Odour emissions, hedonic tones and ammonia emissions from three cage layer housing systems

Odours from animal facilities can negatively affect the quality of life of nearby residents leading to conflicts between neighbours. Ammonia (NH3) is considered as the main odour-causing compound. With the recent shift in Québec’s egg production systems from deep-pit manure storage to manure belt removal systems, the change in odour and NH3 emissions from these systems is of interest. The objective was to compare odour emissions, hedonic tones and NH3 emissions from three cage layer housing systems: a deep liquid manure pit and a manure belt with natural or forced air drying. The former system consists of “A” frame layer cages located over a closed pit containing the hens' droppings into which water is added to facilitate removal by pumping. Manure belt techniques imply that manure drops on a belt beneath each row of battery cages where it is either dried naturally or by forced air until it is removed. The experiment was replicated with 360 hens reared in twelve independent bench-scale rooms during eight weeks (19–27 weeks of age). The manure belt systems reduced between 37 and 42% (0.164 and 0.178 OU s−1 hen−1, respectively) odour emissions, between 43 and 44% (−1.19 and −1.17, respectively) hedonic tones and between 92 and 94% (32.0 and 24.2 g yr−1 hen−1, respectively) NH3 emissions with regard to the deep-pit system (389 g NH3 yr−1 hen−1, −2.06 and 0.283 OU s−1 hen−1). It appears that the use of manure belt systems should be encouraged since they significantly decrease odour emissions, hedonic tones and NH3 emissions.

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► Manure belt systems reduce 40% of odour emissions with regard to deep-pit systems.
► Manure belt systems reduce 43% of hedonic tones with regard to deep-pit systems.
► Manure belt systems reduce 93% of NH3 emissions with regard to deep-pit systems.