Lima Stephanie C, Godoy Kelly C S, Leal Paula V, Lee Stephen T, Pfister James A, Souza Alda I, de Barros Claudio S L, de Lemos Ricardo A A
Programa de pós-graduação em Ciências Veterinárias, Faculdade de Medicina Veterinária e Zootecnia (FAMEZ), Universidade Federal do Mato Grosso do Sul (UFMS), Av. Senador Felinto Muller, 2443, Campo Grande, MS, 79070-900, Brazil.
Poisonous Plant Research Laboratory, Agricultural Research Service, United States Department of Agriculture, 1150 E. 1400 N., Logan, UT 84341, USA.
Toxicon. 2019 Feb;158:47-50. doi: 10.1016/j.toxicon.2018.11.306. Epub 2018 Nov 22.
Toxic plants containing monofluoroacetate (MFA) cause sudden death in livestock in Australia, South Africa and Brazil, causing economic losses to producers. The objective of this study was to determine the amount of MFA present in young leaves, mature leaves, senescent leaves, and seeds of Amorimia pubiflora harvested at different times of the year and to determine their toxic effect on sheep. Samples of Amorimia pubiflora were collected during April, August and December of 2015 and March of 2016, separated according to the vegetative stage (young leaves, seeds, mature leaves, and senescent leaves), dried in an oven, and administered in daily doses of 5 g/kg/body weight (bw) of fresh leaves to sheep through ruminal cannulae. The experiment was divided into four stages according to the time of collection of the plant so that each sheep received a different vegetative stage of the plant (young leaves, mature leaves, and senescent leaves). Only in the second stage of the experiment was it possible to collect A. pubiflora seeds, which were administered using the same method used for the administration of the leaves. The sheep were dosed with the plant until they showed clinical signs of toxicosis or until the plant was no longer available. Aliquots of leaves and seeds of A. pubiflora were analyzed for MFA concentration. The seeds and young leaves had higher concentrations of MFA than did the mature (harvested in August and December) and senescent (harvested in December) leaves. However, all vegetative stages of the plant were toxic and caused fatal poisoning. The results of our study showed that A. pubiflora is toxic to sheep even when MFA concentrations are low, demonstrating that the presence of this substance is a risk factor for the occurrence of poisoning. Knowing the toxic principle and its variations allow us to determine the conditions for the occurrence of plant toxicosis as well as possible treatment, control, and prophylaxis methods, contributing significantly to the reduction of economic losses on farms due to plant poisoning.
含有单氟乙酸（MFA）的有毒植物在澳大利亚、南非和巴西会导致牲畜突然死亡，给养殖户造成经济损失。本研究的目的是确定在一年中不同时间收获的柔毛阿莫里木（Amorimia pubiflora）的幼叶、成熟叶、衰老叶和种子中MFA的含量，并确定其对绵羊的毒性作用。在2015年4月、8月、12月以及2016年3月采集柔毛阿莫里木样本，根据营养阶段（幼叶、种子、成熟叶和衰老叶）进行分离，在烘箱中干燥，然后通过瘤胃插管以每天5克/千克体重的鲜叶剂量喂给绵羊。根据植物采集时间将实验分为四个阶段，以便每只绵羊接受该植物不同的营养阶段（幼叶、成熟叶和衰老叶）。只有在实验的第二阶段才有可能采集到柔毛阿莫里木种子，其给药方法与叶片相同。给绵羊投喂该植物，直至它们出现中毒的临床症状或直至该植物不再可用。对柔毛阿莫里木的叶片和种子等分试样进行MFA浓度分析。种子和幼叶中的MFA浓度高于成熟叶（8月和12月收获）和衰老叶（12月收获）。然而，该植物的所有营养阶段都具有毒性并导致致命中毒。我们的研究结果表明，即使MFA浓度较低，柔毛阿莫里木对绵羊也具有毒性，这表明该物质的存在是中毒发生的一个风险因素。了解毒性原理及其变化使我们能够确定植物中毒发生的条件以及可能的治疗、控制和预防方法，这对减少农场因植物中毒造成的经济损失有重大贡献。
