Assessing\nEnvironmental and Economic Sustainability:\nValorizing Grape Stems for Animal Feed Production

This study evaluated\nan innovative strategy for valorizing grape\nstems (GS) from the winery industry as an animal feed ingredient from\nboth environmental life-cycle and economic perspectives. Two processes\nfor GS-based feed ingredient production were compared: one using hydrolyzed\nGS and the other using nonhydrolyzed GS, alongside the conventional\nanimal feed production process. Using primary pilot-scale data for\nGS-based feed ingredient production and secondary data for animal\nfeed production, life-cycle assessments, and economic analyses were\nconducted. Results showed that hydrolyzing GS leads to 3.8 times higher\nimpacts on human health compared to the nonhydrolyzed variant, primarily\ndue to NaOH and electricity usage, although this difference becomes\nnegligible at the animal feed production stage. Incorporating GS-based\nfeed ingredients was found to reduce the environmental impacts of\nanimal feeds, primarily due to reductions in other ingredients. Economically,\nproducing nonhydrolyzed GS-based feed ingredient proved more feasible,\nwith a net present value of €-106,766 for a plant with a capacity\nof 1000 kg/d. GS valorization scenarios yield lower environmental\nimpacts than landfilling and composting, although not compared to\nincineration, which offers notable energy recovery potential. This\nstudy suggests adopting GS valorization in animal husbandry to support\na circular economy, providing insights for stakeholders.