## 3 Results and Discussion
### Profile and Content of Fatty Acids in Milk
The detailed fatty acid profile of milk fat is shown in Table 4.  
\begin{table}
\begin{tabular}{c 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{2-7}  & **0** & **30** & **60** & **0** & **30** & **60** \\ \hline C4\(\cdot\)0 & 3.22 \(\pm\) 0.31 & 3.20 \(\pm\) 0.04 & 3.24 \(\pm\) 0.18 & 100.14 \(\pm\) 17.40 & 105.65 \(\pm\) 25.23 & 102.67 \(\pm\) 18.70 \\ C6\(\cdot\)0 & 2.19 \(\pm\) 0.22 & 2.13 \(\pm\) 0.10 & 2.29 \(\pm\) 0.15 & 68.04 \(\pm\) 9.87 & 72.09 \(\pm\) 13.26 & 74.72 \(\pm\) 13.72 \\ C8\(\cdot\)0 & 1.27 \(\pm\) 0.17 & 1.23 \(\pm\) 0.09 & 1.38 \(\pm\) 0.14 & 39.26 \({}^{\rm b}\)\(\pm\) 6.28 & 42.37 \(\pm\) 6.70 & 45.88 \(\pm\) 4.40 \\ C10\(\cdot\)0 & 2.85 \(\pm\) 0.45 & 2.77 \(\pm\) 0.20 & 3.27 \(\pm\) 0.49 & 87.17 \({}^{\rm b}\)\(\pm\) 16.16 & 96.71 \  
Limiting the supply of SFAs, particularly C12:0, C14:0, and C16:0 acids, as well as industrial sources of TFAs, is a key dietary recommendation to reduce the risk of cardiovascular disease [27]. The American Heart Association and the American College of Cardiology recommend limiting energy from saturated fatty acids to <7% of total energy intake [28]. In contrast, according to the European Food Safety Authority (EFSA) [29], saturated fatty acids are synthesized by the body and are not required in the diet, hence their supply should be as low as possible. It should be emphasized that the presence of SCSFAs is a unique characteristic of milk fat. They are formed by the rumen microflora of ruminants and are not found in other fats. In the human body, these acids have a number of important biological functions and are the source of, among other things, the energy necessary for the functioning of the heart, liver, kidneys, nervous system, and muscles. C4:0, C6:0, C8:0, and C10:0 acids are oxidized to acetyl-CoA in the liver and do not affect the activity of low-density lipoprotein receptors. They do not increase blood lipid levels, and thus, do not pose a risk of developing obesity and cardiovascular diseases [30]. Dairy products are an important source of calcium, which interacts with SFA to form calcium-FA soaps, thereby increasing fecal fat excretion, which improves the HDL to LDL cholesterol ratio [31]. The reduction in the proportion of MUFA and C18:0 acids resulted in a significant decrease in the proportion of DFA. In the MUFA profile, there was a significantly (\(p\) < 0.05) higher proportion of trans-configuration acids and a lower proportion of cis-configuration acids. With regard to the content of these fatty acids in milk, however, the differences found were not statistically significant. Trans fatty acids are negatively perceived by consumers, but a distinction must be made between trans fatty acids of natural origin and those industrially obtained. Among the trans isomers found in milk fat, vaccenic acid (isomer C18:1 t-11) is particularly important. It exhibits antiatherosclerotic effects by lowering blood levels of triglycerides and LDL cholesterol fractions, anti-cancer effects, and beneficial effects on the immune system. Through desaturation, conjugated linoleic acid (CLA) is formed from vaccenic acid [32; 33]. The effect of introducing the humic-mineral substances into the cows' diets in the present study was a significantly higher proportion of the C18:1 t-11 isomer in milk fat (Table 4). The highest proportion of PUFAs (3.38% FA) (Table 3) was found in milk fat at 30 days of supplementation, which was mainly due to the proportion of C18:2 9t12 and C18:2 9t12 acids (Table 4). Health-related indices such as n6/n3, PUFA/SFA, h/H, HSFA, AI, and TI indices are used to assess the nutritional value and potential impact of product consumption on consumer health. A ratio of PUFA/SFA in the diet above 0.45 and a n6/n3 below 4.0 reduces the risk of developing cardiovascular diseases and cancer [34]. In our study, the PUFA/SFA ratio in milk fat ranged from 0.04 to 0.05 and n6/n3 from 3.91 to 4.23.