PYRROLIZIDINE ALKALOIDOSIS OF CATTLE ASSOCIATED WITH SENECIO-LAUTUS

Serious incidents of pyrrolizidine alkaloidosis of cattle in 10 herds exposed to the Australian native plant, Senecio lautus (Asteraceae), w ere seen in central Queensland during 1988-1992. The deaths of 226 cat tle were recorded. A mean of 8% of cattle died in affected groups (ran ge 2 to 58%). Sickness and deaths usually occurred some months after a ccess to S lautus. Typically, affected cattle lost body condition to t he point of emaciation before dying and had persistent diarrhoea. Some animals developed abnormal behaviour and died after a shorter illness . Liver specimens from affected cattle in all herds contained lesions consistent with pyrrolizidine alkaloidosis. Thin layer chromatography of extracts of blood and liver samples from cattle from 5 herds detect ed pyrrolic metabolites. The identity of these was confirmed by mass s pectroscopy on samples from one herd. Unseasonal autumn and winter rai n after a dry summer appeared to favour growth of S lautus at the expe nse of other pasture species. A subsequent dry period promoted consump tion of S lautus and was followed by a cluster of poisoning incidents.