HIGH-CONCENTRATE DIETS FOR LAMBS: STRATEGIES TO MAXIMIZE NUTRIENT ABSORPTION AND ANIMAL PERFORMANCE

Abstract

Six experiments will be carried out with feedlot lambs receiving diets with high energetic concentration, aiming to define the best nutritional strategy to be used when the objective is to "accelerate" growth rates of lambs, aiming to kill them early with high biological efficiency. In experiments I and II, experimental treatments will be defined by the addition of 0 (CONTROL), 8, 16 or 24 mg/kg DM of monensin to a base diet containing 90% concentrate and 10% coastcross). In experiment I, 56 ram lambs will be evaluated under confinement conditions. The experimental design will be in randomized complete blocks with 14 blocks and 4 treatments. The measured variables will be: DMI, ADG and FE. In experiment II, eight lambs, cannulated in the rumen, distributed in 4 x 4 replicate Latin square will be used. The following variables will be measured: nutrient intake and digestibility, nitrogen balance and ruminal fermentation characteristics. In experiments III and IV, the experimental treatments will be defined by the addition of 5, 10, 15, 20 or 25% of forage (% DM) to a ground corn base diet. In experiment III, 50 lambs distributed in a randomized complete block design (10 blocks and 5 treatments) will be confined. The following variables will be evaluated: DMI, ADG, FE, ingestive behavior, plasma glucose, urea, insulin and aspartate-aminotransferase (AST) and gama-glutamyl transferase enzymes (GGT). In the experiment IV, five lambs, cannulated in the rumen, distributed in 5 x 5 Latin square will be used. The following variables will be evaluated: consumption and digestibility of the nutrients (DM, OM, CP, EE, NDF, NFC and starch), nitrogen balance and ruminal fermentation characteristics (pH, VFA's, N-NH3). In experiments V and VI, the treatments will be defined by the addition of 0 (CONTROL), 10, 15 and 20% of forage (% DM) to a whole maize base diet. In experiment V, 50 lambs distributed in a randomized complete block design (10 blocks and 5 treatments) will be confined, in this experiment the same variables described in experiment III will be evaluated. In the experiment VI, five lambs, cannulated in the rumen, distributed in 5 x 5 Latin square will be used. In this experiment, the same variables described in experiment IV will be measured. All data will be analyzed using the MIXED procedure of SAS (1999). (AU)