Foot pad dermatitis in broiler chickens - effects of hybrid and weather conditions

Foot pad dermatitis (FPD) is a common animal welfare challenge in indoor broiler production. This cross-sectional study investigated the effect of outdoor weather conditions (temperature and precipitation) and hybrid (fast-growing Ross 308 [Ross] vs. slower-growing Hubbard JA787 [Hubbard]) on the prevalence of FPD at slaughter. The study included 420,300 broilers from 4203 commercial flocks, raised in 139 farms in Central Norway and slaughtered in the period from January 1st, 2015, to June 22nd, 2021. The apparent prevalence of mild/moderate FPD and severe FPD, respectively, was 14.06 % and 5.80 % in Ross broilers and 5.72 % and 1.64 % in Hubbard broilers. The effect of hybrid and weather conditions on the prevalence of FPD was estimated using hierarchical multinomial models. At sample mean weather conditions, the risk of mild/moderate FPD and severe FPD were 2.8 (95 % CI: 2.2;3.7) and 5.8 (95 % CI: 3.1;10.7) times higher for Ross than Hubbard broilers, respectively. Sensitivity analyses indicated that these estimates were relatively robust; yet the protective effect of being Hubbard may be slightly overestimated. For both hybrids, the risk of FPD was affected by the weather, and cold weather combined with a precipitation level at the sample mean yielded the highest risk of severe FPD. Hubbard broilers were less sensitive to weather conditions compared to Ross with respect to FPD occurrence. The results from this study add to the growing evidence that the choice of hybrid impacts the health-related aspects of animal welfare in commercial broiler production systems.