Techniques for prevention and control of poisoning by sodium monofluoroacetate (MFA)-containing plants in ruminants

Abstract

Monofluoroacetate (MFA)-containing plants cause sudden death associated with exercise in ruminants, and are responsible for significant losses in Brazilian livestock, estimated at 500,000 bovine deaths annually. Most of the times, the control and treatment of this type of poisoning are not efficient, because disease evolution is superacute, usually causing the death of the animal. Due to the difficulty in controlling this intoxication, several studies have suggested alternatives to prevent it, mainly by making animals resistant to the MFA present in these plants or by avoiding their consumption. This literature review addresses the techniques used experimentally to control the poisoning of ruminants by plants containing MFA. The first studies carried out in Brazil demonstrated that goats and sheep that continuously receive non-toxic doses of plant containing MFA show greater resistance to poisoning than untreated animals, and that this resistance can be transmitted by ruminal fluid transfaunation, suggesting that poisoning occurs due to the presence of bacteria that hydrolyze MFA in the rumen. Based on this hypothesis, several MFA-hydrolyzing bacteria were isolated (Enterococcus faecalis, Bacillus sp., Paenibacillus sp., Burkholderia sp., Cupriavidus sp., Staphylococcus sp., Ancylobacter sp., Ralstonia sp., Stenotrophomonas sp., Pigmentiphaga kullae, and Ancylobacter dichloromethanicus). When some of these bacteria were administered intraruminally, they provided the animal with a different level of protection against poisoning. However, it was observed that protection is gradually lost when the bacterium administration is interrupted. Consequently, to obtain more efficient protection, these bacteria should be administered continuously, probably in the form of probiotics. In another assay, MFA was administered to sheep at non-toxic doses to test the hypothesis that this substance could induce the multiplication of bacteria that hydrolyze it in the rumen. There was no increase in resistance to poisoning after administration of MFA; however, no signs of poisoning were observed when animals received trifluoroacetate and no clinical signs were verified when they were challenged with toxic doses of MFA; in contrast, all control animals presented clinical signs. These results suggest that trifluoroacetate induces the proliferation of MFA-degrading bacteria, and can be used in intoxication prophylaxis. The conditioned food aversion technique, using lithium chloride, has been successfully used experimentally to prevent ruminants from ingesting plants that contain MFA. Another alternative tested was the spraying of Amorimia septentrionalis with the endophytic bacterium Herbaspirillum seropedicae, which degrades MFA, resulting in decreased concentration of this compound in the plants. In conclusion, several experimental techniques have been proved efficient in the control and prophylaxis of MFA-containing plant poisoning; however, none of these techniques are available commercially. Further experiments, mainly in the field, should be carried out to adapt some of these techniques to the conditions of extensive breeding in the numerous areas where MFA-containing plants occur.

Ethnobotanical use of Morinda citrifolia: a literature review

“…According to Pessoa et al (2019), in Brazil, there are about 131 species of toxic plants, divided into 79 genera. Some plants are so toxic that they can even cause sudden death due to the monofluoroacetate compound (MFA), among these plants the family stands out: Rubiaceae, Malpighiaceae, and Bignoniaceae (Arruda et al, 2017).…”

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

“…Fencing off areas to prevent animals from accessing the plant is the most effective preventive measure, and animals that have consumed the plant should not be subjected to exercise. The use of bacteria that hydrolyze fluoroacetate to prevent poisoning has been experimentally proven but is not being used under field conditions ( Silva et al, 2016 ; Pessoa et al, 2019 ).…”

Clinical and laboratory findings in sheep experimentally poisoned by Palicourea marcgravii and the use of magnesium chloride with possible therapeutic effect on poisoning

“…The treatment of poisoning by MFA and other plants having the same intoxication principle is challenging for physicians and veterinarians (Pessoa et al 2019). It has been reported that magnesium chloride (MgCl 2 ) at a dose of 50mg/kg is able to reverse the clinical condition of 90% of mice poisoned with 15mg/kg of MFA (Pereira & Pereira 2005).…”