Effects of Low-Protein, Amino Acid-Fortified Diets Formulated on a Net Energy Basis on Growth Performance and Carcass Characteristics of Finishing Pigs

Smith, J.W.II, O'Quinn, P.R., Goodband, R.D., Tokach, M.D. and Nelssen, J.L. 1999. Effects of low-protein, amino acid-fortified diets formulated on a net energy basis on growth performance and carcass characteristics of finishing pigs. J. Appl. Anim. Res., 15: 1–16. Two hundred eighty-eight crossbred gilts (PIC L326 x C22, initially 48 kg) were used to determine the effects of corn-soybean meal or low protein, amino acid-fortified diets formulated to equal net energy (NE) concentrations on growth performance and carcass characteristics of growing-finishing pigs. Diets were formulated to two NE concentrations, 2.51 and 2.58 Mcal/kg during growing and 2.58 and 2.65Mcal/kg during finishing period. Amino acids were provided from soybean meal or a combination of soybean meal and crystalline amino acids (L-lysine, DL-methionine, L-threonine, and L-tryptophan) formulated on an ideal protein basis. Pigs fed diets containing intact protein had greater (P<0.01) ADG, G:F and percentage lean than pigs provided diets containing crystalline amino acids. For the overall experiment, pigs fed high NE had greater (P<0.10) ADG, ADFI, 10th rib fat depth and percentage lean than pigs fed low NE. This study showed that pigs fed low-protein, amino acid-fortified diets had lower ADG, G:F and percentage lean compared with pigs fed intact protein, regardless of NE.