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Table 3 Occurrence of diseases (divided into main categories) in laying hen flocks submitted to SVA in 2001–2004.

From: Causes of mortality in laying hens in different housing systems in 2001 to 2004

   Bacterial diseases Viral diseases Parasitic diseases Cannibalism
Housing system Total no. of flocks 1 N % N % N % N %
Cages 2 20 13 65.0 6 30.0 2 10.0 1 5.0
Litter-based systems 3 129 94 72.9 15 11.6 23 17.8 24 18.6
Free range 4 23 17 73.9 1 4.4 5 21.7 6 26.1
  1. 1No. of examined flocks. Note that each flock may have several diagnoses.
  2. 2Includes conventional battery cages and enriched cages.
  3. 3Includes single-tiered floor systems and multi-tiered aviary systems.
  4. 4Flocks housed in litter-based systems indoors, with access to outdoor pens and pasture, including organic flocks.