3.3. Chemical Composition of Desho Grass Varieties
The results of the chemical composition of
Desho grass varieties at standardization cut (105 days) are indicated in
Table 4. The result showed that the dry matter, ash, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and cellulose showed a significant difference (
p<0.05) among
Desho grass varieties.
The DM content obtained from Kulumsa /DZF #592 (92.89%) was significantly higher than Areka /DZF #590 (92.15%) and Kindu kosha-1 /DZF #591 (91.44%) (
Table 4). The overall mean DM was 92.16%. In contrast to the current result, earlier reports revealed non-significant differences in the dry matter content of similar
Desho grass varieties [
31,
34,
35]. The present result was lower than the findings of Kefyalew et al. (2020) [
36], who found that the DM content of
Desho grass was 94.58%. These differences may be due to climatic conditions, fertilizer, soil fertility, plant densities, and management conditions.
The higher ash content of
Desho grass was obtained from Kulumsa /DZF #592 (9.38%), while the lowest was obtained from Kindu kosha-1 /DZF #591 (8.89%) (
Table 4). The overall mean ash content was 9.19%. The current ash contents were lower than the previous report for similar
Desho grass varieties tested at the midland and highland Guji zone [
35]. However, the ash content of Areka /DZF #590 and Kulumsa /DZF #592 is higher than the report by Hidosa et al. (2020) [
35], while Kindu kosha-1 /DZF #591 is lower than this author’s report. Such variation might be due to harvesting age and weather conditions.
The higher crude protein content was recorded from Areka /DZF #590 (10.73%), which was at par with Kindu kosha-1 /DZF #591 (10.38%), while significantly lower crude protein content was obtained from Kulumsa /DZF #592 (9.59%) with an overall mean of 10.24% (
Table 4). The current CP content result was higher than in previous reports for
Desho grass harvested at different ages [
21,
40]. However, the present result was lower than the report made by Hidosa et al. (2020) [
34] who stated that the CP content of
Desho grass varieties (Kulumsa /DZF #592 (11.84%), Areka /DZF #590 (14.12%) and Kindu kosha-1 /DZF #591 (13.39%). The variation in crude protein may be due to the environment, sowing season, harvest age, and soil fertility. The current CP content obtained from
Desho grass varieties is above the minimum crude protein requirements (7%) for the maintenance of animals and rumen microbes [
41]. The present result was under the range of most CP content for tropical pasture species between 7 and 12% for grasses [
42]. The present CP result is lower than the recommended CP between 14 and 16% for sustainable production of dairy cattle [
43].
The significantly higher (
p<0.05) NDF content in the current result was obtained from Kindu kosha-1 /DZF #591 (65.98%) followed by Kulumsa /DZF #592 (64.84%), whereas lower NDF content was recorded from Areka /DZF #590 (63.6%) with an overall mean of 64.81% (
Table 4). The overall mean of the current result was comparable with the result of [
28], who noted that the NDF content of sole
Desho grass was 63.15%. The values obtained for NDF from this study were lower than previously reported values for similar
Desho grass varieties grown in Holetta [
32]. However, the current result NDF content was higher than the report made by Hidosa and Getaneh (2021) [
31] for Kulumsa /DZF #592 (61.52%) and Areka /DZF #590 (60.94%) varieties, while it was comparable for Kindu kosha-1 /DZF #591 (65.67%). This difference in NDF content could be attributed to various factors related to the harvesting age, environment, season, soil fertility, and management practices. The feed that contains 45% to 65% NDF is considered a moderate level of quality, whereas feed containing more than 65% NDF is classified as roughages of low quality [
44]. Based on this classification, Kindu kosha-1 /DZF #591 (65.98%) is considered poor-quality feed, whereas Kulumsa /DZF #592 and Areka /DZF #590 can be classified as medium quality. The current values are above the minimal NDF (25–33% DM) needed for lactating cows [
43].
The significantly higher (
p<0.05) ADF content was obtained from Kindu kosha-1 /DZF #591 (42.08%) followed by Kulumsa /DZF #592 (40.31%), whereas significantly lower ADF was recorded from Areka /DZF #590 (39.39%) (
Table 4). The current ADF values were lower than the previous report for similar
Desho grass varieties [
34,
35], but slightly higher than the finding of (Kebede
et al., 2022) [
32]. Furthermore, the current finding was lower than the report of Asmare et al. (2018b) [
21], who noted that the ADF content of
Desho grass at 105 days of harvest age was 47.93%. The variability in %ADF content might be attributed to soil fertility and agro-ecology variation. The current result was under the range between 30 to 45% of the majority ADF content for tropical pasture species [
45]. Kellems and Church (1998) [
46] state that roughages with an ADF content higher than 40% are considered low quality, while those with less than 40% are considered high quality. Based on this classification, Kindu kosha-1 /DZF #591 and Kulumsa /DZF #592 are classified as poor quality, while Areka /DZF #590 can be classified as medium quality. However, the current result was above the minimal ADF (17–21% DM) recommended for lactating cows [
43].
