Comparison of the acute toxicity of zygacine versus zygadenine.

Foothill death camas (Zigadenus paniculatus) is a common poisonous plant found throughout western North America. The toxic alkaloids in foothill death camas are zygadenine, esters of zygadenine, with zygacine, the 3-acetyl ester of zygadenine, often being the most abundant. Two additional esters of zygadenine that are found primarily in the floral parts of foothill death camas are 3-angeloylzygadenine and 3-veratroylzygadeine. Recent research has shown that very little zygacine is detected in the blood of animals dosed with zygacine. A recent investigation into the metabolism of zygacine demonstrated that zygacine is rapidly metabolized to zygadenine, demonstrating a clear first pass effect. The objective of this study was to determine if there is a difference in the acute toxicity of zygacine and zygadenine to mice and sheep. Additionally, two other esters of zygadenine, 3-angeloylzygadenine and 3-veratroylzygadenine, were evaluated for their acute toxicity in a mouse IV LD50 assay. All three esters of zygadenine tested were more toxic than zygadenine, with the following rank order of toxicity in the mouse IV LD50 assay: zygadenine-HCl (59.5 mg/kg) < zygacine-HCl (1.6 mg/kg) < angeloylzygadenine-HCl (1.0 mg/kg) < veratroylzygadenine-HCl (0.5 mg/kg). Similar to the results of the mouse experiments, zygacine-HCl was significantly more toxic than zygadenine-HCl in sheep dosed IV with pure compounds. Sheep dosed with 1.25 mg/kg zygacine-HCl showed severe clinical signs of poisoning. Whereas a dose of 12.5 mg/kg zygadenine-HCl was required to elicit a similar onset and severity of clinical signs. Overall, these data indicate that zygacine is more toxic than zygadenine when administered IV, when first pass metabolism is bypassed.

The use of earwax to determine livestock exposure to teratogenic lupine.

Lupines (Lupinus spp.) are a common plant species on western U.S. rangelands with several lupine species containing alkaloids that can be toxic and/or teratogenic to livestock. In North America, more than 150 lupine species are recognized with some ranches or grazing allotments containing multiple species. One or more of these lupine species may contain alkaloids that are teratogenic to cattle. Previous work has shown that lupine alkaloids can be detected in earwax of cattle grazing lupine infested rangelands. Our hypothesis is that earwax can be used to determine if cattle have been exposed to teratogenic alkaloids from multiple lupine species. Two lupine species, L. sericeus and L. polyphyllus, were present on a rangeland in east-central Idaho. The teratogen, anagyrine, was detected in L. sericeus and the teratogen, ammodendrine, was detected in L. polyphyllus plants collected on this rangeland. In this study, earwax was collected from 69 pregnant cows that had previously grazed a rangeland containing two different lupine species containing alkaloids that cause crooked calf syndrome (CCS). Anagyrine was detected in the earwax of all 69 cows sampled. Ammodendrine, was detected in the earwax of 28 of the 69 cows sampled. Earwax is a good non-invasive sample to aid in the diagnosis of cattle that have consumed lupine and does appear, in this case, to be a good diagnostic tool to differentiate between more than one lupine species that may be the cause of CCS. Concentrations of anagyrine or ammodendrine did not correlate with the incidence of CCS.

Lupine-induced crooked calf syndrome: mitigation through intermittent grazing management of cattle.

Lupines are responsible for a condition in cattle referred to as "crooked calf syndrome" (CCS) that occurs when pregnant cattle graze teratogenic lupines. A proposed management strategy to limit these types of birth defects includes utilizing an intermittent grazing schedule to allow short durations of grazing lupine-infested areas interrupted by movement to a lupine-free pasture. The objective of this study was to determine if an intermittent schedule of ten continuous days of lupine treatment followed by 5 d off treatment would be sufficient to decrease, or prevent, the incidence of lupine-induced malformations. Continuous dosing of the teratogenic lupine (Lupinus leucophyllus) to pregnant cows for 30 d during the most susceptible stage of pregnancy (gestation days 40 to 70) resulted in severe skeletal birth defects in their calves. However, intermittent dosing of the teratogenic lupine demonstrated that interrupted intake of lupine reduced the severity, or eliminated, permanent skeletal malformations in calves born to cows dosed lupine. Toxicokinetic and ultrasound data demonstrated a clear inverse correlation between serum anagyrine (the primary teratogenic alkaloid in some lupines) concentrations in the dam and fetal movement. In the intermittent group, fetal movement quickly returned to normal after lupine feeding stopped and remained normal until lupine treatment resumed. Therefore, interrupting lupine intake for at least 5 d through an intermittent grazing program could reduce the severity of the CCS. Furthermore, this method would allow ranchers to move cattle back into lupine pastures after a brief interruption, which would allow for more efficient utilization of forage resources.

