Amino acid requirements for laying hens: a comprehensive review

Abstract

The main aim of this review is to consolidate the relevant published data examining amino acid requirements of layer hens and to reach a new set of recommendation based on these data. There are inconsistences in lysine, sulphur-containing amino acids, threonine, tryptophan, branched-chain amino acids, and arginine recommendations in data that have surfaced since 1994. This review finds that breed, age, basal diet composition, and assessment method have contributed toward inconsistencies in amino acid recommendations. Presently, the development of reduced-protein diets for layer hens is receiving increasing attention because of the demand for sustainable production. This involves quite radical changes in diet composition with inclusions of nonbound, essential and nonessential amino acids. Increasing inclusions of nonbound amino acids into layer diets modifies protein digestive dynamics, and it may influence amino acid requirements in layer hens. This review considers present amino acid recommendations for layer hens and proposes refinements that may better serve the needs of the layer industry in the future.

Multivariate modeling strategies to predict nutritional requirements of essential amino acids in semiheavy second-cycle hens

“…Threonine plays a vital role in maintaining gut barrier integrity and mucin synthesis, and is associated with the maintenance of the epithelial barrier that is the first defense layer against pathogens (Mehri et al, 2021). It is also related to antibody production, which plays a significant role in immunity, and its requirement could be elevated under challenging conditions, including poor sanitation and chronic diseases (Macelline et al, 2021).…”

Functional role of branched chain amino acids in poultry: a review

“…BCAA are expected to play an important role in egg production in layers, as hepatic yolk-lipoprotein production via fatty acid metabolism in the liver is regulated by BCAA ( Macelline et al., 2021 ). The commercial layer nutrient specification guides for Hy-line and Lohman breeds do not include recommendations for leucine inclusion, whereas NRC (1994) mentions leucine requirements in layers and breeders ( Table 2 ).…”

Low crude protein diets supplemented with free amino acids in laying hens : effects on performance, egg quality, N-efficiency, N-excretion, economics and diet carbon footprint

“…According to a study reviewed the outcome of research in amino acids requirements of laying hens being published between 1994 and 2019, supplying low protein diets with a lysine content of over 8.0 g/kg might reduce feed intake (Macelline et al, 2021). Wang et al (2018) emphasized the regulatory role of amino acids on the appetite centres in CNS and argued that a high level of lysine might suppress the appetite in chickens by the means of L-pipecolic acid, an important metabolite of lysine in the brain.…”