Effects of rearing systems on combs, wattles and shanks colour in layers : preliminary results

Alternative housing systems for hen eggs production represents a clear evidence of the animal housing and husbandry trend towards extensive rearing methods. Consumers demand is oriented towards healthy foods controlled not only under a safety point of view but also under a welfare assessment in animals' life conditions. Among the different alternative systems deep litter and organic production in the recent years have been improved in Italy. The EU regulation pointed out the importance of animal welfare in organic production, nevertheless the production system and associated standards do not automatically provide good animal welfare; thus the organic standards have often been developed under the influence of consumer concerns rather than been based on animal needs. The colour evaluation has been used in different animal species in order to assess food quality but there are few studies on the relationship between body colour and animal temperament or welfare. Comb and wattle colour are very supplied with blood and are mainly influenced from climate and rearing condition. The aim of this study was to evaluate if different rearing system for laying hens may influence comb, shank and wattle colour. Moreover the research had investigated the correlation between colour and reactivity in three groups of laying hens. The study was carried out in one litter floor housing system, one organic housing system and one caged hens facility. In each system the same strain of lying hens (Hyline Brown) was housed. At 70 weeks of age (in summer) the comb, shank and wattle colour have been recorded, using L, a*, b* method (Minolta® CR-400) in 30 birds per rearing system. Moreover the same animals where once tested with the Tonic Immobility (TI) test. The results showed some differences among the three rearing system in comb and wattle colour; hens reared on litter floor showed a significant higher comb a* coefficient compared with both the cage and the organic systems (27,49 floor vs 24,69 cage vs 19,33 organic; p<0,001). Probably this results are due to the fact that in our study the organic hens, due to avian flu, spent almost all the rearing period inside a shelter with only artificial light and without windows, they used the external area only for 6 weeks (from 64 to 70 weeks of age) at the end of the rearing period. On the contrary the floor hens have been reared in a barn with natural light. The shank colour, as expected, didn't reveal any difference mainly depending on diet composition that was very similar in the three systems and bird genetic. Regarding the test no correlation have been found between colour coefficients and TI results probably due to the great individual variability in behavioural reaction, anyway the hens reared on floor showed a greater reactivity level; they showed a lower number of inductions (2.3 floor vs 2.5 of caged and organic hens; p<0,001) and TI duration was lower too (39,1sec floor vs 59,1sec organic and 66,2sec caged; p<0,05). In conclusion L, a* and b* coefficients might be useful predictors of hens temperament as showed in other species, further researches are needed in order to improve and confirm this hypothesis.