Updating the Nutrient Requirements of Poultry29 September 2014
Two US poultry scientists explore the need for an update to the widely used publication, 'Nutrient Requirements of Poultry'.
The US National Research Council (NRC) 'Nutrient Requirements of Poultry' has been a benchmark publication for the research, judicial and regulatory communities domestically and abroad since the first published edition in 1944, according to Todd J. Applegate of Purdue University and Roselina Angel of the University of Maryland.
The poultry scientific community has looked to this publication for benchmark diet formulation, as they explain in a paper in the current issue of the Journal of Applied Poultry Research.
Furthermore, they write: "NRC publications have become a valuable reference for regulatory agencies, both domestically and internationally, as they offer comprehensive evaluations of credible and generally accepted science (for the most part based on published peer-reviewed information) that was current at the time of publication."
The latest version of the 'Nutrient Requirements of Poultry', the ninth, was published by the US National Research Council (NRC) in 1994 – some 20 years ago.
There have been extraordinary developments in the growth and productive potential of modern poultry strains since then. Combined with changes in body composition and egg output, it is highly likely that nutrient needs have changed beyond what the bird can compensate for with increasing intake per unit of bodyweight, the authors suggest.
Applegate and Angel go on to identify a number of other changes in the poultry industry since 1994 including bird genotype; feed ingredient composition; increased use of co-products such as distillers dried grains with solubles (DDGS); enzyme supplementation and quantification of different nutrient and energy digestibility co-efficients in growing birds.
Research publications used for amino acid and phosphorus recommendations in that last NRC are now, at best, from 1991 and at worst from 1947, the researchers say.
For amino acids, Applegate and Angel report that some recent publications have challenged the NRC recommendations as being inadequate for broilers, while formulations for laying hens are generally over-formulated in crude protein and amino acids compared with the 1994 NRC requirements.
Previously, the authors have detailed the large amount of research in broilers and laying hens to define phosphorus needs since the 1994 edition, which relied on publications from the 1980s.
Phosphorus is commonly fed commercially at levels well above the requirements, a situation which Applegate and Angel attribute to a lack of information on requirements, digestible phosphorus content in feed ingredients and their variability.
The authors also highlight that phosphorus nomenclature between the eighth and ninth editions of the NRC poultry requirements caused some confusion. 'Available phosphorus' used in the earlier edition published in 1984 was replaced by 'non-phytate phosphorus' in the 1994 publication without any substantial change in the values. These terms, as Applegate and Angel point out, are not synonymous, the first being a biological term and the latter determined chemically.
To the credit of the poultry science community, substantial amounts of data have been published in those areas to warrant an update to the ninth revised edition of the 'Nutrient Requirements of Poultry', the authors suggest.
Over time, the perception and definition of a nutrient requirement has changed from being a requirement – as a percentage of the diet – to preventing a nutrient deficiency, to now being a requirement to optimise growth or egg production response per unit of nutrient intake.
As economics becomes an increasingly more important driver for the implications of research, the scientific community has begun to embrace the concept of return on investment of nutrient used for compositional growth or egg production.
As these concepts take shape, Applegate and Angel write that the current edition’s format will have to undergo a substantial creative revision; possibly even embracing the concept of modeling of nutrient responses.
Funding for such a revision will require a large financial investment from the NRC, the feed industry, commodity associations, as well as time investment by the scientific community, the authors added.
They conclude that the first challenge is to find a consensus among the poultry industry and its scientists that a new NRC guideline for poultry is needed.
Applegate T.J. and R. Angel. 2014. Nutrient requirements of poultry publication: History and need for an update. J. Appl. Poult. Res. 23(3): 567-575. doi: 10.3382/japr.2014-00980. The paper was previously presented at the 2014 Mid-Atlantic Nutrition Conference in Timonium, Maryland, US.
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