The effect iso-energetic supplements (2.9 Mcal/kg DM; 2% body weight as-dry fed basis) with different crude protein (CP) levels (12, 16 and 20% CP) during early post-weaning phase were evaluated on lamb carcass and meat quality traits. For three years (January-April; 2013, 2015 and 2016), eighty crossbreed lambs (Dohne Merino×Corriedale, with an initial average body weight -BW- of 24.5±4.4.4kg with 4 months of age) were randomly allotted each year to the following treatments:CON:native pastures (NP) without S (supplement); 12CP:NP?+?S with 12% CP; 16CP:NP+S with 16% CP; 20CP:NP+S with 20% CP. Thereafter (April-July), all animals were managed together on an annual forage winter crop (ryegrass or oat) without supplementation until an average slaughter weight of 43kg was reached. Supplementation with different crude protein (CP) levels for approximately 3 months during an early post-weaning rearing period in lambs grazing native pastures, resulted in general in greater pre-slaughter body weight, carcass weight and compactness index without significant effects (P>0.05) on carcass high-value cuts, meat color parameters, pH, and Warner-Bratzler shear force (WBSF) values after a common feeding period on improved pastures. The beneficial fatty acids ratio (n6/n3) linked with human health favoured those animals fed exclusively on pastures. In general, among supplemented groups, the magnitude of the changes found were of little relevance.