WOOL AND BODY GROWTH IN LAMBS DURING THE FIRST 14 MONTHS OF LIFE

Data from 290 grade Corriedale sheep, ranging from 1 to 428 days of age, were used to study the relationships between age and the following characteristics: body weight, staple length, fibre thickness, and clean fleece weight. The difference between means and regressions for sex and type of birth also were evaluated.Body weights increased during the growth period from 50 to 428 days of age but, after 300 days, approached constancy asymptotically. The body weights of single lambs were greater (p <.01) than those of twins; also, wethers were heavier than females at all ages. The average daily rate of gain was higher, though not significantly, for singles and wethers than for twins and females, respectively. However, in the single lambs, the difference in rate of gain between wethers and ewes was significant (p <.05).Staple lengths snowed a declining growth rate with progressing age whereas fibre cross-sectional area showed a linear increase.The increase in clean fleece weight with age was expressed by a quadratic function. The difference in fleece weights between sexes were negligible and the rates of increase were essentially the same. However, there were significant differences (p <.01) in means and regressions between singles and twins.