Abstract
Ewes which were heavier in the fall as yearlings, on the average, weaned more pounds of lamb per ewe year during their lifetime. This advantage of the heavier ewes was due more to a higher per cent of lambs weaned than to heavier weaning weights. Variation in lamb production associated with yearling body weight existed within groups of ewes born as singles and as twins. There was no consistent difference in lamb production between ewes born as singles and twins. Selection on yearling body weight would have about the same effectiveness for increased lamb production within each of the breeds studied as the differences in lamb production between the lightest and heaviest groups of ewes was practically the same for each of the 3 breeds. These differences varied from 13 to 15 pounds of lamb weaned per ewe year. There was an inverse relationship between average lifetime body weight and pounds of lamb weaned per ewe year when considered independently of fall yearling weight. This emphasizes the desirability of basing selection on body weight taken prior to the first breeding. There was a slight advantage in lifetime average fleece weight in favor of the ewes which had been heavier as yearlings but there was practically no differences in the lifetime fleece lengths associated with yearling body weight. Copyright © . .