Fotossensibilização em ovinos associada à ingestão de Brachiaria brizantha no estado do Pará

Abstract

Two outbreaks of photosensitization by Brachiaria brizantha were studied and an experiment was performed in Santa Inês and Dorper crossbred sheep, two to three months old, on a farm in Santa Luzia do Pará municipality. These animals were kept from birth until about two months of age in a suspended stall floor, fed purple elephant grass (Pennisetum purpureum cv. purple), and had minerals and water ad libitum. After this period they were placed into a paddock of B. brizantha. At the time of the outbreaks and the experimental studies, the farm was visited for epidemiological assessment and clinical examination of the sheep, collection of blood samples for measurement of gamma glutamyltransferase, aspartate aminotransferase, conjugated bilirubin, unconjugated bilirubin, urea, and creatinine. Pasture samples were collected for saponin determination and count of Pithomyces chartarum spores. Necropsies with collection of material for histopathological studies were performed. Outbreak 1 occurred at the time of low rainfall, when the grass was scarce and mature, and morbidity and lethality was 43.4% and 81.6%, respectively. Outbreak 2 occurred at the beginning of the rainy season, with morbidity and lethality rates of 16.3% and 76.9%, respectively. From the 50 animals in the experiment, 10 received three times 200ml of rumen fluid taken from mother sheep of the same batch. The first of these administrations was given one day before the sheep were introduced into the pasture and the other two at weekly intervals. After 15 days in the pasture, the animals were unquiet, looked for shade, had edema of the ears, yellowish mucosae, were apathic, had anorexia and showed sloughing of the skin followed by crusting in some areas of the body. Both, the sheep of the outbreaks as those from the experiment, showed increased levels of GGT, AST, BD, BI, BT, urea and creatinine. In sheep which received ruminal fluid the values of urea and GGT were similar to those which did not receive the ruminal fluid. The creatinine, AST and bilirrubine values were lower in sheep that received the ruminal fluid. Two types of saponins, methylprotodioscin and protodioscin, were detected in the samples of B. brizantha from the outbreaks and the experiment. The level of saponins in Outbreak 1 and 2 was 0.92% and 0.88% respectively.

Spontaneous poisoning by Brachiaria decumbens in goats

“…Recent studies in sheep show that there is genetic resistance to poisoning ), i.e. animals from herds that have never had contact with the Brachiaria grasses are more susceptible than those created in this pastures (Lemos et al 1996, Oliveira et al 2012.Perhaps this genetic resistance observed in animals raised in Brachiaria pasture is due to reducing of the mechanism of the toxic effect of the plant such as greatermetabolization capacityand degradation of toxic principle ) and adaptation of ruminal microbiota (Albernaz et al 2010). Moreover, it has been proven the existence of individual sensitivity to intoxication (Saturnino et al 2010.…”

“…Brachiaria spp. have been associated with photosensitivity and death in cattle (Lemos et al 1997, Ecco et al 2004, sheep (Lemos et al 1996, Brum et al 2004, Albernaz et al 2008, goats (Lemos et al 1998), buffalo (Rozza et al 2004, De Oliveira et al 2013) and horses (Barbosa et al 2006). The clinical and pathological aspects are similar in all species in which the poisoning was documented.…”

Identification of lamb flocks susceptible and resistant against Brachiaria poisoning

“…(Tokarnia et al 2012). The consumption of this forage by different farm animal species is associated with toxicosis being sheep and cattle the most susceptible ) and younger stock are more susceptible than mature animals (Albernaz et al 2010, Mustafa et al 2012. Furthermore, sheep from herds that never had contact with brachiaria species are more susceptible than sheep raised with free access to the plant (Lemos et al 1996, Castro et al 2007, Oliveira et al 2012, Faccin et al 2014.…”

“…Furthermore, sheep from herds that never had contact with brachiaria species are more susceptible than sheep raised with free access to the plant (Lemos et al 1996, Castro et al 2007, Oliveira et al 2012, Faccin et al 2014. It is possible that animals raised in brachiaria pastures develop greater capacity in metabolize and degrade the steroidal saponin, the toxic principle of this type of grass (Castro et al 2007) and/or development of a special ruminal flora (Albernaz et al 2010) that make them able to reduce the effects of the toxin.…”

“…Affected animals show apathy, anorexia, icterus, skin pruritus, photophobia, serous ocular discharge, subcutaneous edema in the face and ears; in the skin of poorly pigmented areas there are lesions characterized by erythema, hair loss, and crusts. These areas evolve to necrosis and sloughing of patchy areas of affected skin, associated in many cases to deformity of the ears due to scarring of these lesions (Brum et al 2007, Saturnino et al 2010, Albernaz et al 2010, Mustafa et al 2012, Oliveira et al 2012, Faccin et al 2014.…”