Background

Nutrients are essential elements for the growth of organisms. They must be added intentionally to the production chain of products based on living substrates, if they are not available in sufficient quantity or quality for production to cover the nutritional demand of livestock.

Nitrogen (N) and phosphorus (P) are of relevance as they belong to the four elements with biogeochemical cycles (N, P, carbon, and water), which are regularly recycled around the planet at various temporal scales. With the industrial revolution, these previously stable and self-sustained cycles have been significantly altered by human activities.

The assessment of nutrient flows in different stages of livestock supply chains, as well as the associated environmental impacts, are challenging due to the rapid transformation of the livestock sector and the lack of harmonized scientific method.

In contrast to the assessment of livestock supply chains with a focus on impact categories, a more thorough description of all flows involved is required for the assessment of impacts on nutrient cycles. Due to their inherent characteristics within the environment and techno-sphere, it should account for the impacts linked to losses of polluting nutrient forms, and the efficiency with which nutrients are used in the supply chain. The analysis of these flows offers potential opportunities to improve nutrient management and thus, increase nutrient use efficiency and reduce environmental impacts.

The technical document Nutrient flows and associated environmental impacts in livestock supply chains. Guidelines for quantitative assessment, developed by the Livestock Environmental Assessment and Performance (LEAP) Partnership, aims to introduce an internationally-harmonised approach to assess the potential environmental impacts associated with nutrient use in livestock supply chains while considering the different nutrient flows in the various production systems involved.

About the guidelines

The main purpose of the guidelines is to provide additional recommendations to the existing FAO LEAP guidelines on animal feed and animal supply chains by including recommendations for the life cycle impact assessment, considering all nutrient flows, including loops and recycling flows, which are essential to integrate livestock sector into circular bio-economy.

The document addresses different aspects to model N flows, the impact assessment for eutrophication and acidification, uncertainty analysis and sensitivity analysis; as well as provide additional indicators, such as life-cycle-nutrient use efficiency, that are necessary to support the interpretation of results.

To illustrate inventory data and results from a range of livestock systems, the guidelines include fours case studies: lamb production in New Zealand to consumption in the United Kingdom; beef and sheep extensive grazing system in Uruguay; egg (medium size) production, in combination with pigs and cereal production in Sweden; and fully grazing dairy cattle supply chain in Rwanda.

Livestock species and production system

These guidelines are intended to be relevant to all varieties of livestock species and production systems.

Intended users

The guidelines can be used by stakeholders in all countries to assess the sustainability of nutrient use in livestock supply chains. In particular, they are relevant to a wide array of livestock stakeholders including:

• Livestock producers who wish to develop inventories of their nutrient use and to have the environmental performance of their production systems assessed;
• Supply chain partners such as feed processors, livestock farming organizations, processors of animal products, as well as retailers pursuing a better understanding of the environmental performance of their production processes;
• Policymakers that are interested in developing nutrient use accounting and reporting specifications for livestock supply chains.

Benefits

The benefits of this approach include:

• Use of recognized, robust and transparent methodology developed to take account of the specificity of nutrient use in contrasting production systems;
• Identification of nutrient loss hotspots and opportunities to improve supply chain performance and to reduce environmental impacts;
• Identification of opportunities to increase efficiency and productivity;
• Ability to benchmark performance internally or against industry or government standards;
• Supporting reporting and communication requirements; and
• Raising awareness and supporting action on environmental sustainability

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