The Carbon Footprint of Finishing Yearling Bulls Fed a Diet Containing Vegetable By-Products in Navarra, Spain

Livestock farming is blamed for its significant carbon footprint (CF), contributing to environmental pollution and climate change. Among other approaches, this has highlighted the need to find alternative feeding systems for cattle production that are potentially able to reduce greenhouse gas (GHG) emissions. In this context, the objective of the present study was to compare the CF of producing cattle fed a Conventional diet versus cattle fed a diet that included vegetable by-products (VBP diet) sourced from the local agri-food industry. In this study, twenty-four entire male young bulls were reared in Navarra, Spain. Twelve calves were finished on the VBP diet that also included fodder and grain, and the remaining animals were finished with a local Conventional diet based on concentrate and straw. Results showed a larger CF of meat from animals fed the Conventional diet in comparison with the VBP-fed ones, that is, 117.84 kg versus 42.01 kg of CO2 equivalent per kilogram of meat, respectively. This research demonstrates that using by-products from the local agri-food industry for feeding cattle has an important beneficial effect on the environment. It is not only a circular economy solution that recovers and recycles by-products instead of treating them as waste, but can also notably reduce the GHG associated with livestock production. This study marks the beginning of ongoing research into the effect of introducing regional vegetable by-products in the diet of livestock and their corresponding impacts on productivity and the environment, particularly in terms of GHG emissions per kilogram of feed consumed.