3.1. Floristic Composition of Meadow Sward
The floristic composition of meadow sward in 2009, 2012 and 2013 after grassland renewal coincided with the participation of individual species in mixtures (
Table 4, 
Table 5 and 
Table 6).
The paper presents results concerning floristic composition only from the first swath, because in the remaining swaths they were similar. A mild winter with a period of a short strong frost and surface flooding in the spring of 2010–2011 caused 
Lolium perenne to decline as a percentage of the floristic composition (
Table 4).
Analyzing the mixture on object 1, where the share of 
Lolium perenne in 2009 was 41.0%, it decreased to 2.6% in 2010 and its share in 2011 was 4.1%. The place of 
Lolium perenne in this series of the experiment was taken by: 
Festulolium braunii, Poa pratensis, Dactylis glomerata and 
Phleum pratense. Frost resistance of 
Festulolium braunii is indicated by studies by Thomas and Humphreys [
36], Humphreys et al. [
59], Yamada et al. [
46], Touno et al. [
47], Šimkūnas et al. [
60], Sosnowski [
44], Østrem et al. [
38] and excessive soil moisture by Matoba et al. [
45] and Touno [
61].
A similar arrangement of results concerned all the evaluated mixtures, of which the most stable floristic composition was noted in the case of multi-species mixtures with a low proportion of 
Lolium perenne, i.e., mixtures from 2 to 5. Grass species introduced as components of the aforementioned mixtures showed high resistance to the existing habitat conditions and stability in the floristic composition in particular years (
Table 4).
In the years of more stable weather conditions (2012 and 2013), the composition of mixtures tested in the second experiment proved to be more stable and close to the assumed sowing standard (
Table 5).
In the third experiment, which lasted much longer than the second experiment, with a diverse set of weather conditions (amount and distribution of precipitation, very low temperatures in spring 2016) the floristic composition of the sward was stable in the first three years of the study. On the other hand, in the meadow sward of the first swath of 2016, freezing of plants, especially 
Lolium perenne and partly also 
Festulolium braunii, was observed, due to short-lived very low temperatures that occurred in early spring. This was not observed in 
Festuca arundinacea and 
Phleum pratense, which was reflected in the appearance of meadow sward on individual plots and its floristic composition (
Table 6). Higher resistance to low temperatures of 
Festulolium braunii than 
Lolium multiflorum but lower than 
Festuca pratensis is indicated by the study of Šimkūnas et al. [
60].
The process of sward regeneration with the participation of 
Lolium perenne and 
Festulolium braunii plants lasted until mid-June, because the floristic composition found during the harvest of the second swath (9 June 2016) was repeated in subsequent swaths. The results of all experiments showed that 
Festulolium braunii plants have a high stability of in sward and a lower response to unfavorable weather conditions compared to 
Lolium perenne and are slightly inferior to species such as 
Festuca arundinacea and 
Phleum pratense, which are reported in the literature as persistent species and well-developing in terms of habitat on organic soils [
12,
33].
PCA analysis showed that abundance in the 
Festulolium braunii and 
Lolium perenne sward depended on precipitation in February, March, April, May and June, during the growing season and throughout the year, as well as on temperature in March, April, July and August. The presented climatic conditions in the studied decade had a different effect on the abundance in the sward of 
Festulolium braunii and 
Lolium perenne (
Figure 2). The PCA analysis should be treated with caution because it did not consider short winter and early spring frosts and surface water flooding, which affected 
Festulolium braunii and 
Lolium perenne cover. Nevertheless, this analysis and the results of Fb and Lp coverage obtained clearly indicate that 
Festulolium braunii is more durable in the sward than 
Lolium perenne under varying weather conditions.
The high persistence of 
Festulolium braunii in the habitat even under unfavorable weather conditions is due to its well-developed root system, which it inherited from meadow fescue [
36,
41,
42,
55,
62,
63].
