Intoxicação natural por Brachiaria spp. em ovinos no Brasil Central

Hepatogenic photosensitization in lambs supplemented with different levels of extruded urea in Brachiaria spp. pastures in the Brazilian Cerrado: Case report

The aim was to report cases and risk factors for hepatogenous photosensitization in lambs kept on Brachiaria spp. pastures and supplemented with levels of extruded urea (EU). The herd consisted of 69 Texel crossbred lambs with known parentage (fathers and mothers adapted to the consumption of forage of the genus Brachiaria), randomly divided into 5 groups and distributed in individual paddocks for each group. The animals were supplemented with increasing levels of EU (Amireia® 200S): 0, 6, 12, 18, and 24 g of EU per 100 kg-1 of body weight (BW). The concentration of protodioscin was estimated in the mixed pastures of Brachiaria spp. (cv. Marandu and cv. Basilisk), structural components (leaf, stem, and dead material), samples of each cultivar, and in the months of December (2018), February, and April (2019). The animals were examined daily, and when behavioral changes were identified, they underwent clinical examinations and anamnesis. Weighing was performed every 14 days, followed by necropsy and serum biochemical analysis, including gamma-glutamyltransferase (GGT). The highest concentrations of protodioscin (p < 0.0001) were found in the pastures used by animals supplemented without extruded urea (7.07 ± 0.56), in the Basilisk cultivar (11.35 ± 0.06), in the leaf blade components (2.08 ± 0.05), and thatch (2.20 ± 0.00), and in the month of April (7.34 ± 0.29) (the month with the lowest rainfall), respectively. Fourteen (20.29%) cases of photosensitization were observed in lambs, of which six recovered, and eight died. Serum GGT levels ranged from 42.2 to 225 IU/L; however, in animals that died, values ranged from 209.4 to 225 IU/L. The use of levels 12 g and 18 g per 100 kg-1 of body weight of extruded urea may contribute to the lower occurrence of photosensitization, as the animals selected pastures with lower protodioscin content, presenting a smaller number of cases.

Outbreaks of Brachiaria ruziziensis and Brachiaria brizantha intoxications in Brazilian experienced cattle

Brachiaria species are some of the most used forage species for raising Brazilian cattle because of their great nutritional value and adaptability to the tropical climate. However, cases of animal intoxication have been described. Animal species, age, genetic resistance, and previous adaptation to the forage can influence the susceptibility to intoxication. Cattle (young or adults), other adult ruminants and animals adapted to consumption (experienced flocks) are considered more resistant. The main clinical presentation is that of hepatogenous photosensitization. Brachiaria brizantha and Brachiaria ruziziensis are considered less toxic. The aim of this study is to describe three outbreaks of intoxication by B. brizantha and B. ruziziensis in experienced cattle, as well as to compare the concentrations of protodioscin in paddocks with and without clinical cases. It was observed that the two forage species are toxic to all age groups of cattle adapted to their consumption, and the concentrations of protodioscin present in the plant cannot be used as the only criterion for determining the occurrence of intoxication.

Economic impact of poisoning by Brachiaria grass in lambs from birth to finishing receiving to different levels of supplementation

This study aims to evaluate the economic impact of poisoning by Brachiaria grass in lambs from birth to weaning (suckling) and from weaning to slaughter (finishing) different levels of energy protein supplementation (EPS). In addition, we estimated the economic efficiency of removing lambs from the pasture as a control measure to minimize the losses caused by Brachiaria grass poisoning. Seventy lambs were used in the suckling phase, distributed in two nutritional treatments (control and creep feeding). Hospitalization expenses were US$ 1580.80 for the control treatment and US$ 256.16 for the creep feeding treatment. In the finishing phase, 48 lambs were distributed in four nutritional treatments, which consisted of increasing levels of EPS (mineral salt, 0.8, 1.6 and 2.4% of LW). The largest difference in total revenue (US$) was observed between 2.4% of BW EPS and mineral salt (- 2300.28) treatments. Hospitalization expenses were similar between nutritional treatments, being higher in the treatment 1.6% of BW EPS (US$ 578.15). The biggest difference in gross income (US$) observed was between 2.4% of BW EPS and mineral salt (- 1439.43) treatments. The Brachiaria grass poisoning caused economic losses to the sheep farming system, due to the death of lambs, reduced weight gain and lower weights at weaning and in the finishing phase. Brachiaria grass poisoning caused economic damage to the production system. There were direct losses, with the death of the lambs without supplementation, in the suckling and finishing phases. The supplementation increases the performance and reduces the mortality. The supplementation in high levels is efficient in reducing the economic impact of poisoning by Brachiaria grass in both periods of suckling and finishing.

