FLY-ASH, BASIC SLAG AND GLENBROOK SLAG TOXICITY IN CATTLE

In case studies of two herds of dairy cattle, a herd of 270 Friesian c ows and heifers and a herd of 256 Jersey cows and heifers experienced high death rates and a protracted course of illness when fly ash was b roadcast as a fertiliser over the farms at a rate of about 1 tonne per hectare. The onset of weakness, lassitude and diarrhoea in the cattle first appeared within 4-5 days and both fertility and milk fat produc tion fell off dramatically. In the following 7 months, 51 animals died in the Friesian herd and a similar death rate and performance losses occurred in the Jersey herd. Emaciation and hepatic fibrosis were cons istently reported from autopsies. Heavy metal poisoning was eliminated from the possible diagnosis. The slags and fly ash used as fertiliser had several features in common. They contained 29-40% calcium as calc ium oxide, 15-35 grams of iron per kg, they were all extremely alkalin e and concentrations of lead and arsenic were low. The effect of addin g fly ash to rumen contents in vitro was to raise the pH to greater th an 7.2, at which point fermentation was markedly reduced.