[Lead poisoning in cattle in Northern Netherlands. Follow-up study of 2 farms]

The after-effects of a serious lead intoxication were studied. This intoxication was caused by contaminated feed. Calves and cows of two dairy farms were examined up to half a year after the incident with the contaminated feed in October 1989. Clinical signs were observed and blood samples were taken. Blood parameters like zinc-protoporphyrin (ZPP), haemoglobin, RBC, WBC, MCV, haematocrit, MCHC, and the blood lead levels were analysed. Cattle of one of the most afflicted farms showed severe effects of lead intoxication: blindness, muscle twitching and hyperirritability. Two animals died. Forty percent of the affected cows had to be slaughtered. The ZPP levels in calves of this farm were still elevated after six months. The zinc-protoporphyrin level in blood seemed to coincide better with the clinical signs than the blood lead level. Animals with less than 3 mg ZPP/l RBC showed no irreversible effects of the lead intoxication. It is suggested that ZPP could be a useful predictor for the after-effects of lead intoxication.