Determining Gaseous Emissions from a Novel Pig Housing System with Outdoor Space: Comparison of Different Measurement Approaches

To address the growing demand for environmental and animal-friendly housing with outdoor space, there is a need for reliable techniques to quantify gaseous emissions. However, there is limited research on measurement methods to determine gaseous emissions from these housing systems. Therefore, this study focuses on developing measurement techniques to assess gaseous emissions from a novel concept of a welfare-friendly pig housing system with an outdoor run in the Netherlands. This concept employs measures like an optimal pen design and a daily excreta removal system where urine and faeces are directly separated. Within this concept new-born piglets stay in the same pen until slaughter weight is reached, promoting better excretion behaviour. The outdoor yard is designed with both slatted and solid flooring, aiding pigs in distinguishing between excretion and lying areas. This design feature is intended to contribute to the reduction of emissions and enhance animal welfare. In the current study, to measure emissions and assess the potential for emission reduction, diverse techniques are outlined. Measurements are conducted at both barn and pen levels, employing the micro-meteorological technique coupled with inverse dispersion modeling, and N (and P/K) balance methods at the barn level. The micro-meteorological method measures gas concentrations upwind and downwind as well as the wind parameters, utilizing a modelling approach, i.e. the backward Lagrangian stochastic model, emission rates are computed. The N (and P/K) balance method estimates nitrogen emissions by measuring inputs, animal discharge, and nitrogen content in feces and urine during a balance period. At the pen level, local measurements are conducted to identify sources of ammonia emissions and quantify the emissions from the surface source by using an enclosure method, the fast box measurement system. The urine composition of all pig categories is assessed for NH4-N and urea-N content, as well as pH, through the collection of fresh urine. Urease activity on the solid floor inside and outside the pig house is determined using standard methods. Ammonia emissions from the urine-contaminated solid floor and solid floor with straw are measured at various temperatures and air velocities in the measurement box. Additionally, the urine-soiled area of the inside and outside solid floor, along with the frequency of urine discharges in different locations of the pen is determined using (heat) cameras. This information is then utilized to calculate ammonia emissions through an existing model. The study comprises two phases: development and optimization, followed by implementation. Overall, this research aims to formulate a protocol for emission measurements and determination of the emission factors, contributing to a more comprehensive understanding of emissions from pig housing systems with an outdoor run, and promoting more sustainable and eco-friendly housing systems.