Why was this update to the nutritional recommendations for production poultry necessary?
This document presents a summary of the main developments and approaches of the tenth revised edition of the “Nutrient Requirements of Poultry”, prepared by the National Academies of Science, Engineering and Medicine (NASEM). What this publication provides is a fundamental update to the National Research Council (NRC) report of 1994.
The update was imperative due to the significant changes that have occurred over the past three decades in:
- Poultry genetics: Advances that have led to greater productivity.
- Productivity: Substantial improvements in production efficiency.
- Consumer preferences: Changes in market demand, such as the preference for breast meat.
- Environmental concerns: The need for diets that mitigate ecological impact.
Since 1944, the NRC has periodically published reports on the nutritional requirements of domestic poultry. However, the frequency of these publications has decreased over time, with the 1994 report being the last before this new edition. This three-decade gap contrasts sharply with the rapid evolution and technological advances in the poultry sector, rendering previous recommendations obsolete.
The need to update these guidelines became evident given the advances in poultry productivity and efficiency, as well as in management and feeding techniques. These include:
- Feeding for specific performance outcomes: For example, the formulation of diets optimised for breast meat production.
- Quality parameters: Considerations relating to the quality of the final product (meat and eggs).
- Environmental impact: Nutritional strategies to reduce nutrient excretion and emissions.
- Consumer preferences: Adaptation to market demands for specific poultry products.
Target audience and international scope
The report is designed for a broad spectrum of professionals and stakeholders in the poultry industry:
- Poultry nutritionists
- Feed manufacturers
- Poultry producers
- Consultants
- Veterinarians
- Students
- Regulatory agencies
The internationally revised scope gives this report global relevance for commercial poultry production, consolidating it as an indispensable educational tool for students and professionals worldwide.
Methodological innovations and data inclusion criteria
Unlike previous editions, this report introduces significant changes to its methodology:
Ingredient Composition Database
- No proprietary tables: The report no longer includes ingredient composition tables.
- Reliance on NANP: Instead, it draws on the feed composition database of the National Animal Nutrition Program (NANP).
- Standardisation and continuous updating: This database uses a standardised approach to evaluate data from academic and commercial laboratories as well as peer-reviewed literature. It is continuously updated and contains millions of records for common ingredients used in animal feeding of agricultural importance.
Rigorous Criteria for Data Inclusion
The committee applied rigorous criteria for the inclusion of data underpinning the development of nutritional recommendations. These criteria are crucial for ensuring the scientific validity of the report:
- Use of a common basal diet.
- A sufficient number and range of nutrient levels to establish a dose-response relationship.
- Accurate chemical analyses of nutrient levels.
- Appropriate statistical analyses.
- Environmental and management conditions that do not adversely affect performance.
- Selection of the dietary amount based on optimal performance or the prevention of deficiency signs.
Structure and thematic content of the report
This revised edition is organised into chapters dedicated to specific aspects of poultry nutrition and management:
Essential nutrients
The main chapters cover the following nutrient groups:
- Energy, carbohydrates and fibre
- Protein and amino acids
- Lipids
- Vitamins
- Minerals
Each of these chapters provides:
- Relevant terminology and concepts.
- Nutrient functions and metabolism.
- Signs of deficiency and toxicity.
- Factors affecting requirements.
- Analytical methods.
- Future research needs.
Non-nutritive feed additives
A specific chapter on non-nutritive additives is included, covering a wide range of products:
- Enzymes
- Organic acids
- Antioxidants
- Mycotoxin binders
- General binders
- Probiotics
- Prebiotics
- Essential oils
- Pigments
Nutritional requirements by poultry type
Dedicated chapters address the nutritional requirements of different types of poultry, reflecting their specific physiological and production characteristics:
- Laying hens and pullets
- Broilers
- Broiler breeders
- Turkeys
- Ducks
- Geese
- Quail
- Pheasants
Expression of nutritional requirements
Nutrient requirements are expressed in relation to body weight and production levels, rather than age. This approach seeks to more accurately reflect changes in bird productivity. It is acknowledged, however, that certain limitations in the presentation of data in published scientific articles make it difficult to express requirements in relation to production level for some poultry types.
Digestibility and bioavailability
A key chapter addresses the digestibility and bioavailability of nutrients:
- Digestible/available phosphorus: The use of these values in diet formulation is recommended.
- Amino acid digestibility: Amino acid digestibility assays are discussed, and the lack of a standardised methodology for determining endogenous losses is highlighted.
- Apparent metabolisable energy (AME): Assays for the determination of AME are also addressed.
Feed processing
This chapter details the main stages in feed production:
- Particle size
- Moisture addition
- Pelleting
Nutrient excretion and the environment
An important chapter focuses on reducing nutrient excretion and its environmental impact, with particular emphasis on:
- Nitrogen
- Phosphorus
The role of nutrition in mitigating greenhouse gas emissions from poultry production is also analysed.
Stress physiology in poultry
The physiology of stress and its impacts on nutrient utilisation are reviewed in relation to various factors:
- Housing
- Temperature
- Ammonia
- Lighting
- Toxins and antinutritional factors
- Lipids and oxidative damage
- Non-digestible carbohydrates
- Feed form
- Immune activation
Meat and egg quality
This chapter describes how nutrient levels in poultry products can be modified through dietary supplementation, as exemplified by:
- Enrichment of eggs and meat with omega-3 fatty acids.
- Enrichment with vitamins and minerals.
Predictive Factorial Modelling
Although no chapter is dedicated exclusively to modelling, predictive factorial models were used to generate amino acid requirements for:
- Brown and white egg pullets
- Laying hens
- Broilers
In addition, several prediction equations for feed energy values are included.
Limitations of the NASEM approach and future research priorities
The NASEM approach, while ensuring the quality and scientific rigour of the information, has certain limitations:
- Data restrictions: It limits the volume of data that could lead to changes in nutrient requirements, despite the fact that research is continuously advancing.
- Need for factorial models: It highlights the need to develop predictive factorial models for other nutrients and under different conditions, taking into account the genetic diversity of birds and production objectives.
One of the main inconsistencies noted is that the majority of research has focused on energy expressed as AME (Apparent Metabolisable Energy). For poultry, AME can present inconsistencies that lead to inaccurate estimates and high variability.
Other highlighted research priorities include:
- Lack of data to validate the use of net energy in poultry diet formulation.
- Feed restriction in broiler breeders.
- Determination of digestible calcium content in feeds.
- Specific calcium requirements in poultry.
Conclusions
The tenth edition of the “Nutrient Requirements of Poultry” from NASEM represents an indispensable update to the 1994 report. Its strength lies in a comprehensive review of the scientific literature, which gives it a robust scientific foundation.
Important considerations:
- Safety margins: It is essential to bear in mind that the nutritional requirement values presented do not include the safety margins that are routinely applied in practice. These margins are necessary to compensate for factors such as:
- Errors in feed mixing.
- Natural variation in ingredients.
- Environmental factors (temperature, humidity).
- Nutrient degradation during storage.
- Need for ongoing research: The report emphasises the need for further research across various nutritional aspects.
- Predictive models and a continuous approach: The use of more precise predictive models and a continuous approach to diet formulation is promoted, always taking into account advances in genetics, poultry physiology and sustainability objectives.
Source:
-. Nutritional recommendations in poultry: an essential update: NASEM. D. Korver and K. Klasing. FEDNA Course 2024, Madrid, 6-11-2024