Japanese Yew (Taxus) poisoning of wild ungulates in Utah during the winter of 2022-2023.

Taxus is a genus of coniferous shrubs and trees, commonly known as the yews, in the family Taxaceae. All species of yew contain taxine alkaloids, which are ascribed as the toxic principles. Anecdotally, free ranging ruminants such as antelope, deer, elk, and moose have been regarded as tolerant to yew. Herein several cases of intoxication of deer, elk, and moose by yew from the state of Utah in the winter of 2022-2023 are documented. Ingestion of yew was documented by three means among the poisoned cervids; plant fragments consistent with yew were visually observed in the rumen contents, chemical analysis, and subsequent detection of the taxines from rumen and liver contents, and identification of exact sequence variants identified as Taxus species from DNA metabarcoding. Undoubtedly, the record snowfall in Utah during the winter of 2022-2023 contributed to these poisonings.

Acute death as a result of poisoning tropical (Bos taurus indicus) but not temperate (Bos taurus taurus) cattle after oral dosing with Lupinus leucophyllus (velvet lupine).

Due to climate change and increasing summer temperatures, tropical cattle may graze where temperate cattle have grazed, exposing tropical cattle to toxic plants they may be unfamiliar with. This work compared the toxicity of Lupinus leucophyllus (velvet lupine) in temperate and tropical cattle. Orally dosed velvet lupine in tropical cattle caused death. If producers opt to graze tropical cattle, additional care must be taken on rangelands where toxic lupines like velvet lupine grow.

Consequences of pollen defense compounds for pollinators and antagonists in a pollen-rewarding plant.

Plants produce an array of defensive compounds with toxic or deterrent effects on insect herbivores. Pollen can contain relatively high concentrations of such defense compounds, but the causes and consequences of this enigmatic phenomenon remain mostly unknown. These compounds could potentially protect pollen against antagonists but could also reduce flower attractiveness to pollinators. We combined field observations of the pollen-rewarding Lupinus argenteus with chemical analysis and laboratory assays to test three hypotheses for the presence of pollen defense compounds: (1) these compounds are the result of spillover from adjacent tissues, (2) they protect against pollen thieves, and (3) they act as antimicrobial compounds. We also tested whether pollen defense compounds affect pollinator behavior. We found a positive relationship between alkaloid concentrations in pollen and petals, supporting the idea that pollen defense compounds partly originate from spillover. However, pollen and petals exhibited quantitatively (but not qualitatively) distinct alkaloid profiles, suggesting that plants can adjust pollen alkaloid composition independently from that of adjacent tissues. We found no relationship between pollen alkaloid concentration and the abundance of pollen thieves in Lupinus flowers. However, pollen alkaloids were negatively associated with bacterial abundance. Finally, plants with more alkaloids in their pollen received more pollinator visits, but these visits were shorter, resulting in no change in the overall number of flowers visited. We propose that pollen defense compounds are partly the result of spillover from other tissues, while they also play an antimicrobial role. The absence of negative effects of these compounds on pollinator visitation likely allows their maintenance in pollen at relatively high concentrations. Taken together, our results suggest that pollen alkaloids affect and are mediated by the interplay of multiple interactions.

Ruminant metabolism of zygacine, the major toxic alkaloid in foothill death camas (Zigadenuspaniculatus).

