Livestock Research for Rural Development 22 (2) 2010 Guide for preparation of papers LRRD News

Citation of this paper

Chemical and mineral composition, in-vitro gas production, in-sacco degradation of selected indigenous Kenyan browses

J O Ondiek, S A Abdulrazak* and E N Njoka**

Egerton University, Department of Animal Sciences, P.O. Box 536-20115, Egerton, Kenya
* Secretary/CEO, National Council for Science and Technology, P.O. Box 30623-00100, Nairobi, Kenya
** Principal, Chuka College Campus, P.O. Box 109 Chuka. Kenya
sabdulrazak@yahoo.com

Abstract

Proximate and mineral composition, in-sacco degradation and in-vitro gas production was conducted using fifteen indigenous Kenyan multipurpose tree and shrub (MPTS) leaf browse to assess their potential as goat feed. The species selected from a field survey were Maerua angolensis, Acacia brevispica, Acacia mellifera, Acacia tortilis, Acacia hockii, Zizyphus mucronata, Grewia bicolor, Acacia elatior, Acacia nilotica, Balanites aegyptiaca, Acacia senegal, Acacia abyssinica, Bridelia micrantha, Albizia amara and Albizia coriaria.

 

The CP levels ranged from 112gkg-1DM for Bridelia micrantha to 321 gkg-1DM for Maerua angolensis; the NDF ranged from 218 to 601 gkg-1DM for Acacia hockii and Albizia amara, respectively. The TEPH and TET were in the range of 1.52-26.4 and 0.301-24.4gkg-1DM, respectively. The major minerals Ca, P, Mg, Na and S were in the ranges of 6.51-28.1, 0.838-3.18, 0.442-8.51, 0.318-0.711 and 1.12-2.45gkg-1DM, respectively. The microelements varied widely (mgkg-1DM) as follows: Fe (51.3-267), Mn (13.8-38.5), Cu (4.81-74.9), Mo (13.9-43.4), Co (1.76-17.4), Zn (12.2-93.2) and Se (19.5-124). In-sacco DM degradation at 48hrs shows Zizyphus mucronata was highest followed by Maerua angolensis with degradability of 93.3% and 88.6%, respectively. Gas production (volume (ml)/200mgDM) levels (a+b) ranged from 19.2 to 52.2 in Bridelia micrantha and Maerua angolensis, respectively. The overall levels of nutrients and degradation showed variations but most of the forages were moderate to high in the nutrient composition and degradability parameters. The ranking of the forages in order of increasing nutritive value into three categories of five species was as follows: low (Bridelia micrantha< Albizia amara< Acacia hockii < Acacia nilotica< Acacia tortilis); medium (Acacia abyssinica< Grewia bicolor< Albizia coriaria< Acacia elatior) and high (Balanites aegyptiaca< Acacia mellifera< Acacia senegal< Zizyphus mucronata< Maerua angolensis).

 

It is concluded that Maerua angolensis and Zizyphus mucronata are outstanding and they have potential for ruminant feed and more so as protein supplements to low quality tropical basal diets.

Keywords: Acacia brevispica, Acacia mellifera, Acacia tortilis, Acacia hockii, Acacia elatior, Acacia nilotica, Acacia senegal, Acacia abyssinica, Albizia amara, Albizia coriaria, Grewia bicolor, Balanites aegyptiaca, Bridelia micrantha, Maerua angolensis, nutritive value, protein, Zizyphus mucronata


Introduction

Poor nutrition caused by inadequacies in both quantity and quality of the major grass forages that are low in digestible nutrients may not supply nutrients to meet animals’ requirements (Leng 1990). This is one of the major causes of low livestock productivity in tropical areas, Kenya included. Animals consuming basal diets containing less than 7% crude protein (CP) will require supplementation for improved performance (Abdulrazak et al 1997; Ondiek et al 1999, Ondiek et al 2000), hence there is need to exploit this legume forage resource. Some acacia species including Acacia brevispica, Acacia nubica, Acacia tortilis, Acacia seyal, Acacia nilotica and Acacia mellifera have been shown to contain appreciable crude protein (134-213gkg-1DM) and minerals (Abdulrazak et al 2000).

