ABSTRACT
Advances in understanding and improving the role of amino acids in poultry nutrition William A. Dozier III, Auburn University, USA; and Paul B. Tillman, Poultry Technical Nutrition Services, USA
1 Introduction
2 History of crystalline amino acids
3 Amino acid digestibility of feed ingredients
4 Digestible amino acid requirements/ratios
5 Nitrogen balance
6 Summary
7 Where to look for further information
8 References
Genetic selection of poultry over the past several years has increased the rate and efficiency of growth of poultry (Havenstein et al., 2003a,b, 2007; Aviagen, 2015; Cobb, 2015; Hubbard, 2015). Primary breeding companies for meat birds have placed emphasis on selecting for improved feed conversion and breast meat yield (pectoralis major and minor muscles) due to feed ingredient price volatility and demand for further-processed poultry products. Over the last decade, genetic selection of broilers has increased body weight gain and breast yield, and improved feed conversion by 41 g, 0.50% and 0.02 points, respectively, on an annual basis (Aviagen, 2015). The juvenile broiler undergoes rapid growth rate during the first few days post-hatching. For example, 7-day body weight increases by approximately four-fold from hatching and weighs 3 kilograms in body weight by 6-7 weeks of age. The improvement in feed conversion of the modern broiler relates to increased growth rate per unit of feed consumed, which translates into increased white meat accretion compared with the commercial broiler used in the previous decade (Havenstein et al., 2003a,b). Therefore, while broiler feed intakes have increased, this increase cannot fully compensate for proportionately higher lean muscle growth. Thus, it does stand to reason that the modern broiler will respond to higher concentrations of dietary amino acid density to increase lean tissue mass since lean tissue is relatively high in amino acid content.