Death Camas (Zigadenus spp.) are common poisonous plants distributed throughout North America. The toxic alkaloids in foothill death camas are zygadenine and a series of zygadenine esters, with zygacine, the 3-acetyl ester of zygadenine, being the most abundant. Both cattle and sheep can be poisoned by grazing death camas, however, sheep consume death camas more readily and are most often poisoned. We hypothesized that the presence of enzymes, including esterases present in the rumen, liver, and blood of livestock would metabolize zygacine. The objective of this study was to investigate the metabolism of zygacine in sheep and cattle using in-vitro and in-vivo systems. Results from experiments where zygacine was incubated in rumen culture, plasma, liver S9 fractions, and liver microsomes and from the analysis of rumen and sera from sheep and cattle dosed death camas plant material demonstrated that zygacine is metabolized to zygadenine in the rumen, liver and blood of sheep and cattle. The results from this study indicate that diagnosticians should analyze for zygadenine, and not zygacine, in the rumen and sera for the diagnosis of livestock suspected to have been poisoned by foothill death camas.

Biomarkers and their potential for detecting livestock plant poisonings in Western North America.

The United States National Cancer Institute defines a biomarker as: "A biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease." In Veterinary Medicine, biomarkers associated with plant poisonings of livestock have great utility. Since grazing livestock poisoned by toxic plants are often found dead, biomarkers of plant poisoning allow for a more rapid postmortem diagnosis and response to prevent further deaths. The presence and concentration of toxins in poisonous plants are biomarkers of risk for livestock poisoning that can be measured by the chemical analysis of plant material. More difficult is, the detection of plant toxins or biomarkers in biological samples from intoxicated or deceased animals. The purpose of this article is to review potential biomarkers of plant poisoning in grazing livestock in the Western North America including recently investigated non-invasive sampling techniques. Plants discussed include larkspur, lupine, water hemlock, swainsonine-containing plants, selenium-containing plants, and pyrrolizidine alkaloid containing plants. Other factors such as animal age and sex that affect plant biomarker concentrations in vivo are also discussed.

Phylogenetic patterns of bioactive secondary metabolites produced by fungal endosymbionts in morning glories (Ipomoeeae, Convolvulaceae).

Heritable fungal endosymbiosis is underinvestigated in plant biology and documented in only three plant families (Convolvulaceae, Fabaceae, and Poaceae). An estimated 40% of morning glory species in the tribe Ipomoeeae (Convolvulaceae) have associations with one of two distinct heritable, endosymbiotic fungi (Periglandula and Chaetothyriales) that produce the bioactive metabolites ergot alkaloids, indole diterpene alkaloids, and swainsonine, which have been of interest for their toxic effects on animals and potential medical applications. Here, we report the occurrence of ergot alkaloids, indole diterpene alkaloids, and swainsonine in the Convolvulaceae; and the fungi that produce them based on synthesis of previous studies and new indole diterpene alkaloid data from 27 additional species in a phylogenetic, geographic, and life-history context. We find that individual morning glory species host no more than one metabolite-producing fungal endosymbiont (with one possible exception), possibly due to costs to the host and overlapping functions of the alkaloids. The symbiotic morning glory lineages occur in distinct phylogenetic clades, and host species have significantly larger seed size than nonsymbiotic species. The distinct and widely distributed endosymbiotic relationships in the morning glory family and their alkaloids provide an accessible study system for understanding heritable plant-fungal symbiosis evolution and their potential functions for host plants.

Cestrum axillare (Solanaceae) poisoning in ruminants.

Cestrum axillare poisoning causes significant economic losses in farms of ruminant production due to a fatal acute hepatic disease. The consumption of C. axillare occurs on farms or pastures with a scarcity of feed or with dry forage. Epidemiological, clinical, and pathological data of poisoning outbreaks by C. axillare from 1953 to 2021 in grazing ruminants in southeastern Brazil are reported. A total of 68 bovines, two buffaloes, and two goats exhibited clinical signs and resulted in death due to C. axillare consumption, with 79% of the cases occurring during the dry period. Clinical signs were apathy, anorexia, ruminal arrest, arched back, and constipation with hard stools, sometimes with blood or mucus. Cases with neurological signs due to hepatic encephalopathy showed excitement, aggressiveness, drooling, staggering, and muscle tremors. The pathological findings included hepatocellular necrosis in the liver and microcavitations in the brain's white matter (status spongiosus). The hepatotoxins, carboxyparquin and parquin, were detected in C. axillare leaf samples collected from paddocks grazed by cattle in three southeastern Brazilian municipalities where outbreaks of C. axillare poisoning occurred. This is the first report of parquin and carboxyparquin in C. axillare.

