health elicited by Actigen, please see the article “The role of gut health in productive cage-free egg production” previously published in this series.
Feather condition and feed efficiency The effects of cage-free systems on chickens’ feather con- dition have also been discussed previously in this series of articles. As a brief reminder, feather pecking, which is a major cause of feather loss, can spread more easily and become more serious in cage-free compared to caged flocks, given the larger group size. As a further reminder, the ideal tem- perature interval for poultry falls within the range of 20-27°C. Lower temperatures are associated with an increase in feed intake, which chickens will use as ‘extra fuel’ to generate more heat to maintain their body temperature. The degree to which feed intake increases depends on the interaction of two factors: the ambient temperature and the extent of feather damage or loss. Peguri and Coon (1993)
reported that feed intake increased by 20 grams at a tem- perature of 12.8°C when 50% of the feathers were lost; even at a temperature within the thermoneutral zone (23.9°C), such a level of feather loss increased feed intake by 7 g. These figures are comparable to those published by van Krimpen and others (2014): At 11°C and 21°C, feed intake increased by 18 g and 4 g, respectively, in hens that have lost 50% of their feathers, compared to fully feathered chickens. Across this temperature interval, the FCR worsened, on average, by 10 points in the birds that had lost 50% of their feathers (2.15 vs. 2.05 in the fully feathered group). These figures provide a clear demonstration that feather damage is not only a bird welfare problem but also an im- portant economic issue for egg producers. While not all birds within a commercial flock will show the same scale of feather loss at the same time, there will always be a percentage of hens with a considerable degree of feather damage or loss, especially in older flocks.
▶ POULTRY WORLD | No. 2, 2022
It is widely recognised that cage-free systems are gen- erally less effi- cient than cages due to several production traits.
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