 

Useful forage MPTS are documented (Topps 1992, World Agroforestry Centre 2005) but these vary in nutritive values and, therefore, it is important to assess the local species using simple techniques like proximate analysis, nylon bag and in-vitro gas production methods. The in-vitro gas production technique as modified by Menke and Steingass (1988) is one of the useful tools for determining the potential nutritional value of feed resources consumed by ruminants, especially tree and shrub legume forages containing anti-nutritional factors such as polyphenols, tannins and polyphenolics (Woodward and Reed 1997), which may compromise the nutritive value of the fodders (Swain 1979) when consumed by ruminants. Tannins precipitate protein by forming tannin-protein complexes (Reed 1995), thereby reducing the digestibility of protein and feed dry matter (Hangerman et al 1992).

 

However, tannins may increase the availability of rumen undegradable nitrogen, digestible energy and minerals when fed to livestock (Ash 1990). More studies are reported for introduced forage species but the nutritional value of the abundant indigenous MPTS is scanty. The objective of this study was to assess the potential nutritional contribution of fifteen indigenous Kenyan tree browse species for local goats using proximate, in-sacco and in-vitro methods.

 

Materials and methods 

The fifteen browse species were selected after an initial field survey to evaluate the utilization of multipurpose tree and shrub forages as livestock feed in Western, Nyanza and Rift Valley provinces of Kenya. The leaf browses were harvested by hand clipping leaves from five branches on twenty mature trees in Kakamega, Baringo and East and West Pokot districts of Kenya in the dry season. The sampling sites were Malava, Chemeron Field Station of Egerton University, Kapenguria and Tangulbay, respectively. The forage species were as follows: Maerua angolensis, Acacia brevispica, Acacia mellifera, Acacia tortilis, Acacia hockii, Acacia elatior, Acacia nilotica, Acacia senegal, Acacia abyssinica, Balanites aegyptiaca, Grewia bicolor, Bridelia micrantha, Albizia amara, Albizia coriaria and Zizyphus mucronata. Only the leaves and leaf petioles were harvested and to mimick the parts browsed by goats.

 

Experimental procedures

 

The leaves were collected in gunny bags and dried in a shade for 6 days. The leaf browse was then milled through a 2.0mm screen for in-vivo digestibility, and a sub sample taken and milled further through 1.0mm screen for use in gas production trial, mineral assay and proximate analysis.

 

In-sacco degradation

 

Duplicate nylon bags (bag size, 80mmx140mm; pore size 45Ám) containing 5g of milled dry sample were weighed and then incubated in the rumen of two fistulated Friesian steers 23 months old and weighing 540kg. The bags were then withdrawn after 3, 6, 12, 24, 48, 72 and 96 hours. The zero hour was obtained by soaking the bags in a water bath maintained at 39oC for 1 hour. After the incubation period, the bags were withdrawn then hand washed under running tap water until the water coming out of the bags was clear. The washed bags and contents were then dried for 48 hours at 60oC in a draught oven to determine DM disappearance. The disappearance values were fitted in the equation of McDonald (1981):

Y=a+b (1-e-ct)

where a,b and c are degradation constants.

 

In-vitro gas production

 

The gas production technique of Menke and Steingass (1988) as described by Abdulrazak and Fujihara (1999) was used in the in-vitro gas production assessment. The net gas volumes data was then fitted in the equation of ěrskov and McDonald (1979):

G = a + b (1 - e-c t)

where:

G = the volume of gas produced (ml) at time t,
a = the gas production from the immediately soluble fraction (ml),
b = the gas production from the insoluble but degradable fraction (ml),
a + b = the potential gas production (ml),
c = the rate constant of gas production (fraction/h)

 

OMD48= organic matter digestibility at 48 hours.   

                                                                                                                                  

In-vitro organic matter digestibility calculated from the equation: OMD (%) = 18.53 + 0. 9239 gas production (at 48hrs) + 0.0540 CP (Menke and Steingass 1988).

 

Chemical analysis

 

The proximate composition including dry matter (DM), organic matter (OM), and total nitrogen (N) were determined following standard methods (AOAC 1990) and CP was calculated as N x 6.25. Neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) were determined by the method of Van Soest et al (1991). Phenolics were extracted using 70% aqueous acetone and total extractable phenolics (TEPH) determined using Folin Ciocalteu procedures described by Makkar (2000). The TEPH concentration was calculated using the regression equation of tannic acid standard. Total extractable tannins (TET) were estimated indirectly after being absorbed to insoluble polyvinyl pyrrolidine (PVP) and the concentration calculated by subtracting the TEPH remaining after PVP treatment from the TEPH. Macro -elements calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), sulphur (S) and micro-elements iron (Fe), copper (Cu), zinc (Zn), cobalt (Co), selenium (Se), molybdenum (Mo) and manganese (Mn) were analysed using atomic absorption spectrophotometer.

