Life Cycle Assessment of broiler chicken production using different genotypes and low-input diets

This study evaluated the effect of diet (standard, ST: 3,050 kcal/kg metabolizable energy; 18.5% crude protein; low input, LI: 2,921 kcal/kg ME; 17.5% CP), genotype (a fast-growth genotype; two local breeds – Bionda Piemontese, BP and Robusta Maculata, RM; and their crosses with Sasso strain, SA – BP×SA and RM×SA), and sex on the environmental footprint of broiler production computed by Life Cycle Assessment (LCA). A total of 441 chickens (half males, half females) were housed in 40 pens (2 pens/genotype/sex/diet), and fed from 20 d of age until slaughtering (47 d for Ross, 105 d for all other genotypes) the ST diet or LI diet. The LCA used the pen as the reference unit and considered impacts from animal and manure management and dietary ingredients production to assess the following impact categories: global warming (without and with land-use change; i.e. GWP and GWP_LUC), acidification (AP) and eutrophication (EP) potentials, cumulative energy demand (CED) and land use (LU). The functional unit was 1 kg body weight gained (BWG). Impact values were submitted to ANOVA with diet, genotype, and sex as fixed effects using PROC GLM of SAS. Both diet (P<0.01) and genotype (P<0.001) affected almost all the impact categories (P<0.01). In details, LI diet produced greater GWP, EP and CED (from 5% to 43%) and lower LU (-8%) and GWP_LUC (-55%) than ST diet. Ross showed the lowest impact values, RM×SA and RM intermediate, and BP and BP×SA the greatest ones. Compared to females, male showed a lower impact, from -8% (LU) to -11% (AP), while GWP_LUC was not affected. When the local breeds were compared to Ross, higher environmental impact values were found: differences were greater with ST diet (+82% to +145% in local breeds vs Ross depending on the category) than with LI diet (+26% to +77%) (significant interaction diet × genotype). In conclusion, the higher the broiler performance the lower the environmental impact, but the use of LI diet reduced the difference in environmental footprint between fast-growing chickens and slow-growing local breeds.