This paper reports the emission factors and characteristics of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), and particulate matter (PM10) from two 250,000-bird capacity manure-belt layer hen houses (B-A and B-B) in northern Indiana, USA.
Correlations were observed between total bird capacity and flock supervisor visits, feed delivery and non-integrator commercial visits.
As these variables were important predictors of risk in our model, these correlations suggest that total bird capacity may be a useful proxy for risk.
Correlation analyses found that certain contact rates were significantly and positively associated with farm size as measured by total bird capacity.
Spearman rank correlation in STATA was used to determine correlation between continuous contact frequency data and between basic farm descriptors (number of houses, number of birds per house, and total bird capacity).
The survey queried growers about farm size and business cycle (number of houses, number of birds per house, total bird capacity, frequency and duration of between-flock gap periods), household size, poultry industry and service visitors to and from the farm, frequency of these visits, and biosecurity and waste management practices on the farm.
As a measure of farm size, total bird capacity at one time on the farm was positively correlated with flock supervisor visits (p = 0.045), as well as with a composite variable representing all non-integrator commercial visits (p = 0.013) and marginally with feed delivery visits (p = 0.069).
For birds, the capacity to take to the air potentially opens an almost limitless capacity for dissemination.
The Guardian has obtained internal Faccenda documents highlighting how the supply of birds can exceed capacity at the abattoir and how some end up stored in crates overnight.
"Our results are restricted to zebra finches, but it is very likely that other songbirds and other birds have this capacity for kin recognition," he said.