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.

Indole-diterpenes alkaloid profiles of native grasses involved in tremorgenic syndromes in the Argentine Patagonia.

One of the main intoxications to livestock in the Patagonia region of Argentina is the tremorgenic disease "Mal de Huecú", attributed to the consumption of the native grasses Poa huecu and/or Festuca argentina. In this report, five outbreaks of spontaneous intoxications were investigated. Several indole-diterpene alkaloids were identified in Poa huecu and Festuca argentina including the known tremorgen terpendole C and are likely the cause of "Mal de Huecú" disease.

Identification of two death camas chemotypes within a population and evaluation of toxicity.

Foothill death camas (Zigadenus paniculatus) is a native, cool-season, bulbous perennial forb found throughout the western U.S. The toxins in death camas are steroidal alkaloids. Zygacine is often the most abundant alkaloid in death camas and is believed to be the primary toxic component. A population of death camas with plants consisting of two different chemical profiles (chemotypes) growing within the same location were identified. The objective of this study was to determine the percentage of a death camas population represented by each of the different chemotypes and to determine if there was a difference in toxicity between the two chemotypes. One third of the population sampled consisted of chemotype 1, while two-thirds of the population consisted of chemotype 2. The zygacine concentration of chemotype 1 was three times higher than chemotype 2. Chemotype 2 contained higher concentrations of several other steroidal alkaloids than chemotype 1. We hypothesized that chemotype 1, which consisted of higher concentrations of zygacine, would be more toxic than chemotype 2. The acute toxicity of each chemotype was determined in mice and sheep. In the mouse LD50 study, the acute toxicity of the chemotype 1 alkaloids (2.3 mg/kg BW) was different than the chemotype 2 alkaloids (3.2 mg/kg BW). However, in the sheep study there were no differences in the adverse effects between chemotypes. Based upon the results of this study, caution should be taken when livestock are grazing death camas, as both chemotypes of death camas appear to pose a similar risk to grazing livestock.

Evaluation of diazepam as a drug treatment for water hemlock (Cicuta species) poisoning in Spanish goats.

Water hemlocks (Cicuta spp.) are toxic members of the Apiaceae plant family. The best drug treatment for the convulsions associated with acute water hemlock poisoning in livestock and humans has not been determined experimentally. This work compared the therapeutic actions of benzodiazepines (diazepam) and barbiturates (phenobarbital) on water hemlock poisoning in a goat model. C. maculata tubers were orally dosed to goats. Experimental groups consisted of; control saline; 20 mg/kg phenobarbital; 1.0 mg/kg diazepam; 10 mg/kg diazepam; and 1.0 mg/kg diazepam administered as needed to moderate convulsions by intravenous (i.v.) infusion. Diazepam provided nearly instant control of convulsions. Clinical signs of poisoning were completely controlled for the duration of the experiment in the goats that received the 10 mg/kg diazepam dose. These results suggest that diazepam is effective at managing the clinical signs of water hemlock poisoning in goats. We speculate that diazepam can be used as a potential treatment for water hemlock poisoning in other livestock species and humans.

Endemic Xanthium strumarium poisoning in cattle in flooded areas of the Araguari River, Minas Gerais, Brazil.

