Influences of barley and oat silages for beef cows on occurrence of myopathy in their calves.

Sixteen pregnant Shorthorn cows were winter-fed either oat or barley silage, both of which were low in selenium (less than .1 ppm). Two months before calving, as well as at calving and a month later, four cows on each diet were given intramuscularly a preparation containing 1360 IU of vitamin E and 30 mg selenium as sodium selenite. Barley silage lipids contained higher linoleic (33.2 versus 22.3%) and palmitic acids (32.3 versus 23.1%), and lower oleic (6.3 versus 22.1%) and linolenic acids (20.9 versus 30.9%) than oat silage. Three calves born from the untreated dams on barley silage died from nutritional muscular dystrophy by 50 days of age whereas none of the calves either from the untreated cows on oat silage or from any of the selenium/vitamin E treated cows. Milk from untreated cows fed barley silage contained a higher proportion of linoleic acid than that from treated cows or from those on oat silage. The incidence of nutritional muscular dystrophy was associated closely with ingestion by the calves of an increased amount of dietary dienoic acid. It appears an advantage to include oat silage in winter feeding programs for beef cows to reduce the risk of development of nutritional muscular dystrophy in the offspring.