 

Results and discussion 

The results of the chemical analysis (Table 1.) of the test browses showed modest to high nutrient composition, indicating their potential for feeding ruminants.


Table 1.  Chemical composition (gkg-1DM) of 15 indigenous Kenyan leaf browse

Forage species

DM

OM

CP

NDF

ADF

ADL

TEPH

TET

Acacia tortilis

890

924

117

443

335

137

7.65

6.02

Maerua angolensis

876

941

321

449

332

969

11.4

0.301

Acacia nilotica

899

935

121

290

212

108

26.4

24.4

Acacia mellifera

879

837

183

392

306

118

4.93

3.59

Acacia brevispica

891

927

187

460

329

174

5.36

1.75

Acacia senegal

884

904

249

423

266

125

4.33

2.57

Zizyphus mucronata

859

929

200

393

222

88.2

7.23

4.08

Grewia bicolor

894

919

196

528

362

143

9.39

8.18

Acacia elatior

889

879

162

503

355

175

5.74

4.61

Balanites aegyptiaca

867

867

137

349

266

154

1.52

0.313

Acacia abyssinica

890

937

165

531

462

286

5.85

4.43

Bridelia micrantha

903

940

112

481

421

212

9.35

4.76

Albizia.amara

898

953

167

601

413

250

8.25

4.39

Albizia coriaria

874

935

169

482

373

156

1.89

0.324

Acacia hockii

888

952

121

218

160

53.1

26.7

24.3

SEM

3.18

8.56

14.3

25.3

21.6

56.4

2.03

2.01


The relatively high CP range (112 to 321 gkg-1DM) of Acacia abyssinica, Acacia mellifera, Acacia brevispica, Acacia senegal, Zizyphus mucronata, Grewia bicolor, Albizia coriaria, Albizia amara and Maerua angolensis  browses show the potential contribution as protein feed resources for ruminants, especially browsing goats. This has been demonstrated in other tree legume browse in various studies (Ebong 1995, Abdulrazak et al 1997, Ben Salem et al 1997, Ondiek et al 1999, Abdulrazak et al 2000, Ondiek et al 2000, Abdulrazak et al 2001, Adjorlolo et al 2001, Nantoume et al 2001). Most of the reported parameters agree with the results of Abdulrazak et al (2000) who worked with acacia species. They reported high total extractable condensed tannins (100-480mgkg-1DM) and total extractable phenolics (104-512mgkg-1DM) for Acacia tortilis, Acacia seyal and Acacia nilotica that are very commonly used in the arid and semi arid areas of Kenya as livestock browse. The current study found both Maerua angolensis and Balanites aegyptiaca to be low in total extractable tannins 3 and 3gkg-1DM and 114 and 152gkg-1 DM in total extractable phenolics, respectively. The highest TEPH and TET were found in Acacia nilotica and Acacia hockii being 264, 267 gkg-1DM and 244, 243 gkg-1DM, respectively. Elseed et al (2002) indicated also similar levels of nutrients for some species. The Southern African browses reported by Dube et al (2001), using different mineral assays showed that Acacia nilotica, Acacia tortilis, Acacia senegal and Acacia albida had phenolic contents of 298, 107, 47 and 113gkg-1DM, respectively. Elseed et al (2002) in a study of Sudanese browses reported variations between the early and late dry season with some nutrients (OM, NDF, ADF) being higher in the late dry season whereas CP, minerals, and digestibility of OM, N, In-vitro OMD and estimated energy showing higher values in the early dry season. They found Zizyphus spina-christi, Balanites aegyptiaca, Acacia tortilis and Acacia mellifera to be potentially valuable for dry season feeding and as protein and energy supplements. In the current study the materials were harvested after the rains and this could have had an effect on the nutritional composition and these compare favorably with those of Osuga et al (2006).

 

The macro and micro element composition of the forages is shown in table 2.


