PROPAGATION, FORAGE PRODUCTION AND 
FORAGE QUALITY OF SOME GHANAIAN BROWSE PLANTS

A THESIS PRESENTED TO THE BOARD OF GRADUATE STUDIES 
OF THE UNIVERSITY OF GHANA, LEGON

BY

ALBERT ADDO-KWAFO

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE 
DEGREE OF MASTER OF PHILOSOPHY

DEPARTMENT OF ANIMAL SCIENCE 
FACULTY OF AGRICULTURE 
UNIVERSITY OF GHANA 
LEGON

FEBRUARY, 1996



( S .  347479
' SB \^Z ' I  6-3 Ad °L



DECLARATION

I hereby declare that this is an original Research work 

carried out and completed by Albert Addo-Kwafo with 

exception of other people’s work which has been duly cited, 

and that this Thesis either in whole or in part, has not been 

presented for another degree anywhere else.

Albert Addo-Kwafo 
(Student)

i



ACKNOWLEDGEMENT

This work has been possible through the grace, love, mercy, wisdom^as^gniaance 

of the Almighty Lord without whom it could not have materialised.

I wish to express my sincere gratitude to my supervisors, Prof, F.K. Fianu and Dr. 

J.E. Fleischer, for their guidance as well as their constructive criticism in the preparation 

of this thesis. I also want to thank Dr. I.K. Ofori of the Crop Science Department for 

offering useful advice throughout the course of the study. Sincere thanks go to Dr. A. 

Naazie for helping with the statistical analysis of the data and the drawing of graphs.

I am indebted to Mr. J.R. Amoah for his assistance in many ways, and Mr. Yacubu 

Abukari, the Chief Technician of the Nutrition Laboratory, Department of Animal Science 

for his immense help in the analysis of the forage samples. I wish to thank Mr. Budu- 

Biney for helping with the In sacco degradability of the forage samples.

Grateful acknowledgement are made to all the lecturers in the Animal Science 

Department for their love, help and encouragement during the study period. Many workers 

of the Departments of Animal Science and Crop Science and the Animal Research Institute 

(ARI) showed kindness and support in many ways but most importantly during forage 

sampling exercises. Special thanks go to Mr. J.K. Ennin for taking his time to type the 

scripts, lastly but not the least, I like to thank the National Agricultural Research

Project (NARP), the Council for Scientific and Industrial Research (CSIR) and the Animal 

Research Institute (ARI) for sponsoring me for the programme.



DEDICATION

Dedicated to my lovely Wife, Mrs. Evelyn Adubea Addo-Kwafo, and my 

children: Chief Kwaasi Addo-Kwafo, Akua Kyekye Addo-kwafo and Nana 

Akomobea Addo-Kwafo for toiling day and night to sustain me during the 

course of the study.

iii



TABLE OF CONTENTS
Page

DECLARATION..................................... - ... r . . . .  i
ACKNOWLEDGEMENT .............................................  ii
DEDICATION................................................... iii
TABLE OF CONTENTS..............................................iv
LIST OF T A B L E S ............................................. viii
LIST OF FIGURES............................................... ix
A B S T R A C T ......................................................xi
Chapter
1.0 INTRODUCTION.............................................. 1
2.0 LITERATURE REVIEW ....................................... 3
2.1 HERBAGE PRODUCTION AND NUTRIENT RECYCLING  .............  3
2.2 IMPORTANCE OF BROWSE PLANTS ...............    6
2.3 FACTORS INFLUENCING PRODUCTIVITY AND SURVIVAL OF

BROWSE P L A N T S ..................................   7
2.3.1 Climatic factors ...................................  7
2.3.2 Biotic factors .....................................  9
2.4 METHODS OF PROPAGATION OF BROWSE PLANTS ...............  10
2.4.1 Seed propagation and factors affecting seed

germination......................................... 10
2.4.1.1 Dormancy as a factor affecting seed germination . . 10
2.4.1.2 Methods of breaking seed dormancy................... 11
2.4.1.2.1 Mechanical scarification........................... 12
2.4.1.2.2 Chemical scarification............................. 12
2. 4.1.2.3 Heat treatment..................................... 13
2.4.1.2.3.1 Hot water treatment........................13
2 .4 .1. 2 .3 . 2 Dry heat treatment..........................13
2.4.1.2.4 "After ripening" in dry storage................  14
2.4.2 Vegetative propagation ......................... 14
2.5 MANAGEMENT OF BROWSE PLANTS .........................  15
2.6 PLANT GROWTH ANALYSIS ................................  17
2.7 EVALUATION OF FEED QUALITY OF BROWSE P L A N T S ...............19
2.7.1 Percentage crude protein ........................  19
2.7.2 Cell wall constituents...........................2 0
2.7.3 Mineral content..................................... 22
2.7.4 In vitro dry matter digestibility................... 23
2.7.5 In sacco degradability............................. 24
2.8 TOXIC PRINCIPLES IN BROWSE PLANTS ................... ! 27
3.0 EXPERIMENT ONE  ...................................29
3.1 INTRODUCTION........................................... ’ 29
3.2 MATERIALS AND METHODS '................................ 2 9
3 .3 R E S U L T S ................................................. 31
3.4 DISCUSSION............................................... 3S
4.0 EXPERIMENT T W O ........................................ 4 0
4.1 INTRODUCTION........................................  4 0
4.2 MATERIALS AND M E T H O D S ...................................41
4.3 R E S U L T S .............................................. ...
4.4 DISCUSSION............................................... 49

iv



5.0 EXPERIMENT THREE ......................................  51
5.1 INTRODUCTION............................................. 51
5.2 MATERIALS AND M E T H O D S ................................... 51
5.3 R E S U L T S ................................................. 53
5.4 DISCUSSION............................................... 57

6.0 EXPERIMENT F O U R ......................................... 59
6.1 INTRODUCTION............................................. 59
6.2 MATERIALS AND M E T H O D S ................................... 60
6.3 R E S U L T S ................................................. 64
6.4 DISCUSSION............................................... 70
6.4.1 Seedling emergence ...............................  70
6.4.2 Plants survival...................................... 70
6.4.3 Plant height at 24 w e e k s ............................71

7.0 EXPERIMENT F I V E ......................................... 72
7.1 INTRODUCTION............................................. 72
7.2 MATERIALS AND M E T H O D S ................................... 72
7.2.1 Chemical analysis .................................  73
7.2.2 In vitro dry-matter digestibility (IVDMD) ....... 73
7.2.3 In sacco CP and DM degradation of the forages . . .  73
7.2.4 Statistical analysis .............................  75
7.3 RESULTS.................................................. 75
7.3.1 Chemical composition .............................  75
7.3.2 In sacco DM and CP digestibility of the browse

p l a n t s ..............................................97
7.4 DISCUSSION.............................................. 100
7.4.1 Chemical composition .............................  100
7.4.2 Dry matter c o n t e n t .................................101
7.4.3 Crude protein (CP) c o n t e n t .........................102
7.4.4 Cell wall constituents (CWC) digestibility and

minerals.......................................... 102
7.4.5. In sacco degradability of the forages .............  104

