Juscivete F. Fávero

Activity of nucleoside triphosphate diphosphohydrolase, 5′-nucleotidase, and adenosine deaminase in cattle fed on pastures treated with different nitrogen fertilizers

ABSTRACT The aim of this study was to evaluate nucleoside triphosphate diphosphohydrolase, 5′-nucleotidase, and adenosine deaminase activities in cattle fed on cuttings from pastures fertilized with urea compared to animals fed on cuttings from organically fertilized or from non-fertilized pastures. Blood samples were collected up to 9 h after feeding, and nitrite and enzyme activities were evaluated. The animals feeding on urea-fertilized pasture suffered subclinical intoxication. Serum nitrite levels increased by about 50% and adenosine deaminase activity increased almost sixfold 4 and 6 h after feeding on urea-fertilized pasture, and adenosine deaminase in platelets almost doubled 6 and 9 h after feeding. In platelets, nucleoside triphosphate diphosphohydrolase activity with adenosine triphosphate as substrate increased 2, 4, 6 and 9 h after feeding while nucleoside triphosphate diphosphohydrolase with adenosine diphosphate as substrate and 5′-nucleotidase activities increased only 9 h after feeding. Increased activities of these enzymes may be implicated in the pathophysiology of subclinical intoxication since they are involved in many biochemical functions.

Oxidative stress in dairy cows seropositives for Neospora caninum

Bovine neosporosis is caused by the protozoan Neospora caninum and is one of the major causes of abortion in cows. Cattle are intermediate hosts of this parasite and may have asymptomatic or symptomatic infections. Therefore, the aim of this study was to evaluate oxidative stress marker reactive oxygen species (ROS), thiobarbituric reactive acid substances (TBARS) levels, glutathione S-transferase (GST), adenosine deaminase (ADA), and butyrylcholinesterase (BChE) activities in dairy cows seropositives for N. caninum (asymptomatic or symptomatic). Dairy cows (n=90) were tested by immunofluorescent antibody assay (IFA) for N. caninum and divided accordingly into three groups: the group A (seronegatives, n=30), the group B (seropositives and asymptomatic, n=30), and the group C (seropositives and symptomatic, n=30). It was observed increased levels of TBARS and reduced (P<0.05) BChE activity in seropositives either asymptomatic or symptomatic animals. ROS levels and ADA activity increased, and GST activity decreased (P<0.05) only in seropositives symptomatic dairy cows (the group C) compared to seronegatives dairy cows (the group A). Based on these results, it was observed that seropositive animals showed cell damage associated with oxidative stress and inflammation, mainly in those with symptomatic infections. Increased seric ROS levels and BChE activity may have influenced N. caninum pathogenesis in symptomatic animals due to increased cell damage and exacerbated inflammatory response, leading to the development of clinical signs.

Risk factors for Toxoplasma gondii in sheep of southern Brazil

Toxoplasma gondii is responsible for reproductive failure in sheep, and it is considered a zoonotic parasite. Therefore, the aim of this study was to evaluate the prevalence of toxoplasmosis and its risk factors at the farm level. For that, 314 sheep from 18 farms of 7 municipalities of the West part of Santa Catarina State, Southern Brazil were used. To identify possible risk factors associated to the disease, a survey was applied to farmers with questions regarding farm characteristics, type of management, and history of animal reproductive problems. Out of 314 sera samples, 118 (37%, CI 95% 32.3–43.3) were positives for T. gondii. Multivariate analyses showed that allowing cats to have access to sheep feed was significantly associated to toxoplasmosis, with an odds ratio of 2.42. Similarly, keeping cats in the farm increased 1.67 times the chances of T. gondii infection by sheep. Therefore, we concluded that sheep infection by T. gondii in the West of Santa Catarina state is distributed very similarly to other regions of Brazil, and the presence of cats in the property is strongly correlated to the occurrence of the disease.