Effects of Ratios of Essential Amino Acids to Nonessential Amino Acids in Low Protein Diet on Nitrogen Excretion and Fat Deposition of Broiler Chicks

Two experiments were conducted to determine whether the ratios of essential amino acids (EAA) to nonessential amino acids (NEAA) in low protein diets affects the performance, nitrogen excretion and abdominal fat deposition of broiler chicks. Low crude protein (19% CP) diets with different ratios of EAA/NEAA (E/N) (0.85, 1.03 and 1.17 in experiment 1, 0.76, 0.99 and 1.29 in experiment 2), and control diets (0.96 in experiment 1, 1.04 in experiment 2, E/N ratio in 21% CP) were fed to 7-day-old chicks for 14 days.Body weight gain and feed efficiency of chicks fed the 1.17 (experiment 1), 0.99 and 1.29 E/N (experiment 2) diets were the same as those of chicks on the control diets. Excreted nitrogen expressed as percentages of nitrogen intake was lower for chicks fed higher E/N diets compared to the control diets in both experiments, and decrease with increasing E/N in experiment 2. Abdominal fat weight increased with feeding 19% CP diets, but in experiment 2, 0.99 and 1.29 E/N diet chicks showed essentially the same abdominal fat deposition as those on the control diet.It follows from the present results that 1.29 E/N ratios in 19% CP diets reduce nitrogen excretion (g/4 days) by 20% without lowering performance compared to the control diet, and prevents excess fat deposition by lowering dietary CP.