A survey of Senecio spp. affecting livestock in Uruguay and their associated pyrrolizidine alkaloid content/Senecio spp. Afetando a pecuaria no Uruguai e sua associacao com alcaloides pirrolizidinicos

In Eastern Uruguay there has been a significant increase of seneciosis in grazing livestock with most affected localities related to counties neighboring the Brazilian border. A survey in 28 farms associated with poisoning outbreaks in grazing cattle in Eastern Uruguay was carried out. Fifty populations of Senecio plants were collected for alkaloid analysis and species identification. Four species were identified: S. oxyphyllus DC, S. madagascariensis Poir, S. brasiliensis (Spreng.) Less., and S. selloi DC. Alkaloids were identified by a combination of GC-MS and HPLC-MS analysis and included: retrorsine in S. oxyphyllus; retrorsine, usaramine, and senecivernine/senecionine in S. selloi; retrorsine, senecivernine/senecionine, integerrimine, and usaramine in S. madagascariensis; and integerrimine, retrorsine and senecionine in S. brasiliensis. Total mean alkaloid concentration was reported to be highest in S. brasiliensis (17.6mg/g) followed by S. oxyphyllus (6.2mg/g), S. selloi (1.8mg/g) and S. madagascariensis (0.6mg/g). Alkaloid concentrations were also reported to be higher in 2015 vs. 2016probably due to a common environmental factor. The species S. oxyphyllus and S. madagascariensis were not previously recognized as toxic plants in Eastern Uruguay. Particularly, S. oxyphyllus was present in 82% of the farms surveyed and occurred in high density with relative high concentrations of pyrrolizidine alkaloids suggesting S. oxyphyllus may be the main species involved in the reported outbreaks of seneciosis. Key words: seneciosis, plant secondary metabolites, ruminants, poisonous plants, Asteraceae. No leste do Uruguai houve um aumento significativo da seneciosis no gado de pastagem com a maioria das localidades afetadas em municipios vizinhos a fronteira brasileira. Aplicou-se um questionario em 28 fazendas associadas a surtos de intoxicacao em bovinos de pastagem na fronteira leste do Uruguai. Coletaram-se cinquenta populacoes de Senecio para analise de alcaloides e identificacao de especies. Identificaram-se quatro especies: S. oxyphyllus DC, S. madagascariensis Poir, S. brasiliensis (Spreng.) Less. e S. selloi DC. Identificaram-se os seguintes alcaloides mediante analise combinado de GC-MS e HPLC-MS: retrorsina em S. oxyphyllus; retrorsina, usaramina e senecivernina/ senecionina em S. selloi; retrorsina, senecivernina/senecionina, integerimina e usaramina em S. madagascariensis; e integerrimina, retrorsina e senecionina em S. brasiliensis. A concentracao