Dietary isoleucine responses in male broiler chickens

Abstract

1. Three experiments were conducted to measure growth and carcase responses of growing and finishing broilers fed on test diets formulated to be deficient in isoleucine (Ile).

2. Dose titration methodology was used to measure growth and carcase responses of growing and finishing broilers to graduations of Ile in three additional experiments.

3. The experiments were conducted from d 18 to 30, 30 to 42, and 42 to 56.

4. Broilers given Ile-deficient test diets had poorer weight gain, feed conversion and carcase responses than broilers fed on Ile test diets containing a surfeit of Ile. Adding supplemental Ile to the test diet resulted in equivalent growth and carcase responses to those of broilers fed on the control diet with equal Ile from intact protein sources.

5. Recommended total Ile needs varied between 6·7 and 7·1 g/kg from d 18 to 30, 6·4 to 6·6 g/kg from d 30 to 42, and 5·5 to 6·6 g/kg from d 42 to 56.

Acknowledgements

This work was supported, in part, from funds provided by Ajinomoto-Heartland, Chicago, IL, USA. The authors wish to thank the staff of the Department of Poultry Science for support during this project. Special thanks are extended to S. Barber and D. Zumwalt. American Protein Corporation (Boone, IA, USA) is acknowledged for providing blood cells. Feed grade amino acids provided by Degussa, Ajinomoto, and Kyowa Hakko are greatly appreciated. This is Journal Article Number J10291 from the Mississippi Agricultural and Forestry Experiment Station supported by MIS-322140. Use of trade names in this publication does not imply endorsement by the Mississippi Agricultural and Forestry Experiment Station of the products, nor similar ones not mentioned.