The Relation of Face Covering to Lamb and Wool Production in Range Rambouillet Ewes

Abstract

The lifetime lamb production of 798 Rambouillet ewes born during the years of 1938 through 1940 at the Western Sheep Breeding Laboratory, Dubois, Idaho, was studied in relation to face covering. Ewes with open faces produced 11.3 percent more lambs and 11.1 more pounds of lamb per ewe bred than those with covered faces. Ewes with partially covered faces weaned 8.6 percent more lambs and 7.7 more pounds of lamb per ewe bred than those with covered faces. Differences in face covering within these groups were associated with corresponding differences in lamb production. These advantages for ewes with open faces occurred in spite of three periodic clippings around the eyes of all ewes subject to wool blindness. About 46 percent of the advantage of open-faced ewes was due to a greater number of lambs born per ewe lambing; 26 percent was due to higher weaning weights; 19 percent was attributed to a higher proportion of the ewes becoming pregnant; and 9 percent was due to greater viability to weaning of offspring. Open-faced ewes excelled covered-faced ewes in lamb production at each year of age. The greatest advantage for open-faced ewes in pounds of lamb per ewe bred was found at 3 years of age followed in order by 2, 4, 6, and 5 years. The yearling grease and clean fleece weights and staple lengths of 2499 Rambouillet ewes and the lifetime grease fleece weights of 798 Rambouillet ewes were slightly greater for covered-faced ewes than for those with open faces. The differences were not significant except for staple length and were not large enough to be economically important. The great economic importance and high heritability of face covering indicate that it should receive as much or more attention in selection than any other trait in sheep if wool blindness is a problem. Copyright © . .