Differences between behavioral time budget and welfare indicators in two different slow-growing broiler genotypes kept in the free-range system

The consumer interest for meat from slow growing broilers in free-range system has increased recently. Therefore, the need for knowledge about behaviour and welfare of birds in these systems has increased. The aim of this study was to compare the differences between behavioral time budget, tonic immobility and clinical welfare indicators in two slow growing broiler genotypes (Hubbard ISA Red JA-57 and Sasso XL44 × SA51A) kept in a free-range system. In total, 480 one-day old chicks were reared, and the birds were regularly scored for behavioral time budget and multiple welfare indicators. The eating and drinking tended to decrease in Sasso birds, whereas they showed an increment in Hubbard birds with increasing of age (P < 0.01). Hubbard birds had the highest percentage of explorative pecking (7.65%) of the total time budget compared to the Sasso birds (4.33% at day 63, P < 0.01). Comb pecking wounds, skin injuries and gait scores were affected by both genotype and age (P < 0.01). The duration of tonic immobility was found to be longer, as well as the number of tonic immobility inductions was higher in Sasso birds compared to the Hubbard (26.49 vs. 19.68 s; 1.54 and 1.24, respectively P < 0.01). These findings indicate that birds of the Hubbard genotype may be more prone to comb pecking and skin injuries, but they showed less fearful and higher walking ability, compared to Sasso birds.