Natural intoxication caused by protodioscin in lambs kept in Brachiaria pastures

Protodioscin poisoning of Brachiaria spp. has been a serious problem for lambs in grazing systems. The defoliation process can stimulate the appearance of new leaves and, the younger leaves have a lower concentration of protodioscin. Thus, it was aimed to assess the effect of different leaf offerings on the protodioscin content in forage and if protodioscin can interfere with the dry matter intake (DMI) and on metabolic and productive parameters of lambs. Twelve tester lambs (average weight 17.5 ± 3.48 kg) were divided into four groups of different levels of dry leafy matter (60, 75, 90, or 105 g/kg body weight). In addition to these, 33 regulator lambs were used as needed to adjust the leaf offerings of pasture. The animals were divided and kept in 12 paddocks, each with a tester lamb. The DMI was estimated using chromic oxide as an external marker. In vitro digestibility and degradation kinetics and ruminal, blood, and urinary parameters were measured in the forage sampled by the hand plucking method. The protodioscin concentration in forage was determined by high-performance liquid chromatography. The DMI increased linearly as a result of the supply of leaves. However, the protodioscin content and its consumption showed a quadratic behavior. There was no effect of leaf supply on in vitro digestibility, in vitro degradation kinetics of forage, and on ruminal, blood, and urinary parameters of lambs. However, a negative correlation was observed between the DMI and the concentration of protodioscin at the highest level of leaf supply. This is due to the fact that in the most intense grazing, there is a stimulus for greater regrowth; therefore, there was an increase in the concentration of protodioscin in forages in older forages. Protodioscin poisoning was confirmed by urinary and blood parameters.

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

ABSTRACT: Plants of the genus Brachiaria, used in several countries as forage, are poisonous to some livestock species. Their toxic principle is protodioscin, and the main form of clinical presentation of the toxicosis is hepatogenous photosensitization. Here we compare protodioscin levels in B. decumbens and B. brizantha and review the literature on the concentrations and methodologies of collection and analysis of the toxic principle in Brachiaria spp. and the risk of contamination of pastures by more toxic species that may facilitate poisoning by plants of this genus in sheep. The experiment was conducted in pastures originally formed by B. brizantha, with many B. decumbens invasion points. The occurrence of cases of poisoning by Brachiaria spp. was the criterion for confirming pasture toxicity. The forage samples were collected at ten random points every 28 days through manual grazing simulation. The samples were analyzed for protodioscin by high-performance liquid chromatography (HPLC) with light scattering by evaporation (ELSD) after being dried and crushed. In the flock of 69 sheep, five poisoning cases occurred, three sheep died, and two recovered. The protodioscin levels found in the evaluated pastures ranged from 0.70 to 0.45%; higher levels appeared in B. decumbens (7.09%) compared to 1.04% in B. brizantha. We suggest that Brachiaria spp. should be avoided in pastures where sheep are grazing.

