CABBAGE POISONING IN RUMINANTS

A complaint of poor productivity was investigated in a herd of Jersey cattle and a small flock of Dorper sheep that had been fed cabbage for 5 to 6 months per year, over a number of years. During that time a number of lambs were lost as a result of swayback, some cows aborted, milk production was down, and although the farmer was an experienced inseminator, the conception rate in the Jerseys was low. After rectal examination and consulting the records, 26% of the cows were found to have been open for more than 150 d and 28% had been inseminated more than 3 times. The body condition of the cows ranged from poor to moderate, the hair coats were dull and some cows were anaemia. The young lambs had visibly enlarged thyroids. Haematological investigations revealed a typical Heinz body type haemolytic anaemic. In the cattle the anaemia appeared to be macrocytic, hypochromic and associated with thrombocytosis, while in the sheep it seemed to be normochromic and slightly microcytic. Plasma copper concentrations were severely depressed in all cases. Most thyroxine concentrations were within the normal range, although some were on the low side. Analysis of cabbage revealed a high sulphur content and marginally low copper and zinc levels. The main factor in cabbage which is responsible for poor animal performance, is the high sulphur content. High levels of this mineral exert detrimental effects, in order of priority, by elevating s-methyl cystine sulphoxide, diminishing the availability of copper and raising the glucosinolate content of the plant.