In order to measure the nutrient content of four grasses studied a proximate analysis (AOAC, 1995) was conducted and the results of the proximate analysis can be seen in Table 1.
Table 1
Nutrient content of feedstuffs studied
Nutrient | Elephant grass | Mini elephant grass | Panicum maximum grass | Brachiaria decumbens grass | Rice bran |
Dry matter (%) | 28.02 | 26.29 | 23.63 | 33.04 | 90.30 |
Organic matter (%) | 82.23 | 82.82 | 88.41 | 90.81 | 85.32 |
Crude protein (%) | 14.79 | 12.13 | 11.19 | 15.31 | 7.71 |
Crude fiber (%) | 31.84 | 27.44 | 33.42 | 31.02 | 32.19 |
Crude fat (%) | 3.95 | 6.00 | 5.75 | 4.65 | 3.03 |
Ash (%) | 16.77 | 17.18 | 11.59 | 9.19 | 15.68 |
NFE (%) | 32.65 | 37.25 | 33.50 | 39.83 | 31.68 |
NDF (%) | 66.22 | 62.71 | 68.14 | 68.24 | 49.65 |
ADF (%) | 41.23 | 36.90 | 42.24 | 39.70 | 38.80 |
Cellulose (%) | 36.17 | 32.80 | 35.36 | 35.36 | 22.13 |
Hemicellulose (%) | 24.99 | 25.81 | 25.90 | 28.54 | 10.85 |
Lignin (%) | 2.08 | 2.05 | 3.30 | 2.66 | 8.85 |
Source: Laboratorium of Chemical Feed and Nutrition, Hasanuddin University. NFE = Nitrogen-free extract. |
Table 1 indicated that those of all grasses studied contain a good and similar amount of nutrient content which could be used as a good protein and energy sources for ruminant. There is similarity in the nutrient content between one and another grass studied except rice bran. Rice bran used in this experiment tended to contain lower crude protein, but higher dry matter and ash content. A good quality of feed and contain high amounts protein and energy sources is important to support optimum growth of rumen microbes as well as the maximum degradability of the feed in the rumen (Siregar, 2007; Soeparno, 1994). The result of feed voluntary intake measurement can be seen in Table 2.
Table 2
Average of feed voluntary intake of goat fed GP diet
Goat | DM intake as fed basis (g/d) | DM intake (g/d) | OM intake as fed basis (g/d) | CP intake as fed basis (g/d) |
Goat-1 | 1242 | 500.12 | 1069.80 | 151.92 |
Goat-2 | 1157 | 465.75 | 996.29 | 141.48 |
Goat-3 | 1050 | 422.83 | 904.48 | 128.45 |
Goat-4 | 1125 | 452.99 | 968.99 | 137.61 |
Average | 1144 | 460.42 | 984.89 | 139.87 |
Note: DM = dry matter, OM = organic matter, and CP = crude protein. |
Table 2 showed that the average feed voluntary intake of goat fed GP (general purpose) diet was 460.4 g/head/d, that means that all goat consumed total feed of about 3% from their body weight. Dry matter intake of about 3% from their body weight is just about a standard dry matter requirement of ruminant (Tilman et al., 1999). Total dry matter intake by ruminant might be affected by several factors such as body weight, feed quality, palatability, and the energy content of the feed consumed (Parakassi, 1999; Cruch and Fontenot, 1979; Kamal, 1999). Whereas the crude protein requirement of goat of about 14kg live weight is 12–14% of total diet consumed (Kearl, 1982). The results measurement of four grasses studied at 4, 8, 12, 24, 48, and 72 hours after incubation in the rumen of goat is shown in Table 3.
Table 3
Dry matter loss (%) of four grasses in the rumen of goat
Incubation time (h) | Elephant grass | Mini elephant grass | Panicum maximum grass | Brachiaria decumbens grass |
4 | 6.51a | 7.99 a | 5.94 a | 7.71 a |
8 | 14.85ab | 15.76bc | 13.83a | 16.51c |
12 | 22.58ab | 23.58b | 22.07ab | 20.87a |
24 | 33.98b | 34.04b | 32.59ab | 31.24a |
48 | 52.84c | 53.18c | 49.60b | 42.68a |
72 | 55.73b | 55.61b | 53.25b | 46.10b |
Source: The result of experiment in sacco. |
Table 3 indicated that the DM loss of all grass studied increased as time of incubation time increased. The DM loss at 8, 12, 24, and 46 hours after incubation are significantly difference (p < 0.05) between four grasses. But there is no significantly difference (p > 0.05) in the DM loss between four grasses at 4 and 72 hours after incubation. There is significantly difference (p < 0.5) in the DM loss at 8, 12, 24, and 48 hours after incubation. Brachiaria decumbens (BD) grass tended to have DM loss lower than that of 3 other grasses. Although BD grass tended to contains higher nutrient it seems that those of nutrient content have been degraded and fermented slowly than that of 3 other grasses. This is confirmed by the results of degradation curve of the BD grass in the rumen of goat (see Fig. 1). Ørskov (1992) stated that the optimal degradation and fermentation of roughages in the rumen is about 48 to 72 hours. The higher the DM degradation of the roughages in the rumen indicated the higher quality of the roughages consumed by ruminant (Yusmadi, 2008).
