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Title: Evaluation of solar exposure on the experimental intoxication by Brachiaria decumbens in sheep

Author
item PORTO, M - University Of Brasilia
item SATURNINO, K - Federal University - Brazil
item LIMA, E - University Of Brasilia
item Lee, Stephen
item LEMOS, R - Universidade Federal De Mato Grosso
item MARCOLONGO-PEREIRA, C - Universidade Federal De Pelotas
item RIET-CORREA, F - Federal University Of Campina Grande
item CASTRO, M - University Of Brasilia

Submitted to: Pesquisa Veterinaria Brasileira
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2013
Publication Date: 8/12/2013
Publication URL: http://handle.nal.usda.gov/10113/5498091
Citation: Porto, M.R., Saturnino, K.C., Lima, E.M., Lee, S.T., Lemos, R.A., Marcolongo-Pereira, C., Riet-Correa, F., Castro, M.B. 2013. Evaluation of solar exposure on the experimental intoxication by Brachiaria decumbens in sheep. Pesquisa Veterinaria Brasileira. 33(8):1009-1015.

Interpretive Summary: Twenty-six five month-old lambs with no previous contact with Brachiaria spp. pastures were divided into three groups. Two groups were fed daily with fresh Brachiaria decumbens. One of the groups fed Brachiaria decumbens was kept in an area exposed to the sun. The other group fed Brachiaria decumbens was kept in stalls shielded from the sun. A control group fed Cynodon dactylon grass hay and Pennisetum pupureum fresh grass were also kept in an area exposed to the sun. Three of the nine lambs fed Brachiaria and exposed to the sun showed clinical signs of Brachiaria spp. poisoning, and two died. One of the lambs fed Brachiaria decumbens and shielded from the sun, showed clinical signs and died. Clinical signs included apathy, weight loss and photophobia. Dermatitis due to photosensitization was not observed. Serum blood chemistries in the lambs fed Brachiaria decumbens and eposed to the sun were significantly higher than the other two groups. These results suggest that sun exposure does not define intoxication, but exacerbates the toxicity of Brachiaria decumbens.

Technical Abstract: Twenty-six five-month-old lambs originated from flocks with no previous contact with Brachiaria spp. pastures were divided into three groups. Two groups (GS and GSB) were fed daily with fresh harvested Brachiaria decumbens ad libitum. GS was kept in an area with solar exposure and GSB was kept in stalls sheltered from solar exposure. Control group (GC) was also kept under solar exposure, but fed with Cynodon dactylon grass hay and Pennisetum purpureum fresh grass. All sheep from the three groups were supplemented with 200g daily of a commercial concentrated food. Evaluation of clinical signs was carried out daily and blood samples were collected twice a week to determine AST and GGT serum activities. Three out of nine lambs of GS presented clinical signs of Brachiaria spp. poisoning, and two died. One animal showed clinical signs and died in GSB. The main clinical signs observed were apathy, weight loss, photophobia, conjunctivitis, ocular mucous discharge and jaundice. Dermatitis due to photosensitization was not observed. Mean serum AST and GGT activities were significantly higher (p<0,05) in the group exposed to sun, than in the other two groups, and the GGT activities were significantly higher in the group sheltered than in the control group (p<0,05). All animals at the end of the experiment were submitted to liver biopsy and died lambs were necropsied. Histopathological evaluation of liver samples from sheep with clinical signs evidenced swelling and vacuolization of hepatocytes, individual hepatocytes necrosis, presence of foamy macrophages, crystal negative images within bile ducts and foamy macrophages, biliary duct hyperplasia and periportal mononuclear infiltration. These results suggest that sun exposure does not define intoxication, but exacerbates the toxicity of the grass.