PSXII-14 Fiber content in diets for feedlot lambs: performance

Abstract

Abstract High-grain diets have been used with great success in the feedlot systems for lambs production in Brazil. Then it became important to define the ideal dietary fiber content in the diet when the goal is to produce heavy lambs for early slaughter. The objective in this trial was to evaluate the levels of fiber on performance of lambs feed high-grain diet. Fifty-eight Dorper x Santa Inês ram lambs (initial BW 20.7 ± 1.19 kg and 75 ± 10.83 d old) were assigned to a randomized complete block design. The treatments were defined by the fiber (“Coastcross” hay) content in diets (CP: 16,12% ± 0.92): 0F: no forage diet (NDF: 10.4%); 5F: 5% of forage (NDF: 12.1%); 10F: 10% of forage (NDF: 15%); 15F: 15% of forage (NDF: 15.5%); 20F: 20% of forage (NDF: 20.8%) and 25F: 25% of forage (NDF: 23.5%). The experiment lasted 89 days and lambs were weighted after 16 hours fasting on days 0, 31, 57 and 89. DMI, ADG and FE were determined in each period. There was no interaction effect between diets and periods. There was a quadratic effect in DMI (0F: 0.96; 5F: 0.97; 10F: 1.04; 15F: 1.00; 20F: 1.02; 25F: 0.88 kg/d; P = 0.02), ADG (0F: 0.27; 5F: 0.26; 10F: 0.28; 15F: 0.28; 20F: 0.26; 25F: 0.21 kg/d; P = 0.01) and FE (0F: 0.28; 5F: 0.28; 10F: 0.28; 15F: 0.29; 20F: 0.26; 25F: 0.25; P = 0.05). Consequently, the increased levels of forage result in quadratic effect on final BW (0F: 44.5; 5F: 44.7; 10F: 46.1; 15F: 45.5; 20F: 43.9; 25F: 39.7 kg; P < 0.01). In conclusion, the inclusion of 10–15% of forage improves the performance of feedlot lambs feed high-concentrate diets, but it was proved the real possibility of finishing lambs with diet without forage source.