Human-edible protein conversion efficiency and environmental sustainability of chicken genotypes differing in egg-productive aptitudes

This study assessed food protein conversion efficiency (HEPCE) and environmental impacts of two Italian chicken breeds (Bionda Piemontese, BP and Robusta Maculata, RM), their crossbreeds with Sasso T44 (SS) (BP × SS, RM × SS) and a commercial laying hen hybrid (Lohmann Brown, LB). A total of 300 female chickens were reared either in enriched cages or free-range (three replicates per group) and monitored from week 25 to 66 (10 pullets/genotype/rearing system). Productive performances were assessed every 14 days. The HEPCE was estimated as the ratio of protein outputs (eggs and meat from spent hens) and protein inputs (feed intake and initial body weight). Life Cycle Assessment (LCA) was performed per kg of human-edible protein output (Functional Unit, FU). Rearing system had a negligible effect on productive performance and was not considered for HEPCE and LCA. Overall, both BP and RM exhibited the lowest values (p < 0.001) for egg deposition rate, egg weight, egg mass, as well as HEPCE (17.0 and 17.7%, respectively) and the highest feed conversion ratio (p < 0.001) and contribution to the environmental impact categories. BP × SS and RM × SS enhanced productive parameters and HEPCE (22.1 and 22.2%, respectively) mitigating (−15/-25%) the contribution to the selected impact categories per FU compared with local breeds, without reaching the performance levels of LB. Feeding (30/90%) and manure (15/60%) represented the highest contributors to the environmental impacts. In conclusion, crossbreeding local chicken breeds with more productive genotypes might be a potential strategy to improve productive and sustainability traits of local breeds.