Photosensitization by Brachiaria ruziziensis in a sheep herd

Some species of the genus Brachiaria are cultivated worldwide in tropical and subtropical climate regions as the main feed for ruminants. Several studies report photosensitization by Brachiaria decumbens, Brachiaria brizantha, and Brachiaria humidicola, but the poisoning by Brachiaria ruziziensis have been reported only twice. Cutaneous and hepatic lesions may be caused by the steroidal saponins present in the leaves or by the mycotoxin sporidesmin produced by the saprophyte fungus Pithomyces chartarum. The present report describes the clinical and pathological changes observed in an outbreak of hepatogenic photosensitization in sheep kept in B. ruziziensis pastures. In addition, the present study will provide a better understanding of the etiology of this photosensitization through the evaluation of the saponin protodioscin and the spore count of P. chartarum. Santa Inês and Lacaune mixed-breed sheep showed signs of photosensitization after feeding B. ruziziensis. Clinical signs included jaundice, apathy, dehydration, and photosensitization characterized by facial edema and cutaneous scars, especially in the ears. Pathological examination of the liver revealed diffuse infiltrates of foamy cells, rare multinucleated cells, and mild enlargement of hepatocytes (megalocytosis). The skin showed acute epidermal and dermal necrosis with occlusive thrombi. B. ruziziensis showed low levels of protodioscin (0.020 ± 0.024% in mature leaves and 0.065 ± 0.084% in sprouts) but high P. chartarum spore counts (mean of 479,844 ± 443,951 spores/g plant). Thus, sheep grazing B. ruziziensis pastures must be closely monitored because of the risk of photosensitization.

Poisoning by Brachiaria spp. in various lamb breeds at increasing levels of supplementation during growth

ABSTRACT: The study evaluate the frequency of poisoning by Brachiaria spp. at the rearing, growth and termination stages in various lamb breeds at increasing supplementation levels. Forty-five lambs were used in the growth phase in pastures of Brachiaria spp. with a history of having induced poisoning. The lambs were distributed in nutritional treatments: lambs receiving mineral supplementation (MS), energy/protein supplementation (EPS) at 0.8% of body weight (bw), EPS at 1.6% bw and EPS at 2.4% bw. The lambs were allotted two flocks (F1 and F2) of 21 and 24 lambs each. Clinical signs of poisoning were observed in all treatments. All MS lambs died. The frequency of poisoning were highest in the 0.8% EPS and 1.6% EPS treatments. All lambs in the 2.4% EPS treatment recovered. F1 lambs had a higher frequency of poisoning than F2 lambs regardless of nutritional treatment. Morbidity rates for the F1 and F2 lambs were 52.3 and 16.7%, respectively. Supplementation was not sufficient to decrease the frequency of poisoning in lambs at the termination stage, which was dependent on the genetic origin of the lambs. EPS of 2.4% bw treatment, was an efficient nutritional strategy to minimize the effects of poisoning in lambs fed on Brachiaria spp.

Comparison of two collection methods to determine protodioscin concentrations in Brachiaria spp. and to monitor Brachiaria spp. Poisoning

ABSTRACT: The objective of this study was to evaluate the methods of collecting Brachiaria spp. (Simulated Grazing vs. Total Collection) for the determination of protodioscin concentrations and to monitor the intoxication in sheep susceptible and resistant to poisoning by Brachiariaspp. The collection of Brachiaria spp. was done through two different methods. The first one consisted in throwing a metallic square at 10 random picket points. The second was performed simulating, with the hands, the grazing behavior of sheep. The leaf blades obtained by the two methods were conditioned in a forced ventilation oven. The extraction and quantification of protodioscin from the dry milled plant material was done by reverse-phase high-performance liquid chromatography (HPLC). The collections were carried out at three stages of the life of experimental lamb (suckling, rearing, and finishing). The lambs were divided into resistant and susceptible to intoxication by Brachiaria spp. The criterion for a lamb to be considered sensitive was to present some clinical signs at some stage of its life. No significant differences were observed between the general averages of the two collections when the evaluation was done in the whole period. However, a significant difference was found at the onset of the clinical signs. The concentrations of protodioscin in this period were higher in Brachiaria spp. collected by the simulating grazing method. Both methodologies were efficient to determine the level of protodioscin in the pastures of Brachiaria spp. However, during the periods when the outbreaks occurred, the simulated grazing method was more reliable.

