STATISTICAL MODELING OF GAS CONCENTRATIONS IN AUSTRALIAN PIGGERY BUILDINGS

Abstract

The aim of the research presented here was to model the effects of important housing andmanagement factors on the concentrations of ammonia and carbon dioxide in order to predict andcontrol the internal concentrations and emissions of these gases from piggery buildings. Theproject aim was achieved by conducting a comprehensive survey (160 piggery buildings in foursstates of Australia between autumn 1997 and autumn 1999) and measuring the concentrations ofthese gases in the study buildings. Ammonia and carbon dioxide concentrations were measuredcontinuously over 60 hours at each monitoring occasions using a multi-gas monitoring machine(MGM). Engineering and management characteristics of the piggery buildings were recorded atthe time of sampling and used in the subsequent multivariate analysis. The mean ammonia andcarbon dioxide concentrations measured in the piggery buildings were 3.7 ppm and 858 ppm,respectively. A general linear model (GLM PROC) statistical procedure was used to model theeffects of housing and management factors on the concentrations of ammonia and carbondioxide. According to the model developed, ammonia concentrations were primarily affected bythe level of pen hygiene, shed size, pig flow management and seasons. Carbon dioxideconcentrations were affected by the classification of the buildings, seasons, ventilation control ofthe wall and ridge vent openings, ceiling height of the buildings, size of the wall openings andheight of the ridge vent opening. The results highlighted potential strategies to be used to reducethe negative effects of poor air quality on pig production, environment, health and welfare andthe working environment of piggery staff.