Age dependent energy and digestible amino acids of common Australian feedstuffs


The principal role of feed ingredients is to provide the nutrients that can be utilised for maintenance and productive functions by the bird at different ages. Phase-feeding, a form of precise-feeding, is a feeding system in which energy content of the diet is increased and dietary amino acids (AA) levels are reduced steadily over time in an attempt to reduce costs associated with excess dietary protein. The potential of phase feeding, however, is not being effectively harnessed due, among others, to the lack of information on nitrogen-corrected apparent metabolisable energy (AMEn) and digestible AA content of different feed ingredients for broilers of different age groups. Currently, the evaluation of AMEn and AA digestibility in ingredients for broiler chickens is conducted using older birds (typically 28-35 days of age) and the determined estimates are applied to all the phases of bird’s growth. The application of a single value of AMEn and digestible AA to all growth phases of broilers is clearly fraught with serious flaws and highlights the need for age-dependent estimates for use in feed formulations. Therefore, the fundamental aim of this project is to explore the impact of bird age on the nutrient utilisation in broilers. In a series of studies, we will determine age dependent AMEn and standardised ileal digestible (SID) AA values for common raw materials used in the Australian meat chicken industry. This project will investigate three cereals (wheat, sorghum and barley) and three protein sources (soybean meal, canola meal and meat and bone meal).


Chicken Meat

Research Organisation

Massey University

Objective Summary

The results will provide clear guidelines to nutritionists to use in formulating appropriate phase-feeding diets. The outcome will be increased efficiency of chicken meat production and reduced feed waste and resultant pollution. Our proposal is aligned with priority research ideas listed for 2018/2019 and is relevant to addressing the current industry objective to “Increase the productivity and efficiency of chicken meat production”. The major objective of this project is to determine AMEn and SID values of AA in three cereals commonly used in Australia (wheat, sorghum and barley) and three protein sources (soybean meal, canola meal and meat and bone meal) at different ages of broilers. Refining AMEn and SID values of AA for bird age will allow more accurate formulation of broiler diets for different growth phases and has the potential to reduce nutrient wastage and emissions to the environment whilst improving broiler performance.

Project Code


Project Stage


Project Start Date

Thursday, March 12, 2020

Project Completion Date

Sunday, April 30, 2023

Journal Articles From Project

Apparent metabolizable energy of cereal grains for broiler chickens is influenced by age Poultry Science Journal (Issue: 00 on 1/7/2021)

National Priority

An environmentally sustainable Australia

National Priority

CME-Improve chicken meat production through the whole supply chain