Variation in feed intake as a cause of variation in wool production of grazing sheep

Abstract

Observations were made to determine whether differences between sheep in wool production under field grazing conditions reflected differences between individuals in feed intake. Sheep were selected for high, intermediate, and low levels of clean wool weight per unit body weight under field grazing conditions, and the feed intakes and wool production of these sheep were subsequently measured under pen conditions. On controlled feed intakes differences between sheep and between groups were less than those under field grazing conditions or under ad libitum pen feeding conditions. It was concluded that a, significant portion of the differences in wool production at grazing was referable to differences in feed intake. The group of sheep having high levels of wool production per unit body weight were found to have higher efficiency of conversion of feed to wool and also to have higher levels of feed intake under ad libitum feeding conditions. The rate of wool production of the high group was 22 per cent. greater than that of the low group under conditions of equal feed intake and 37 per cent. greater under conditions of ad libitum feed intake.