This study presents a meta-analysis of measured ammonia (NH₃) and methane (CH₄) emissions from dairy barns. A total of 27 peer-reviewed articles were selected to explore relationships between gas emission rates and housing system, measurement methods and environmental factors using linear mixed effect models. A large variation in measured gas emission rates from dairy buildings was observed, with 3.6–109.4 g AU⁻¹ d⁻¹ (AU refers to Animal Unit equalling 500 kg live mass) for NH₃ emission and 102.1–462.2 g AU⁻¹ d⁻¹ for CH₄ emission. Ammonia emissions were mainly influenced by temperature and relative humidity, with higher temperature leading to higher NH₃ emission but conversely for relative humidity. There were no significant differences in NH₃ emission rates among measurement techniques for ventilation rate and gas concentration. The emission of CH₄ from dairy barns increased with increase of temperature but was less affected by relative humidity and wind speed. Measurement techniques for ventilation rate could significantly affect CH₄ emission estimates, with higher emission measured by CO₂ balance methods and inverse dispersion and lower emission when measured by anemometers. Both NH₃ and CH₄ emissions presented no significant difference between solid floor and slatted floor, or between flushed and scraped systems. Our results indicate that environmental factors have more pronounced effects on NH₃ and CH₄ emissions than housing factors. It is necessary to establish gaseous emission factors for particular climate zones. Standardised measurement methods for gas emission rates from dairy barns are needed to reduce large variability and uncertainty.

这项研究提出了从奶牛仓中测得的氨（NH ₃）和甲烷（CH ₄）排放量的荟萃分析。选择了27篇经过同行评审的文章，以使用线性混合效应模型探讨气体排放率与房屋系统，测量方法和环境因素之间的关系。观察到奶场的气体排放率变化很大，NH ₃排放为3.6–109.4 g AU ^-1 d ^-1（AU表示动物单位等于500 kg活质量），AU ^-1 d为102.1–462.2 g AU ^-1 d CH ₄为^-1排放。氨的排放主要受温度和相对湿度的影响，较高的温度导致较高的NH ₃排放，但相对湿度则相反。在通风率和气体浓度的测量技术之间，NH ₃排放率没有显着差异。奶牛场中CH ₄的排放随温度的升高而增加，但受相对湿度和风速的影响较小。通气率的测量技术可能会显着影响CH ₄排放估算，通过CO ₂平衡方法测量的排放较高，而通过风速计测量的则为反扩散和较低的排放。NH ₃和CH₄排放量在实心地板和板条地板之间，或冲洗和刮擦系统之间没有显着差异。我们的结果表明，环境因素对NH ₃和CH ₄排放的影响比住房因素更为明显。必须为特定的气候区确定气体排放因子。需要减少奶牛场气体排放率的标准化测量方法，以减少较大的可变性和不确定性。