Table 2.  Major and trace elements in 15 indigenous Kenyan browses

Species

Major elements,  gkg-1 DM

Trace elements, mgkg-1DM

Ca

P

Mg

Na

S

Fe

Mn

Cu

Mo

Co

Zn

Se

Maerua angolensis

12.1

2.42

4.22

0.539

2.12

116

21.5

41.8

25.8

2.54

17.2

19.5

Acacia brevispica

7.03

0.838

2.42

0.358

1.53

130

33.5

64.9

40.2

4.45

22.2

38.9

Acacia mellifera

18.6

1.32

8.67

0.627

1.54

224

22.1

31.4

30.9

3.63

15.9

47.8

Acacia tortilis

28.1

1.45

3.89

0.581

1.72

229

29.9

38.7

13.9

3.65

12.2

124

Acacia hockii

22.4

1.37

0.442

0.567

2.02

122

21.9

15.4

21.7

5.22

15.5

62.4

Zizyphus mucronata

17.4

2.61

8.51

0.667

1.74

74.8

38.5

14.4

16.6

2.97

55.7

47.3

Grewia bicolor

12.2

3.18

0.643

0.679

1.33

51.3

19.9

22.1

29.5

1.76

42.3

38.3

Acacia elatior

13.3

2.52

1.67

0.711

1.12

88.9

27.9

28.3

19.3

2.01

93.2

63.7

Acacia nilotica

12.1

1.49

1.81

0.458

2.03

200

32.3

74.9

41.9

4.61

22.8

87.9

Balanites aegyptiaca

24.4

1.58

6.33

0.542

1.81

123

22.5

33.7

19.3

2.34

32.5

48.2

Acacia senegal

15.6

1.77

2.23

0.654

2.45

267

27.6

4.81

43.4

5.26

22.1

113

Acacia abyssinica

6.51

1.33

3.38

0.537

1.47

129

18.3

6.83

22.5

2.93

18.9

53.4

Bridelia micrantha

7.24

1.04

2.23

0.318

2.24

106

13.8

13.1

31.2

3.34

13.5

38.4

Albizia amara

8.02

1.53

3.67

0.491

2.34

123

15.2

19.1

27.2

17.4

20.3

65.1

Albizia coriaria

9.11

2.22

3.89

0.433

1.52

89.3

13.2

22.6

26.3

2.11

19.4

39.4

SEM

1.69

0.222

0.689

0.0221

0.111

16.2

1.91

5.23

2.31

1.01

5.53

7.52


Generally the ash levels in acacia leaves of between 5 and 10% show that mineral contents in the forages are either deficient or moderately adequate (Sawe et al 1998). Fujihara et al (1992), Fujihara et al (1995) and Serra et al (1995) reported their work on minerals in various forages in dry and wet seasons. Fujihara et al (1992) found that the forages had on average 24Ágkg-1DM of Se while the Cu and Zn levels ranged between 7.6-24.3 and 11.4-50.6mg/kgDM, respectively. While Se was lower than the requirements (200Ág/kgDM) for ruminants, the Cu and Zn were adequate for sheep rather than goats, indicating that goats need a higher level of these elements. The macro and micro-elements in diets selected by sheep reported by Serra et al (1995) indicated that the macro mineral levels (%) as follows: Ca (0.51), K (0.93), Mg (0.19), Na (0.44), and P (0.27) and micro minerals (mgkg-1DM): Cu (13.5), Fe (510.9), Mn (43.8), and Zn (29.5). These values vary with those found in the current study, especially with Ca, Mg, P, Fe, Mn and Cu which were generally lower. However, the value for Na was similar to that reported.

 

The mineral content of the tree browses varies from moderate to high (Abdulrazak et al 2000). Although the P and Ca showed variability, the acacia species reported were rich in the micro-elements Mn, Mo, Zn, Co, Cu, Fe and Se showing that animals may consume adequate amounts and may only require specific supplementation. The current study reports the highest mineral levels for the macro elements Ca, P and Mg at 28, 3.2 and 8.7 gkg-1DM and lowest levels at 7, 0.8 and 0.4 gkg-1DM, respectively. Generally, the major minerals except sodium, were within the range of values previously reported (McDowell 1985). The values are adequate to meet the requirement for growth. The micro-element content in the current study is consistent with other reports (Topps 1992, Norton 1994, Ramirez and Ledezma-Torres 1997, Sawe et al 1998, Khanal and Subba 2001). In most studies reported, Na was generally low (Sawe et al 1998, Abdulrazak et al 2000, Khanal and Subba 2001). These agree with the results of the current study. Kendall et al (2001) reported the performance of sintered soluble glass Cu, Co and Se bolus that sustained adequate levels of the three trace elements in blood of sheep. For all the treated sheep the Co, Cu and Se in blood serum and liver increased compared to the non treated sheep, indicating that the sintered soluble glass Cu, Co and Se boluses could supplement these minerals for sheep.

