The present study was conducted to evaluate the growth performance of lambs and to assess the effect of non-genetic factors on growth traits of indigenous sheep population in highlands of Gurage area, South Ethiopia. Two districts were selected purposively based on highland sheep population distribution and flock size. Birth weight and live body weight records at different age of interval were monitored from 197 heads of lambs under smallholder farmers’ management condition. The effects of non-genetic factors on pre-weaning and post-weaning average daily weight gain were also estimated. The data were analyzed using GLM procedure of SPSS (version 21). The overall least square mean weight (kg) at birth, 3, 6, 9 and 12 months of age were 2.39 ± 0.03, 8.74 ± 0.14, 11.46 ± 0.22, 15.09 ± 0.25 and 19.70 ± 0.26, respectively. Sex, season and birth type significantly (p <0.05) affect live body weight at most of age group. There was also significant (P<0.01) difference on pre-weaning and post-weaning average daily weight gain of lambs among sex, birth type and season group. The overall average daily weight gain (g/day) of lambs at birth to 90-days, 90 to 180-days and yearling age of intervals were 69.14 ± 1.33, 31.28 ± 1.72 and 46.72 ± 0.65, respectively. In general, the study indicated that non-genetic factors exerted a significant effect on growth performances of lambs. Therefore, to increase growth performance of lambs’ improvement of management options like supplementation of feeds during dry season and planning of breeding season are important.

Keywords: Growth performance, birth weight, weaning weight, yearling weight