Comparison of two collection methods to determine protodioscin concentrations in Brachiaria spp. and to monitor Brachiaria spp. Poisoning

Abstract

The objective of this study was to evaluate the methods of collecting Brachiaria spp. (Simulated Grazing vs. Total Collection) for the determination of protodioscin concentrations and to monitor the intoxication in sheep susceptible and resistant to poisoning by Brachiariaspp. The collection of Brachiaria spp. was done through two different methods. The first one consisted in throwing a metallic square at 10 random picket points. The second was performed simulating, with the hands, the grazing behavior of sheep. The leaf blades obtained by the two methods were conditioned in a forced ventilation oven. The extraction and quantification of protodioscin from the dry milled plant material was done by reverse-phase high-performance liquid chromatography (HPLC). The collections were carried out at three stages of the life of experimental lamb (suckling, rearing, and finishing). The lambs were divided into resistant and susceptible to intoxication by Brachiaria spp. The criterion for a lamb to be considered sensitive was to present some clinical signs at some stage of its life. No significant differences were observed between the general averages of the two collections when the evaluation was done in the whole period. However, a significant difference was found at the onset of the clinical signs. The concentrations of protodioscin in this period were higher in Brachiaria spp. collected by the simulating grazing method. Both methodologies were efficient to determine the level of protodioscin in the pastures of Brachiaria spp. However, during the periods when the outbreaks occurred, the simulated grazing method was more reliable.

Protodioscin levels in Brachiaria spp. in a sheep production system and a brief review of the literature of Brachiaria spp. poisoning in ruminants

“…These pastures were occupied in previous years by sheep that developed poisoning with Brachiaria spp. (Pupin et al 2016, 2019a. The grazing areas had drinking fountains and a small covered area with free access for night shelter and protection against eventual rainfalls or intense sunlight exposure.…”

“…The criterion used to consider an adapted or resistant sheep was the absence of clinical signs throughout its lifespan, even when kept in pastures made up exclusively of Brachiaria spp. (Gracindo et al 2014, Melo et al 2019a). The ram breeder of the herd was supposedly adapted.…”

“…poisoning. These include edema, erythema, and crusts in the non-pigmented areas of the face and ears, apathy, anorexia, and jaundice (Mustafa et al 2012, Porto et al 2013, Faccin et al 2014, 2019a. When those signs were spotted in any lamb, it underwent thorough clinical examinations and immediately removed from the lot, kept in stalls sheltered from sunlight, consuming mineral salt, energy-based protein concentrate soybean meal, and crushed corn fresh millet and water ad libitum.…”

“…Plants of the genus Brachiaria are used in several countries as forage (Muniandy et al 2020) and cause spontaneous poisoning in cattle (Souza et al 2010), sheep (Riet-Correa et al 2011, Faccin et al 2014, 2019a, goats (Rosa et al 2016), buffaloes (De Oliveira et al 2013), and horses (Barbosa et al 2006). The poisoning was reproduced in sheep (Cruz et al 2001, Driemeier et al 2002, Saturnino et al 2010, Porto et al 2013, and rabbits (Utiumi et al 2018).…”

“…is responsible for the poisoning (Souza et al 2010, Ogliari et al 2018. In those instances, the protodioscin concentrations were not determined (Lemos et al 1996, Caicedo et al 2012, Rosa et al 2016, Utiumi et al 2018, and even when they were, each plant species was not analyzed separately (Mustafa et al 2012, Diamantino et al 2018, 2019a, 2019b.…”