 

The in-vivo degradation characteristics of the forage DM varied widely among the 15 forage species. The DM degradation characteristics exhibited a wide variation in the A and B portions and the fractional degradation ‘c’ rates in the species (Table 3).


Table 3.  In-vivo degradation data of 15 Kenyan indigenous browse species

Sample

Hour

Degradation constants

RSD

LT

Degradation constant

k= 0.05

24

48

A

B

A+B

c

Acacia abyssinica

26.9

33.9

21.1

55.1

76.2

0.00498

2.72

0.0011

27.4

Acacia elatior

51.9

67.7

31.1

43.2

74.3

0.0376

2.73

3.25

46.4

Acacia mellifera

63.7

76.7

35.3

47.8

83.1

0.0385

2.24

0.00111

56.4

Acacia senegal

63.8

77.9

0.0395

83.8

83.8

0.0366

2.22

0.00297

58.9

Balanites aegyptiaca

71.7

76.9

37.5

40.4

77.9

0.0786

2.56

0.104

62.2

Grewia bicolor

32.7

49.9

8.01

84.4

92.5

0.0116

4.06

0.648

31.3

Acacia hockii

56.8

74.7

0.0199

97.7

97.7

0.0187

4.66

0.00394

49.8

Maerua angolensis

85.3

88.6

48.4

40.1

88.5

0.245

2.28

1.60

78.9

Acacia tortilis

48.2

75.6

21.3

72.8

94.1

0.0233

4.65

0.002

44.3

Zizyphus mucronata

81.8

90.7

24.8

68.7

93.5

0.0596

6.09

0.596

62.9

Albizia amara

25.1

29.9

21.6

14.9

36.5

0.0168

1.33

3.85

24.7

Bridelia micrantha

33.7

43.7

28.7

54.3

82.9

0.0101

1.77

11.4

33.3

Acacia brevispica

64.5

72.3

30.5

43.4

73.9

0.0631

1.04

2.79

56.7

Albizia coriaria

68.9

74.9

41.7

36.8

78.7

0.0749

3.61

2.35

60.5

Acacia nilotica

65.6

75.7

41.8

36.5

78.3

0.0542

1.73

3.01

57.9

SEM

4.91

4.83

3.82

5.79

3.66

0.0152

0.433

0.762

3.92

Y=a+b (1-e-ct); where a,b and c are degradation constants (McDonald 1981). The modified model includes the lag time and washing loss:

Y=A, the initial washing loss; B= the asymptote of the exponential b (1-e-ct); c= rate constant. Then (a+b)= potential degradability.


Acacia hockii had the highest proportion of the ‘B’ fraction (97.7% DM) followed by G.bicolor (84.4% DM) at degradation rates ‘c’ of 0.0187 and 0.0116, respectively; while Albizia amara was the least degradable with a low ‘A’ value (21.6%) and the lowest ‘B’ fraction (14.9% DM) with an equally slow fractional degradation rate ‘c’ of 0.0168. The DM degradation of most of the forages improved from 24 to 48 hours, showing that they require more time to effectively degrade. The degradation at 48hrs shows Zizyphus mucronata was highest followed by Maerua angolensis at 90.7% and 88.6%, respectively. With these degradation potentials, the two species exhibited a reversed fractional out flow rates at k=0.05, these being higher for Maerua angolensis (78.9%) compared to Zizyphus mucronata (62.9%). This is desirable for the forages as the higher the degradability of the potentially degradable dry matter content the better the nutrient supply to the host animal. The two of the highly degradable forages Maerua angolensis and Zizyphus mucronata the DM is rapidly degraded initially for the former than the latter. These variations have been reported for tropical browses (Salawu et al 1999, Melaku et al 2003). These variations arise due to the phonological stage of development at harvest, (Salawu et al 1999) and nutrient composition of the various parts of the forage used (Melaku et al 2003). Therefore, the forages at 48hr degradation, could be categorized into three classes of low potential (29.9-50.2%), Albizia amara, Acacia abyssinica, Bridelia micrantha and Grewia bicolor; medium potential (50.3-70.5%), where only Acacia elatior fitted; and those that were observed to have high potential (70.6-90.7%) as Acacia brevispica, Acacia hockii, Albizia coriaria, Acacia tortilis, Acacia nilotica, Balanites aegyptiaca, Acacia mellifera, Acacia senegal, Maerua angolensis and Zizyphus mucronata. This latter group of forages could greatly contribute to goat and ruminant feed in general, and since they are also high in crude protein, they are potential protein supplements.

