## 4 Discussion  
[PERSON] [21] reported that crude fiber content in forage for ruminants should range from 200 to 250 g kg\({}^{-1}\)DM. Additionally, [PERSON] and [PERSON] [22] argued that amounts of crude fiber exceeding 260 g kg\({}^{-1}\)DM caused the feeling of satiety, but because of the low energy value of the forage, nutritional requirements were not met. It was found that the interaction of slurry and soil conditioners resulted in more favorable raw fiber content than in plants treated with slurry on its own, or with slurry combined with mineral fertilizers, which confirms the second research hypothesis. In effect the grass treated with slurry and soil conditioners contained the amount of nutrients which, according to [PERSON] and [PERSON] [22] and [PERSON] and [PERSON] [11], was more favourable. In the present research crude fiber content of _Festulolium braunii_ ranged within 260.0-310.0 g kg\({}^{-1}\) and was above the standard set by [PERSON] [21], which was undoubtedly caused by very adverse temperature and water conditions in both growing seasons. In the first one (2016), optimal weather conditions were only in September. May was very wet, while June, July, and August, months with the greatest impact on plants, were fairly dry, dry, and extremely dry, respectively. During the next growing season (2017) the dry period lasted from May to August, and in other months the weather conditions were not conducive to plant growth either. According to [PERSON] [23], the minimum amount of fiber in forage for cattle should be 13%, while for dairy cows it should range from 18% to 22%. The results of the present studies were also confirmed by other authors [24; 25; 26]. Many of them [27; 28; 29] reported a much higher fiber content in hay, from 281.1 to 331.8 g kg\({}^{-1}\)DM. Additionally, [PERSON] and [PERSON] [30] in their research on organic grassland recorded 300 g kg\({}^{-1}\) of crude fiber in the forage. Crude fiber content of _Festulolium braunii_ significantly varied across harvests. Its smallest content in both years was in the first harvest. Water scarcity affects crude fiber content of grass, and according to [PERSON] [31], a decrease in the amount of fiber caused by drought depends on the species of grass. On the other hand, [PERSON] and [PERSON] [32] suggested that high temperatures might increase fiber content. This was confirmed in the present studies, with the highest fiber content of _Festulolium braunii_ in the second harvest of 2016, when air temperatures were high, reaching the average of 21 \({}^{\circ}\)C in August. Neutral detergent fiber content in forage is strictly dependent on the harvest and, especially, on thermal conditions [28]. Its content in hay for dairy cows should be about 400 g kg\({}^{-1}\)[33]. In the present studies, being generally higher than that recommended by [PERSON] [33], NDF content was significantly differentiated by treatments in both years of the experiment, but it complied with the feed requirements provided by [PERSON] and [PERSON] [11]. The increase in NDF content was higher in plants treated with slurry and soil conditioners than in those treated with slurry on its own and slurry combined with NPK. In the present research, both slurry combined with soil conditioners, and with mineral fertilizers, contributed to an increase in NDF fraction content in grass. However, studies on meadow plants conducted by [PERSON] et al. [26] showed that the use of manure and slurry resulted in its significant reduction. The components of acid detergent fiber such as cellulose, lignin, and silica are the least digestible [11]. Their optimum content in forage should range from 190 to 210 g kg\({}^{-1}\)DM, as elevated values deteriorate its digestibility. Similar content of the ADF fraction in _Festulolium braunii_ was reported by [PERSON] [34] in an experiment with the UGmax soil conditioner and mineral fertilizers. [PERSON] [35] reports that increasing nitrogen doses contribute to reducing the proportion of the ADF fraction in meadow hay.