In this paper, we describe poisoning outbreaks of Xanthium strumarium in cattle on the borders of the Araguari River, Southeastern Brazil. In this region, several hydroelectric plants promote transient flooding, which creates a favorable environment for the invasion of X. strumarium in extensive areas, often as the predominant species in those areas. The outbreaks occurred between July and September (dry season). Bovines of all ages were affected, including suckling animals. Mortality varied from 2% to 5.5%. The animals exhibited ataxia, weakness, loss of balance, recumbency, and the majority were found dead. Laboratory results showed a marked increase in the serum activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and gamma-glutamyltransferase. Histological and ultrastructural changes in the liver consisted of centrilobular necrosis and hemorrhage. On toxicological evaluation, the dicotyledons contained 0.30 µg/mg of atractyloside and 0.37 µg/mg of carboxyatractyloside. Considerable economic loss has occurred in this region due to the lack of knowledge regarding X. strumarium as a toxic plant and its adaptation to the environmental and climatic conditions of the region, which have made the condition endemic.

Use of Herbarium Voucher Specimens To Investigate Phytochemical Composition in Poisonous Plant Research.

Poisonous plants cause large losses to the livestock industry through death, reduced production efficiency, reproductive dysfunction, and compromised harvesting of rangeland and pasture forages. Research investigating poisonous plants is complex because there are hundreds of genera of toxic plants representing thousands of species. To investigate the effects of poisonous plants on livestock, a clear understanding of the taxonomic identity of the plant and the ability to collect the plant in sufficient quantities for scientific studies is required. Subsequently, the active principles must be defined and investigated in the taxa of interest to better predict risk and make recommendations to reduce losses. Herbaria are collections of preserved plant specimens and are an important resource in poisonous plant research. Voucher specimens have often been used in the identification of the plant for the experimental reproduction of suspected livestock poisoning associated with a spontaneous case. More recently, herbarium specimens have been used to investigate the chemical composition of toxic plants as well as the distribution of different chemotypes over the landscape. The primary purpose of this review is to highlight the chemical analysis of herbarium specimens in poisonous plant research.

Clinical, pathologic, and toxicologic characterization of Salvia reflexa (lance-leaf sage) poisoning in cattle fed contaminated hay.

Salvia reflexa (lance-leaf sage)-contaminated alfalfa hay was fed to ~500 mixed-breed beef cattle. Within hours of exposure, nearly half of the cattle developed lethargy, anorexia, depression, and recumbency, followed by bellowing, colic, and death. Even though the uneaten contaminated hay was removed the first day, nearly 100 animals died within the first 48 h. Three of these cattle were examined postmortem, and tissues and hay samples were collected for microscopic and chemical analysis. Several days later, a smaller number of the clinically poisoned cattle developed neurologic disease with aberrant behavior, aggression, icterus, blindness, exhaustion, and death. A total of 165 cattle were fatally poisoned. Poisoned cattle had swollen, dark, mottled livers that had a prominent nutmeg-like lobular pattern on cut section. Histologically, there was severe centrilobular-to-panlobular hepatic necrosis with marked hepatocellular swelling, degeneration, and necrosis. The surviving cattle developed liver disease characterized by altered serum biochemical analyses and microscopic hepatocellular degeneration and necrosis. In subsequent biopsies and analysis, these lesions resolved within 6-7 mo. After confirming toxicity of the hay in cattle, goats, and mice, followed by a mouse bioassay-guided chemical fractionation process, Salvia reflexa was identified as the contaminant in the hay responsible for the hepatotoxicity. S. reflexa has not been reported previously to cause fatal hepatotoxicity in livestock in North America, to our knowledge.

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.

RESUMO: Plantas do gênero Brachiaria, utilizadas em vários países como forragem, são tóxicas para várias espécies pecuárias. Seu princípio tóxico é a protodioscina, e a principal forma de apresentação clínica da toxicose é a fotossensibilização hepatógena. Este estudo teve como objetivo comparar os níveis de protodioscina em B. decumbens e B. brizantha e revisar a literatura sobre as concentrações e metodologias de coleta e análise do princípio tóxico em Brachiaria spp. e o risco de contaminação das pastagens por espécies mais tóxicas que podem facilitar a intoxicação por plantas desse gênero em ovinos. O experimento foi conduzido em pastagens originalmente formadas por B. brizantha, com diversos pontos de invasão por B. decumbens. Ocorrência de casos de intoxicação por Brachiaria spp. foi o critério para confirmação da toxicidade da pastagem. As amostras de forragem foram coletadas a cada 28 dias em dez pontos aleatórios por meio de simulação de pastejo manual. As amostras foram analisadas para protodioscina por cromatografia líquida de alta eficiência (HPLC) com dispersão de luz por evaporação (ELSD) após serem secadas e trituradas. No rebanho de 69 ovelhas, cinco desenvolveram a intoxicação, três morreram e duas se recuperaram. Os níveis de protodioscina encontrados nas pastagens avaliadas variaram de 0,70 a 0,45%; níveis mais elevados apareceram em B. decumbens (7,09%) em comparação com 1,04% em B. brizantha. Sugerimos que Brachiaria spp. deve ser evitada no pasto de ovelhas em pastejo.

