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By Justin Emery , ADAS, UK
Welfare can be compromised during depopulation, especially as hens are susceptible to bone breaks due to the demands made on their skeletons during the process of egg shell production. The Scottish Agricultural College (SAC) recently reported that conventional cage systems were the most damaging in this respect, with 24% of birds showing new fractures.The problem appears to have been persistent too, as earlier research (by T G Knowles and L J Wilkins) found “unacceptably” high incidences of bone breakages in 1998, linked to increased rates of disuse osteoporosis in the hen.
According to the SAC, there are fewer breakages at the time of depopulation in alternative and enriched cage systems. For example, free-range and barn-egg layers had 10% new fractures and birds from enriched colony units just 6%. This is attributed to better design of gates, a larger opening area and a minimum 35 cm legal height over the floor, which makes the removal of hens much easier for catchers.
Crucial guidance
Similar research in Germany in 2008 also found promising improvements in the bone strength of hens in large enriched colony units compared to furnished conventional cages, due to the extra space available for activity. This is encouraging as in 2012 conventional cages will no longer be legal, so the problem of disuse osteoporosis will be much reduced. But, whatever the production system involved - and multi-tier free-range systems are too recent to be part of published studies on new fractures - responsibility for the catching process and the welfare of the birds rests with the producer.
Similar research in Germany in 2008 also found promising improvements in the bone strength of hens in large enriched colony units compared to furnished conventional cages, due to the extra space available for activity. This is encouraging as in 2012 conventional cages will no longer be legal, so the problem of disuse osteoporosis will be much reduced. But, whatever the production system involved - and multi-tier free-range systems are too recent to be part of published studies on new fractures - responsibility for the catching process and the welfare of the birds rests with the producer.
The “DEFRA Welfare Code for Laying Hens” in the UK provides crucial guidance to individuals involved in this process, while the “Joint Industry Welfare Guide on the Handling and Transport of End-of-Lay Hens” provides further information.
Even with the new production systems, the advice contained in these documents is still valid, especially that of double-leg catching and carrying no more than three birds in one hand.
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Source: World Poultry, Vol. 27, No. 2, 2011
