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Estimation of the Tryptophan Requirement of Chickens for Maximum Body Weight Gain and Feed Efficiency

Department of Poultry Science, The University of Georgia, Athens, Georgia 30602-2772; Phone: (706)542-1351; FAX: (706)542-1827

Correspondence: A. Rosa

Tryptopahn is an essential amino acid for chickens and has many metabolic roles. The world's literature on the tryptophan requirement of starting chickens (0 to 3 weeks) was reviewed. Data were pooled from 29 different experiments into two groups: broilers and other genotypes. The nonlinear mathematical models [ascending line with plateau (ALP) and ascending quadratic line with plateau (AQP)] were fitted to estimate the tryptophan requirement from these data sets. The tryptophan requirements estimated for body weight gain (BWG) and feed efficiency (FE) of broilers using the ALP model were 0.20 ± 0.002% (BWG) and 0.25 ± 0.2% (FE). Using the AQP model, the requirements were 0.24 ± 0.004% (BWG) and 0.29 ± 0.03% (FE). The tryptophan requirements for the other stocks using the ALP model were 0.24 ± 0.02% (BWG) and 0.20 ± 0.02% (FE). Using the AQP model, the requirements were 0.32 ± 0.06% (BWG) and 0.28 ± 0.05% (FE). Based on this analysis, it was concluded that the current National Research Council (NRC) [1] estimate of the tryptophan requirement (0.20% of the diet) is probably low.

Key Words: Tryptophan • broilers • chickens