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Air Quality in Alternative Housing Systems May Have an Impact on Laying Hen Welfare. Part I—Dust
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Animals 2015, 5(3), 886-896;

Air Quality in Alternative Housing Systems may have an Impact on Laying Hen Welfare. Part II—Ammonia

Norwegian Veterinary Institute, P.O. Box 750 Sentrum, 0106 Oslo, Norway
French Agency for Food, Environmental and Occupational Health Safety (Anses), BP 53, 22440 Ploufragan, France
Norwegian University of Life Sciences, Pb 8146 Dep, 0033 Oslo, Norway
Author to whom correspondence should be addressed.
Academic Editor: Christine Nicol
Received: 7 April 2015 / Revised: 26 August 2015 / Accepted: 1 September 2015 / Published: 3 September 2015
(This article belongs to the Special Issue Poultry Welfare)
Full-Text   |   PDF [114 KB, uploaded 3 September 2015]


The EU ban on conventional barren cages for laying hens from 2012 has improved many aspects of laying hen welfare. The new housing systems allow for the expression of highly-motivated behaviors. However, the systems available for intensive large-scale egg production (e.g., aviaries, floor housing systems, furnished cages) may cause other welfare challenges. We have reviewed the literature regarding the health, behavior, production characteristics, and welfare of laying hens when exposed to ammonia in their housing environment. Concentrations of ammonia gas are commonly high in aviaries and floor housing systems in which manure is not regularly removed, whereas they are usually lower in furnished cages. High levels are found during the cold season when ventilation flow is often reduced. Ammonia is a pungent gas, and behavioral studies indicate chickens are averse to the gas. High concentrations of gaseous ammonia can have adverse health effects and, when very high, even influence production performance. The most profound effects seen are the occurrence of lesions in the respiratory tract and keratoconjunctivitis. There is also evidence that high ammonia concentrations predispose poultry to respiratory disease and secondary infections. We conclude that there are animal welfare challenges related to high ammonia levels, and that immediate actions are needed. Development of improved systems and management routines for manure removal and ventilation will be important for the reduction of ammonia levels and hence will contribute to safeguarding hen welfare. View Full-Text
Keywords: furnished cages; loose housing; aviaries; behaviour; health; poultry furnished cages; loose housing; aviaries; behaviour; health; poultry
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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David, B.; Mejdell, C.; Michel, V.; Lund, V.; Moe, R.O. Air Quality in Alternative Housing Systems may have an Impact on Laying Hen Welfare. Part II—Ammonia. Animals 2015, 5, 886-896.

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