Influence of including Arthrospira platensis as a functional ingredient in dairy cow feed

The sustainability of dairy production faces challenges due to environmental concerns and the high cost of conventional feed ingredients. Arthrospira platensis , a protein-rich cyanobacteria with bioactive compounds, has been proposed as a functional feed ingredient to enhance milk quality while supporting sustainable livestock practices. This study evaluates the effects of Arthrospira supplementation on milk production, nutritional composition, physicochemical properties, and animal health indicators, alongside its economic feasibility. A 35-day feeding trial was conducted on 12 Holstein dairy cows, each having a live body weight of 510–532 kg and 2–4 parities. They were divided into a control group and an Arthrospira-supplemented group (250 g/day, 1 % w /w of the feed ration). Milk production was monitored daily while milk composition (protein, fat, lactose, and solids-not-fat), physicochemical properties (cryoscopic point and electrical conductivity), bacterial content, somatic cell count (SCC), and milk urea nitrogen (MUN) were analysed weekly. Economic viability was assessed based on feed cost variations with the different Arthrospira levels included. The results showed an initial reduction in milk yield due to feed rejection, which stabilized over time. Arthrospira supplementation did not significantly alter key milk components, but bacterial counts decreased at the beginning of the trial, suggesting antimicrobial benefits. The SCC and MUN remained within normal ranges, indicating no adverse effects on udder health or nitrogen metabolism. However, the economic analysis revealed a feed cost increase from €0.30/kg to €0.55/kg when 1 % w /w Arthrospira was included, highlighting the need for cost reduction strategies. This preliminary study suggests that Arthrospira platensis can serve as a sustainable functional feed ingredient, helping to maintain milk quality while offering antimicrobial benefits - though economic constraints limit large-scale adoption at present. • 1% Arthrospira platensis in dairy cow feed maintained milk yield and composition. • Milk bacterial count dropped, showing antimicrobial benefit of Arthrospira. • No adverse effects on udder health or milk urea concentration were found. • Arthrospira increased feed cost, suggesting need for cost-reduction strategies. • Study supports microalgae as a sustainable feed for agri-food systems.