Standardized ileal digestible tryptophan requirements for japanese laying quails

This study aimed to estimate the nutritional requirement of standardized ileal digestible (SID) tryptophan for Japanese quails during the initial laying phase and to assess its effects on egg quality, organ weights, leukocyte differential count, and heterophile: lymphocyte ratio. The experimental design was completely randomized, with 5 treatments (0.14%, 0.19%, 0.24%, 0.29%, 0.34%) and 5 replicates, resulting in 25 experimental units with 12 quails per unit, totaling 300 birds aged 42 to 126 days. Based on the results, a SID tryptophan level of 0.14% was optimal for the laying phase. Oviduct weight exhibited a quadratic effect, suggesting a requirement of 0.24% SID tryptophan. A decreasing linear effect was observed in heterophiles and basophils, while lymphocytes and monocytes showed an increasing linear effect. The heterophile: lymphocyte ratio demonstrated a quadratic effect, indicating a requirement of 0.31% SID tryptophan. However, for birds aged 63 to 126 days, 0.14% SID tryptophan was sufficient for optimal performance, with a SID tryptophan: lysine ratio of 13% and a SID tryptophan intake of 34.67 mg per bird per day. Thus, reducing tryptophan levels in the diet did not adversely affect bird performance.

Keywords:
egg production; egg quality; essential amino-acids; blood count