8.0 GENERAL DISCUSSION ....................................  107

9.0 CONCLUSIONS AND RECOMMENDATIONS.........................114

REFERENCES...............................................116

v



A P P E N D I X ................................................... 13 2
1 Symbols representing the browse species used and

the date of h a r v e s t ................................... 132
2 ANOVA on percentage germination of eight species

of browse plants under different seed treatment . . . .  133
2a ANOVA for Cajanus c a j a n ................................. 134
2b ANOVA for Albizia lebbek................................. 134
2c ANOVA for Milettia thonningii.......................... 135
2d ANOVA for Afzelia africana .............................  135
2e ANOVA for Pithecellobium dulce.......................... 135
2f ANOVA for Khaya senegalensis............................ 136
2g ANOVA for Grewia carpinifolia ......................... 137
2h ANOVA for Dialium guineense............................. 137
2i ANOVA for control treatment ...........................  138
2j ANOVA for warm water treatment.........................13 8
2k ANOVA for hot water treatment.........................13 9
21 ANOVA for mechanical scarification ..................... 13 9
3 ANOVA on days taken to germinate by eight species

of browse plants under different seed treatment....... 140
3a ANOVA for Cajanus c a j a n ................................. 141
3b ANOVA for Albizia lebbek................................. 141
3c ANOVA for Milettia thonningii.......................... 142
3d ANOVA for Afzelia africana .............................  142
3e ANOVA for Pithecellobium dulce.......................... 143
3f ANOVA for Khaya senegalensis ...........................  143
3g ANOVA for Grewia carpinifolia .........................  144
3h ANOVA for Dialium guineense.............................144
3i ANOVA for C o n t r o l .......................................145
3j ANOVA for warm water treatment.......................... 145
3k ANOVA for hot water treatment......................... 14 6
31 ANOVA for mechanical scarification .....................  146
4 ANOVA on rate of germination of eight species of

browse plants under different seed treatment........... 147
4a ANOVA for Cajanus c a j a n ............................... 14 8
4b ANOVA for Albizia lebbek.................................148
4c ANOVA for Milettia thonningii.......................... 149
4d ANOVA for Afzelia africana .............................  149
4e ANOVA for Pithecellobium dulce...........................150
4f ANOVA for Grewia carpinifolia .........................  150
4g ANOVA for Khaya senegalensis ...........................  151
4h ANOVA for Dialium guineense.............................151
4i ANOVA for Control . .  .................................. 152
4j ANOVA for warm water treatment...........................152
4k ANOVA for hot water treatment...........................153
41 ANOVA for mechanical scarification .....................  153

vi



5
5a
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

154
154
155
156
157
158
159
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175

ANOVA for leaf area determination . . . .
ANOVA for dry matter accumulation . . . .
ANOVA for seedling emergence ............
ANOVA for seedling survival ............
ANOVA for plant height ..................
ANOVA for dry matter yield ...............
ANOVA for dry matter content
ANOVA for crude protein content ........
ANOVA for neutral detergent fibre (NDF) 
ANOVA for acid detergent fibre (ADF) . . .
ANOVA for cellulose content ............
ANOVA for hemicellulose content ........
ANOVA for lignin content ................
ANOVA for calcium content ..............
ANOVA for phosphorus content ............
ANOVA for magnesium content ............
ANOVA for potassium content ............
ANOVA for sodium content ................
ANOVA for zinc content ..................
ANOVA for copper content ................
ANOVA for manganese content ............
ANOVA for in vitro dry matter digestibility

vii



Table Page
3.1 Percentage germination of eight species of

browse plants under different seed treatment ..........  32
3.2 Effect of sed treatment on germination time of

browse plants (days) ...................................  33
3.3 Rate of germination of browse plants under different

seed treatments..........................................35
4.1 Number of seeds of browse plants that emerged'

from the s o i l ............................................45
4.2 Growth rates (cm d'1) of browse plants to 30 and 60 days

after planting............................................47
4.3 Leaf area development of browse plants to 2 0 weeks

of growth (cm2)  47
4.4 Dry matter yield of browse plants to 20 weeks of

growth ( g ) ................................................48
4.5 RGR, NAR and LAR of five browse plants to 70 days growth 49
5.1 Sprout check on cuttings 2 and 4 weeks after planting . 55
6.1 Climatic data for Legon for the experimental period,

January 1993-Feb 1994   62
6.2 Percentage seedling emergence and percentage survival

to 16 weeks of 5 browse plants........................... 64
6.3 Dry matter yield of 5 browse plants as influenced by

age (t/ha.)  65
6.4 Stem girth (cm) of 5 browse plants at 16 and 24 weeks

of g r o w t h ................................................68
7.1 Foliage dry matter content of 5 browse plants as

influenced by age (g/kg)................................. 76
7.2 Foliage crude protein content of 5 browse plant as

influenced by age (%)  77
7.3 Fliage NDF content of 5 browse plants as influenced

by age ( % ) ................................................84
7.4 Foliage ADF content of 5 browse plants as influenced

by age ( % ) ................................................85
7.5 Foliage cellulose content of 5 browse plants as

influenced by age (%)  86
viii

LIST OF TABLES



7.6 Foliage hemicellulose content of 5 browse plants as 
influenced by age (%)  87

7.7 Foliage lignin content of 5 browse plants as influenced by 
age (%)  88

7.8 Foliage calcium content of 5 browse plants as
influenced by age (%)  89

7.9 Foliage phosphorus content of 5 browse plant as 
influenced by age (%)  90

7.10 Foliage -potassium content of 5 browse plants
as influenced by age ( % ) ................................. 91

7.11 Foliage magnesium content of 5 browse plants as 
influenced by age (%) .................................92

7.12 Foliage sodium content of 5 browse plants as
influenced by age (%)  93

7.13 Foliage zinc content of 5 browse plants as influenced by age 
(ppm) ....................................................94

7.14 Foliage copper content of 5 browse plants as
influenced by age (ppm) ..................................95

7.15 Foliage manganese content of 5 browse plants as 
influenced by age (ppm) .................................. 96

7.16 Foliage IVDMD of 5 browse plants as influenced
by age ( % ) ................................................97

7.17 In sacco degradability characteristics (a, b and c) 
of DM and CP of browse species harvested at 6, 7
and 8 months after p l a n t i n g ............................. 98



