Space use and navigation ability of hens at housing in the aviary for the laying phase: effect of enrichment with additional perches and genotype

The present study tested the hypothesis that increased availability of perches could favor the adaptation and navigation ability of pullets of different genotypes at housing in a new aviary system for the laying phase. To this purpose, 900 Lohmann White-LSL and 900 Hyline Brown were randomly allocated at 17 wk of age in 8 pens of an experimental aviary, according to a bifactorial arrangement with 2 genotypes (Brown vs. White) x 2 types of pens (enriched or not enriched with additional perches besides those of the aviary). Data collected between 17 and 20 wk of age showed that the enrichment with additional perches decreased the use of the aviary perches while the rate of successful landings/take-offs was unaffected. As for the effect of genotype, during the night a lower rate of hens on the floor (0.15 vs. 6.63%) and a higher rate of hens on the additional perches (2.47 vs. 0.98%) was found in White compared to Brown hens (P < 0.001); the former hens also used the third tiers for sleeping on the aviary upper-most perches (P < 0.001). During the day, White hens used more the third tier (32.8 vs. 15.6%; P < 0.001) and the additional perches (3.88 vs. 0.91%; P < 0.01) compared to Brown hens, while they stood less on the floor (18.3 vs. 22.6%; P < 0.05). White hens performed a significantly higher number of landings (80.7 vs. 21.9; P < 0.001) and of take-offs (74.3 vs. 10.0; P < 0.001) per pen compared to Brown hens. The risk of unsuccessful landings was higher in Brown compared to White hens (odd ratio: 6.65; 95% confidence interval: 4.36-10.1; P < 0.001). In conclusion, the enrichment with additional perches played a major role in hen distribution and space use than in their navigation ability. At the same time, the significant differences between the 2 genotypes call for a careful evaluation of the aviary design and animal management to optimize welfare at housing and possibly productive results of laying hens.