Relationships between range use, performances and health and welfare related traits in four strains of organic broilers
Résumé
In organic as in other alternative rearing systems, chickens may have access to an outdoor area that allows them to express natural behaviours of the species to a greater extent than in conventional systems. In addition to a higher physical activity, this access to the range is a way to supplement and diversify the nutritional resources. However, a great variability in outdoor use exists, which can impact performances as well as physiology and welfare of the birds, and the product quality. The aim of this study was to assess the relationships between those latter traits and a low or a high range use in four genetic strains of slow (S757N, White Bresse and dual-purpose) or intermediate (JA757) growing rate. In all strains but the dual-purpose, a reduction in carcass weight was observed in high-rangers (HR) compared to low-rangers (LR), which was accompanied by lower thigh and breast weights. Only carcass yield was reduced in HR of the dual-purpose, maybe because of a lower physical activity of this strain on the outdoor area and/or the intake of feed found on the range. Regarding breast meat quality, higher range use led to a higher ultimate pH and a darker colour in the JA757, suggesting that the higher physical activity on the range decreased the muscle glycogen reserves of these birds. Breast meat yellowness was higher in HR than LR in JA757 too, as well as the dual-purpose, probably because of carotenoids intake from the grass. Regarding blood biomarkers, greater higher range use did not affect (in JA757, White Bresse and dual-purpose) or tended to reduce (in S757N) the level of inflammation measured by haptoglobin-like activity. The antimicrobial potential linked to lysozyme activity was also reduced in JA757 and S757N high-rangers. Regarding the redox status, the main effects were observed in JA757 and to a lesser extent S757N, with a reduction in HR group of molecules with antioxidant properties while the concentration of reactive oxygen was increased. In conclusion, this study showed that a compromise must be sought between range use and performances and health and welfare related traits, and that the balance is partly dependent on genetics. Further research is continued to better model these relationships in a population with a continuum of low-ranger and high ranger slow-growing birds. The project PPILOW has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement N°816172.
Domaines
Sciences du Vivant [q-bio]Origine | Fichiers produits par l'(les) auteur(s) |
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