Experimental poisoning by Brachiaria decumbens in rabbits

ABSTRACT: 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.

Intoxicação espontânea por Brachiaria híbrida cv mulato I em ovinos e caprinos e experimental por Brachiaria híbrida cv mulato II em ovinos

RESUMO: Descreve-se a epidemiologia, sinais clínicos e lesões de uma enfermidade em ovinos e caprinos que cursa com fotossensibilização e morte. A doença espontânea ocorreu no município de Abelardo Luz, SC. De um rebanho de 350 ovinos e 278 caprinos, de corte, mantidos em pastagem de Brachiaria híbrida cv mulato I, adoeceram 27 animais, dos quais, 17 morreram e 10 recuperaram-se após terem sido removidos do local. A enfermidade caracterizou-se por lacrimejamento, hiperemia, edema das faces, das orelhas e das pálpebras seguidas de formação de crostas, corrimento nasal seroso, ulcerações na córnea e esclera e conjuntiva levemente amarelada. Seis ovinos e onze caprinos foram necropsiados na propriedade. As lesões macroscópicas observadas foram fígado de coloração castanha, vesícula biliar com conteúdo aumentado e bile grumosa, rins acastanhados com pontos vermelhos na superfície. Na avaliação microscopia foram observadas no fígado, lesões de intensidade leve a moderada caracterizadas principalmente por tumefação e ou, vacuolização de hepatócitos, megalocitose, fibrose periportal, proliferação biliar, pequenos aglomerados de macrófagos, aleatórios e infiltrado de eosinófilos, neutrófilos e macrófagos na periferia do lóbulo. Na luz de ductos biliares encontravam-se imagens negativas de cristais. Nos rins havia dilatação de túbulos variando de leve a acentuada, contração de tufo glomerular e distensão do espaço de Bowman. Quatro ovinos receberam experimentalmente Brachiaria híbrida cv mulato II ad libitum pelo período de 90 dias e não manifestaram alterações clinicas.

Spontaneous poisoning by Brachiaria decumbens in goats

Abstract: An outbreak of Brachiaria decumbens poisoning in goats in the state of Mato Grosso do Sul, Brazil, is described. Out of a herd of about 1,000 goats, seven goats died after showing photosensitivity (3 out 7 goats) and icterus (4/7). Other clinical signs included lethargy, dehydration and weight loss (7/7). At necropsy there was either hepatomegaly or liver atrophy; orange, yellow or gray discoloration - were observed in the liver of six goats. Two had accentuation of lobular pattern and punctate, linear or stellar fibrous depressions were randomly distributedover the capsular surface. Macroscopic changesattributedto liver failure consisting of hydropericardium (2/7) and ascites (2/7) were observed. Histologically, there was accumulation of refringent crystals in the bile ducts and infiltration of foamy macrophages in the liver of all goats. Foamy macrophages were also present in the hepatic and mesenteric lymph nodes of two goats. The diagnosis of B. decumbens poisoning was based on epidemiology, clinical signs, necropsy findings and histopathology.

Identification of lamb flocks susceptible and resistant against Brachiaria poisoning

