Perennial Ryegrass Staggers
J. Glenn, Veterinary Medicine Extension, UC Davis; F. Galey, California Veterinary Diagnostic Laboratory System; I. Gardner, University of California, Davis
Problem: Ryegrass staggers can affect both sheep and cattle. In California, it is diagnosed more frequently in sheep. Perennial ryegrass is well adapted to the North Coast climate of California and is a common component of pastures there. In certain locations, however, there is a recurrent problem with ryegrass staggers in the late summer when an endophytic fungus (Acremonium lolii) produces toxins (lolitrems). Affected animals develop tremors and may even die if stressed by excitement or movement after feeding on the infected plant material. There is some evidence that affected ewes may have drastically reduced milk production after lambing.
Approach: A survey has been done of sheep producers on the North Coast, and the data is being analyzed to determine the areas where the disease occurs, the climatic conditions that trigger it, and management strategies that may increase or decrease the severity of the problem.