Salah, Nizar, Legendre, Héloïse, Paiva, Erika, Duclos, Julie, Briche, Maxime, Maaoui, Mariem, Scholten, Jasper, and Garat Boute, Céline
Simple Summary: In this study, a life cycle assessment (LCA) was performed to quantify the environmental impacts of milk production in dairy cows with and without yeast probiotic supplementation. Faced with an ever-increasing population, livestock farming is in a paradoxical situation. Indeed, we went from a simple equation of how to increase animal performance to a more complex equation of how to increase performance and feed efficiency while reducing the environmental footprint as a pillar to guarantee more sustainable livestock systems for current and future generations, which is highly requested by all stakeholders in the chain including farmers, consumers, and society. Probiotics such as live yeast are commonly used to improve the performance and resilience of high-yielding dairy cows. In this study, we used a life cycle assessment (LCA) principle to quantify the environmental impact of a yeast probiotic, Saccharomyces cerevisiae (CNCM I-4407, 1010 CFU/g, Actisaf® Sc 47), in dairy cows during three different trials. On average, during the period of supplementation, Actisaf Sc 47 reduced carbon footprint by 5%. Reported on a yearly scale including all lactation cycles, dry cows, and periods with and without supplementation, the use of Actisaf Sc 47 during the three trials reduced the carbon footprint, land use, water use, resource use, acidification, freshwater eutrophication, marine eutrophication, and terrestrial eutrophication by 2.9, 2.05, 2.47, 1.67, 2.28, 2.18, 2.14, and 2.28%, respectively. The supplementation of Actisaf Sc 47 showed very low contribution to the total carbon footprint, ranging from 0.005 to 0.016%. Today, one of the major challenges of dairy farmers is to reduce their environmental footprint to establish more effective, efficient, and sustainable production systems. Feed additives such as yeast probiotics could potentially allow them to achieve these objectives through the improvement of milk production, feed efficiency, and ration valorization, hence mitigating the environmental impacts of milk production. In this study, the life cycle assessment (LCA) principle was performed to estimate the environmental impact of the production and supplementation of a commercial yeast probiotic (Actisaf Sc 47) in three trials performed in three different countries that are representative for around 50% of the milk production in Europe: France (French trial), United Kingdom (UK trial), and Germany (German trial). For each trial, two groups of animals were compared: control, without Actisaf Sc 47 supplementation, used as baseline; and experimental, with Actisaf Sc 47 supplementation at 5 or 10 g/cow/day. Different impact categories were analyzed for each group to calculate the impact of producing 1 kg of fat- and protein-corrected milk. An initial analysis was done only during the period of Actisaf Sc 47 supplementation and showed than the supplementation with Actisaf Sc 47 reduced, on average by 5%, the carbon footprint during the three trials. A second analysis was done via the extrapolation of all the data of each trial to an annual farm level, including the lactation period (305 days), dry period (60 days), and the period with and without Actisaf Sc 47 supplementation. Reported at a farm annual scale, the average reduction allowed by Actisaf Sc 47 supplementation was 2.9, 2.05, 2.47, 1.67, 2.28, 2.18, 2.14, and 2.28% of the carbon footprint, land use, water use, resource use, acidification, freshwater eutrophication, marine eutrophication, and terrestrial eutrophication, respectively. On average, the production of 1 kg of fat- and protein-corrected milk by using Actisaf Sc 47 was shown to improve environmental impacts compared to control. Regarding Actisaf Sc 47 production, the LCA showed that the production of 1 kg of Actisaf Sc 47 emitted 2.1 kg CO2 eq with a negligible contribution to total the carbon footprint of milk ranging from 0.005 to 0.016%. The use of Actisaf Sc 47 in dairy cows could then result in different positive outcomes: improving performance and efficiency while reducing the global carbon footprint. [ABSTRACT FROM AUTHOR]