Understanding the dust and odor generated by poultry sheds can go a long way in helping to reduce opposition when new sheds are planned. This need is only likely to increase as demand for poultry meat grows and available land decreases.

Along with need to better understand odor and emissions has come an improvement in measurement techniques, including new olfactory and dust measurement standards, improved sample collection methods and the use of use of alternative measurement technologies, such as electronic sensing arrays and gas chromatography-mass spectrometry.

The results of a study of broiler and layer houses started in Australia in 2005 have now been made available. While the ultimate goal of the study to produce a comprehensive odor emissions model proved elusive, the work, nevertheless, resulted in recommendation for how dust and odor sampling should be conducted.

The project, under researcher Mark Dunlop and supported by the Poultry Cooperative Research Centre, has significantly enhanced the understanding of the many variables influencing the emission of odor and dust from poultry sheds and improved sampling and analytical methods suitable for the study of emissions from modern poultry farms.

The work covered both broiler and layer farms, and made recommendations on how to measure emissions at both types of farms. As far as broiler farms are concerned, the study resulted in the following recommendations.

Odor  

Odor sampling programs and methodologies should be carefully chosen to provide meaningful and representative emission rates, as broiler shed odor emissions can be highly variable.

At the time of sampling, it is essential to record information, including:

  • Sampling conditions – the time, date and sampling position
  • Ambient conditions – ambient temperature, ambient humidity, internal shed temperature, and internal shed humidity
  • Shed dimensions and conditions – ventilation rate, number and position of active fans, fan details (dimensions, manufacturer), mode of ventilation (tunnel or mini vent), shed length, shed width, status (single use or reused litter), lighting conditions and drinker type
  • Batch information – bird age, bird numbers, bird live weight, total live weight, number of birds placed at the start of the batch, bird breed

The researchers recommend that daily fan activity should be understood and surveyed for that time of the batch and year, and that odor sampling should be scheduled so that samples are collected at a representative ventilation rate or at several ventilation rates during the night when odor emission rates are lowest. This is also the time when atmospheric conditions are most stable and poor odor dispersion is likely.

When testing, fan activity should not be manually overridden, and stabilization time should be allowed following each change in fan activity. If fan activity changes during the collection of samples, it is recommended to record the changes in fan activity.

If fan activity changes during the collection of samples, it is recommended to record the changes in fan activity and to calculate a time-weighted-average ventilation rate rather than manually lock in the number of active fans. By locking in fans, abnormal shed conditions may be produced, especially in terms of temperature, bird activity and odor production/release mechanisms, and this will result in the measurement of unrealistic odor emissions.

Odor samples should be collected and analyzed in duplicate to improve olfactometry confidence and accuracy. Samples should be analyzed as soon as possible following collection.

Disturbance of chickens should be kept to a minimum prior to, and during, sampling, as additional activity may increase the release of odor from the litter and birds.

Measuring dust emissions  

As with odor measurement, dust sampling programs and methodologies need to be carefully chosen to provide meaningful and representative emission rates as poultry dust emission can be highly variable.

Continuous, size-resolved dust measurements are necessary for studies that attempt to characterize the mechanisms of dust generation in intensive poultry sheds.

For studies that integrate dust measurements over extended periods of time, for example gravimetric filter analysis, it should be recognized that large variations in dust concentration are likely to occur during the sample collection period.

At the time of sample collection, it is essential to record information, including:

  • Sampling conditions – time, date, and sampling position
  • Ambient conditions – ambient temperature, ambient humidity, internal shed temperature, and internal shed humidity
  • Shed dimensions and conditions – ventilation rate, number and position of active fans, mode of ventilation (tunnel or mini-vent), shed length, shed width, wall height, roof apex height, ceiling baffle height, litter moisture content, litter depth, litter reuse status (single use or reused litter), lighting conditions, drinker type
  • Batch information – bird age, bird numbers, bird live weight, total live weight, number of birds placed at the start of the batch, bird breed