Effect of starter ration supplementation on pre- and post-weaning growth performance of Dorper × Menz lambs

Pre-weaning nutrition is critical for improving lamb growth, as inadequate nutrient supply during early life can limit growth potential. This study evaluated the effects of starter ration supplementation, with or without vetch hay, on the growth performance of Dorper × Menz lambs. The experiment was conducted using a randomized complete block design (RCBD) with 36 lambs allocated to four treatments: dams’ milk + concentrate offered to their dams (T1), dam milk + vetch hay (T2), dam milk + starter ration (T3), and dam milk + starter ration + vetch hay (T4). Data were analyzed using a linear mixed-effects model, with treatment, time, and treatment × time interaction specified as fixed effects. Statistical significance was declared at p < 0.05. Pre-weaning body weight (BW) increased progressively with time and was significantly affected by treatment, measurement time, and their interaction ( p ≤ 0.004). At weaning, treatment significantly affected final body weight (FBW), body-weight change (BWC), and average daily gain (ADG) ( p < 0.001), with ADG of 185 and 196 g/d in T3 and T4, respectively, compared with 106 g/d in T1. Post-weaning BW was significantly affected by treatment and time ( p < 0.001), whereas the treatment × time interaction was not significant ( p = 0.529). Growth traits were strongly positively correlated ( r = 0.69–0.92) with birth weight and dam-related traits, indicating that early body weight was strongly associated with subsequent body weight. Early-life starter ration supplementation, particularly when combined with vetch hay, enhanced lamb growth under the conditions of the present study. These findings indicate that improved early nutritional management can contribute to better lamb productivity under the on-station conditions of this experiment. Further studies should evaluate economic feasibility and longer-term effects under smallholder production conditions.