## 3 Results and Discussion
### Microbiological Analysis  
Microbiological analyses revealed the compliance of milk quality with the legal requirements (Commission Regulation (EC) No 2073/2005 of 15 November 2005 on microbiological criteria for foodstuffs [43]) for the production of raw milk cheeses. Indeed, the _Salmonella_ spp. and _L. monocytogenes_ milk pathogens were absent, whereas the count of _S. aureus_ was below the detection limits (Table 3). Although many factors can influence the microbial composition of raw milk [44; 45] such as milking conditions, temperature, duration of milk storage and transport as well as the diet of the cows [46; 47; 48] no statistical differences (\(p>0.05\)) were observed for the analyzed microbial groups, except for _E. coli_, and thermophilic lactococci densities (Table 3). Indeed, compared to CTR milk, in ECO samples, the number of _E. coli_ bacteria was lower, while the thermophilic lactococci were more abundant. Overall, both LAB and the total mesophilic bacteria were the most abundant counted groups, with a density above 4.00 log cfu/mL in both CTR and ECO milk, followed by lactococci and enterococci. Concerning _Enterobacteriaceae_, molds, and yeasts, the viable count was below 3.00 log cfu/mL and comparable for both milk samples, whereas the lowest count was observed for total coliforms, especially in ECO milk. Figure 2: Two-D scatterplots for cheese and milk samples categorized by diet. Insert: loading plot for PC1 and PC2. CTR: milk and cheese made by dairy cows fed concentrate without olive cake supplements. ECO group: milk and cheese made by dairy cows fed concentrate with 7% enriched olive cake as 7% of a DM. Regarding cheese samples, a general increase in almost all microbial groups investigated was observed. The levels of the viable count of the CTR and ECO cheese samples are shown in Table 4.  
Overall, all undesired species such as _Salmonella_ spp., _L. monocytogenes, E. coli_, and _E. coli_ O157, generally associated with poor hygiene of dairy production, were never detected in the analyzed samples, reinforcing the safety of the dairy environment [14]. Moreover, the viable counts of the remaining analyzed microbial groups did not significantly differ (\(p>0.05\)) among all samples, except for the thermophilic lactococci whose density was significantly higher (\(p\leq 0.05\)) in ECO cheees (Table 4). Although the cell density of thermophilic LAB usually increases after cheese manufacturing, and it is well known that the microbial dynamics leading from raw cows' milk to pasta filata cheese include all typical manufacturing steps [49], the observed increase in thermophilic lactococci levels in milk and later in cheeses here detected can probably be explained by the resistance of this group to polyphenol content of the olive cake supplementation. A previous work revealed the high resistance of lactococci to different classes of polyphenols, intentionally inoculated into raw ewe's milk, showing their ability to perform rapid acidification [50]. It is also noteworthy that Lactococcus genus significantly contributes to the texture and flavor characteristics of fermented products by enhancing the rheological properties of fermented milk products [51] through the production of extracellular polysaccharides. In this study, the lactococci counts were between 6.91 and 6.68 log cfu/g, and the presumptive