## 4 Conclusions  
The present study is the first on the effect of humic-mineral supplementation for cow feed on the nutritional value of milk fat in raw milk and the most important product as cheese. In summary, the addition of the humic-mineral substances from oxyhumolite to the ration of cows amounted to 100 g/cow/day, and significantly increased the fat content of the milk, and significantly affected the partial sums of the fatty acids profile and the nutritional fatty acid ratios and indices, both in the fat of the milk and the cheese made from it. However, from a nutritional point of view, it is difficult to unequivocally assess the changes as beneficial or not for the consumer. In light of current dietary recommendations, deterioration in the quality of milk fat was observed, which was associated with a higher proportion of HSFA, higher AI and TI values, and a lower h/H index and a lower proportion of DFA and MUFA. However, there was an increase in PUFAs, BCFAs, and SFAs, including SCSFAs, which, despite being classified as saturated fatty acids, are seen as nutritionally beneficial. The cheese showed an increase in the content (mg/100 g) of SFA (includingSCSFA and LCSFA), OCFA, BCFA, MUFA, and DFA. Adverse changes also included a higher content of n6 group acids and a higher ratio of n6/n3, HSFA, and TI. The results obtained are promising, especially in terms of the natural origin of the supplement and its health-promoting properties, which is in line with the European Green Deal. However, depending on the source of humic-mineral substances, the dose used, and the time of administration, its effectiveness may be varied. Therefore, in order to unequivocally establish the effect of humic-mineral supplementation in cows' diets on the nutritional quality of fat in milk and milk-based products, the research should be continued and extended to other parameters characterizing fat quality.  
Conceptualization, A.T.; methodology, A.T. and P.D.; formal analysis, A.T., P.D. and M.K.-M.; investigation, A.T., P.D. and M.K.-M.; writing--original draft preparation, A.T.; writing--review and editing, M.F. and P.D.; visualization, W.S.-Z.; supervision, M.F.; project administration, A.T. All authors have read and agreed to the published version of the manuscript.  
This research was funded by project ZIO/MN-2/19 'Assessment of the possibility of improving the nutritional value of milk and its suitability for cheese production by adding humic acids to the diet of high-producing cows'.  
Ethical review and approval were waived for this study. According to the Directive 2010/63/EU of The European Parliament and of The Council of 22 September 2010 [45] and Polish legislation--Act of 15 January on the protection of animals used for scientific purposes [46], research described in the manuscript was not a procedure and therefore did not need the approval of the Local Ethics Committee. The current EU Commission Regulation 2017/1017 of 15 June 2017 [47] allows the use of leanadite as a feed material (Item no. 13.10.2), whereas oxyhumolite is referred to as European leanadite due to the similarity in chemical composition and properties [48]. The feed additive was used strictly according to the manufacturer's recommendations. Therefore, the feed used did not cause a clinical anomaly or pain, so the applied nutrition is not a procedure requiring the approval of the Commission.  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest.