Dietary tryptophan effects on growth and stress responses of male broiler chicks

Abstract

1. Three experiments were conducted to determine growth of broiler chicks fed on test diets formulated to be deficient or adequate in tryptophan (Trp) using gelatin by-product as a means of generating a Trp deficiency. Growth response estimates of broiler chicks to graduations of Trp were determined by dose–response criteria and regression analyses. Experiments were conducted using broiler chicks from 1 to 20 d of age.

2. Broiler chicks fed Trp-deficient diets had poor body weight gain, feed intake and feed conversion. Recommended total Trp needs were 2·0, 2·1 and 2·2 g/kg for feed intake, body weight gain and feed conversion, respectively.

3. Blood plasma Trp exhibited a sigmoidal trend while blood plasma glucose increased in a linear manner to supplemental Trp. Physiological stress variables measured were unaffected by dietary Trp.

Acknowledgements

This is Journal Article Number J10539 from the Mississippi Agricultural and Forestry Experiment Station supported by MIS-322140. Use of trade names in this publication does not imply endorsement by USDA or the Mississippi Agricultural and Forestry Experiment Station of the products, nor similar ones not mentioned. The authors would like to thank Ajinomoto-Heartland for the analysis of the experimental diets. Authors would also like to thank Lee Southern for his scientific input.