## 3 Results and Discussion
### Profile and Content of Fatty Acids in Milk
Such a low value for the PUFA/SFA ratio was due to the high content of SFA acids. There was no significant effect of the use of humic-mineral substances in the feeding of cows on the proportion of these acids. However, significant (\(p\) < 0.05) changes were found in the values of the HSFA, h/H, AI, and TI indices, resulting from a higher proportion of hypercholesterolemia fatty acids and thus a deterioration in the nutritional quality of milk fat after the introduction of the dietary modification in cows (Table 3). [PERSON] and [PERSON] [35] proposed the AI \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Fatty Acid**} & \multicolumn{3}{c}{**\% of Total FA**} & \multicolumn{3}{c}{**mg/100 mL**} \\ \cline{2-6}  & **0** & **30** & **60** & **0** & **30** & **60** \\ \hline C20:4n6 & 0.12 \(\pm\) 0.03 & 0.12 \(\pm\) 0.03 & 0.11 \(\pm\) 0.03 & 4.02 \(\pm\) 0.83 & 4.44 \(\pm\) 1.94 & 3.77 \(\pm\) 1.25 \\ C22:0 & 0.07 \(\pm\) 0.02 & 0.07 \(\pm\) 0.02 & 0.09 \(\pm\) 0.02 & 2.52 \(\pm\) 1.24 & 1.98 \(\pm\) 0.76 & 3.04 \(\pm\) 1.37 \\ C230 & 0.60 \({}^{\pm}\) 0.03 & nd. & 0.08 \({}^{\flat}\) 0.02 & 19.46 \({}^{\pm}\) 0.99 & nd. & 2.86 \({}^{\flat}\) 0.91 \\ C24:0 & nd. & nd. & 0.07 \(\pm\) 0.01 & nd. & nd. & nd. & 2.29 \(\pm\) 0.23 \\ C22:5n3 & 0.09 \(\pm\) 0.02 & 0.08 \(\pm\) 0.01 & 0.08 \(\pm\) 0.02 & 3.00 \(\pm\) 0.77 & 2.97 \(\pm\) 0.62 & 2.82 \(\pm\) 0.62 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._and TI indices. As the values of these indices increase, the risk of cardiovascular disease increases, so products with the lowest possible levels of AI and TI should be selected [36]. In our study, after 60 days of supplementation, the AI value of milk fat was 30% higher and the TI value was 22% higher, but the index values were not higher than 4. The ranges of AI values for cereals, fish, meat, and dairy products are 0.084-0.55, 0.21-1.41, 0.165-1.32, and 1.42-5.13, respectively, and the TI index is 0.139-0.56, 0.14-0.87, 0.288-1.694, and 0.39-5.04, respectively. It is recommended to consume products with the lowest possible AI and TI values to minimize the risk of developing cardiovascular disease, but current dietary guidelines do not recommend values for these indices [36]. To the best of the authors' knowledge, only two papers have so far been published on the effect of using humic substances in the feeding of cows on the fatty acid profile of milk. The results of the presented studies do not correspond with previous reports. [PERSON] et al. [37] fed clay-derived humic substances to cows at two doses: 5 and 10 g/kg feed (no information on the content of humic acids). Regardless of the dose used, there was no change in the fat content of the milk. There were also no significant changes in the proportion of SCSFA and MUFA. However, there was an increase in the proportion of PUFA, including isomeric forms of linoleic acid (C18:249t12 and C18:2c9t12), and a decrease in the values of the AI and TI indices and the PUFA/SFA ratio. [PERSON] et al. [38] fed humic substances to cows at doses of 20 and 40 g per cow per day. The feed additive used contained 90% humic acids and 10% minerals. Beneficial changes in the fatty acid profile were shown; i.e., a significant increase in the proportion of MUFA, PUFA, and CLA, and a reduction in AI values from 2.32 to 1.97 with the higher dose of the supplement applied. No changes were found in the proportion of SFA. The ambiguity of the information presented may be due to the use of humic substances of different origins, and therefore chemical composition or dosage, in the study. This can be a problem in comparing the results of studies on humic substances as animal supplements, so further research is needed to expand knowledge in this area.