J. D. Bobb, DVM
International SheepLetter
Vol. 18 No. 1, January-February 1998

Wool slip is a term that has been coined to describe a problem that is associated with shearing housed ewes in the winter months. Wool slip usually occurs several weeks after shearing and can affect a single animal or a large percentage of the flock. The wool falls out usually leaving a pink bald lesion over the back of the ewe. It is common to see from 1/4 to 1/2 of the ewes back without any wool. This unsightly lesion causes much concern to producers who often call wondering if their feed or mineral rations are lacking.

Wool slip is caused by cold stress which increases the sheeps' cortisol levels. Shorn ewes require housing to protect them from the cold winter weather. It is a known fact that shorn ewes will require 15 to 20% more feed than unshorn ewes, this is, however, offset by the shorn ewes producing lambs that are born heavier and a higher survival rate in the newborn lambs born to mothers that have been shorn. In some flocks the wool slip can be traced to related individuals which might indicate that genetics play a role such as the thickness of the hide or internal body fat reserves. Club lamb ewes tend to be more sensitive than wool breeds of sheep. If you notice large bald areas after shearing you need to determine first if the sheep are showing any signs of external parasites such as lice or keds. Generally if sheep have external parasites they are itching and rubbing on feed bunks and fences or chewing at their sides. If your ewes have wool slip give them additional feed to increase energy due to heat loss and adequate shelter from the cold weather.