Figure Page
4.1 Height (cm) of seven browse species during 20 weeks of 

growth.................................................... 44
5.1 Effect of hormone application on the growth of 4 browse 

plants .................................................. 56
6.1 Height (cm) of five browse species during 24 weeks of 

growth.................................................... 66
6.2 Development of primary branches of 4 browse species

during 24 weeks of g r o w t h ................................. 6 9
7.1 In situ DM disappearance (%) from 4 selected browse

plants, harvested at 6 months after planting
incubated in the rumen of s h e e p ........................... 78

7.2 In situ DM disappearance (%) from 4 selected browse plants,
harvested at 7 months after planting incubated in the rumen 
of sheep..................................................79

7.3 In situ DM disappearance (%) from 4 selected browse
plants, harvested at 8 months after planting incubated
in the rumen of s h e e p ................................. 8 0

7.4 In situ CP disappearance (%) from 4 selected browse
plants, harvested at 6 months after planting incubated
in the rumen of s h e e p .................................... 81

7.5 In situ CP disappearance (%) from 4 selected browse
plants, harvested at 7 months after planting incubated
in the rumen of s h e e p .................................... 82

7.6 In situ CP disappearance (%) from 4 selected browse plants,
harvested at 8 months after planting incubated in the rumen 
of sheep..................................................83

LIST OF FIGURES

x



ABSTRACT

Experiments were carried out to examine the ease of establishment of some native 

browse species through both seed and stem cuttings, the forage production from these 

browse species and the nutritive quality of the forage produced as livestock feed. Five 

experiments were therefore conducted to address the problem.

Experiment I: The objective of this experiment was to test in vitro techniques for breaking 

the dormancy of the seed of some native browse plants. Germination tests were performed, 

after no treatment (control) soaking in warm water, immersion in hot water and 

mechanical scarification, on the seed of ten browse plants namely: Cajanus cajan, Dialium 

guineense, Afzelia africana, Khaya senegalensis, Grewia carpinifolia, Pithecellobium dulce, 

Albizia lebbek, Milettia thonningii, Baphia nitida and Griffonia simplicifolia. The 

experimental design was 1 0 x 4  factorial arranged in a completely randomised design with 

four replicates. The factors were the ten browse species and the four seed treatment 

methods.

Percentage germination was high (54-98%) with mechanical scarification for all the 

species except Grewia carpinifolia and Khaya senegalensis (11-16%). The other treatments 

also gave high percentage germination (above 48%) with the exception of Grewia 

carpinifolia, Khaya senegalensis and Dialium guineense which were very low (5-41%). 

Number of days taken to germinate in the different browse species was significantly shorter 

(P<0.05) for the scarified seed than the other treatments. Regardless of the type of 

treatment adopted Cajanus cajan and Milettia thonningii took the same time to germinate 

for all the treatments (3 and 4 days respectively). Mechanical scarification reduced the 

number of days to germination from 13.8 to 2.3 and 12.7 to 6.3 in Albizia lebbek and



Afzelia africana respectively. For Grewia carpinifolia and Dialium guinegm'4 B^tn warm 

and hot water treatments increased the number of days to germination. The control and 

mechanical scarification were similar. Species differed significantly (P<0.05) in the rate 

of germination. Mechanical scarification increased the rate of germination of the species 

more than the other treatments.

Experiment II: The objective of this experiment was to study the changes in plant height 

with time, the relative growth rate (RGR), net assimilation rate (NAR) and Leaf area ratio 

(LAR) of the browse plants. The seed of the browse plants used in Experiment I were 

planted in polybags and their RGR, NAR, LAR and dry matter accumulation were noted. 

The experimental design was a completely randomised design with 8 replicates. The RGR 

was highest (0.052 g g'1 d'1) in Cajanus cajan and lowest (0.021 g g'1 d'1) in Afzelia 

africana. The NAR ranged between (153 and 491) x 10'6 g cm'2d‘' with Cajanus cajan 

and Albizia lebbek accounting for the lowest and highest values respectively. LAR values 

ranged between 60 and 339 cm2 g'1 being lowest and highest in Pithecellobium dulce and 

Cajanus cajan respectively. Dry matter accumulation was highest in Cajanus cajan (280g) 

and lowest in Afzelia africana (4g). The NAR value of Cajanus cajan suggests that it was 

very poor in putting on dry material contrary to actual observation. Thus care should be 

taken when comparing species using their NAR values.

Experiment III: The objective of this experiment was to study the sprouting ability as 

well as the growth rate of these native browse plants, using hardwood stem cuttings treated 

with a rooting hormone. Cuttings of all the browse plants mentioned in experiment I in 

addition to those of Spondias mombin and Ficus exasperata were planted in polybags with 

the aid of a rooting hormone. It was observed that, the establishment of the browse plants



studied. The percentage seedling emergence was over 80% for all the species while the 

percentage plant survival to 16 weeks was over 78% for all the species reaching 100% in 

Cajanus cajan.

Experiment V: The objective of this experiment was to study the feed quality of the 

forage produced in Experiment IV in the laboratory. The dry matter content of the species 

ranged between 302-703 g/kg. The dry matter yield of Afzelia africana (0.08 t/ha) was so 

low that enough was not available for the determination of NDF, ADF cellulose, 

hemicellulose and lignin. Average crude protein (CP) content for the six, seven and eight 

months period were 21.52%, 19.67% and 19.36% respectively and ranged between 14.76 - 

25.00%. The calcium (Ca) content of the species ranged between 2.2-5.6% while the 

phosphorus (P) content ranged between 0.15 and 0.23% for all the species over the three 

periods.

The In vitro dry matter digestibility (iVDMD) ranged from 44-63% with Cajanus 

cajan, the lowest value and Afzelia africana having the highest. The in situ disappearance 

after 48 hours of incubation for both DM and CP was in the range of 40-70% and 29-68% 

respectively. The most promising species for dry season supplementary feeding of 

ruminants from these studies were Albizia lebbek, Cajanus cajan, Milettia thonningii and 

Pithecellobium dulce. These forages when supplemented to ruminants especially during the 

dry season could play a vital role in the improvement of animal production. It is therefore 

suggested that very efficient management practices should be adopted in the propagation 

agronomy of these browse species so that enough would be available for dry season 

supplementary feeding. The work done so far should be extended to include studies with

xiii



animals so as to ascertain the voluntary intake and in vivo dry matter digestibility and 

animal preference.

xiv



CHAPTER ONE

1.0 INTRODUCTION

Ghana, according to the Medium Term Agricultural Development Programme 

(1990) is producing only 22-25% of its total meat requirement. Chief among the 

several reasons for this low level o f output, is the inadequate supply o f good quality 

feed. There is plenty o f green forage available for ruminant livestock during the 

rainy season which may even be underutilized. However, the grasses become wiry 

and parched during the dry season, resulting in their poor nutritive value. Thus, 

animals gain weight during the rainy season only to lose it during the dry season. 

