Measuring and Modeling Mechanical Ventilation for Long-Term Environmental Monitoring in Large Commercial Laying Hen House

Determining ventilation rates in commercial animal buildings has been technically challenging. This study aimed to develop an innovative method and a ventilation model and provide new insights into animal building ventilation. A layer house with 46 fans was studied over six months. A full-size and fast-response portable fan tester was developed for on-site fan ventilation measurement. Results indicated that the house differential pressures (dP) varied from +10.4 to <-100.0 Pa but remained between -10 and -30 Pa for 75.7% of the time. The mean house dP was -18.1 ± 8.9 Pa (mean ± standard deviation). Fan rotational speeds ranged from 495 to 580 rpm, with an average of 555 ± 14 rpm. Daily mean house ventilation rates ranged from 1800 to 22,142 m³ min^-1, averaging 4.68 m³ h^-1 per hen. This study concluded that house dP can be greatly affected by strong winds in addition to fan operations and air inlet openings. Fan rotational speeds are influenced by pulley sizes and fan belt maintenance. On-site fan tests with the fan tester can generate reliable data for fan ventilation characterization. Fan models that incorporate both fan rotational speeds and differential pressures considerably improve ventilation rate calculations.