In June 2004, an outbreak of leukoencephalomalacia in mules from the state of Pará, northern Brazil, was reported. The disease affected 13 of the 80 mules in the farm. Until one week before the outbreak, the mules were supplemented daily with 60 kg of ground whole maize and 30 kg of African palm oil meal. One week before the outbreak, the amount of food was increased to 150 kg of the ground maize, 60 kg of African palm oil and 120 kg of poultry litter. The clinical signs in the affected mules were ataxia, muscular tremors, aggressiveness, absence of palpebral reflex, decreased tongue and upper and lower lip tone, decreased sensibility of the face and palate, and muscular slackening. All animals died with 10-24 h after manifestation of clinical signs. Postmortem examination revealed cavitations, haemorrhages and yellow discolouration in the thalamus and mesencephalon. Mild haemorrhagic lesions were also observed in the pons. Histopathologically, areas of malacia in the white matter were characterized by a vacuolated neutrophils with oedema and haemorrhages. No significant lesions were observed in other organs. The differences in clinical signs and location of the lesions in mules with those reported in horses and donkeys are discussed. To the authors' knowledge, this is the first report on leukoencephalomalacia in mules in Brazil.
The clinical, biochemical and histopathological results of various locoweed (Astragalus and Oxytropis spp.) and swainsonine poisoning studies in rats, hamsters, sheep, cattle, horses and mule deer (Odocoileus hemionus) are presented and compared to determine the distribution, severity and nature of locoweed poisoning. Based on the results, all the examined species are susceptible to locoweed poisoning. However, there are species-specific differences in sensitivity to poisoning and the distribution and severity of locoweed-induced lesions. Horses appear to be the most sensitive as they are highly susceptible to the effects of locoweed. Cattle and sheep have a similar susceptibility, while rats, hamsters and mule deer are relatively resistant to locoweed poisoning.
The changes in liver and hepatic lymph nodes of 19 sheep in Mato Grosso, Brazil, that grazed on Brachiaria spp. and the carbohydrate residues stored within the foamy cells were studied using lectin histochemistry. Tissues of sheep fed exclusively lucerne (alfalfa) hay and concentrate served as controls. It was shown that there were infiltrates of foamy macrophages and negative images or cholesterol clefts associated with crystals in the lumen of the bile ducts, hepatocytes and foamy macrophages of the livers and lymph nodes. It is suggest that the inhibition of a lysosomal lipase enzyme could be involved in the formation of the foamy macrophages, leading to the intracellular storage of glycoconjugates in cells of sheep grazing on Brachiaria spp. pastures.
Researchers continue to oven-and air-dry cxtrusa samples from esophageally-ted atdmals, despite evidence that this pra&e leads to erroneous nutritional evaluations. Two studies were conducted to determine bow method of d@ng affects the nutritional composition of esophageal extrusa collected from sheep and goats browsing forage at different stages of maturity. In trial 1, extrusa collected from free-ranging sheep and goats In Northeast Brazil from July to April was freeze-or oven-dried (400 C) and analyzed for neutral detergent fiber (NDF) and Ugnin (L). NDF and L were artificially elevated (31-9396) in oven-dried extrusa collected from January to April when forage was immature. No differences were observed in the fiber content of oven-and freeze-dried extrusa collected during the dry season (July-December). In trial 2, Ducty-&glomuata, Med&ago sativa, A cer gramfidentatum and Pursh& tridimtata were hand-harvested and fed to esophageally flstulated sheep. Extrusa was either freeze-, air-or oven dried (40" C) and analyzed for hemicellulose, cellulose, L and in vitro organic matter digestibility (IVOMD). Hemicellulose and L concentrations were significantly increased ia air-and oven-dried forage for all plant species. Cellulose was least affected by method of drying. IVOMD was depressed most by oven-and air-drying in species containing phenolic compounds. When there were significant treatment by period interactions, method of drying was most critical early in the growing season. Results reemphasize that freeze-dqing extrusa is an important preliminary step to obtain 8ccurate nutritional information.
The objective of this study is to determine the effects of intermittent locoweed (O. sericea) poisoning on the development of clinical and histological lesions. Results suggest that sheep and possibly cattle may ingest locoweeds for short periods, 5 days or less, if allowed withdrawal periods of 7 to 14 days without developing behavioural or functional lesions.
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