Liveweight losses o f up to 11% for cattle Rose Innes, 1961 and 15% for sheep 

Otchere et al. 1977 have been reported in the country.

Comparative studies o f sheep and goats in Nigeria’s forest zone showed that 

sheep and goats spent over 90% of their total feeding time browsing (Carew et al. 

1980). In the semi-arid and arid regions, shrub and tree fodder become even more 

important as feed resources due to the harsh environment which makes feed supply 

uncertain. The role o f leguminous shrubs in integrated farming systems has been 

highlighted by various workers (Kang et al. 1984, Atta-Krah and Francis, 1986, Atta- 

Krah, 1989). Browse plants, especially leguminous trees and shrubs, beside 

providing feed for livestock, supply other needs o f man.

It has been suggested that woody leguminous browse species o f high nutritive 

value if  established in the subhumid and semi-arid savanna zones would alleviate the

1



problem of slow growth o f livestock (Rose Innes and Mabey 1964a). This would 

ensure adequate high quality feed for livestock throughout the year and hence 

increase production o f meat in the country. Studies on germinability, establishment, 

yield and quality o f native/introduced browse plants used by stockmen in the country 

seem not to have been conducted. This knowledge gap needs to be filled. A 

successful establishment o f such plants will require efficient means o f propagation. 

Those that establish quickly, have high growth rate and produce high yield o f 

nutritious forage would then be selected for production.

The main objectives o f this work were to study the seed germination, ease o f 

establishment, forage yield potential and nutritive value o f some indigenous browse 

plants.

2



CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 FORAGE PRODUCTION AND NUTRIENT RECYCLING

Multipurpose trees have been used in various cropping practices for the 

maintenance o f soil nitrogen and other nutrient elements. In this regard, Leucaena 

leucocephala has been one o f the most highly studied species (N.A.S. 1977, 

Guevarra et al. 1978). Reports from field trials in Hawaii indicate that under 

favourable growing conditions, 500-600kg N/ha/yr. is possible if  the foliage 

harvested from this plant were incorporated into the soil. The herbage produced is 

also a potential feed for livestock and constitutes a very important nitrogen source 

to the animal.

"Kang et al; (1984) reported that a well established hedgerow o f Leucaena 

leucocephala variety K-28, grown in a sandy Entisol in Nigeria at 4m interrow 

spacing, produced between 15-20 tonnes o f fresh prunings per year (5.0 - 6.5 t 

DM/ha with five prunings per year). These prunings, excluding stakes, yielded over 

160kg N, 15kg P, 150kg K, 40 kg Ca and 15kg Mg/ha/yr. In Colombia, Rachie 

(1983) reported that 127kg N/ha was obtained from four months old leucaena plants.

A comparison o f biomass and nutrient yield o f Leucaena leucocephala, Acioa 

barter ii, Alchornea cor difolia and Gliricidia sepium  planted in an alley farming 

system in Nigeria indicated that biomass yield ranged between 3.0 - 7.4 t DM/ha/yr 

while the nutrient yields were as follows: 40.5 - 246.5 Kg N/ha/yr., 3.6-19.9 kg. 

P/ha/yr., 20.4 - 184.0 kg K/ha/yr, 14.7 - 104.3 kg Ca/ha/yr. and 5.4 - 17.6 kg

3



Mg/ha/yr. (Kang and Reynolds 1986).

Nye and Stephens (1962) reported that Acioa barterii 

accumulated more calcium and magnesium than natural secondary forest. Nye 

(1958) observed that in the savanna region o f Northern Ghana, Cajanus cajan 

planted at close spacing, accumulated larger quantities o f nutrients than Adropogon

Supplementing poor quality diets to a protein level o f at least 7% will increase 

feed intake and animal production (Minson and Milford 1967). Since browse 

maintains a high nutritive value throughout the year it is valuable for 

supplementation (Reynolds and Adeoye, 1986).

Reynolds and Adeoye (1986) reported that a mixed Leucaena/Gliricidia 

browse fed in a cut and carry system of feeding increased the productivity index (Kg 

of offspring weaned/ewe/year) by 55% over those receiving only a basal diet o f 

Panicum maximum. Parturition interval in sheep reduced in year round continuous 

breeding when supplementary Leucaena and Gliricidia were made available 

(International Livestock Centre for Africa (ILCA), 1986). Similarly supplementation 

with tree legume foliage was shown by van Eys et al. (1986) to improve goat growth 

rates.

Reynolds and Adediran (1988) showed that supplementation o f a grass and 

cassava peel based diet with a mixed Leucaena/Gliricidia feed, significantly 

increased both growth rate and survival (up to 24 weeks) o f lambs. Reynolds (1989) 

fed West African dwarf goats at four levels o f Leucaena and Gliricidia with a basal

4



diet o f Panicum maximum  and dried cassava peel to study its effect on growth and 

survival rates o f the offspring in two breeding seasons. Productivity, (calculated as 

weight o f kids weaned/doe/year) increased by 0.64kg for each lOOg of browse DM 

consumed by the does. Dry matter intake also increased as the level o f 

supplementation rose from 200-800g DM/hd/day, reaching 180g/kg0 75/day for 

lactating adults.

Smith et al. (1990) using the leaves o f Cajanus cajan as supplement to maize 

stover, observed that the total intake o f Cajanus increased significantly whilst that 

o f maize stover fell. Both nitrogen intake and retention were increased by the 

Cajanus. Again, Biru et al. (1990) fed milking cows with freshly cut Sesbania 

sesban or Leucaena leucocephala to replace part o f the concentrate ration normally 

given to cows during dry season grazing o f natural pastures. They observed that 

milk yield o f the browse fed group was significantly higher than the control. 

Hashim (1990) supplementing the feeding'of range forage sheep with the seed pods 

o f Dicrostachys cinera and Acacia albida during the dry season, reported that dry 

matter intake was 814g/head/day for sheep supplemented with seed pods o f 

Dicrostachys, 855.9 g/head/day for sheep supplemented with Acacia albida and 

908.6 g/head/day for the control. The sheep supplemented with Acacia albida 

gained significantly more liveweight than those on Dicrostachys cinera. The 

controls lost weight during the experiment.

Fodder from trees and shrubs form the bulk o f the feed o f ruminant animals 

in confinement in most towns and villages in Ghana. Fodder trees and shrubs are

5



2.2 IM PO RTA N CE O F BROW SE PLANTS

Browse has been defined as the leaves, shoots and sprouts including tender 

twigs and stems of woody plants and vines, flowers, pods, and seeds which are eaten 

to varying extent by both domestic and wild animals (Rose Innes 1977, Devendra 

1989, Gutteridge and Shelton 1994).

