The objective of the present study was to investigate the effect of varying crude protein (CP) levels on intake, growth performances and nutrient digestibility of Dorper lambs at pre- and post-weaning period. Twenty lambs at 7 days old with an initial body weight of 2.91 kg were individually penned and randomly assigned into four (4) dietary groups using a randomised complete block design. In Trial I, pre-weaning lambs were fed with creep feeding (CF) diet containing 14% crude protein (CP) as a control diet (CON14), 16% (CF16), 18% (CF18) and 20% (CF20) of CP for 84 days. Following Trial 1, the animals were fed with a growing ration (GR) diet for 96-day feeding trial. The diets consisted of 11% CP as a control diet (CON11), 14% (GR14), 16% (GR16) and 18% (GR18) of CP. The water was available ad libitum and the feed intake was measured daily by the difference of feed offered and refused. The increase of CP level resulted in a linear increase of dry matter intake (DMI), nutrient intake and average daily gain (ADG) in pre- and post-weaning lambs. The DMI (g/day) of lambs fed with CF20 (1059.92) was significantly higher (p < 0.05) than CON14 (605.30), but it did not differ significantly with CF16 (866.80) and CF18 (680.40). Besides, the DMI (g/day) of lambs fed GR18 was found significantly higher than CON11 and GR16. In pre- and post-weaning lambs, there was a quadratic effect of increased CP level on the ADG. The ADG (g/day) of pre-weaning lambs fed with CF18 (247.86) and CF20 (251.28) were not significantly different (p > 0.05) compared to those fed with CF16 (217.95). For post-weaning lambs, GR16 had significantly higher ADG than CON11 (43.14), but it was no difference with GR14 (72.94) and GR18 (69.41). However, increased CP level resulted in linear increase of DM, ash, organic matter (OM) and CP digestibility. The present finding suggested that the optimum CP level for pre- and post-weaning Dorper lambs in Malaysia was 16% and 14%, respectively.
