Preferences of laying hens for different dustbathing substrates
Within the EU, adequate dustbathing material to enable scratching, pecking and dustbathing in cage-kept laying hens will be a legal demand after 2012. Presently, hens are mainly provided with food particles, which are dropped on Astroturf mats, due to a coupling of food chain and supply pipe of dustbaths. This study investigates the use of different substrates for selected behavioural traits in laying hens in order to particularily verify whether hens would choose food particles for dustbathing when different non-nutritive types of substrates were simultaneously offered. In 2 identical trials, 72 hens (LSL, LB) were kept in 12 compartments (6 hens each) equipped with wire floor and additionally containing 4 different dustbathing areas (1000cm²/hen). Dustbaths contained wood shavings (WS), Lignocellulose (L, soft wood fibre, pelleted), Astroturf mat without substrate (A) and food particles (F). Hens were transferred to the experimental pens at the age of 18 weeks. After habituation, 3 video observations (week 21, 24, 27) were conducted. The number of hens dustbathing, scratching and pecking in the different dustbaths and dustbath lengths were recorded over 2 days in each week. A significant effect of substrate was found for dustbathing frequency (Kruskal-Wallis-Test, Chi-Quadrat 21.6, DF=3, p<0.001) with less dustbathing in F (26 dustbaths during observation period) compared to L (321, p<0.001) and WS (109, p=0.06) and least dustbaths on A (12). Lengths of dustbaths, however, tended to be longer in F compared to L. No effect of age or layer line was detected. Hens significantly preferred F to L (p<0.01), WS (p<0.05) and A (p<0.001) for scratching and also for pecking (L, WS, A: p<0.001). In conclusion, F was preferred for pecking and scratching but less attractive for dustbathing. This might be due to its nutritive character or fat content, which might have inhibited the lipid removal from hens' plumage.