The significantly higher (
p<0.05) ADL content was obtained from Kulumsa /DZF #592 (6.40%), which was at par with Kindu kosha-1 /DZF #591 (6.23%), while significantly lower ADL was recorded from Areka /DZF #590 (5.69%) (
Table 4). The ADL values in this study were lower than the reported values, which ranged from 6.47% to 12.03% and 8.8% to 26.7% in Guji midland and highland areas for similar
Desho grass varieties, respectively [
35]. However, it was slightly higher than the values reported by Kebede et al. (2022) [
32], which ranged from 4.3% to 4.5% for similar
Desho grass varieties. This variation might be due to harvesting age, season, soil fertility, climate, and management conditions. Van Soest (1982) [
47] found that lignin content above 6% has a negative impact on the digestibility of forage. Based on this, only the Areka /DZF #590 variety had lignin content below this threshold, resulting in less impact on the digestibility of ruminants.
In the current result, the hemicellulose content among varieties of
Desho grass was not significantly different (
p>0.05) (
Table 4). The current hemicellulose of
Desho grass varieties ranged from 23.91% to 24.53% with an overall mean of 24.22%. The hemicellulose content of most tropical grasses is 35.4% as reported by Moore and Hatfield, (1994) [
48], and therefore, the hemicellulose content of
Desho grass in the present result was lower than that of most tropical grasses. On the other hand, cellulose content differed significantly (
p<0.05) among
Desho grass varieties. The significantly higher cellulose was obtained from Kindu kosha-1 /DZF #591 (35.84%), while significantly lower cellulose was recorded from Areka /DZF #590 (33.69%). Van Soest (1994) [
49] also found that the cellulose content of most forage plants accounts for 20 to 40% of DM, confirming the present result.
3.4. In Vitro Digestibility and Metabolizable Energy Content of Desho Grass Varieties
A significant difference (
p<0.05) was observed in in vitro dry matter digestibility (IVDMD), in vitro organic matter digestibility (IVOMD), and metabolizable energy (ME) content among
Desho grass varieties at standardization cut (105 days) (
Table 5).
The highest dry matter digestibility was obtained from Areka /DZF #590 (62.47%), followed by Kulumsa /DZF #592 (58.43%), while the minimum was obtained from Kindu kosha-1 /DZF #591 (58.09%) with an overall mean of 59.66% (
Table 5). The present result disagrees with the result of Kebede et al. (2022) [
32], who reported that IVDMD among
Desho grass varieties showed no significant difference. The present result was lower than the previous report for IVDMD of Kindu kosha-1 /DZF #591 (62.4%) and Kulumsa /DZF #592 (61.5%), but higher than for Areka /DZF #590 (58.0%) [
32]. The digestibility of fodder or forages was strongly affected by seasonal variations [
50]. The present result lies within the 40-70% IVDMD range for grasses found in tropical and subtropical areas [
51]. The current %IVDMD values are above 45%, which is the required level for maintenance cattle in the tropics [
52]. However, the present result is lower than the threshold reported by Rivera and Parish (2010) [
53], who noted that IVDMD greater than 65% indicates good feeding value, and values below this threshold level result in reduced intake. Therefore, the current result implicates lower voluntary intake.
Regarding IVOMD significant difference (
p<0.05) was observed among varieties of
Desho grass (
Table 5). The highest was obtained from Areka /DZF #590 (60.84%), followed by Kindu kosha-1 /DZF #591 (57.61%), whereas the minimum was obtained from Kulumsa /DZF #592 (55.91%) with the overall mean of 58.12%. This difference could be due to the performance of a variety under the same managemental condition. The present result was comparable with the result of Wamatu (2021) [
28] who stated that the IVOMD of sole
Desho grass was 58.10%. The current result was lower than the values reported by Chapman (1986) [
54] who noted that the IVOMD of tropical grasses ranged from 61.2 to 69.6%. This difference could be due to forage species. The present %IVOMD values were observed above the critical threshold level of 50% required for feeds to be considered as having acceptable digestibility [
55].
Regarding metabolizable energy (ME), a significant difference (
p<0.05) was observed between
Desho grass varieties (
Table 5). The maximum ME was recorded from Areka /DZF #590 (9.13 MJ/kg
-1) followed by Kindu kosha-1 /DZF #591 (8.64 MJ/kg
-1), while the minimum was recorded from Kulumsa /DZF #592 (8.39 MJ/kg
-1) with an overall mean 8.72 MJ/kg
-1. The current result was relatively comparable with the report of Mengistu (2018), [
56], who noted that the ME content of
Desho grass was 8.22 MJ/kg
-1, and with the result of Wamatu (2021) [
28] who stated that the ME content of sole
Desho grass was 8.12 MJ/kg
-1. The current finding reveals that Kindu kosha-1 /DZF #591 and Kulumsa /DZF #592 are classified as low energy feeds (<9 MJ/kg), whereas Areka /DZF #590 is considered as medium energy (>9 MJ/kg) feed based on the classification reported by Lonsdale (1989) [
57] for the ME content of feedstuffs. The current ME values obtained were lower than the acceptable range for cattle, sheep, and some classes of dairy cattle (9.97 - 10.52 MJ/kg DM) [
58].