Dynamic, Mechanistic Modeling Approach as a Tool to Mitigate N Excretion in Broilers

Abstract

The nitrogen (N) load of broiler meat production is known for its high contribution to the environmental footprint of animal agriculture. The modeling work presented here is to be used as a tool to understand and quantify N excretion via a dynamic mechanistic nutrient partitioning simulation. The model has been developed for broilers, representing energy and protein utilization. Three case studies are presented and discussed, such as (1) feeding schedules with adjusted protein content feeds; (2) feeding diets with different digestibility of crude protein; and (3) feeding diets with the same digestible protein and different SID lysine, methionine plus cystine or threonine contents. In addition to N retention and total N excretion, diagnostic variables for N excretion via urine and obligatory urinary N excretion were studied to evaluate N partitioning in response to different feeding schedules. The excess N was calculated in each scenario for the whole fattening period. This in silico study has confirmed that unprecise diet formulation has considerable consequences: overestimation of digestibility or oversupply of dietary protein increases the total ammonia N in the manure and thus the N emission potential of poultry meat production. The presented approach may be recommended to design alternative feeding strategies with a low environmental footprint.