 

The gas production method of estimating nutritive value of feeds has been used to assess the rumen fermentation of the browses. The total gas production (ml/200mgDM) at 48hrs shown in table 4 indicate variations in the forage degradability and digestibility potential, with Maerua angolensis (52.2) and Zizyphus mucronata (45.7) being the highest and second highest, while Albizia amara (17.1) was the lowest.


Table 4In-vitro gas production (ml/200 mg DM) of 15 indigenous Kenyan browses

Sample

Corrected gas production

 

 

 

 

48

a

b

c

a+b

RSD

B

A+B

LT

OMD48, %

Bridelia micrantha

19.2

1.48

25.3

0.0223

26.5

0.672

20.6

26.5

11.5

36.5

Acacia nilotica

40.4

0.332

46.4

0.0433

45.6

1.68

16.1

45.6

25.9

47.1

Albizia amara

17.1

2.03

18.1

0.0414

20.1

0.901

18.1

20.1

0.253

35.2

Acacia senegal

35.1

0.224

38.8

0.0566

47.4

9.42

39.2

1.43

24.9

48.9

Balanites aegyptiaca

35.4

6.89

44.7

0.0914

37.8

8.45

37.8

2.11

17.9

51.8

Acacia mellifera

41.3

2.27

43.3

0.0576

45.3

1.58

45.3

1.56

16.1

54.1

Acacia  hockii

41.2

2.19

49.9

0.0354

47.7

1.11

18.1

47.7

27.4

59.3

Maerua angolensis

52.2

3.56

41.3

0.0586

37.7

1.09

7.57

37.7

33.3

68.5

Acacia brevispica

38.8

0.566

39.1

0.0521

39.7

1.18

9.67

39.7

26.2

54.8

Acacia abyssinica

39.2

6.04

35.9

0.0411

41.9

1.65

21.2

41.9

12.8

62.4

Acacia tortilis

27.5

1.72

61.2

0.0406

59.5

1.16

61.2

59.5

16.8

48.2

Grewia bicolor

44.6

3.45

59.7

0.0417

56.2

1.89

59.7

56.2

22.8

66.4

Acacia elatior

44.3

2.24

47.2

0.0605

49.3

2.88

15.5

49.3

12.6

64.4

Zizyphus mucronata

45.7

2.78

58.6

0.0535

61.4

6.21

12.5

61.4

1.64

73.9

Albizia coriaria

32.2

4.06

39.6

0.0702

5.67

1.72

39.6

35.4

30.7

46.4

SEM

2.53

0.495

3.11

0.00433

3.766

0.667

4.45

5.27

2.57

2.91

A, B, and c are constants in the equation (ěrskov and McDonald 1979; OMD48: OMD (%) = 18.53 + 0. 9239 gas production (at 48hrs) + 0.0540 CP

(Menke and Steingass 1988).


These resulted to an estimated OMD at 48hrs of 73.9% and 68.5% and 35.2%, respectively. This shows that these browses are potentially degradable and can contribute to the nutrition of goats. However, they can be categorized as lowly degradable (35.2%-48.1%) for Bridelia micrantha, Acacia nilotica, Albizia amara, and Albizia coriaria; medium potential (48.2%-61.1%) for Acacia senegal, Balanites aegyptiaca, Acacia mellifera, Acacia brevispica, Acacia hockii and Acacia tortilis while the others were highly degradable (62.4%-73.9%) which included Acacia brevispica, Grewia bicolor, Acacia elatior, Zizyphus mucronata and Maerua angolensis.  The least gas production was obtained from Albizia amara, being 17.1ml/200mg. Presence of phenolic compounds could have contributed towards the low gas production shown by the forages under study, especially Albizia amara and Bridelia micrantha. These also had the lowest OMD values, being respectively 35.2% and 36.5%. As the presence of high levels of polyphenolic compounds in the forage could restrict preference and intakes of the leaf forages, it is possible that this attribute could contribute to the potentially low in-vivo DM degradation as well as gas production.

 

These assessments indicate that the forages are appreciably rich in protein, highly degraded and fermented in the rumen and contain low to moderate polyphenolic components and, therefore, could benefit ruminants in improving their protein nutrition especially when the availability of quality forages is low. Considering all parameters measured, the two outstanding forages are Maerua angolensis and Zizyphus mucronata which ranked first and second and this shows their potential for ruminant feed.

