| Livestock Research for Rural Development 10 (3) 1998 | Citation of this paper |
A study was carried out at Cantho University from March to June 1997 to determine effects of foliage of Sesbania grandiflora , Leucaena leucocephala , Hibiscus rosa -sinensis and Ceiba pentadra on intake, digestion and rumen environment of growing goats. The design used four goats (10-12 kg live weight) in a Latin square arrangement of four treatments (the tree foliages) with 21 day periods. Feed intake, total faecal and urine output were recorded during the last fifteen days of the study period. On the last day of each period, rumen fluid was obtained with a stomach tube before and 4 hours after offereing feed in the morning. Intake of fresh foliage was similar (P=0.24) on all treatments but dry matter and crude protein intakes differed significantly (P=0.001) with highest values for Sesbania, followed by Leucaena, Ceiba and Hibiscus. Apparent dry matter digestibility coefficients were 74.8, 75.9, 68.0 and 76.0 % for Sesbania, Leucaena, Hibiscus and Ceiba, respectively, and did not differ between foliages. There were significant differences (P=0.038) in apparent digestibility of crude protein with lower values for Hibiscus and Ceiba (50.5 and 49.3 %) compared with Sesbania and Leucaena (63.7 and 66.5 %). Feed dry matter intake was highly correlated (R² = 0.86) with intake of crude protein. Changes in liveweight were 143, 80, 51 and 74 g/day (P=0.067) for Sesbania, Leucaena, Hibiscus and Ceiba, respectively. Rumen ammonia levels and protozoal counts after feeding were higher for Sesbania and Leucaena than for the other two foliages.
It is concluded that the foliage of Sesbania grandiflora and Leucaena leucocephala has a higher feeding value for goats than that from Ceiba pentadra and Hibiscus rosa -sinensis, but that all four foliages will provide more than maintenance needs for growing goats.
Native goats are found in many regions of Vietnam where they are managed primarily for meat production under conditions of free or supervised grazing. An improved dual purpose breed (the Bach Thao) was developed in Tien Giang province and is being used in mountainous and hilly areas as the basis of a programme of milk and cheese production (FAO/TCP/VIE/6613 Project) http://www.hcm.fpt.vn/inet/~ecofarm. The aim is to enhance incomes of small scale farmers emphasizing the use of local resources in a full or partial confinement system of management. The use of multi-purpose trees in such systems is especially appropriate as trees are good for the environment and the foliage of trees and shrubs is the natural feed of the goat (Devendra and Burns 1983). Leucaena leucocephala is the tree which has received most attention because of its multi-purpose role (Shelton et al 1994). However, apart from its susceptibility to insect attack (Geiger et al 1994), it does not yield well on acid soils (Blamey and Hutton 1994) which predominate in most regions of Vietnam. Also it is more suited to grazing than "cut and carry" systems as the harvest rate (quantity of foliage harvested manually per unit time) is low (Nguyen Thi Hong Nhan 1998; Preston T R personal communication).
The present study is part of a programme to assess the nutritive value for goats of a range of other trees and shrubs which are better adapted to local ecosystems. In the Mekong delta, the location of the present study, Sesbania grandiflora, Hibiscus rosa -sinensis and Ceiba pentadra are legume trees which are indigenous to Vietnam and are well adapted to local conditions. The objective of the present experiment was therefore to assess the feeding value of the leaves from the above trees, using Leucaena leucocephala as a control in view of its known high nutritive value.
The trial was carried out at the Cantho University Research Farm in the Mekong Delta between March and June, 1997 .
Four growing goats with an average body weight of 12 ± 2 kg and aged 4-5 months were used. These animals were accustomed to feeding on Sebania grandiflora since weaning . The animals were vaccinated against foot and mouth disease and dewormed before the initiation of the experiment. The goats were kept individually in metabolism cages, constructed of wood and bamboo. They had free access to a feed trough and to fresh water.
Treatments and design
The treatments were the fresh foliages of Sebania grandiflora (SG), Leucaena leucocephala (LL), Hibiscus rosa-sinensis (HB) and Ceiba pentadra (CP). The branches from these trees were cut every morning. The fraction offered to the goats included the fine stems and leaves and was given ad libitum. The trial was designed according to a Latin square with four treatments and four experimental periods. Each experimental period lasted 21 days. The adjustment period was six days allowing goats to adapt to the experimental diets followed by 15 days for collection of data. The allocation of the goats to the treatments is shown in Table 1.
