Abstract
In 4 of 17 high yielding dairy cows, acute hoof lameness occurred immediately after changing formula feed, showing edema, fibrin thrombosis, perivascular lymphocyte infiltration and hypertrophied tunica muscularis media of the artery in the corium. The crude fat content of the formula feed was 7.8%(DMbasis) and mostly of the plant origin (soybean and cotton seed) containing a large amount of unsaturated fatty acids. In the neighboring farms the milk protein level markedly decreased after giving the same diet. These observations suggested that the higher concentration of unsaturated fatty acids might induce the disorder of microbial fermentation in the rumen, producing the same factors causing acute laminitis.