The results measurement of characteristics degradation of the grasses in the rumen can be seen in Table 4.
Kurva degradasi BK = DM degradation curve, BK loss = DM loss, Masa inkubasi = Time of incubation (hours). Elephant grass (R1), Mini elephant grass (R2), Panicum maximum grass (R3) and Brachiaria decumbens grass (R4).
Table 4
DM Characteristic degradation of four grasses in the rumen of goat
Grasses | Characteristics degradation |
a | b | a + b | c | Lag Time |
Elephant grass | 9.88c | 50.41c | 60.29c | 0.039 | 5.5c |
Mini elephant grass | 16.50d | 44.99b | 61.49c | 0.038 | 8.3d |
Panicum maximum grass | 7.42b | 49.64c | 57.06b | 0.040 | 4.5b |
Brachiaria decumbens grass | 6.79a | 40.63a | 47.42a | 0.045 | 3.0a |
Note: Difference superscripts in the same columns indicated significantly difference (P < 0.05). |
Table 4 showed that there was significantly difference (p < 0.05) in the value of soluble materials (a) between the grasses. Mini elephant grass contains higher soluble materials compared to that of 3 other grasses. Whereas Barchiaria decumbens grass contains lowest soluble materials (6,7%). One of the factors affected the soluble value (a) might be the cells content of the grasses, the higher the cells content the higher the soluble materials of the grasses (Van Soest, 1982). The value of b (potential but slowly degradable materials) of the grasses were significantly difference (p < 0.05) between the grasses. Barchiaria decumbens grass contains lowest b value, while Elephant grass contains highest b value. This might be due to the difference content of ADF and NDF in the four grasses (Wati et al., 2012). Elephant grass contains ADF and NDF 66.2% and 41.2% respectively. Whereas Mini elephant grass contains ADF and NDF 62.7% and 36.9%, Panicum maximum grass contains 68.1% and 42.2%, and BD grass contains 68.2% and 39.7%, respectively. NDF contains hemicellulose which be easily degraded in the rumen but ADF contains cellulose, lignin, silica which hardly degraded by rumen microbes (Hakim, 1992). The strong cellulose lignin bond could likely inhibit the microbial degradation in the rumen of goat (Zakariah et al., 2016).
There is no significantly difference (p < 0.05) in the rate of feed degradation in the rumen of goat. The rate and extension of feed degradability were similar between those of four grasses where BD grass 4.5% per hour, followed by Panicum maximum grass 4% per hour, Elephant grass 3.9% per hour, and Mini elephant grass 3.8% per hour. This in line with previous study in sacco reported by Sjamsuddin Rasjid and Ismartoyo (2014). There are significantly differences (p < 0.05) in the lag-t between four grasses as shown in Table 4. Rumen microbes takes longer time (8.3 hours) to adapt to the presence of and to start degrade Mini elephant grass compared to that of by Panicum maximum grass 4.5 hours, Elephant grass 5.5 hours, and BD grass 3.0 hours. This might be due to the differences in the ADF content and its structure especially in the structure of cellulose-lignin bond between four grasses.
The degradability of crude protein in the rumen is very important factor in feed evaluation system in ruminant. As matter of fact often quality of feed depends on the crude protein content and its degradability in the rumen (Puastuti et al, 2012). The results of this experiment (Table 5) indicated that there were significantly differences (p < 0.05) in the rate and extent of crude protein content between four grasses after incubation of 24, 48, and 72 hours. But at incubation of 4, 8, and 12 hours the degradability of crude protein in the rumen of goat was similar (p > 0.05) between four grasses.
