Carbon and Nitrogen Budget of Commercial Cage-Grown Broilers

Understanding the fate of carbon (C) and nitrogen (N) inputs and outputs from commercial broiler operations is important for increasing the flock C and N efficiency and reducing gaseous emissions. This study was conducted to determine the C and N balance for broiler chickens grown in cages from day old to 42-d market age. Concentrations of ammonia (NH3), methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) gases in three side-by-side mechanically ventilated caged broiler houses were measured using an infrared photoacoustic multi-gas monitor coupled with a multi-channel sampler system. Bird manure was removed out of the houses daily. Ventilation rate (VR) was determined by continuously monitoring the building static pressure and operational status of the exhaust fans whose performance was determined in-situ with a fan assessment numeration system (FANS). At the end of 42-d growth period, the N recovery relative to the total feed N intake was 148.2±3.78 g N·bird-1 (mean±SD) 58.6±2.20% in live birds, 34.5±1.42% in manure, and 3.14±0.60% in TAN emissions, with the amount of N2O emitted being negligible. The C input recovery relative to the total feed C intake was 1,738±33.4 g C·bird-1,31.3±1.17% in live birds, 22.5±0.11% in manure, 41.4±3.47% in CO2-C emissions, and 0.27±0.01% in CH4-C emissions. The C and N accumulation of the market broilers was, respectively, 544 g·bird-1 and 86.9 g·bird-1, whereas the manure C and N accumulation was, respectively, 390 g C·bird-1 and 51.1 g N·bird-1. Total TAN emissions over the 42-d growth period averaged 4.65±0.84 g·bird-1. The total emission of CH4-C and CO2-C for the same period was 4.72±0.12 g·bird-1 and 718.9±47.5 g·bird-1, respectively.