Browse forms an important component o f the diet o f ruminant animals 

especially goats, sheep and camels and to a lesser extent buffaloes and cattle 

(Devendra 1989).

This appears to be the most important use o f browse plants in arid lands. According 

to Le Houerou (1978), nearly one-third o f the world’s land surface is natural 

grassland with varying degrees o f shrub components which serve as an important 

source o f feed for both domestic animals and wildlife. The feed includes leaves, 

flowers, fruits, seeds which are rich in protein, vitamins and minerals even in the dry 

season. Adegbola (1985) found that the major advantage of browse in the feeding 

of ruminants is that, they maintain a fairly good quality foliage all the year round. 

In the absence o f this forage, animals during the dry season have only straw from 

native grasses which are poor in quality and may result in avitaminoses, mineral 

deficiency and severe debilitations. The trees and shrubs Enable standing feed 

reserves to be built up so that herds can survive critical periods o f shortfall or

therefore very important, for without them, ruminant production especially in the

semi-arid areas would have been near impossible.

6



2.2 IMPORTANCE OF BROWSE PLANTS

Browse has been defined as the leaves, shoots and sprouts including tender 

twigs and stems o f woody plants and vines, flowers, pods, and seeds which are eaten 

to varying extent by both domestic and wild animals (Rose Innes 1977, Devendra 

1989, Gutteridge and Shelton 1994).

Browse forms an important component o f the diet o f ruminant animals 

especially goats, sheep and camels and to a lesser extent buffaloes and cattle 

(Devendra 1989).

This appears to be the most important use o f browse plants in arid lands. According 

to Le Houerou (1978), nearly one-third o f the world’s land surface is natural 

grassland with varying degrees o f shrub components which serve as an important 

source o f feed for both domestic animals and wildlife. The feed includes leaves, 

flowers, fruits, seeds which are rich in protein, vitamins and minerals even in the dry 

season. Adegbola (1985) found that the major advantage o f browse in the feeding 

of ruminants is that, they maintain a fairly good quality foliage all the year round. 

In the absence o f this forage, animals during the dry season have only straw from 

native grasses which are poor in quality and may result in avitaminoses, mineral 

deficiency and severe debilitations. The trees and shrubs 'enable standing feed 

reserves to be built up so that herds can survive critical periods o f shortfall or

therefore very important, for without them, ruminant production especially in the

semi-arid areas would have been near impossible.

6



prolonged drought without losses (Rose Innes and Mabey 1964a; NAS, 1979; Le 

Houerou 1980a).

Le Houerou (1980a) stressed that browse species are often an effective means 

of utilising marginal land on which normal crop production is poor owing to 

climatic, topographic and edaphic constraints. Leguminous browse plants are 

included in the group o f plants known as multipurpose trees (M PT’S) as they have 

many other uses apart from their use as feed for ruminants (McKell, 1974). 

Multipurpose trees provide several needs o f man. According to Le Houerou (1980a) 

and Nitis (1992) these needs include wood for fuel, building and fencing. In 

addition they provide various foodstuffs such as fruits and spices as well as 

medicine, dyes and fibre for clothing, ropes, bags and shade. Multipurpose trees also 

serve as a means to prevent soil erosion, increase or maintain soil fertility and 

productivity and in the long term help the balance o f highly sensitive ecosystems 

(Fianu, 1992a,b).

2.3 FACTORS INFLUENCING PRODUCTIVITY AND SURVIVAL OF
BROWSE PLANTS

2.3.1 Climatic factors

Climatic factors such as rainfall, temperature, daylength, humidity, wind and 

light are known to affect the productivity of browse plants. Brewbaker et al. (1985) 

reported that Leucaena leucocephala performs well in areas of rainfall between 

650mm and 3000mm. Calliandra calothyrsus is known to be adapted to altitudes

7



ranging from sea level to 1860m and annual precipitation ranges from 700mm - 

3000mm (Lowry and Macklin, 1989) while Albizia lebbek grows well under rainfall 

regimes ranging from 400 mm to 2500 mm (Lowry et al, 1994). Similarly 

Erythrina bacteroana grows from sea level to elevations o f 2000 m in South 

America with rainfall ranging from 800 - 5000 mm per annum (Kass, 1994). On the 

other hand, Prosopis spp. are very drought tolerant, and have been found in areas 

receiving less than 100 mm (Gutteridge, 1994).

Tropical species such as Leucaena require warm temperatures o f 25 to 30°C 

during the day for optimum growth (Brewbaker et al. 1985). Whiteman et al. 

(1986), in south east Queensland, found that Gliricidia sepium  became leafless when 

night temperatures fell below 15°C. Again, Wood and Larkens (1987) reported that 

Sesbania glandijlora is well adapted to hot humid environments and it does not grow 

well in the subtropics particularly in areas with cool season minimum temperatures 

below 10°C.

Little is known about the effect of day length on growth and yield o f tropical 

browse plants. However Hammerton (1976) reported that long daylength increased 

the herbage yield and depressed the seed yield o f pigeon pea (Cajanus cajan) in the 

West Indies. In Leucaena and others shading reduced growth but the legumes 

tolerated reduced light better than non-legumes (Benjamin et al., 1991).



2.3.2 Biotic factors

Le Houerou (1980a) and Adegbola (1985) reported that one o f the factors that 

threaten the survival o f browse plants is their overexploitation. Due to the high 

human population growth rate, there is increased pressure on land. Trees are being 

cleared at a fast rate as cultivated and urban areas expand. This has consequently 

reduced the area occupied by browse plants (Fianu 1975, 1990). On the Accra 

plains alone, Fianu (1990) estimated the loss o f grazing land and thickets (in which 

browse abounds) to real estate to be about 2500 hectares yearly.

Bray and Woodroffe (1991) have reported that the psyllid (Heteropsylla 

cubana) reduced the production of edible material o f Leucaena spp by 52% and that 

o f the stem by 79% in south east Queensland. The establishment o f Albizia lebbek 

can be affected by mice, rabbits and domestic ruminants which attack the young 

plant. Mature leaves are largely unaffected by insects but young leaves may be 

subjected to heavy predation by the grass-yellow butterfly (Eurema hecoba) (Lowry 

et al. 1994). Recently, a psyllid has been reported to attack seedlings o f Albizia in 

India (Lowry et al. 1994). Diseases of browse plants are not widely documented 

in the literature. However, Brewbaker et al, (1985) have reported that damping off 

in moist soils caused by the fungus Phythium or Rhizoctonia Spp. is a very serious 

Leucaena disease in the nursery. It is probable that other species o f browse may 

encounter similar problems. Damage by wildlife can be a serious hazard to the 

establishment o f browse plants. In Australia, marsupials, hares, cockatoos and ducks 

have been reported to chew Leucaena seedlings to the ground level (Shelton 1994b).

