Estimation of the Availability and Effect of Some European Agro-Industrial By-Products to Reduce the Carbon Footprint of Sheep and Goat Diets

This study aimed to assess the availability and environmental impact of some widespread agro-industrial by-products in Europe, and their potential to reduce the environmental impact of small ruminant diets by replacing conventional feed ingredients. Grape, olive, and tomato pomaces, and spent grains of beer were considered. A Carbon footprint of products (CFP) approach was used to quantify the environmental impact of agro-industrial by-products, according to the ISO 14067:2018 standard. The system boundary was defined as gate to gate, while 1 kg of dried by-product was chosen as functional unit (FU). The system included the relevant stages of agro-industrial by-products production, from the drying process of agro-industrial by-products to the treatments carried out in the feed industry (e.g., milling, mixing, pelleting). The CFP of grape, olives, and tomatoes pomaces and spent grains of beer was 0.26, 0.22, 0.31 and 0.21 kg CO2equivalents (CO2e)/FU, respectively. Reusing grape, olive, tomato and brewery industry by-products available in Europe, in replacement of conventional ingredients in sheep and goats’ diets, reduced the CFP by 2% to 90% and allowed to save 5.15 Megatons of CO2e. These results suggest that the recovery of some agro-industrial by-products can effectively represent a sustainable strategy to reduce the environmental impact of conventional ingredients commonly used in animal feeding. Defining an optimal level of inclusion of these by-products can help to improve the implementation of this strategy.