奶牛，对农场的年度牛奶收入产生了38.2%的负面影响。
