# Partition of Amino Acids Requirement for Maintenance and Growth of Broilers III. Tryptophan

• Kim, J.H. (Department of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University) ;
• Cho, W.T. (Department of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University) ;
• Shin, I.S. (Department of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University) ;
• Yang, C.J. (American Soybean Association) ;
• Han, In K. (Department of Animal Science and Technology, College of Agriculture and Life Sciences, Seoul National University)
• Accepted : 1996.12.21
• Published : 1997.06.01

#### Abstract

Purified diets containing five graded levels of tryptophan were fed to growing chicks to evaluate tryptophan requirements for growth and maintenance. A model was developed to separate tryptophan requirement for maintenance from requirement for growth. From this model, the daily tryptophan requirement for growth was 2.16 mg/g gain, and the daily requirement for maintenance 0.029 times metabolic body size ($Wg^{0.75}$). Based on nitrogen gain response, the tryptophan requirement for growth was 0.078 mg/mg N gain, and the daily maintenance requirement was 0.029 times metabolic body size. The total tryptophan requirements were 71.56 mg/day or 0.173% of the diet, 69.48 mg/day or 0.168% of the diet based on the weight gain response and nitrogen gain response, respectively. Previous tryptophan requirements for growing chicks aging 1-28 days are in close agreement with these estimates. Based on the relationship of weight gain and N gain, about 1.25% of the retained CP was consisted of tryptophan; the previously reported value of tryptophan content of chick muscle CP was 1.03%.

#### Cited by

1. Estimates of individual factors of the tryptophan requirement based on protein and tryptophan accretion responses to increasing tryptophan supply in broiler chickens 8 – 21 days of age vol.59, pp.3, 2005, https://doi.org/10.1080/17450390500147925
2. A comparative evaluation of functions for partitioning nitrogen and amino acid intake between maintenance and growth in broilers vol.146, pp.02, 2008, https://doi.org/10.1017/S0021859607007423