Table 1: Allocation of the goats to the experimental diets |
||||||
Periods |
Goat 1 |
Goat 2 | Goat 3 | Goat 4 | ||
1 |
SG |
LL |
HB |
CP |
||
2 |
LL |
SG |
CP |
HB |
||
3 |
HB |
CP |
SG |
LL |
||
4 |
CP |
HB |
LL |
SG |
||
Measurements
The animals were weighed before feeding in the morning at the start and at the end of each collection period of 15 days. The feeds offered and refused were recorded for each animal daily. Samples of 100 g were taken of the feeds offered and the residues for chemical analysis. Dry matter (DM) , nitrogen (N) and ash were assayed on the offered and refused feed using the method of AOAC (1990). Faeces were collected twice daily at 08.00 and 16.00 hr from each goat. About 10% of faecal fresh weight from each goat was taken daily and accumulated in a deep freezer at - 20 ºC until the end of the experiment. The samples were then thawed, mixed and sub-samples taken to analyze for dry matter, nitrogen and ash following AOAC (1990) procedures. At the end of the experiment sub-samples were analyzed for nitrogen.
Rumen liquor (about 50 ml) was taken from each goat by oesophageal tube on the last day of each period at 0 and 4 hours after offering feed.The pH of these samples was measured immediately using a digital pH meter (pH-831, Japan). Ammonia-N concentration of rumen fluid was determined according to the micro-kjeldahl procedure (AOAC 1990). Protozoa in the fresh rumen liquid were counted directly under the microscope.
The data on feed intake, digestibility, rumen parameters and weight change were subjected to analysis of variance using the least squares General Linear Model (GLM) procedure of the Minitab Statistical Software Release 10.2 (1994). When differences in treatment means were significant at the probability level of P<0.05 the means were compared using the Tukey test (Minitab Statistical Software Release 10.2, 1994).
Data on chemical composition of the foliages are in Table 2.
| Table 2. Chemical composition of the foliages (% of DM basis except for dry matter content) | |||||
Dry matter |
N*6.25 |
Crude fibre |
Ether extract |
Ash |
|
| Sesbania grandiflora | 27.9±1.1 |
21.4±1.6 |
13.6 |
7.4 |
8.52 |
| Leucaena leucocephala | 26.2±2.8 |
20.5±2.3 |
17.1 |
7.1 |
6.73 |
| Hibiscus rosa -sinensis | 20.0±1.3 |
13.8±0.81 |
14.6 |
7.32 |
11.6 |
| Ceiba pentadra | 21.2±2.9 |
14.3±1.1 |
11.6 |
3.74 |
8.48 |
There was a wide range in dry matter content with highest values for Sesbania and Leucaena and lowest ones for Hibiscus and Ceiba. Protein content also had a wide variation with over 20% in dry matter for Leucaena and Sesbania and less than 15% for Hibiscus and Ceiba
Feed intake
The mean values for intake of dietary constituents are shown in Table 3. Intake of fresh foliage did not differ between treatments but intake of dry matter varied widely (P=0.001). Dry matter intake was highest on Sesbania followed by Leucaena with lowest value for Hibiscus. As the protein contents of Sesbania and Leucaena were much higher than those of Hibiscus and Ceiba the intake of protein was even more varied, with the former foliages supporting almost twice the protein intake of the latter.
| Table 3: Mean values for intake of fresh foliage, dry matter and crude protein | ||||||
Sesbania grandiflora |
Leucaena leucocephala |
Hibiscus |
Ceiba pentadra |
SE |
Prob. |
|
| Fresh foliage, kg/d | 2.72 |
2.55 |
2.45 |
2.75 |
0.12 |
0.235 |
| DM, g/d | 726a |
635b |
438d |
557c |
15 |
0.001 |
| N*6.25, g/d | 169a |
137b |
69.6c |
88.0c |
9.8 |
0.001 |
| abcd Means within rows with different superscripts differ significantly at the probability level shown | ||||||
 |
| Figure 1: Relationship between intake of dry matter and
intake of crude protein |
Protein intake appeared to be a major determinant of dry matter intake as there was a close relationship between the two variables (Figure 1; R² = 0.86). The importance of protein intake as the determinant of performance in ruminants has been strongly emphasized by Preston and Leng (1987).
The coefficients of apparent digestibility of dry matter, organic matter and crude protein, and the changes in liveweight are shown in Table 4. There were no significant differences between foliages for apparent digestibility of dry matter and organic matter. The values for apparent digestibility of dry matter and organic matter were high for all the foliages. The dry matter digestibility values obtained for Sesbania grandiflora and Leucaena were considerably higher than those reported by Norton (1994a) for Leucaena in goats (68%) and Sesbania grandiflora in sheep (63%). The dry matter digestibility coefficients for Hibiscus (62%) and Ceiba (69%) are similar to the value (66%) reported by Keir et al (1997) for young growing goats fed the leaves of the Jackfruit tree (Artocarpus heterophyllus). Apparent digestibility of crude protein was higher (P=0.038) for Sesbania (63.7%) and Leucaena (66.5%) compared with Hibiscus (50.5%) and Ceiba (49.3%). Liveweight gain appeared to be higher for Sesbania compared with the others but the difference was not significant (P=0.067).
