The sheep continuous grazing on tropical forages during dry season requires supplementation with protein-based feed to improve production efficiency.The objective of this study was to evaluate the productive performance of grazing lambs supplemented with diets using 2 levels of inclusion of lime-hydrolyzed [Ca(OH)₂] feather meal. Experimental work was conducted at Rancho of the Temascaltepec University Center of the Autonomous University of the State of Mexico, from February to May. The treatments were: T1: grazing+diet with 6% feather meal; T2: grazing+diet with 9% feather meal; and T3: grazing+diet with 14% soybean meal.The diets were isoprotein (15.7%) and isoenergetic (4.6 Mcal/kg) and prepared with ground grain sorghum, wheat bran, molasses and minerals. The variables evaluated were daily weight gain, forage intake and feed conversion.Thirty lambs (Katahdin × Pelibuey) (initial weight of 26.1 kg ± 3.076) were used in the study. All lambs were weighed at the beginning of trial and thereafter every week before grazing.The lambs were randomly distributed among the 3 treatments.They grazed for 6 h daily in 3 mixed paddock (1.0 ha) of Panicum (Tanzania and Mombasa) and Brachiaria (Insurgente and Mulato II). At the beginning of each week the forage supplied was measured, and at the end of the week, the remaining forage was measured. Grass was cut using grass shears utilizing the quadrat. After grazing each day, each lamb was fed 250 g of the corresponding supplement.The lambs were kept in individual pens. A totally random design was used, with 3 treatments and 10 repetitions (each lamb representing one repetition).The Tukey’s test was used (P < 0.05).The highest daily weight gain (P < 0.05) was obtained with the T2 (59.9 g d⁻¹) and T3 (67.6 g d⁻¹) treatments. No statistical difference (P > 0.05) in feed conversion was found between the T2 and T3 treatments, obtaining relations of 11:1 and 10:1, respectively. We concluded that lime-hydrolyzed feather meal may be used as a protein supplement, when it represents 9% of the diet of grazing lambs during the dry season, and may thus replace soybean meal in their diet.