Lolim perenne is a very valuable grass of high fodder value willingly eaten by cattle. It is the main component of grassland sward in Europe [
64]. This grass is durable and expansive but not very tolerant of adverse environmental conditions [
37]. Kulik and Baryła [
65], sowing a mixture of composition: 
Lolium perenne—35%, 
Trifolium repens—35%, 
Dactylis glomerata—10% and 
Phleum pratense—20% on organic soil, after previously applying Roundup herbicide and biting and rolling, found high persistence of 
Lolium perenne in pasture sward. After 12 years, the share of this species in the sward averaged 19.9% in the first regrowth and 22.0% in the third regrowth. These authors found large changes in the share of 
Lolium perenne in particular years, which was related to habitat conditions, especially water and thermal conditions. They found the loss of perennial ryegrass in frosty winters and its regeneration in the years when it increased its share in pasture sward. In general, during 12 years with favorable weather conditions, the fluctuations of 
Lolium perenne share in the pasture sward ranged from 7.3% to 63.0%. Such an arrangement of results is confirmed by our study, in which in conditions of low temperatures during winter and excess water in spring, there was a significant decrease in the share of 
Lolium perenne. The fast regeneration of 
Lolium perenne, as indicated by the quoted authors, was not confirmed in our study, as the lower share of this species found in 2010 was maintained in the next year 2011. The high expansiveness of 
Poa pratensis in the period less favorable for 
Lolium perenne, which was indicated in peat-muck soils Kamiński [
33], Baryła and Drozd [
66] and Kulik and Baryła [
65] was confirmed in our study. High prevalence of 
Poa pratensis on organic and organic-mineral soils of Western Pomerania in Poland was found by Czyż et al. [
67,
68].
   3.2. Dry Matter Yield
Biomass obtained from objects sown with particular mixtures with different share of 
Festulolium braunii in the sward was characterized by a similar dry matter content, therefore in this study it was limited only to dry matter yields (
Table 7 and 
Table 8). In the first experiment carried out in the years 2009–2011, the highest dry matter yield was obtained on object 5 (13.85 t∙ha
−1 average from years), where the sward was a multi-species mixture with following composition: 
Festulolium braunii (39.5–29.9%), 
Lolium perenne, 
Poa pratensis, 
Dactylis glomerata and 
Phleum pratense. The yields obtained were higher than the other mixtures with a similar share of this species in mixtures 4 and 6 by 9.6% on average and with a higher share of 
Festulolium braunii in the sward in mixtures 1–3 by 12.3% on average (
Table 6).
Average results from the years of the study indicate that the sward of plot 5, where the mixture of the following composition was sown: 
Festulolium braunii—21.0%, 
Lolium perenne—29.0%, 
Poa pratensis—11.0%
, Phleum pratense—18.0%, 
Dactylis glomerata—21.0% was characterized by the highest production potential, even when 
Lolium perenne almost completely fell out of the sward in the second year the study. It is noteworthy that the same mixtures, despite a significant fall out of 
Lolium perenne from the sward in 2010, in the third year of the study, yielded 42.3% higher than in 2009 and 60.5% higher than in 2010 (
Table 7). This proves that the species used for mixtures including 
Festulolium braunii, apart from 
Lolium perenne, survived the excessive humidity of the habitat well (in winter and early spring 2010) and regenerated the sward, causing high yielding. The lowest yields were obtained from object 2, where the following species were used for regeneration: 
Festulolium braunii (43%), 
Poa pratensis (29%) and 
Lolium perenne (28%). The annual yield of biomass, obtained from grassland, is a component of yields from individual swaths.
The dry matter yields of mixtures in the second experiment were on average higher than those obtained in the first two years of use in the first experiment, but lower than the average yields from the third year by 6.7% (
Table 7). In this experiment, the mixtures studied, regardless of the year of the study, yielded at a similar level with respect to the object, on which 
Festulolium braunii was sown in the greatest amount (50%), the yield of the remaining mixtures was higher than the average of 2.1% to 8.0%. In this experiment, also high yields of dry matter were obtained from an object sown with a multi-species mixture of 
Festulolium braunii—30%, 
Lolium perenne—20%, 
Poa pratensis—10% and 
Dactylis glomerata—40%.