9



2.4 METHODS OF PROPAGATING BROWSE PLANTS

Browse plants have either been propagated by seed or vegetative means (Le 

Houerou 1980a, Adegbola 1985).

2.4.1 Seed propagation and factors affecting germination

The establishment o f browse plants by seed is the most common method for 

sowing (Shelton 1994a). Most tree legumes are readily established from transplanted 

seedlings. The seedlings are first raised in polythene bags until they reach a height 

of about 30-50cm, and after a short period o f "hardness" in the open air are directly 

transplanted into the field in moist soils. Various factors have been found to affect 

germination. These include seed viability, moisture, temperature, light, gases 

especially oxygen, speed (rate) o f germination and seed dormancy. Among these 

factors, dormancy is seen to be a potential problem which must be overcome in order 

to ensure adequate germination. A rapid fate o f seed germination is often beneficial 

to field establishment. Competition with fast germinating weeds or survival before 

soil drying are both favoured if  the seed germinate quickly (Humphreys, 1987).

2.4.1.1 Dormancy as a factor affecting seed germination

Dormancy is a condition in a viable seed which prevents it from germinating 

when supplied with conditions normally adequate for germination (Greulach, 1973; 

Mayer and Poljakoff-Mayber, 1975; Harper, 1977; Ellis et al. 1985) Dormancy has 

an important survival value particularly in regions with marked seasonal changes in

10



environmental factors such as rainfall and temperature (Tybirk, 1991). Different 

types o f dormancy are encountered in nature. One type is due to impermeable seed 

coat to water or oxygen. This type o f dormancy results from the impregnation o f 

the seed coat with waxes or other water proofing substances. Many legumes 

including clovers, alfalfa and locust beans have this type o f dormancy (Ellis et al. 

1985; Tybirk, 1991). Another type o f dormancy is innate dormancy which is 

associated with rudimentary embryos or physiologically immature embryo. A 

number o f plant species have seeds that contain only partially developed embryos 

at the time of seed dispersal. Such seeds therefore need time to ripen. Enforced 

dormancy is the condition where viable seeds do not germinate because o f some 

limitation in the environment such as the absence o f light and reduced temperature 

(Greulach 1973, Mayer and Poljakoff-Mayber 1975, Ellis et. al., 1985, Tybirk 1991). 

For a dormant seed to germinate, there is the need to break or remove the dormancy.

2.4.1.2 Methods of breaking seed dormancy

Various methods have been used to break dormancy in order to obtain fast and 

homogenous germination either in the laboratory or nursery. These include 

mechanical and chemical scarification, heat treatment and "after ripening" in dry 

storage.

11



2.4.1.2.1 Mechanical scarification

This involves the nicking, filing, drilling or shaking the seed in a container 

lined with emery paper or containing gravel (Hartman and Kester 1959, Quinlivan 

1966, Mayer and Poljakoff-Mayber 1975, Ellis et al. 1975, Tybirk 1991). These 

treatments may be detrimental to the seed (Tybrik 1991) as they can crack the seed. 

However when properly done it is efficient, raising germination percentages close 

to hundred within a few days in most species such as Albizia lebbek (Tybirk 1991).

2.4.I.2.2. Chemical scarification

Concentrated H2S04 or NaOH may be used to soak the seed for some time 

before sowing (Greulach 1973, Mayer and Poljakoff-Mayber 1975, Ellis et al. 1985, 

Tybirk 1991). Soaking time varies according to the plant species. For example with _ 

Acacia. albida. 5 minutes; Acacia nilotica 20-120 minutes, Cassia siamea 10-30 

minutes. Often good results are obtained with 50-90% germination within one day 

to two weeks when the seeds are thoroughly watered (Tybirk 1991). Other chemical 

compounds that have also been used to remove seed dormancy and which have been 

reported to promote germination of dormant seed include hydrogen peroxide, ethyl 

alcohol, sodium hypochlorite, thiourea, marcaptoethanol, nitrates, nitrites, cynides, 

azide, gibbrellins, cytokinin (for example kinetin) and hydroxyl amine (Ellis et 

al. 1985).

12



2.4.1.2.3 Heat treatment

Heat application methods that have been used to remove seed dormancy 

include hot water treatment, dry (oven heat) heat, temperature fluctuations and warm 

water treatment.

2.4.1.2.3.1 Hot water treatment

Seeds can be soaked in boiling water for sometime to break dormancy before 

sowing. Soaking time varies from five seconds for Acacia Senegal to one hour for 

Acacia sieberiana. This method has often given varied results. For example soaking 

in boiling water resulted in no effect on Pterocarpus lucens, 2%  germination in 

Acacia nilotica, 60% germination in Acacia sieberiana and 90% germination in 

Prosopis juliflora (Tybirk, 1991). Instead o f boiling water, seeds can be immersed 

in hot water at 60-80°C for one to ten minutes to soften the seed coat o f Leucaena 

leucocephala and Centrosema pubescens (Tybirk, 1991). Soaking seeds in warm 

water for 24 hours enhances germination o f Pithecellobium dulce (Fianu, personal 

communications).

2.4.1.2.3.2 Dry heat treatment

Heating the seed in an oven with temperatures ranging between 80-250°C 

from a few seconds to several minutes, helps to break seed dormancy in some 

species. Heating for ten minutes at 110°C has been used to break dormancy in 

Acacia hockii (Tybirk, 1991).

13



Temperature fluctuations with an amplitude o f 15°C has been found to hasten 

germination o f hard seeded legumes such as Acacia nilotica (Tybirk, 1991). 

Microwave oven has also been used to break seed dormancy. This treatment 

depends on the moisture content of the seed as well as the species. Microwave 

treatment cracks the seed coat as happens in Australian Acacias (Tybirk, 1991).

2.4.1.2.4 "A fter ripening" in dry storage

"After ripening" is post harvest maturation. It is the loss o f dormancy that 

gradually occurs when seeds are stored in an air dry state (Hartmann and Kester, 

1959; Greulach, 1973; Mayer and Poljakoff-Mayber, 1975; Grant, 1979; Ellis et al., 

1985; Tybirk, 1991).

2.4.2 Vegetative propagation

In some plant species, vegetative propagation is the only means by which the 

plant can be established. This may be due to the fact that few or no viable seeds are 

produced by such species. For some species propagation through the seed is so slow 

that the best way possible is to use vegetative propagation. Vegetative propagation 

can be done in many ways. The three common methods used are either by planting 

with stem cuttings, rootstock or by grafting (Kempana and Chandrasekharia, 1959, 

Kempana et al. 1961, Greulach 1973, Le Houerou 1980c, Adegbola 1985).

