Sulfur-associated polioencephalomalacia in cattle grazing plants in the Family Brassicaceae.
Polioencephalomalacia was diagnosed histologically in cattle from two herds on the Darling Downs, Queensland, during July-August 2007. In the first incident, 8 of 20 18-month-old Aberdeen Angus steers died while grazing pastures comprising 60%Sisymbrium irio (London rocket) and 40%Capsella bursapastoris (shepherd's purse). In the second incident, 2 of 150 mixed-breed adult cattle died, and another was successfully treated with thiamine, while grazing a pasture comprising almost 100%Raphanus raphanistrum (wild radish). Affected cattle were either found dead or comatose or were seen apparently blind and head-pressing in some cases. For both incidents, plant and water assays were used to calculate the total dietary sulfur content in dry matter as 0.62% and 1.01% respectively, both exceeding the recommended 0.5% for cattle eating more than 40% forage. Blood and tissue assays for lead were negative in both cases. No access to thiaminase, concentrated sodium ion or extrinsic hydrogen sulfide sources were identified in either incident. Below-median late summer and autumn rainfall followed by above-median unseasonal winter rainfall promoted weed growth at the expense of wholesome pasture species before these incidents.
McKenzie
R A
RA
Department of Primary Industries & Fisheries' Biosecurity Sciences Laboratory, Animal Research Institute, Locked Mail Bag No.4, Moorooka, Queensland 4105, Australia. ross.mckenzie@dpi.qld.gov.au
Carmichael
A M
AM
Schibrowski
M L
ML
Duigan
S A
SA
Gibson
J A
JA
Taylor
J D
JD
D000821:Animal Feed / Q000009:adverse effects*; D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D019607:Brassicaceae / Q000009:adverse effects / Q000737:chemistry*; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D002540:Cerebral Cortex / Q000473:pathology*; D004678:Encephalomalacia / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D005260:Female; D008297:Male; D010939:Plant Poisoning / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D011793:Queensland / Q000453:epidemiology