| Table 4. Coefficients of apparent digestibility (%) of the foliages fed to the goats, retention of nitrogen and changes in liveweight | ||||||
|
|
Sesbania grandiflora |
Leucaena leucocephala |
Hibiscus rosa-sinensis |
Ceiba pentadra |
SE of means |
Prob. |
| Dry matter | 73.6 |
75.9 |
68.0 |
76.0 |
1.75 |
0.055 |
| Organic matter | 78.0 |
79.7 |
73.5 |
80.4 |
1.67 |
0.093 |
| Crude protein | 63.7a |
66.5a |
50.5b |
49.3b |
3.81 |
0.038 |
| Liveweight change, g/day | 143 | 80 | 51 | 74 | 19 | 0.067 |
| abc Means within rows with different superscripts differ significantly at the probability level shown | ||||||
Mean values for pH, ammonia and protozoal numbers in rumen fluid before and after feeding are shown in Table 5. pH values were in the normal range for roughage diets (Ærskov and Ryle1990) and showed no consistent effects due to source of foliage. Rumen ammonia levels after feeding for Sesbania and Leucaena (about 400 mg/litre) were higher than what is considered to be the necessary minimum (200 mg/litre) for digestion of roughages and maximizing intake (Preston and Leng 1987). Values for foliages of Hibiscus and Ceiba, although at a high level, were lower (300 and 200 mg/litre, respectively). Protozoal populations were high on all diets with significantly greater values for Sesbania and Leucaena.
| Table 5: Mean values for rumen parameters (pH, ammonia and protozoal population) for goats fed different foliages (samples taken by stomach tube before and 4 hours after feeding) | ||||||
Sesbania grandiflora |
Leucaena leucocephala |
Hibiscus-rosa |
Ceiba pentadra |
SE of means |
Prob. |
|
| pH | ||||||
0h |
7.42b |
7.32c |
7.31c |
7.58a |
0.04 |
0.01 |
4h |
6.46 |
6.48 |
6.58 |
6.67 |
0.08 |
0.11 |
| Ammonia-N, mg/litre | ||||||
0h |
304 |
285 |
288 |
254 |
17.4 |
0.3 |
4h |
399a |
412a |
297b |
208b |
49.8 |
0.05 |
| Protozoa (106/ml) | ||||||
0h |
4.38a |
4.06a |
3.25b |
4.0a |
0.21 |
0.05 |
4h |
4.56a |
4.44a |
3.38b |
3.88b |
0.18 |
0.01 |
| abc: Means within rows with different superscripts differ significantly at the probability level shown | ||||||
The high levels of rumen ammonia recorded for all the four legume species can be interpreted as supporting the viewpoint of Leng (1997) that the value of tree foliages is mainly to provide nutrients for the rumen microbial fermentation. All four species are likely to be adequate in this respect. Lower values of rumen ammonia, lower dry matter intakes, and lower digestibility of the protein fraction, on the Hibiscus and Ceiba foliages, may indicate the presence of greater quantities of condensed tannins or other secondary plant compounds that partially shield the protein from microbial attack (Leng 1997). However, there is still much confusion about the advantages and disadvantages of the presence of condensed tannins in tree foliages (Norton 1994b; Leng 1997). In the present study the best results in terms of dry matter intake, digestibility, and liveweight gain, were with Sesbania grandiflora. Nguyen Thi Thuy (1996) also reported high dry matter intakes and liveweight gains for 4-5 month old goats fed fresh foliage of Sesbania grandiflora as the sole diet. Yet the leaves of this species are reported to contain condensed tannins and to be toxic when included at low levels in diets for fish (Tilapia) or chickens (Norton 1994b). There appears to be no information on the levels of secondary plant compounds in Hibiscus rosa-sinensis and Ceiba pentadra.
The results from this study indicate that:
Inevitably, this study called for participation of many individuals without whose help- financial, technical, logistical and moral - I would not have completed it .
I would like to express my deepest gratitude to University of Tropical Agriculture and the Danish Embassy, Hanoi for financially supporting my research. A preliminary version of this paper was submitted to the University of Tropical Agriculture in November 1998 in partial requirements for the MSc degree (http://www.hcm.fpt.vn/inet/~utaf.
I am very much obliged to Dr Thomas R Preston and Frands Dolberg who provided useful guidance, encouragement , patience and kindness and made it possible for me to complete the task. I also wish to thank Cantho University for allowing me to pursue this study .
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Received 10 December 1998