Couto Luiz Fellipe Monteiro, Bastos Thiago Souza Azeredo, Morais Igor Maciel Lopes de, Salvador Vanessa Ferreira, Leal Luccas Lourenzzo Lima Lins, Falavigna Ricardo Backstron, Spricigo José Felipe Warmling, Mota Rinaldo Aparecido, Cruz Breno Cayero, Colli Marcos Henrique Alcantara, Scarpa Alexandre Braga, Soares Vando Edesio, Ferreira Lorena Lopes, Lopes Welber Daniel Zanetti
Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.
Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Goiânia, Goiás, Brazil; Faculdade Anhanguera, Anápolis, Goiás, Brazil.
Vet Parasitol. 2024 Aug;330:110221. doi: 10.1016/j.vetpar.2024.110221. Epub 2024 Jun 5.
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.
本研究评估了位于无周期性传播媒介地区的一个奶牛群中，两年间慢性间日疟原虫感染对繁殖、生产和经济方面的影响。使用商用快速检测法将动物分为间日疟原虫抗体阳性（慢性感染）或阴性。此外，分析了奶牛血清样本中抗犬新孢子虫抗体的存在情况。在妊娠30天、60天以及之后每21天直至妊娠第144天，通过直肠触诊和超声检查进行妊娠诊断。如果在妊娠晚期发生流产，则对犊牛进行间日疟原虫和犬新孢子虫的血清学检测和巢式聚合酶链反应检测。记录繁殖期、产犊间隔和妊娠损失情况。测量了每头动物在305天泌乳期的产奶量，并使用收益减去饲料成本（RMFC）指标计算了产奶的年度经济影响。在177头奶牛中，71.75%为慢性感染，13.50%为间日疟原虫阴性。未观察到间日疟原虫和犬新孢子虫之间的共感染相关性（p = 0.8854）。阴性奶牛所需的人工授精次数比慢性感染奶牛少（p≤0.05）。在妊娠81天前，间日疟原虫与妊娠损失无显著关联（p = 0.7893）。慢性感染间日疟原虫的奶牛在妊娠82至144天期间发生妊娠损失的几率高4倍（p = 0.0280）。18头奶牛流产，2头间日疟原虫抗体阳性，1头犬新孢子虫抗体阳性。犊牛间日疟原虫和犬新孢子虫检测均为阴性。与维持妊娠的奶牛相比，慢性感染奶牛和间日疟原虫阴性且发生妊娠损失（妊娠82 - 144天）的奶牛怀孕所需的繁殖期更长（p≤0.05），因此产犊间隔也更长。当慢性感染间日疟原虫的奶牛在妊娠82至144天期间发生妊娠损失时，产奶量差异明显（p≤0.05）。RMFC表明，由于存在慢性感染奶牛，农场年度牛奶收益受到38.2%的负面影响。
