Use of free amino acids and low protein feed formulation (nitrogen emissions)

Last update: 2 June 2023

• Action: Optimisation of nitrogen intake (completion of animal acids requirements).
• Animal category: Monogastrics.
• Technique: Adding amino acids to compound feed while reducing the crude protein level of the feed.
• Mode of action: The use of free amino acids helps to balance the amino acid profile of the diet, thus better matching animals requirements; efficiency of feed increases as the amount of plant protein sources required is reduced and excretion of nitrogen is minimised.
• Potential of efficacy: A reduction by 1% of dietary protein may lower nitrogen excretion by up to 10% for poultry and growing/finishing pigs; a 2% reduction on dietary protein may lower ammonia emission of broilers by up to 24%.
• Nature of evidence of efficacy: Peer-reviewed scientific publications; Joint Research Center Best Available Techniques Reference document for Intensive rearing of poultry or pigs.
• Factors impacting on efficacy: Diet composition (feed ingredients, protein digestibility, metabolisable energy content and concentrations of other nutrients); breed and age of the animal; environmental conditions (temperature and humidity).
• Mode of use: Via complete feed formulation.
• Requirements/limitations: Only amino acids authorized as feed additives can be used; they must be added to a mixture by a registered feed business operator applying HACCP (R183/2005); the reduction of the crude protein content of a diet is possible only to a certain minimum (12/13 %) without any impact on performance; some conditionally essential amino acids (Gly, Glu) that could allow for further protein reduction are not registered as feed additives in the European Union; synthetic free amino acids are not authorized in organic farming; the EU is largely dependent upon Third Countries for the supply in synthetic amino acids.
• Economic consequences: The calculated economic feed margin is strongly influenced by the availability and price of the protein-rich raw materials and the price of free amino acids; the higher costs of feed rich in highly digestible proteins may be compensated by higher feed efficiency and better feed conversion ratio; volatility of costs of amino acids due to high dependency on global market.
• Other considerations: The reduction of crude protein is limited since proteins are essential nutrients for animals; reducing the amount of crude proteins below the need of the animal has negative effects on animal performance and welfare; in general, young animals’ protein requirements are higher than that of older animals (additional needs to grow and build muscles).
• References:
  • JRC (2017). Best Available Techniques Reference document for Intensive rearing of poultry or pigs.
  • Van Harn et al. (2021). 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. Report / Wageningen Livestock Research; No. 1343. https://doi.org/10.18174/557184
  • Lemme et al. (2019). Reduction of dietary protein in broiler diets not only reduces n-emissions but is also accompanied by several further benefits. ScienceDirect. https://doi.org/10.3382/japr/pfz045
  • Ferket et al. (2002). Nutritional strategies to reduce environmental emissions from non-ruminants. Journal of Animal Science 80(2):168-182. https://www.researchgate.net/publication/303258722
• Other techniques: Use of highly digestible protein sources; use of phytase (release of nitrogen blocked by phytic phosphorous); use of protease (improving protein digestibility).