The effect of adding essential amino acids and vitamins to the rations of broilers

Four experiments were carried out to investigate the amino acid and vitamin requirements of broilers. The performance of birds fed on control diets formulated according to the recommendations of the National Research Council (1977) was compared to that of birds fed on experimental diets containing additional amounts of essential amino acids (L-lysine and DL-methionine) and vitamins. The control diets varied in protein and metabolizable energy content; the experimental diets were obtained by adding varying additional amounts (10 to 50%) of one or both amino acids and vitamins to the control diets. The experimental diets resulted in consistently better body weight gains than the control diets. The results showed that under the conditions of these experiments, the levels of amino acids and vitamins in the control diets were not optimal for the proper growth and development of broilers and must be increased.