## 2 Materials and Methods  
### Animals, Diets, and Mozzarella Cheese Production  
All cows enrolled in this study were handled in compliance with the Italian legislation concerning the protection of animals used for scientific purposes (DL n. 26, 4 March 2014), and all procedures involving animals used in this study were reviewed and approved by the Ethical Animal Care and Use Committee of the University of Napoli Federico II (Prot. 2020/007143 of 8/1/2020).  
The trial was conducted on a buffalo dairy farm in the Southern Italian region of Campania (40\({}^{\circ}\)48\({}^{\prime}\) N 15\({}^{\circ}\)01\({}^{\prime}\) E; 14 m a.s.l.) between March 2021 and July 2021. Twenty-four late pregnant dairy buffaloes (_Bubalus bubalis_) were blocked for expected calving date and assigned to either a control or experimental group (hereafter referred to as C and S, respectively) balanced for cows' number (\(n\) = 12), parity (3 secondiparous and 9 pluriparous), and milk yield from the previous lactation (2642 \(\pm\) 503 kg/head and 2729 \(\pm\) 492 kg/head for C and S, respectively).  
The two groups were housed in 2 adjacent free-stall barns (13 \(\times\) 10 m each) equipped with feed bunks, water troughs, and an outdoor exercise area. The experimental period lasted 120 days in total, including an adaptation period of 30 days before calving and a sampling period covering the early 90 days of lactation. Across the adaptation and sampling periods, all cows were fed the same standard total mixed ration (TMR) formulated to meet or exceed the recommended nutritional requirements for dairy buffalo in the near dry period and early lactation, as recommended by [PERSON] et al. [17] and [PERSON] et al. [18], respectively. As for the farm routine, both TMRs were offered once a day at 08:00 h, allowing for approximately 10% feed refusal. In the Spirulina group, the freeze-dried Spirulina was top-dressed just after the TMR delivery at a daily dose of 50 g/head until calving and 100 g/head during lactation. Table S1 lists the detailed ingredients and chemical compositions of the experimental TMRs (dry and lactation diets). The used Spirulina biomass (Table 1) was provided by ATI Bio-tech s.r.l. (Castel Baronia, Avellino, Italy). Cultivation was performed through industrial-scale outdoor open raceway ponds by using standard Zarrouk's culture medium (20 \({}^{\circ}\)C; pH 10.25).  
From 3 (\(\pm\)1) days of ind onwards, buffaloes were milked two times a day (05:00 and 17:00 h) in the auto-tandem milling parour equipped with a pipeline milking system that transports milk to a refrigerated (4 \({}^{\circ}\)C) tank.  
After the first 30 days of milking, four mozzarella cheese-making sessions between the 2 nd and 3 rd month of lactation, with 2 sessions per month, were carried out by using refrigerated (4 \({}^{\circ}\)C) bulk tank milk that was separately collected at the evening milking session from each group (approximately 60 kg/group per milking). Bulk milk from each group was processed at the dairy farm, in separate vats, following the traditional procedure adopted for the PDO mark (Protected Designation of Origin) detailed by [PERSON] et al. [3]. In brief, the raw milk was heated to 37 \({}^{\circ}\)C, and natural starter cultures and liquid calf rennet were added. The curd was then broken into small particles (2-3 cm) and left under whey until the pH reached 4.85. At this pH, the curd was manually stretched in water kept at 90-95 \({}^{\circ}\)C. Finally, 50 g of mozzarella (spherical shape) were cut mechanically, cooled in water, and left in brine (10% NaCl).