Changes in swainsonine, calystegine, and nitrogen concentrations on an annual basis in Ipomoea carnea

A review on mycotoxins and mycotoxicoses in ruminants and Equidae in South America

Of the mycotoxicoses caused by molds contaminating grains or their byproducts, leukoencephalomalacia of horses and less frequently aflatoxicosis in cattle have been reported in South America. However, the most important group of mycotoxins in the region are those caused by fungi that infect forages and other types of plants and have regional distribution. In this group, ergotism is important, both caused by Claviceps purpurea infecting grains or by Epichloë coenophiala infecting Schedonorus arundinaceus. Other important mycotoxicoses are those caused by indole-diterpenes produced by Clavicipitaceous fungi including Claviceps paspali in Paspalum spp., Claviceps cynodontes in Cynodon dactylon, and by Periglandula a seed transmitted symbiont associated with the tremorgenic plant Ipomoea asarifolia. The latter is an important poisoning in the northeastern and northern Brazil. Other important mycotoxicoses are those caused by swainsonine containing plants. It was demonstrated that swainsonine contained in Ipomoea carnea var. fistulosa is produced by an epibiotic fungus of the order Chaetothyriales whose mycelia develop on the adaxial surface of the leaves. Swainsonine is also produced by the symbiotic, endobiotic fungi Alternaria section Undifilum spp., which is associated with Astragalus spp. in the Argentinian Patagonia causing poisoning. Another form of mycotoxicosis occurs in poisoning by Baccharis spp., mainly B. coridifolia, a very important toxic plant in South America that contains macrocyclic trichothecenes probably produced by an endophytic fungus that has not yet been identified. Pithomycotoxicosis caused by Pithomyces chartarum used to be an important mycotoxicosis in the region, mainly in cattle grazing improved pastures of legumes and grasses. Slaframine poisoning, diplodiosis and poisoning by barley contaminated by Aspergillus clavatus has been rarely diagnosed in Brazil, Uruguay and Argentina.

Plants causing poisoning outbreaks of livestock in South America: A review

This paper reviews toxic plants for livestock in South America. We included 219 plants in this review, considering only the plants that caused at least one demonstrated outbreak of poisoning. Plants reported as toxic in other regions and present in South America, but with no confirmed outbreaks of poisoning in this region, are not included. We report the main aspects of the epidemiology, clinical signs, pathology and economical importance of the poisonings. Initially, the toxic plants are described based on their toxic compounds, but because the toxic compound is unknown in 92 (42%) of the plants we also classify them according to the affected system. This review highlights the great diversity of toxic plants capable of affecting livestock in South America, and for this reason studies in this regard should be intensified.

Toxicity of the swainsonine-containing plant Ipomoea carnea subsp. fistulosa for goats and sheep

In order to determine the toxicity of swainsonine present in Ipomoea carnea for goats and sheep, 12 goats and 12 sheep were divided into 3 groups of 4 goats (G1, G2 and G3) and 3 groups of 4 sheep (S4, S5 and S6) each. Groups G1 and S4 were used as controls; G2 and S5 received 1 mg/kg body weight of swainsonine from plant material and G3 and S6 received 3 mg/kg. Groups G2 and G3 presented the first clinical signs, on average, after the 54th and 39th days of ingestion of the plant, respectively. Groups S5 and S6 presented the first clinical signs, on average, on the 64th and 42nd days of the experiment, respectively. In sheep, in addition to having a longer period of ingestion until the onset of clinical signs, these signs were less severe, being evident only after the animals were forced to move. These results demonstrated that goats are more susceptible to swainsonine poisoning than sheep. Complete regression of clinical signs was observed in 5 goats and 6 sheep. However, three goats and one sheep remained with clinical signs until 120 days of the experiment, suggesting that to control the poisoning the animals should be removed from the pastures immediately after the first clinical signs. There were no significant differences in weight between the different groups, suggesting that for goats ingesting the plant, toxic Ipomoea species can be used as forage for intermittent periods of 15-30 days.

Clinical and pathological comparison of Astragalus lentiginosus and Ipomoea carnea poisoning in goats

The indolizidine alkaloid swainsonine, found in some Astragalus and Oxytropis (i.e., locoweed) species, is a potent cellular glycosidase inhibitor that often poisons livestock. Other toxic genera such as some Ipomoea species also contain swainsonine as well as calystegines which are similar polyhydroxy alkaloids. The toxicity of calystegines is poorly characterized; however, they are also potent glycoside inhibitors capable of intestinal and cellular glycoside dysfunction. The objective of this study was to directly compare A. lentiginosus and I. carnea poisoning in goats to better characterize the role of the calystegines. Three groups of four goats each were treated with ground alfalfa (control), I. carnea or A. lentiginosus to obtain daily doses of 0.0, 1.5, and 1.5 mg swainsonine/kg bw per day, respectively, for 45 days. Animals were observed daily and weekly body weights, serum enzyme activities, and serum swainsonine concentrations were determined. At day 45 all animals were euthanized and necropsied. Goats treated with A. lentiginosus and I. carnea developed clinical disease characterized by mild intention tremors and proprioceptive deficits. Goats treated with A. lentiginosus developed clinical disease sooner and with greater consistency. No differences in body weight, serum swainsonine concentrations and serum enzyme activity were observed between goats treated with A. lentiginosus and I. carnea. Additionally, there were no differences in the microscopic and histochemical studies of the visceral and neurologic lesions observed between goats treated with A. lentiginosus and I. carnea. These findings suggest that I. carnea-induced clinical signs and lesions are due to swainsonine and that calystegines contribute little or nothing to toxicity in goats in the presence of swainsonine.

Toxic plants affecting the nervous system of ruminants and horses in Brazil

ABSTRACT: This review updates information about neurotoxic plants affecting ruminants and equidae in Brazil. Currently in the country, there are at least 131 toxic plants belonging to 79 genera. Thirty one of these poisonous plants affect the nervous system. Swainsonine-containing plants (Ipomoea spp., Turbina cordata and Sida carpinifolia) cause numerous outbreaks of poisoning, mainly in goats, but cattle and horses are occasionally affected. The poisoning by Ipomoea asarifolia, a tremorgenic plant, is very common in sheep, goats and cattle in the Northeastern region and in the Marajo island. Poisoning by the pods of Prosopis juliflora are frequent in cattle in Northeastern Brazil; occasionally this poisoning affects goats and more rarely sheep. Some poisonings by plants, such as Hybanthus calceolaria, Ipomoea marcellia and Talisia esculenta in ruminants and Indigofera lespedezioides in horses were recently described and needs to be accurately investigated about its occurrence and importance. Other plants poisonings causing nervous signs in ruminants and equidae are less important, but should be considered for the differential diagnosis of neurologic diseases.