Raising stem cuttings in the nursery improves survival rates (Le Flouerou 

1980c, Adegbola 1985). Application of growth regulators such as 2, 4- 

dichlorophenoxy acetic acid (2, 4-D) and Naphthalene acetic acid (NAA) may

14



improve root development (Kempana and Chandrasekharia 1959, Kempana et al. 

1961, Chaudhuri 1965) and thus enhance the survival rates o f the cuttings. Browse 

plants can also be propagated by air layering with the aid o f growth regulators 

(Kempana et al. 1961). Age of stem cuttings, diameter and length o f the cuttings, 

the position o f the cutting on the parent tree, the type o f cut, length o f the storage 

time and depth o f planting are important factors affecting vegetative propagation. 

Falvey (1982) conducted some studies into these aspects and reported that gliricidia 

cuttings should be taken from stems that are at least 6 months old, 0.5 - 2 m in 

length and from the lower part o f the tree. Stem sections should also be planted as 

soon as possible after cutting. Glover (1989), as cited by Shelton (1994a), reported 

that cuttings should be mature branches, greater than 7 cm in diameter and which are 

brownish green in bark colour. The cut is normally made obliquely at both ends, 

discarding the younger tips, and the base inserted 20-50cm into the soil. Cuttings 

for live fences may be up to 200cm while those for hedgerows may be 30-50 cm in 

length.

2.5 MANAGEMENT OF BROWSE PLANTS

Plant spacing and density adopted depend on the size o f the browse plant and 

the management procedure to be adopted and its utilisation such as in intensive feed 

gardens, hedgerow browse, and alley farming (Le Houerou, 1980c; Adegbola,

1985). Browse plants can be planted on millet, groundnut or sorghum fields. I f  a 

browse plant such as Faidherbia albida is planted on such fields, a planting density

15



of fifty trees per hectare in rows o f 10m x 20m could be adopted (Le Houerou, 

1980c; Adegbola, 1985). Generally, for all species of browse plants, wide spacing 

encourages fruit production while higher stocking densities promote the production 

of leaf biomass per unit area.

A compound fertilizer providing N, P and K applied at the rate o f 25-50 kg/ha 

encourages early growth. Watering after planting is beneficial especially in arid 

zones. Watering on two or three subsequent occasions may be necessary depending 

on local and seasonal conditions (Le Houerou, 1980c; Adegbola, 1985).

A major problem encountered during the establishment of shrubs and trees is 

competition with weeds. The growth rate o f shrub/tree seedlings is often very slow, 

thus competition from weeds may result in high plant mortality (Maasdorp and 

Gutteridge, 1986; Ivory, 1989). Therefore, considerable advantages are gained if 

the seeds are germinated and the young plants raised in a nursery before 

transplanting to the field. I f  the shoots .and roots are trimmed, at the time of 

transplanting, it reduces transpiration and stimulates root development (Pound and 

Martinez - Cairo, 1983). Such seedlings are better able to compete with weeds after 

transplanting.

Le Houerou (1980c) and later Adegbola (1985) have enumerated the following 

procedures as essential in the management o f browse plants. During the first year 

after planting, it is always good to reduce or eliminate competition from weeds and 

this could be achieved by ploughing a strip 1 to 2m wide on each side o f the planted 

row. This ensures higher survival of the plant and more rapid growth. Species

16



which are normally bushy, for instance Faidherbia albida, should be pruned and 

protected from browsing until they are strong enough to survive. Certain species like 

Leucaena leucocephala, need to be cut back to keep them within the reach o f some 

of the animals. Finally, the plantation should be enclosed to prevent uncontrolled 

grazing and subsequent damages to the plantation.

2.6 PLANT GROWTH ANALYSIS

Growth analysis is a useful tool in studying the complex interaction between 

plant growth and the environment (Noggle and Fritz 1986). Two basic 

measurements are normally required to carry out a simple growth analysis. These 

include a measure of the plant material present (W) and a measure o f the magnitude 

of the assimilatory system (A) of that plant material (Watson 1947a, Radford 1967). 

In practice, the most common measures of W and A are the total weight o f the 

individual plant and the total leaf area- o f the plant. For plants that form a 

continuous canopy cover such as a sward, W is the total dry weight o f the plant 

material per unit area o f the ground. Other measures of W that have been used are 

the total dry weight of the plant material above ground level, above harvest cutting 

height and some distinctive plant fractions (Watson 1947 a,b.; Blackman et al. 1955, 

Radford, 1967). The measure of A has been taken as the total photosynthesising 

area, leaf weight, leaf protein, leaf chrolophyll (Williams 1946, Watson 1952).

17



Common measures o f growth include:

Crop growth ra te  (CGR). The CGR of a canopy is defined here as the 

increase in total foliar dry matter per unit area per unit time.

CGR = dw/dt. It helps to determine the rate o f foliar dry matter accumulation
I

of a crop.

Relative Growth Rate (RGR). The RGR of a plant in this study refers to 

increase in total folia dry matter per unit plant present per unit time.

RGR = 1/W . dw/dt (g g 1 d '1).

RGR helps to assess the efficiency of herbage production' over a time period. 

Net Assimilation R ate (NAR). The NAR is defined as the increase in weight 

o f leaves per unit o f assimilatory surface per unit time.

NAR = 1/A . dw/dt (g cm'2 w k'1).

The NAR is a measure o f the amount o f photosynthetic product going into the 

forage, thus it is an estimate o f net photosynthesis harvested in the forage. 

L eaf Area Ratio (LAR). The LAR of a plant is defined as the ratio o f the 

assimilatory surface per unit leaf weight. LAR = A/W (cm2 g '1). It 

reflects the density of photosynthetic material in the leaf.

It follows from the above definitions that RGR = NAR x LAR (Williams 

1946; Watson 1952, 1956; Thorne 1960, Radford 1967, Leopold and Kriedman 

1975).

These measurements are relevant to the present study in that they throw light 

on the rate and efficiency of dry matter formation in these plants and contributes to

18



the understanding of their genetic potential for photosynthesis.

2.7 EVALUATION OF FEED QUALITY OF BROWSE PLANTS

2.7.1 Percentage crude protein

The minimum level of crude protein (CP) which is1 normally considered 

adequate for moderate level of production for ruminants is reported to be 11-12% 

(ARC, 1980). Various workers have reported that browse plants in general have 

higher CP content (8-30%) than natural or native grasses (2-10%) in the same area 

(Rose Innes and Mabey, 1964b; Mecha and Adegbola, 1980; Norton, 1994).

