Experimental poisoning by Brachiaria decumbens in rabbits

Abstract

Animais de Produção/Livestock Diseases RESUMO.-[Intoxicação experimental por Brachiaria decumbens em coelhos.] Brachiaria ssp. são importantes fontes de forragem para ruminantes no Brasil, devido ao fácil cultivo, boa resistência a seca, boa adaptação a diferentes solos e baixo custo de manutenção. Entretanto, a ingestão desta gramínea está relacionada a surtos de fotossensibilização, em bovinos e ovinos, principalmente, ocasionando prejuízos econômicos significativos. Os efeitos hepatotóxicos relacionados à ingestão da gramínea são a formação de cristais e macrófagos espumosos causados pelo acúmulo de metabólitos tóxicos. A utilização de bovinos e ovinos em experimentos envolvendo a planta apresenta vários empecilhos, tanto no âmbito ético, econômico e no manejo dos animais. O objetivo do presente trabalho foi avaliar a sensibilidade de coelhos como modelo experimental para intoxicação por B. decumbens. No presente estudo foram realizados dois experimentos. O Experimento ABSTRACT.-Utiumi K.Brachiaria spp.are important sources of forage for ruminants in Brazil, due to the easy cultivation, good resistance to drought, good adaptation to different soils and low maintenance cost. However, the ingestion of this grass has been related to photosensitization outbreaks in cattle and sheep with significant economic losses. The hepatotoxic effects related to the ingestion of grass are the formation of crystals and foamy macrophages due to the accumulation of toxic metabolites. The use of cattle and sheep in experiments involving the plant presents several obstacles in the ethical, economic and animal management. The objective of this study was to evaluate the sensitivity of rabbits as an experimental model for B. decumbens poisoning. Two experiments were carried out. In Experiment 1 four rabbits received the fresh plant in daily doses of 10, 20, 40 and 80g/kg body weight for 120 days. In Experiment 2 three rabbits received the fresh plant in amounts of 500g daily with duration of 210 days. The animals of Experiment 1 showed no clinical signs and no macroscopic and microscopic changes characteristic of B. decumbens poisoning. In Experiment 2 the animals also showed no clinical signs or significant macroscopic alterations. Histological analysis showed isolated foamy macrophages or present in random groups of cells in the liver and mesenteric lymph nodes. Samples of liver and mesenteric lymph nodes of the rabbits of Experiment 2 were submitted to the lectin-histochemistry technique. The WGA, sWGA and RCA lectins showed reactivity in foamy macrophages in both organs. This is the first study of our knowledge that demonstrates histopathological lesions caused expetimentally by Brachiaria spp. in rabbits, demonstrating its potential as an animal model.INDEX TERMS: Experimental model, hepatogenic photosensitization, lectin histochemistry, foamy macrophages, toxicoses.

Protodioscin levels in Brachiaria spp. in a sheep production system and a brief review of the literature of Brachiaria spp. poisoning in ruminants

“…Plants of the genus Brachiaria are used in several countries as forage (Muniandy et al 2020) and cause spontaneous poisoning in cattle (Souza et al 2010), sheep (Riet-Correa et al 2011, Faccin et al 2014, 2019a, goats (Rosa et al 2016), buffaloes (De Oliveira et al 2013), and horses (Barbosa et al 2006). The poisoning was reproduced in sheep (Cruz et al 2001, Driemeier et al 2002, Saturnino et al 2010, Porto et al 2013, and rabbits (Utiumi et al 2018). The main clinical presentation of the toxicosis in all livestock species is hepatogenous photosensitization (Riet-Correa et al 2011, Collett 2019).…”

“…is responsible for the poisoning (Souza et al 2010, Ogliari et al 2018. In those instances, the protodioscin concentrations were not determined (Lemos et al 1996, Caicedo et al 2012, Rosa et al 2016, Utiumi et al 2018, and even when they were, each plant species was not analyzed separately (Mustafa et al 2012, Diamantino et al 2018, 2019a, 2019b.…”