Ryegrass staggers

Abstract

Extract

Ryegrass Staggers is the name given to a condition of tetanic muscle spasm that develops under certain conditions in grazing sheep, cattle, or horses. In most cases, the pastures on which animals become affected have contained a considerable proportion of perennial ryegrass, and this has given rise to the name, tout there is no direct proof that ryegrass is the cause; at least one out-break has occurred on short-rotation ryegrass. The condition occurs in the summer or autumn when the pastures have been dried up, but when there is just sufficient moisture for a small amount of slow growth in the ryegrass. In a few cases, which will be described later, the condition has occurred on longer summer grass or on aftermath growth after a grass seed crop had been harvested. Sheep are the most frequently affected, cattle next; horses are not often grazed solely on pasture that causes the disease, so that an assessment of their susceptibility relative to the other species may be misleading. It may equally be misleading to suggest that sheep are more susceptible than cattle, as the greater incidence in sheep may be due to the ability of the sheep to graze closer than cattle and hence to be able to eat the short grass that is presumed to carry the causative agent.