The results of the dry matter yield obtained in the third experiment (
Table 8) prove that under the tested habitat conditions, higher yields are obtained when mixtures with a richer species composition—mixture 3—are used to sow grassland, compared to two-component mixtures of 
Festulolium braunii and 
Lolium perenne (on average from the years of the study) by 10.8% (for a mixture with composition: 34 + 66%) and by 9.1% for the mixture with 50% share of the two species in sowing. The results from the six years of the study indicate that using short-lasting species (
Lolium perenne and 
Festulolium braunii) in large quantities in grassland mixtures contributes to an increase in dry matter yields up to four years, while in subsequent years to a decrease in average yields by 34.1%—in the fifth and by 35.9% in the sixth year of the study (
Table 8).
It follows from our own long-term studies that 
Festulolium braunii tolerates varied atmospheric conditions very well during the vegetation period and ensures stable sward yield in mixtures. 
Lolium perenne, on the other hand, under unfavorable weather conditions decreases its share in the sward, thus decreasing the harvested yield. PCA analysis (
Figure 3) showed that the yield of sward dry matter depended most strongly on the share of 
Lolium perenne. Its place in the studied sward is largely taken by 
Festulolium braunii, which stabilizes yield but does not affect its growth.
Ward’s analysis grouped the objects (grass mixtures) according to similar meadow sward yield quality. The study considered a split with a bond distance of 4, yielding 4 aggregates of grass mixtures (
Figure 4). The extreme groups include grass mixtures in which: (1) the proportion of 
Lolium perenne decreased greatly and that of 
Festulolium braunii increased; and (2) the proportion of 
Lolium prenne and 
Festulolium braunii did not change much. Such grouping of investigated mixtures indicates that quantitative increase in 
Festulolium braunii and decrease in 
Lolium prenne influences yield productivity and quality. The decrease in the proportion of 
Lolium prenne in the meadow sward largely compensates for the increase in the proportion of 
Festulolium braunii (stabilizing productivity and yield quality). The introduction of 
Festulolium braunii to the sward in progressing climatic changes is a good solution to maintain high and good quality sward yields. The results of research on cultivars of this hybrid indicate that dry matter yields are high—from about 6 t/ha DM in the absence of mineral fertilisation to 18.13 t/ha DM with adequate mineral fertilisation [
38,
44,
69,
70,
71,
72]. This species shows a favorable response to nitrogen fertilisation [
73].
Gutmane and Adamovich [
69], Grønbæk [
70] and Østrem, et al. [
38] indicate that 
Festulolium braunii hybrids yield better than 
Lolium perenne.
  3.3. The Value of Food and Energy of Meadow Sward
The fodder obtained from a unit of area can be assessed by the quantity or quality of the harvest. According to Staniak and Harasim [
49], and Olszewska [
74], forage quality is influenced by many factors: sward species composition, plant development stage, soil moisture and nutrient abundance, and weather conditions.
The results of our study presented in 
Table 9 confirm the research Czyż et al. [
75], which showed that the chemical composition, as well as the energy concentration, depends on the floristic composition of the sward. In our study, where the floristic composition of the sward (especially in the first years of the study) was similar to the share of individual species in the mixture used for grassland regeneration, the sward from the multi-component mixture of plot 6, where 
Festulolium braunii, 
Lolium perenne, 
Poa pratensis and 
Phleum pratense were found in the floristic composition, had the highest crude protein content. In general, the protein content in the research objects ranged from 124 to 158 g∙kg
−1 DM (
Table 9).
PCA analysis showed that the crude protein content of forage harvested (under varying weather conditions), was due to the high proportion of Festulolium braunii in the sward.
