# Amino-Acid-Balanced Low-Protein Diets Reduce Nitrogen Excretion Without Affecting Growth Performance in Broilers

## TL;DR

A low-protein diet balanced with amino acids reduces nitrogen waste in chickens without harming their growth, helping make poultry farming more sustainable.

## Contribution

AALP diets reduce nitrogen excretion by 31% in broilers without compromising growth performance.

## Key findings

- Birds on AALP diets excreted 31% less nitrogen over 50 days.
- Growth performance was maintained with improved feed efficiency in the AALP group.
- Liver weight tended to increase in the AALP group, but other organ weights were unaffected.

## Abstract

Livestock farming produces greenhouse gases, including nitrous oxide (N2O), which is released from chicken manure during composting. Because N2O emissions are associated with nitrogen levels in manure, reducing nitrogen excretion is an important mitigation strategy. This study examined whether feeding broiler chickens a low-crude-protein diet, balanced with amino acids, could lower nitrogen excretion without compromising growth performance. Chickens were fed a control or an amino-acid-balanced low-protein (AALP) diet for 50 days. Birds receiving the AALP diet showed maintained growth, had improved feed efficiency during the grower phase, and excreted approximately 31% less nitrogen. These results suggest that AALP diets can reduce nitrogen output while maintaining productivity, thereby lowering the substrate for downstream emissions and offering a practical approach toward sustainable poultry farming.

Reducing greenhouse gas emissions from the livestock industry is essential for climate change mitigation. In poultry production, nitrous oxide (N2O) emissions from composted manure are a major concern because they are closely associated with nitrogen content in the manure. This study investigated whether feeding broilers amino-acid-balanced low-crude-protein (AALP) diets throughout the entire rearing period could reduce nitrogen excretion without affecting growth performance. Thirty-six male broiler chicks were assigned to a control diet or an AALP diet, and nitrogen excretion was estimated over 50 days using chromic oxide as an indigestible marker. Overall growth performance was maintained in the AALP group, with a significant improvement in feed conversion ratio during the grower phase. Organ weights were largely unaffected, although liver weight tended to increase. Nitrogen excretion was significantly reduced at most time points in the AALP group, with a cumulative reduction of 31.1% compared to the control, as estimated by model-based integration over days 7–47. These findings suggest that our designed AALP diets can effectively reduce nitrogen excretion while maintaining productivity, thereby contributing to sustainable poultry production and supporting national climate goals.