Influência da quimioprofilaxia para tristeza parasitária bovina na taxa de prenhez em fêmeas submetidas a protocolo de inseminação artificial em tempo fixo

Abstract

The most common hemoparasites in cattle are Anaplasma marginale, Babesia bovis and Babesia bigemina, which trigger the bovine parasitic sadness (BPS) complex. The agents are spread through vectors where B. bovis and B. bigemina are transmitted through ticks, in addition to these, A. marginale can also be spread through hematophagous insects, in an iatrogenic and transplacental way. The state of Rio Grande do Sul is considered an area of enzootic instability, as, due to the subtropical climate, there is an oscillation in the tick population, thus favoring the occurrence of disease outbreaks. BPS is responsible for causing several productive losses in cattle farming, such as weight loss, reduced milk production, abortion, temporary infertility, mortality, among others. In this context, the aim of the study was to verify the impact of chemoprophylaxis against these hemoparasites on the reproductive performance of cattle in fixed-time artificial insemination (FTAI) protocols. For the study, 297 bovines were selected, these animals participating in the FTAI protocol were divided into two groups. In group 1, an application of chemoprophylaxis with diminazene diaceturate and oxytetracycline was performed on day zero of the FTAI protocol and in group 2 not treated, thus being the control group. The animals were divided into categories, where nulliparous are females that never gestated and multiparous are cows between 30 and 120 days post parturition. There were two collections of blood samples from each animal with an interval of 40 days between them. The first collection was on day zero of the FTAI protocol and the second on the day of pregnancy diagnosis (PD). The collections were performed in order to assess hematocrit (HTC), total plasma protein (PPT) and blood smears for hemoparasites. Comparing the results of the HTC and PPT exams performed on day zero and day of PD, it appears that for the nulliparous category both exams showed an increase (HTC p < 0.001; PPT p < 0.005). Analyzing the groups, it is observed that group 1 had an increase in the HTC test (p < 0.001) and group 2 had an increase in the HTC and PPT teste (p = 0.002; p = 0.005, respectively). The investigation of the hemoparasites in the blood smear resulted in 94.2% of the animals being negative in the first collection and 98.9% in the second. The average pregnancy rate considering all animals was 54.2%. In general, the animals that received chemoprophylaxis showed a performance of 60.56% in the pregnancy rate while the control group resulted in 48.38% (p < 0.05). Based on the results, it was found that HTC and PPT values for the species. Most of the blood smears were negative for hemoparasites, which could occur in situations of low parasitemia, as none of the study animals were showing clinical signs compatible with the disease. Because the difference in pregnancy rate between groups 1 and 2 is significant, it is suggested that the use of the chemoprophylactic protocol against BPS agents, associating diminazene diaceturate and oxytetracycline, is interesting to increase performance reproductive system of bovine females. [resumo fornecido pelo autor]