 

Conclusions


Acknowledgement
 

The authors are grateful to the African Academy of Sciences for funding, Tatton Demonstration Farm for facilities and technical support from N K Kibitok, E K Shakala and J Museti.

 

References 

Abdulrazak S A and Fujihara T 1999 Animal Nutrition: A Laboratory Manual. Kashiwagi Printing Co. (Matsue-shi Japan).

 

Abdulrazak S A, Fujihara T, Ondiek J O and ěrskov E R 2000 Nutritive evaluation of some Acacia tree leaves from Kenya. Animal Feed Science and Technology 85:89-98.

 

Abdulrazak S A, Muinga R W, Thorpe W and ěrskov E R 1997 The effect of incremental supplementation with Gliricidia sepium and Leucaena leucocephala on voluntary food intake, rumen fermentation, microbial N supply and live-weight changes of Bos taurus x Bos indicus steers offered Zea mays stover ad libitum. Livestock Production Science 49:53-62.

 

Abdulrazak S A, Nyangaga J N and Fujihara T 2001 Relative palatability, in-sacco degradation and in-vitro gas production of some multipurpose fodder trees. Asian-Australasian Journal of Animal Science 14 (11):1580-1586.

 

Adjorlolo L K, Amaning-Kwarteng K and Fianu F K 2001 In vivo digestibility and effect of supplemental mucuna forage on treated rice straw degradation. Small Ruminant Research 41:239-245

 

AOAC 1990 Association of Official Analytical Chemists. Official Methods of Analysis, Washington, DC.

 

Ash A J 1990 The effect of supplementation with leaves from leguminous trees Sesbania grandiflora, Albizia chinensis and Gliricidia sepium on the intake and digestibility of Guinea grass hay by goats. Animal Feed Science and Technology 28:225-231.

 

Ben Salem H, Nefzaoui A, Ben Salem L and Tisserand J L 1997 Effect of Acacia cyanophylla Linndl. Forage supply on intake and digestion by sheep fed Lucerne hay based diets. Animal Feed Science and Technology 68:101-113.

 

Dube J S, Reed J D and Ndlovu L R 2001 Proanthocyanidins and other phenolics in acacia leaves of Southern Africa. Animal Feed Science and Technology 91:59-67.

 

Ebong C 1995 Acacia nilotica, Acacia seyal and Sesbania sesban as supplements to Teff (Eragrostis teff) straw fed to sheep and goats. Small Ruminant Research 18:233-238.

 

Elseed F A M A, Amin A E, Khadiga A, Ati A, Sekine J, Hishinuma M and Hamana K 2002 Nutritive evaluation of some fodder tree species during the dry season in Central Sudan. Asian-Australasian Journal of Animal Science 6:844-850.

 

Fujihara T, Hosoda C and Matsui T 1995 Mineral status of grazing sheep in the dry area of mainland China. Asian-Australasian Journal of Animal Science 8:179-186.

 

Fujihara T, Matsui T, Hayashi S and Robles A Y 1992 Mineral status of grazing Philippine goats II. The nutrition of selenium, copper and zinc of goats in Luzon Island. Asian-Australasian Journal of Animal Science 5:389-395.

 

Hangerman A E, Robins C T, Weerasuriya Y, Wilson T C and McArthur C 1992 Tannin chemistry in relation to digestion. Journal of Range Management 45:57.

 

Kendall N R, Mackenzie A M and Telfera S B 2001 Effect of a copper, cobalt and selenium soluble glass bolus given to grazing sheep. Livestock Production Science 68:31–39.

 

Khanal R C and Subba D B 2001 Nutritional evaluation of leaves from major fodder trees cultivated in the hills of Nepal. Animal Feed Science and Technology 92:17-32.

 

Leng R A 1990 Factors affecting the utilization of 'poor quality' forages by ruminants particularly under tropical condition. Nutrition Research Reviews 3:277-303.

 

Makkar H P S 2000 Quantification of tannins in tree foliage. A laboratory manual for the fao/iaea co-ordinated research project on, “use of nuclear and related techniques to develop simple tannin assays for predicting and improving the safety and efficiency of feeding ruminants on tanniferous tree foliage”. FAO/IAEA working document IAEA, Vienna, Austria.

 

McDonald I 1981 A revised model for the estimation of protein degradability in the rumen. Journal of Agricultural Science, Cambridge 96:251-258.

 

McDowell L R 1985 Nutrition of grazing ruminants in warm climates. Academic Press/Harcourt Brace, London.

