Perches or grids? What do rearing chickens differing in growth performance prefer for roosting?

The domestic fowl (Gallus gallus f. dom.) is highly motivated to roost on elevated structures. Previous studies indicated that broiler chickens hardly use elevated perches but frequently use elevated platforms. However, it is unclear which height and type of elevated structures broilers prefer at various daytimes. We investigated the use of elevated perches and grids varying in height (10, 30, and 50 cm above the floor) by chickens of 3 strains differing in growth performance. In 2 successive trials, male chickens of Ross 308 (Ross, fast growing, n = 200), Lohmann Dual (Dual, medium growing, n = 200), and Lohmann Brown Plus (LB, slow growing, n = 200) were tested in 12 experimental compartments (each strain in 4 compartments), respectively. Usage of structures was recorded on video and analyzed with time-sampling observation for each week of age during dawn, the light period, dusk, and the dark period. In addition, behavioral activity was measured with an antenna-transponder system. The results showed that Ross and Dual chickens preferred grids to perches throughout the entire observation period. With increasing age, chickens of all strains increasingly used the elevated structures during all daytimes. In contrast to Dual and LB, Ross chickens reduced the use of structures from the 3rd to 4th week of age during the light but not the dark period. Additionally, during the dark period, chickens of all 3 strains at the end of fattening period used elevated structures at 50 cm height most often. The behavioral activity decreased significantly in all 3 strains but was much lower in Ross chickens compared with Dual and LB. The results indicated that chickens are motivated to roost at nighttime on high-elevated and suitable structures such as grids. Further studies are needed to assess the space requirements for elevated structures that should be offered to chickens.