CHRONIC GYPSUM FERTILIZER INGESTION AS A SIGNIFICANT CONTRIBUTOR TO AMULTIFACTORIAL CATTLE MORTALITY

Objective To assess the validity of claims that heavy metal contaminat ion from an open-cut mine caused the death of 226 cattle on a nearby f arm over a period of 18 months, and to investigate other possible cont ributing factors. Procedure A retrospective assessment of previous inv estigations combinded with additional chemical analyses. Results Exten sive chemical analyses produced no evidence of heavy metal contaminati on associated with the mine. Analysis of bones indicated exposure to f luoride in greater than normal amounts. The main source of fluoride se ems to have been gypsum that was included in a feed supplement and als o ingested from fertiliser dumps on paddocks. The gypsum itself may ha ve contributed significantly to the ill health. Other factors probably affected some classes of animals, notably the young carves. Conclusio ns What originally seemed to be a disease problem of single aetiology probably was an expression of interacting multifactorial causes. This investigation has high lighted the potential toxicity of gypsum to liv estock and the need for further studies to establish its basis.