ATYPICAL PNEUMONIA ASSOCIATED WITH RYEGRASS STAGGERS IN CALVES

A group of 6- to 8-month-old carves developed head tremors, stiff gait , and staggering after consuming ryegrass straw that contained 3,711 m u g of lolitrem-B/kg. Signs were consistent with ryegrass staggers syn drome. At necropsy, all calves examined had atypical interstitial pneu monia, with marked emphysema and bullae, Infectious organisms and pneu motoxins were not identified. Experimentally, feeding the same ryegras s straw to age-matched calves induced similar neurologic signs, but di d not result in pneumonic lesions. The high concentration of lolitrem- B in the straw or other, undefined factors, such as feed changes, may have contributed to the atypical interstitial pneumonia in the natural ly exposed calves.