Nutritional modulation of environmental credentials of slow growing broiler chickens featuring data from a controlled replicated feeding study

Of all livestock systems, broiler chicken production has a relatively low environmental impact. However, the recent increase in the use of slow growing broiler chickens (SGB) in place of fast growing broilers (FGB), is predicted to increase environmental indicators. Nutritional interventions have been suggested. This study determines the impact of dietary nutrient density on environmental credentials per kg liveweight (LW) of FGB and SGB reared over the same period. A higher protein and energy diet, designed for FGB, or a lower protein and energy diet, designed for SGB, were fed to the commercial FGB breed, Ross 308, and the commercial SGB breed, Hubbard Redbro. Soybean meal (SBM) associated with low incidence of land conversion (LC) was the baseline scenario. A scenario using SBM from a region with greater LC (LC+) was modelled. Uncertainty was tested using Monte Carlo simulations. Statistical differences were assessed using generalised linear models, with the distribution family chosen based on characteristics of the response variable. In the baseline scenario, feeding the HS diet to SGB reduced the global warming impact per kg LW by 6.5%, eutrophication by 10%, and acidification by 8%. In the LC+ scenario, GW increased by 83–97%, FWEu by 55–62%, and TA and MEu by 16%. Manure emissions of Nitrogen and CH4 per kg LW were not impacted by breed or diet. Feeding a HS diet reduced impact category results per kg broiler LW without impacting manure emissions and may be considered as a strategy to reduce the impact of SGB production.