According to Staniak [
76], this hybrid under drought conditions does not respond by lowering the crude protein content of the sward. Moreover, under unfavorable environmental conditions, it favorably influences the development of other grass species more sensitive to the variability of weather conditions, which indirectly affects the protein content of the sward [
76]. The crude protein content of 
Festulolium braunii has a wide range (from 66 g∙kg
−1 DM to 194 g∙kg
−1 DM) depending on environmental conditions and fertilisation [
49,
61,
70,
71,
72,
76]. Despite the significant amount of crude protein in 
Festulolium braunii, similar to the content in grasses with high forage value, these amounts are generally insufficient for the nutritional requirements of cattle. The content of crude protein in the feed of dairy cattle should not fall below 150 g∙kg
−1 DM [
72]. Therefore, this hybrid should occur with legumes and grasses with high protein content. On the other hand, Touno et al. [
61] showed that despite lower crude protein in 
Festulolium braunii than in 
Phleum pratense L, milk yield in cows was higher in animals fed 
Festulolium braunii forage.
The crude fiber content ranged from 284 to 307 g∙kg−1 DM. The upper value refers to objects 4 and 5, where the largest share of Dactylis glomerata was found in the sward.
PCA analysis showed that the proportion of Festulolium braunii and Lolium perenne had no effect on crude fibre content in the sward. In contrast, the proportion of other grasses in the sward had a significant effect.
Too high a fibre content worsens the digestibility of the forage. Smaller amounts of crude fibre between 211–243 g∙kg
−1 DM in the sward with 
Festulolium braunii were found by Staniak [
76]. At the same time, the author showed that under drought conditions 
Festulolium braunii contained less crude fibre than under optimal moisture conditions. Touno et al. [
61] found 293 g∙kg
−1 DM crude fibre in 
Festulolium braunii. The author indicated that this hybrid has significantly less fibre than 
Phleum pratense. Significant variations in crude fibre content in 
Festulolium braunii (from 179 to 320 g∙kg
−1 DM under optimal moisture conditions and from 206 to 241 g∙kg
−1 s.m under drought conditions were found by Staniak and Harasim [
49].
In terms of soluble sugars (108 and 104 g∙kg
−1 DM), the sward from objects 1 and 2 in the floristic composition, of which only two species of 
Festulolium braunii and Lolium perenne were found, was outstanding. This is in consistent with opinion of Ciepiela [
77,
78], Kozłowski et al. [
79], Downing and Gamroth [
80], who state that 
Lolium perenne and 
Festulolium braunii have a high soluble sugar content among other species. According to Ciepiela [
78] 
Festulolium braunii has a low tendency to accumulate unstructured carbohydrates. A similar opinion of 
Lolium perenne was expressed by Kozłowski et al. [
79] and Piecuch et al. [
81].
PCA analysis showed that only the proportion of Festulolium braunii positively shaped the content of water-soluble carbohydrates in the dry matter of the studied sward.
Studies by Gronbak [
70], Staniak and Harasim [
49], Staniak [
76] showed that 
Festulolium braunii is characterized by a high variation in water-soluble carbohydrate content most often from about 60 to about 100 g∙kg
−1 DM, while not exceeding 240 g∙kg
−1 DM. No clear effect of drought on carbohydrate content in the hybrid was found [
49,
76]. The high carbohydrate content of 
Festulolium braunii predisposes this species to form mixtures with high-protein legumes, e.g., limpet, alfalfa [
74,
76,
82]. Forages with a high proportion of water-soluble carbohydrates improve protein digestibility and reduce nitrogen losses, they also have good digestibility, which results in good development of cattle [
83,
84]. In addition, cattle prefer grasses with a high proportion of carbohydrates [
84].
