## 4 Discussion
[PERSON] and [PERSON] [63] and [PERSON] et al. [64] reported that the CFr content in soybean seeds remained unchanged when nitrogen fertilizers were applied. An increased crude ash (CA) content implies considerable soil pollution, which might raise the content of insoluble fiber components in neutral detergent fiber (total cellulose) solution greatly. In our study, this measure was not affected by the assessed factors, although there was a tendency for CA content to be higher with the increase in available nitrogen, and a slightly greater 2-year value (5.65% DM) was recorded in plots fertilized with compost (Table 5). The CA content of amelina oilseed cake was reported to vary from 4.9% to 6.3% [50]. [PERSON] et al. [65] demonstrated that high rates of nitrogen increased the CP content and decreased the content of CF, as well as causing a significant decrease in ash and CFr content in soybean seeds. Carbohydrates (CHO) represent the principal source of energy for rumen microorganisms, as well as the primary plant energy reserve, comprising 50-80% of total reserves [66]. CHOs offer energy to livestock, with the rumen performing the majority of digestion in the case of ruminants [67]. The CHO of amelina seed meal comprises monosaccharides, disaccharides, as well as polysaccharides [4]. The total CHO content declined linearly in the current experiment, with increasing levels of nitrogen supply to the plant (Table 4) due to the increased usage of these cards to convert available nitrogen into protein as a natural plant reaction [68; 69]. Regarding the residual oil content in amelina oilseed cake, the combined analysis of variability showed that organic fertilization only influenced this trait. Specifically, the highest 2-year mean value was discovered in compost treatment (14.11% of DM), while the lowest was obtained from untreated (13.79% DM). The current findings distinctly reveal that a substantial quantity of oil continues to exist in the cake after mechanical screw press extraction of oilseeds. In addition, cold-pressed cakes preserve more oil than solvent-extracted meals [32]. As a result, cold-pressed cakes contribute a substantial quantity of energy to livestock rations due to their high content of residual oil [4; 32]. The fatty acid (FA) composition of amelina oilseed cake is presented in Table 6. The results revealed that the cold-pressed cake was distinguished by low quantities of saturated fatty acids (SAFA), of which palmitic acid (C160) was the predominant one. During the two experimental years, the contents of SAFA and palmitic acid were only affected by organic fertilization, presenting a similar trend. Specifically, the highest concentrations in the first year of the study were achieved after vermicompost application, with the maximum average values of SAFA and palmitic acid content being 9.85% and 9.28% DM, respectively, whereas, during the second year, the highest values of SAFA (9.91% DM) and palmitic acid (7.39% DM) were recorded after compost fertilization, with the differences among compost and vermicompost fertilization not being statistically significant. In the present study, this similar response trend of SAFA and palmitic acid content is also confirmed by the very strong and positive correlation among the above-mentioned traits (_r_ = 0.956, \(p\) < 0.001, respectively) (Figure 3). The amount of SAFA and palmitic acid content in amelina seed cake seems to be lower than that found in soybean meal (19.9%) and rapeseed cake (16.3%), although higher compared with that found in hempseed cake (7.7%) [70; 71]. Concerning the proportion of monounsaturated fatty acids (MUFA), this was substantially affected by both examined factors. In particular, the conventional tillage system, with a 2-year mean value of 33.47% DM, was significantly higher than that of minimum tillage, with a 2-year mean value of 33.14% DM. In terms of fertilization, the highest 2-year mean value (33.73%) was observed in the untreated plots.