Effects of Low-Protein Diets with Different Levels of Essential Amino Acids and Metabolizable Energy on Productivity and Metabolic Processes in Pigs

Resumo

An experiment with growing meat pigs has proven the productive efficiency of low-protein diets rich in essential amino acids. In order to achieve a live weight of 20 kg, the use of 10.08 g lysine (accessible 9.0 g), 6.09 g threonine (accessible 5.33 g), and 5.04 g methionine (accessible 4.19 g) are required. In the growth period, 8.08 g (6.39 g), 5.26 g (4.46 g), and 5.04 g (4.23 g), respectively, are required, while 7.49 g (3.97 g), 4.93 g (4.43 g), and 4.72 g (3.97 g), respectively, are required in the fattening period; the metabolizable energy is expressed as 13.30–12.69 MJ/kg fodder. In addition, the ratios of lysine to the metabolizable energy (g/MJ), the threonine, and the sum of methionine and cystine should be in the ranges of 0.79, 0.60, and 0.51, respectively, in order to reach the live weight of 20 kg. In the growth period, these items should be in the ranges of 0.64, 0.65, and 0.62, respectively, while they should comprise 0.61, 0.65, and 0.63, respectively, in the fattening period. The data on the blood plasma urea concentration and the urinary excretion of nitrogeneous waste can prove the more efficient use of the amino acids in the biosynthetic processes under the experimental conditions.