Clinical evaluation and reproductive indices of dairy cows naturally infected with Trypanosoma vivax

Abstract

The present study was aimed to assess the clinical changes and reproductive indices of dairy cows naturally infected with Trypanosoma vivax in a herd located in the Central Sertão of Ceará, Brazil. For the study, 40 animals were selected from a herd consisting of 210 dairy cows, and subdivided into two groups: group I, consisting of 20 cows naturally infected with T. vivax, and group II, consisting of 20 uninfected cows. Data on the parameters of reproductive efficiency were evaluated using a farm database (Propad Profissional GP®), in which the individual reproductive characteristics of the animals were stored. Data collected both before and after the outbreak were compared. The cows from group I showed a sudden drop in milk production, mucosal pallor, depression, anorexia, and a significant increase in rectal temperature and decreased hematocrit during the parasitemia outbreak. These clinical signs of the disease disappeared over time. However, T. vivax was detected by polymerase chain reaction (PCR) in animals with a negative parasitological test one year after the occurrence. Comparison of the reproductive index data for cows from groups I and II before and after the outbreak showed significant differences in first postpartum estrus, service period, and intervals between deliveries. In addition, repetition of estrus and abortion were significantly associated with T. vivax infection. Analysis of the reproductive indices of cows in groups I and II suggests that T. vivax infection decreased the reproductive efficiency of the study cows.