A grass tetany-like disease with a reduced serum level of magnesium as a main symptom broke out in the authors' branch at the end of the grazing period, in autumn. Four cows died on the day when clinical signs became apparent. They had been satisfactory in nursing calves, which showed regular growth.
Autopsy revealed no marked changes, except petechiae in the intestine and epi-and endocardium. Serum levels of minerals were estimated in 17 cows of the grazing ones in this branch. As a result, the serum level of magnesium ranged from 0.2 to 0.7mg/d
l. subcutaneously with 100ml of 25% MgSO
4solution, these cows showed an increase in this level and a recovery from clinical symptoms.
To prevent puerperal cows from the disease in question, 100m
lof 25%MgSO
4solution was injected subcutaneously on the neck. Besides, cows were administered with MgO 2 months before the beginning of grazing on pasture. These steps were effective to prevent death among grazing cows.
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