Performance, meat quality and blood parameters in four strains of organic broilers differ according to range use

Summary

Chicken meat production in organic systems involves free-range access where animals can express foraging and locomotor behaviours. These behaviours may promote outdoor feed intake, but at the same time energy expenditure when exploring the outdoor area. More generally, the relationship of range use with metabolism, welfare including health, growth performance and meat quality needs to be better understood. We studied four strains of intermediate (JA757) to slow-growing (S757N, White Bresse and a dual-purpose strain) meat-type chickens with outdoor access. We selected 25 males high- (HR) and low-rangers (LR) per strain. Only in JA757, HR exhibited lower body weight before range access, which may have predisposed them to use the range more. Carcass weight and/or carcass yield were significantly lower in HR compared to LR, showing a negative trade-off between range use and growth performance in all strains. Breast meat yellowness was higher in HR compared to LR in JA757 and the dual-purpose strain, probably due to carotenoids intake from the grass. No relationship between range use and welfare indicators at slaughter was reported whatever the strain.
Chicken metabolism differed by range use as HR and LR diverged for blood biomarkers of oxidative and metabolic status, immune and inflammatory system response.