Protodioscin levels in Brachiaria spp. in a sheep production system and a brief review of the literature of Brachiaria spp. poisoning in ruminants / Níveis de protodioscina em Brachiaria spp. em um sistema de produção de ovinos e uma breve revisão da literatura da intoxicação por Brachiaria spp. em ruminantes

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.(AU)

Plantas do gênero Brachiaria, utilizadas em vários países como forragem, são tóxicas para várias espécies pecuárias. Seu princípio tóxico é a protodioscina, e a principal forma de apresentação clínica da toxicose é a fotossensibilização hepatógena. Este estudo teve como objetivo comparar os níveis de protodioscina em B. decumbens e B. brizantha e revisar a literatura sobre as concentrações e metodologias de coleta e análise do princípio tóxico em Brachiaria spp. e o risco de contaminação das pastagens por espécies mais tóxicas que podem facilitar a intoxicação por plantas desse gênero em ovinos. O experimento foi conduzido em pastagens originalmente formadas por B. brizantha, com diversos pontos de invasão por B. decumbens. Ocorrência de casos de intoxicação por Brachiaria spp. foi o critério para confirmação da toxicidade da pastagem. As amostras de forragem foram coletadas a cada 28 dias em dez pontos aleatórios por meio de simulação de pastejo manual. As amostras foram analisadas para protodioscina por cromatografia líquida de alta eficiência (HPLC) com dispersão de luz por evaporação (ELSD) após serem secadas e trituradas. No rebanho de 69 ovelhas, cinco desenvolveram a intoxicação, três morreram e duas se recuperaram. Os níveis de protodioscina encontrados nas pastagens avaliadas variaram de 0,70 a 0,45%; níveis mais elevados apareceram em B. decumbens (7,09%) em comparação com 1,04% em B. brizantha. Sugerimos que Brachiaria spp. deve ser evitada no pasto de ovelhas em pastejo.(AU)

Fatal stagger poisoning by consumption of Festuca argentina (Speg.) Parodi in goats from Argentine Patagonia.

The present study describes the spontaneous and experimental poisoning of goats by Festuca argentina in Argentine Patagonia. In April 2017, eight seven-month-old Creole male goats were accidentally introduced into a paddock that contained F. argentina. After four days, two of the goats were found dead and four out of the six remaining goats were clinically affected. Two of the latter had to be later euthanized in extremis. The main clinical signs were progressive nervous signs, starting with moderate muscle tremors, wide-based stance and ataxia. Postmortem examination was performed on the two euthanized goats. Epidermal fragments of F. argentina were found in the rumen samples from the necropsied goats and the fecal samples from the four affected goats. For the experimental poisoning, fresh sheaths of F. argentina collected from the paddock were offered to two goats at 10 g/kg body weight for 3 days. After 24-36 h, both animals exhibited severe muscle tremors, reluctance to move, tetanic convulsions, and opisthotonus. In both the spontaneously and experimentally poisoned goats, gross lesions were similar and consisted of dehydration, petechial hemorrhages in the epicardium and congestion. The main microscopic findings consisted of degeneration and loss of Purkinje cells and torpedoes in the granular layer of the cerebellum. The F. argentina sheaths collected from the pasture were found to contain tremorgenic indole-diterpene alkaloids. Taken together, the results of the present study suggest that the tremorgenic syndrome observed in the spontaneously poisoned goats was due to poisoning by F. argentina.