Avaliação dos macrófagos espumosos hepáticos e do peso de carcaça quente de bovinos criados extensivamente no pasto de Brachiaria spp

Abstract

The Brachiaria grass, with broad geographic distribution in Brazil, has been shown to cause photosensitization and appearance of foamy macrophages in the liver and liver and mesenteric lymph nodes of ruminants. Weight loss of 2.52% in cattle with subclinical hepatogenous photosensitization was documented and it is estimated that in one year in a single slaughterhouse more than R$ 100,000 in annual losses are caused by liver damage resulting from consumption of Brachiaria spp. The aim of this study was to corelate the extent of liver parenchyma containing foamy macrophages with hot carcass weight of cattle. Carcasses of cattle aged 20-36 months were weighed and divided into two groups: Group 1 (544.87-607.13 pounds) and Group 2 (689.42-757.24 pounds) The livers of bovines were weighed and samples of the right lobe were collected for histopathologic analysis. The areas of hepatic parenchyma containing foamy macrophages were measured using the ImageJ® program. Statistical analysis of the parameters (liver weight, hot carcass weights and affected area of liver tissue) was performed quantitatively, by calculating the mean, standard deviation and coefficient of variation. These data were analyzed for normality and homogeneity of variances, through the Kolmogorov-Smirnov and Bartlett tests. As the variables were homogeneous and had a normal distribution were evaluated by parametric test analysis of variance. The correlation of variables was performed by Spearman test. The significance level was set at 5% and all descriptive analyzes were performed by EXCEL program and statistical tests by the software R. Cattle grazing Brachiaria spp. presented hepatic lesions characterized by degeneration, necrosis, presence of mild inflammatory infiltrates and small area of hepatic tissue containing foamy macrophages. There was no influence of the affected area of the hepatic parenchyma containing foamy macrophages with hot carcass weight of cattle.