Abstract: This study was designed to assess the influence of genetic resistance against brachiaria poisoning in sheep. Two groups of sheep, one identified as susceptible (formed by two ewes and one ram) and the other as resistant against brachiaria poisoning (formed by three ewes and one ram) were selected. Sheep considered susceptible were those that presented clinical signs of brachiaria poisoning at any time of their life; resistant sheep were those that even raised on Brachiaria spp. pastures, did not developed any sign of the poisoning during their life. The offspring of the two flocks (15 lambs from the sensitive flock and 9 lambs from the resistant flock) were placed into brachiaria pasture (initially Brachiaria decumbens and B. brizantha,and only B. decumbens after weaning) and followed up during two years (2013-2014). The determination of protodioscin levels in B. decumbens pasture was performed only in 2014 and revealed significant amounts of the toxic principle. Eleven lambs of the susceptible group were affected to some degree of brachiaria poisoning and six died; no lamb of the resistant group was affected. Clinical signs consisted of varying degrees of subcutaneous edema of the face and, erythema and loss of hair of the ears, crusts on the skin of ears, around the eyes and on planum nasale, scar deformation of the ears, and bilateral ocular discharge; affected lambs also sought for shadowy shelters and they were poor doers. Several sheep recovered from the condition and then relapsed. Necropsy findings in six lambs included pale mucous membranes, emaciation, dermatitis, scar deformation of the ears, large yellow livers with marked lobular pattern, and moderate infestation by Haemonchus contortus. Histologically the liver lesions were similar in all necropsied lambs but with varying degrees of severity; they were consistent with brachiaria poisoning and included architectural disruption of hepatocellular trabecula, clusters of foamy macrophages occasionally forming multinucleated giant cells, swollen and vacuolated hepatocytes, crystals or negative images of crystals in the biliary system, bilestasis, bile duct proliferation and lymphoplasmacytic infiltrate in portal triads. The skin lesions were those of photodermatitis and included epidermal necrosis, hyperkeratosis and dermal neutrophilic infiltrate. The results of this study allow to conclude that there is a genetic related resistance to brachiaria poisoning in sheep since the progeny of resistant sheep did not manifest the poisoning. The use of resistant flocks in brachiaria pastures is suggested as a valuable option for the prevention of brachiaria poisoning in sheep.

Avaliação da exposição solar na intoxicação experimental por Brachiaria decumbens em ovinos

Foram utilizados 26 ovinos, entre 3 e 4 meses de idade, divididos em 3 grupos, provenientes de rebanhos que nunca tiveram contato com pastos de Brachiaria spp.. Dois grupos receberam Brachiaria decumbens no cocho diariamente ad libitum, sendo que um deles permaneceu em área com exposição solar (GS) e o outro foi mantido em baias cobertas protegidos do sol (GSB). O grupo controle (GC) foi também mantido em local com exposição solar e alimentado com feno de Cynodon dactylon e capim Pennisetum purpureum triturado. Todos os grupos receberam alimentação em cochos e foram suplementados com 200g/dia/animal de ração comercial para ovinos. Foi realizada a avaliação clínica diária dos ovinos e colhidas amostras duas vezes por semana para dosagem sérica de AST e GGT. Os animais que morreram foram submetidos a necropsia e em todos os ovinos sobreviventes foi realizada biópsia hepática no final do experimento. Três animais do grupo GS adoeceram e dois morreram. Um ovino do grupo GSB adoeceu e morreu. Não houve alterações clínicas nos ovinos controles. Os principais sinais clínicos observados nos animais que adoeceram foram apatia, emagrecimento, fotofobia, hiperemia e secreção ocular e icterícia. Nenhum animal apresentou lesões cutâneas de fotossensibilização. O grupo que permaneceu no sol apresentou atividades séricas médias de AST e GGT significativamente maiores que a dos demais grupos (p<0,05) e os animais que permaneceram na sombra apresentaram níveis maiores de GGT (p<0,05) em comparação ao grupo controle. A histopatologia das amostras de fígados dos ovinos com sinais clínicos demonstrou tumefação e vacuolização de hepatócitos, necrose individual de hepatócitos, macrófagos espumosos com cristais birrefringentes intracitoplasmáticos e dentro de ductos biliares e infiltrado mononuclear periportal. Amostras do capim fornecidas aos cordeiros evidenciaram níveis médios de 0,94±0,80% da saponina protodioscina. As observações do presente experimento sugerem que a não exposição ao sol não evita a presença de sinais clínicos da intoxicação, mas que a exposição solar exacerba os sinais clínicos.