 

Melaku S, Peters K J and Tegegne A 2003 In-vitro and in-situ evaluation of selected multipurpose trees, wheat bran and Lablab purpureus as potential feed supplements to Teff (Eragrostis tef) straw. Animal Feed Science and Technology 108:159-179.

 

Menke K H and Steingass H 1988 Estimation of the energetic feed value obtained from the chemical analysis and in-vitro gas production using rumen fluid. Animal Research and Develeopment (Germany) 28:7-55.

 

Nantoume H, Forbes T D A, Hensarling C M and Sieckenius S S 2001 Nutritive value and palatability of guajillo (Acacia berlandieri) as a component of goat diets. Small Ruminant Research 40:139-148.

 

Norton B W 1994 Tree legumes as dietary supplements for ruminants. In: Gutteridge R C, Shelton H M (Editors), Forage Tree Legumes in Tropical Agriculture CAB International pp. 177-191 http://www.fao.org/Ag/agp/agpc/doc/PUBLICAT/Gutt-shel/x5556e0k.htm

 

Ondiek J O, Abdulrazak S A, Tuitoek J K and Bareeba F B 1999 The effects of Gliricidia sepium and maize bran as supplementary feed to Rhodes grass hay on intake, digestion and live-weight of dairy goats. Livestock Production Science 61:27-38.

 

Ondiek J O, Tuitoek J K, Abdulrazak S A, Bareeba F B and Fujihara T 2000 Use of Leucaena leucocephala and Gliricidia sepium as nitrogen sources in supplementary concentrates for dairy goats offered Rhodes grass hay. Asian-Australasian Journal of Animal Science. 13:1249-1254.

 

ěrskov E R and McDonald I 1979 The estimation of protein degradability in the rumen from incubation measurements weighed according to rate of passage. Journal of Agricultural Science Cambridge 92:499-503.

 

Osuga I M, Abdulrazak S A, Ichinohe T and Fujihara T 2006 Rumen degradation and in-vitro gas production parameters in some browse forages, grasses and maize stover from Kenya. Journal of Food Agriculture and Environment 4 (2):60-64.

 

Ramirez R G and Ledezma-Tores R A 1997 Forage utilization from native shrubs Acacia regula and Acacia fernesiana by goats and sheep. Small  Ruminant Research 25:43-50.

 

Reed J D 1995 Nutritional toxicology of tannins and related polyphenols in forage legumes. Journal of Animal Science 73:1516-1528  http://jas.fass.org/cgi/reprint/73/5/1516.pdf

 

Salawu M B, Acamovic T, Stewart C S and Roothaert R L 1999 Composition and degradability of different fractions of Calliandra leaves, pods and seeds. Animal Feed Science and Technology 77:181-199.

 

Sawe J J, Tuitoek J K and Ottaro J M 1998 Evaluation of common tree leaves or pods as supplements for goats on range area of Kenya. Small Ruminant Research 28:31-37.

 

Serra A B, Serra S D, Serra F B, Domingo I J, Cruz, L C and Fujihara T 1995 Diets of the Philippine indigenous sheep: Its comparison to indigenous goats diets and influence of sampling methods. Asian-Australasian Journal Animal Science 8:163-169.

 

Swain T 1979 Tannins and lignins. In: G Rosenthal and D H Jansen (Editors) Herbivores, Their interaction with secondary plant metabolites. Pp 657. Academic Press, New York.

 

Topps J H 1992 Potential, composition and use of legume shrubs and trees as fodder for livestock in the tropics (a review). Journal of Agricultural Science Cambridge 118:1-8.

 

Van Soest P J, Robertson J D and Lewis B A 1991 Methods of dietary fiber, neutral detergent fiber and non-starch polysaccharides in relation to animal nutrition. Journal of Dairy Science 74:3583-3597 http://jds.fass.org/cgi/reprint/74/10/3583.pdf

 

Woodward A and Reed J D 1997 Nitrogen metabolism of sheep and goats consuming Acacia brevispica and Sesbania sesban. Journal of Animal Science 75:1130-1139 http://jas.fass.org/cgi/reprint/75/4/1130.pdf

 

World Agroforestry Centre 2005 Useful trees and shrubs for Kenya. World Agroforestry Centre – Eastern and Central Africa Regional Programme (ICRAF-ECA). Nairobi, Kenya.



Received 3 December 2008; Accepted 20 November 2009; Published 7 February 2010

Go to top