Table 5
CP degradation of four grasses in the rumen of goat
Incubation time (hour) | Elephant grass (%) | Mini elephant grass (%) | Panicum maximum grass (%) | Brachiaria decumbens grass (%) |
4 | 19.59 | 14.34 | 14.68 | 14.68 |
8 | 27.89 | 25.17 | 29.49 | 27.96 |
12 | 37.33 | 32.08 | 36.55 | 36.58 |
24 | 56.27a | 43.38b | 48.94b | 49.14b |
48 | 69.52a | 61.49b | 69.19a | 61.09b |
72 | 71.97a | 62.71b | 72.08a | 62.47b |
Note: Difference superscripts in the same rows indicated significantly difference (P < 0.05). |
The CP rumen degradability at 48 hours and 72 hours incubation of Elephant grass and Panicum maximum grass higher than that of Mini elephant grass and BD grass. Incubation time of 48 to 72 hours is ideal time for rumen microbes feed degradation in the rumen (Gallo et al., 2019). While after 24 hours incubation the degradability of Elephant grass higher than that of 3 others grasses. This result suggested that Elephant grass tended to have better CP rumen degradability compared to Mini elephant grass, Panicum maximum grass, and BD grass (see CP degradation curve in Fig. 2).
Kurva degradasi PK = CP degradation curve, PK loss = CP loss, Masa inkubasi = Time of incubation (hours). Elephant grass (R1), Mini elephant grass (R2), Panicum maximum grass (R3) and Brachiaria decumbens grass (R4).
Higher CP rumen degradability will increase the availability of rumen ammonia in the rumen which is important for optimum growth of rumen microbes (Franzolin dan Aves, 2010). Rumen ammonia is a good indicator for examine the CP degradability in the rumen (Riswandi et al., 2015) the higher the rumen CP degradability the higher the rumen ammonia will be (Mushandri, 2022).
The CP characteristics feed degradation (a, b, c, a + b, and lag-t) in the rumen can be seen in Table 6.
Table 6
CP degradation of four grasses in the rumen of goat
Grasses | Characteristics CP degradation |
a | b | a + b | c | Lag Time (t) |
Elephant grass | 9.88b | 64.37ab | 74.25a | 0.0550 | 1.2b |
Mini elephant grass | 16.50a | 45.24c | 61.74b | 0.0460 | 4.2a |
Panicum maximum grass | 7.42c | 68.24a | 75.66a | 0.0471 | 1.3b |
Brachiaria decumbens grass | 6.79d | 56.19b | 62.98b | 0.0698 | 1.2b |
Note: Difference superscripts in the same columns indicated significantly difference (P < 0.05). |
Table 6 showed that the CP characteristics degradation in the rumen of goat except the rate of CP degradation (c) were significantly differences (p < 0.05) between four grasses studied. The quickly CP degradable materials (a) of the grasses which associated with water soluble materials (Baiti, 2012) were Mini elephant grass highest one and BD grass the lowest one. This suggested that Mini elephant grass contains more easily degradable CP materials than other grasses. In contrast BD grass contains the lesser readily CP degradable materials compared to that of 3 others grasses.
The slowly but potential materials of the CP grasses (b) were significantly differences (p < 0.05) between four grasses studied. Panicum maximum grass contains highest b value (68.2%) than that of Elephant grass (64.4%), Mini elephant grass (61.7%), and BD grass (62.9%). The differences in the b value between four grasses might be due to the differences in the crude protein content which strongly bound with components including lignin which resistant to rumen microbial degradation in the rumen (La Goffe, 1991; Widyobroto et al., 1995).
There are no significantly differences (p > 0.05) in the rate and extent (c) of CP degradability of four grasses in the rumen of goat (Table 6). This suggested that CP content in those of four grasses were degraded in similar rate in the rumen of goat. This might be also due to the similarity in the nutrient content and the structure as well as cell’s component of quickly degradable materials (Van Soest, 1994) of four grasses used in this experiment.
Total potential CP degradability (a + b) in the rumen of goat was significantly differences (p < 0.05) between four grasses. The total potential CP degradability of Panicum maximum grass (75.6%) was highest one, followed by Elephant grass (74.2%), BD grass (62.9%), and Mini elephant grass 61.7%. Whereas lag-t of CP degradability of Elephant grass was the highest one (4.2 hours) compared to that of other grasses (Table 6). This suggested that the rumen microbes take longer time to start degrade CP content of Elephant grass than that of other grasses.
The results of this experiment also indicated that there is a good correlation (r = 0.77, p < 0.05) between DM degradability and DM feed intake. The DM intake is well known affected by the DM degradability in the rumen. The higher the DM degradability in the rumen the quicker the degraded materials left from the rumen hence the DM intake increased (Tomaszewska et al., 1993; Usman, 2015). The CP degradability in the rumen was also have a good correlation (r = 0.76, p < 0.05) with CP intake by goat. The degradation and fermentation will enable rumen microbes to utilize non-protein nitrogen (NPN) as protein source of microbial protein which contains various amino acids needed by ruminant for production purposed (Hungate, 1996).