Managing feed supply chains for GHG mitigation must also take
into consideration nitrogen use efficiencies. N losses from poultry
manure are the second largest contributor to GHG emissions in
both pullet and layer facilities, and the upstream impacts of N
fertilizer production and use are a primary determinant of feed
input GHG intensity. Feed formulation, breeding, and selecting
manure management strategies for optimal N use efficiencies are
therefore powerful tools in supply chain carbon footprint reduction.
Here, we modeled N losses using nutrient balances and
emissions factors derived from IPCC protocols. Given the margin of
error associated with manure N sampling, we recommend using
this modeling approach. This will also maximize inter- and intracompany
and product comparability. However, we also suggest
continued efforts to improve and standardize company-level
manure-N sampling accuracy, in order to allow for differentiation
between facilities and production strategies looking forward.