In assessing forage quality, the ratio of water-soluble carbohydrates to crude protein is important, indicating protein availability to cattle [
85]. A ratio in the range of 0.8–1.5 is beneficial for cattle (good nitrogen utilisation), but should not be less than 0.4 [
82,
84,
85]. The tested mixtures with 
Festulolium braunii had sugar–protein ratios > 0.4. Equally favorable sugar–protein ratios in mixtures with 
Festulolium braunii (0.46) were obtained by Sosnowski [
82]. On the other hand, Malinowska [
71] found a clear effect of fertilisation on the sugar-protein ratio in 
Festulolium braunii (from 0.704 to 1.53). The ability of 
Festulolium braunii to accumulate sugars also plays an important role in its resistance to stress conditions, especially water stress [
76].
The energy concentration of the sward from all plots was similar: from 6.0 to 6.3 MJ∙kg
−1 NEL (
Table 9). Assessing the fodder value of the meadow sward on the basis of the net energy concentration, it was found that it was at the level recommended for fodder (6 MJ∙kg
−1 DM), which ensures the proper development of farm animals [
86].
PCA analysis showed that the net energy concentration of the harvested sward depended positively to a small extent on the share of Festulolium braunii and other grasses, and negatively on the share of Lolium perenne.
Studies by Gronbaek [
70] showed that different cultivars of 
Festulolium braunii were characterised by energy concentrations ranging from 6.02 to 6.16 MJ∙kg
−1 NEL DM and 
Lolium perenne 6.43 MJ∙kg
−1 NEL DM.
In the second year of the study (2010), as a result of very low temperatures in winter and spring floods, the beginning of vegetation was significantly delayed and significant changes in the floristic composition were found: these concerned mainly 
Lolium perenne, the share of which was very much reduced and was replaced by 
Dactylis glomerata, Poa pratensis and 
Phleum pratense and, to a lesser extent, 
Festulolium braunii (
Table 4).
There was also a delay in harvesting the first swath (12 June 2010). Harvesting was carried out in the phase of the dominant species earing. The consequence of the delayed harvest was higher fiber content and lower protein and sugars (
Table 9). Jankowska et al. [
87] conducting research on a three-cut meadow with a grass community dominated by 
Festuca pratensis, 
Dactylis glomerata and 
Poa pratensis, found 157 g∙kg
−1 DM crude protein, 75.5 g∙kg
−1 DM soluble sugars and 260–290 g∙kg
−1 DM of crude fiber in the sward from the first swath. Comparing the results obtained in our study with the data of Jankowska et al. [
87], it should be stated that in the first year of the study (2009), in which four swaths were collected, the protein and fiber content in the first swath was consistent with the literature data, while the content of soluble sugars was twice as high. The literature underlines that 
Festulolium braunii with legumes is a very good feed for cattle [
52,
76,
82].
Biomass production in particular regrowth (swaths) took place under different habitat conditions (groundwater level, air temperature, sunshine) and, therefore, not only were the values of particular parameters different, but also the sward quality was differentiated. The results of our study (
Table 9) show, that in the years in which four or five swaths with the best fodder value were collected, the share of 
Festulolium braunii and 
Lolium perenne in the floristic composition of individual plots was significant. The highest content of crude protein, soluble sugars and net energy concentration (NEL) and the lowest content of crude fiber were found. Gos and Kitczak [
88], conducting research on grasslands located on organic soil, found that harvesting four swaths, biomass was obtained with good parameters, especially of the formation of protein and fiber. According to our assessment of the fodder value of biomass from individual swaths, the best values of analyzed parameters were obtained in the first swath. The greatest differences between swards from particular swaths concerned sugar content. Swaths harvested in summer were characterized by a much lower concentration of soluble sugars than swaths harvested in spring and autumn. The clear decrease in the concentration of unstructured carbohydrates in the summer can be explained by the increased respiration of the plants under high temperature conditions, and mainly sugars are used in this process [
89,
90]. Similar results were obtained Kozłowski et al. [
79], Goliński and Kozłowski [
91], Downing and Gamroth [
80] and Ciepiela [
78].