Amino acid digestibility and poultry feed formulation: expression, limitations and application

Abstract

-The nutritional value or quality of dietary proteins used for poultry feed formulation varies: amino acid availability is an important measure of protein quality. Determination of ileal digestibility values has become the preferred method for estimating amino acid availability. This review discusses the different approaches to the expression of digestibility results, including correction for endogenous loss and the derivatisation of standardised values. Sources of variation in values include, the assay protocol, anti-nutritional factors in feedstuffs and feed milling. Feed formulating with ileal digestibility values should allow higher dietary inclusion levels of protein feedstuffs of lower quality provided that values of different feedstuffs are additive, the age of the bird and the use of feed enzymes are considered. An Australian data set of "ileal digestible amino acid values in feedstuffs for poultry" that has recently be published is described. This overview is intended to stimulate interest in the generation and application of ileal digestibility as a method for estimating amino acid availability in poultry nutrition.Key Words: amino acids, apparent digestibility, chickens, endogenous loss, feedstuffs, ileum Digestibilidade de aminoácidos e formulação de rações para aves: expressão, limitações e aplicações RESUMO -O valor nutritivo ou a qualidade das proteínas dietéticas utilizadas para a formulação de rações para aves varia: a disponibilidade de aminoácidos é uma medida importante da qualidade da proteína. A determinação dos valores de digestibilidade ileal tornou-se o método preferido para a estimativa da disponibilidade de aminoácidos. Nesta revisão são discutidas as diferentes abordagens para a expressão dos resultados de digestibilidade, incluindo a correção de perdas endógenas e a derivação de valores padronizados. As fontes de variação dos valores incluem o protocolo do ensaio, os fatores antinutricionais na alimentação e a indústria de alimentação. A formulação de rações com base nos valores de digestibilidade ileal deve permitir a inclusão de maiores níveis dietéticos de alimentos com proteína de qualidade inferior, desde que sejam considerados os valores dos diferentes alimentos aditivos, a idade da ave e o uso de enzimas para alimentação animal. Um conjunto de dados australianos de "valores de aminoácidos digestíveis ileais em alimentos para aves" acaba de ser publicado.Esta visão procura estimular o interesse na geração e aplicação de digestibilidade ileal como um método para estimativa da disponibilidade de aminoácidos na nutrição de aves.

Digestible Amino Acids: Significance and Prospects in Poultry

“…Fuller (2003) defined digestibility as digestion of dietary consumed protein and AA and absorption form the intestinal lumen. The DAA values are preferably used to represent available AA (Bryden and Li, 2010). Reliable DAA values permit more efficient poultry ration formulation (Lemme et al, 2004); therefore, the approach to formulate diet on DAA basis instead of total AA (TAA) is considered good.…”

Determination of Ileal Amino Acid Digestibilities of Some By-products for Chickens

“…However, a question often posed by commercial nutritionists is which digestible amino acid system is the most appropriate for use in poultry diet formulation [9]. Apparent digestibility measures the digestibility of amino acids of both dietary and endogenous origins [10].…”

“…While, standardized digestibility includes a correction for endogenous amino acid secretions [11]. The choice of the D DAVID PUBLISHING Determination of Ileal Amino Acid Digestibilities of Some By-products for Chickens 464 appropriate system of digestible amino acids may depend on the diet formulation method [9]. If diets are being formulated to the least-cost using linear programming, then apparent ileal digestibility values are the most appropriate, as they take into account the endogenous cost of digestion.…”

“…If diets are being formulated to the least-cost using linear programming, then apparent ileal digestibility values are the most appropriate, as they take into account the endogenous cost of digestion. On the other hand, in case of formulating diets with computer simulation models, then standardized digestibility values will be relevant if the model corrects for the endogenous cost of digestion [9]. Notwithstanding, it should be appreciated that both digestible amino systems are better than the total amino acid system, and all systems have specific applications and shortcomings [9].…”

“…On the other hand, in case of formulating diets with computer simulation models, then standardized digestibility values will be relevant if the model corrects for the endogenous cost of digestion [9]. Notwithstanding, it should be appreciated that both digestible amino systems are better than the total amino acid system, and all systems have specific applications and shortcomings [9]. This study was carried out with the purpose of determining standardized ileal digestibility of amino acids in some by-product ingredients (copra meal, rapeseed meal, feather meal, hydrolyzed poultry meal, meat and bone meal and shrimp head meal) for broiler.…”