Mohamed-Saleem et al. (1979) found that the CP content o f browse species 

ranged from 12.3-21.8%, 5.3-15.6% and 5.5-16.6% respectively for the heavily 

browsed, moderately browsed and occasionally browsed species. The CP content o f 

browse plants also depends on the location. For example, Mecha and Adegbola 

(1980) found the protein content o f Nigerian browse to be different from that of 

Australia as reported by Wilson (1977). The report by Pellow (1980) showed that 

there were differences in the CP composition o f six Acacia species studied. Old 

leaves were shown to have lower protein content than young leaves and this 

confirms the fact that CP content decreases as the plant ages. The average protein 

content o f browses in Tropical West Africa was 12.5% (Le Houerou, 1980b). Rose 

Innes and Mabey (1964 a,b) identified a number o f browse species palatable to local 

cattle and performed digestibility trials on some of them. The recommended species 

included Griffonia simplicifolia, Baphia nitida and Antiaris africana. The results

19



showed that Baphia nitida had the highest CP among the three. The CP content o f 

the species were 21.2%, 18.6% and 11.4% for Baphia nitida, Griffonia simplicifilia 

and Antiaris africana respectively.

Research at the Animal Research Institute (ARI) in Ghana in the late 1960’s 

showed that the crude protein content o f seeds o f such broWse plants as Samanea 

saman, Albizia lebbek, Bauhinia monandra, Khaya senegalensis, Caesalpinia 

pulcherrima and Cassia occidentalis varied (ARI, 1968). A t the University o f 

Ghana, Adjei and Fianu (1985) worked on Aeschynomene americana and Cajanus 

cajan cut at 60, 90 and 120 days to assess regrowth and yield o f the plants. They 

reported a mean dry matter yield of 4.7 t ha'1 and 4.9t ha'1 and mean crude protein 

content o f 25.2% and 21.4% for Aeschynomene and Cajanus respectively. Karbo 

and Barnes (1993) studied the preference by sheep and goats o f four browse plants - 

Gliricidia sepium, Leucaena leucocephala, Sesbania sesban and Cajanus cajan. 

They reported that the crude protein content o f the browse ranged from 19 to 26% 

and when offered a forage choice o f the browse species Djallonke sheep selected 

Cajanus cajan whilst the West African dwarf goat preferred Leiicaena leucocephala.

2.7.2 Cell wall constituents

Van Soest (1966, 1967) separated the plant material into soluble and various 

components using detergent solutions. The cell wall components which represent 

the neutral-detergent fibre (NDF) is-the residue after extraction with boiling neutral 

detergent solutions of sodium lauryl sulphate and ethylenediminotetraacetic acid

20



(EDTA). It consists mainly o f hemicellulose, cellulose, lignin and silica.

The acid-detergent fibre (ADF) is the residue after refluxing with 0.5M 

sulphuric acid and cetyltrimethylammonium bromide (CTAB) and represents 

essentially the crude cellulose, lignin and silica. Therefore, it is commonly accepted 

that the hemicellulose content is determined as a result o f  the difference between 

NDF and ADF.

Cellulose and hemicellulose account for a large proportion o f energy obtained 

from forages, but they differ in their yield o f useful energy due to differences in 

digestibilities and to a lesser extent to the end product they yield on breakdown in 

the digestive tract (Crampton, 1956). This difference is attributed to the cellulase 

enzyme of the microbes which readily ferments cellulose to a greater extent than 

the hemicellulose. The lignin is highly indigestible and reduces the digestibility o f 

other components possibly because of encrustation.

McDonald et al. (1988) reported that the extent to which cellulose is digested 

in the rumen depends particularly on the degree of lignification o f the plant material. 

Lignin and also the related substance, cutin, is resistant to attack by anaerobic 

bacteria probably because of its low oxygen content and its condensed structure 

which inhibits hydrolysis. Lignin therefore appears to hinder the breakdown o f 

cellulose with which it is associated (McDonald et al. 1988).

Norton (1994) reported that the digestibility of plant material in the rumen is 

related to the proportion and lignification o f plant cell walls (NDF), and that tree 

forages with low NDF content (20-35%) are usually o f high digestibility, while

21



species with high lignin contents are often low in digestibility. Stems have been 

reported to have higher lignin contents than leaves and hence are less digestible than 

leaves (Norton, 1994). There are a few exception now, according to available 

literature.

2.7.3 Mineral content

The dietary requirements o f livestock for minerals have been reported to vary 

with the species, breed o f the animal, its age and rate o f growth or production and 

with the biological availability o f the mineral in the diet (Underwood, 1981). The 

minimum requirement o f ruminants for P varies from 0.12 - 0.24% (dry matter basis) 

depending on the physiological function o f the animal (Norton 1994). The minimum 

requirement o f sodium for ruminants for satisfactory growth, and lactation and 

maintenance are estimated to be 0.07 - 0.1% of the dry diet (Hagsten et al. 1975, 

Morris and Peterson 1975, Norton 1994). Le Houerou (1980b) and Norton (1994) 

have lamented that there is inadequate information on the mineral content o f browse 

plants.

Le Houerou (1980b) reported that the P and Mg content o f browse in Africa 

is generally adequate for stock feeding P(0.15%) and Mg (0.60%) but is a little high 

in Ca (1.7%) and K (1.5%). However, the Ca/P ratio is usually too high (11) as 

against the optimum figure of 1-2. Although calcium is rarely limiting in forage 

trees as it is true for forages generally, high concentrations o f oxalic acid in leaves 

may decrease Ca availability during digestion (Norton 1994).'

22



Vercoe (1987) working on the foliage o f 23 tree species used for livestock 

feeding in Australia found considerable variation in their chemical composition. 

P(0.5 - 0.18%), K (0.41 - 1.78%) Ca (0.29 - 3.52%), S (0.21 - 1.13%), Na (<0.01 -

0.41%), Mg (0.21 - 0.62%), Cu 4 - 152 ppm), Al (26 325 ppm) and B (16 - 59 

ppm).

The minimum needs o f sheep and cattle for Mg for growth can generally be 

met by pastures or rations containing 0.07% Mg on dry basis (Underwood 1981).

2.7.4 In vitro dry matter digestibility

Lignin in grasses and other plants is frequently assumed to be completely 

indigestible by ruminants, although many examples to the contrary exist in the 

literature (Sullivan, 1959; Ahn et al. 1989). Sullivan (1959) reported that within a 

plant species, an increase in lignin content almost invariably resulted in a decrease 

in digestibility. Ahn et al. (1989) also reported that lignin and) condensed tannins are 

responsible for low digestibilities in forages.

Dry matter digestibility values for some browse plants have been determined 

by several workers in different ecological zones (Adegbola, 1985). These include 

the summaries o f Mabey and Rose Innes (1964 a, b) for Ghana which averaged 

53.69% and that o f Barnes (1979) as cited by Adegbola (1985) for southern Africa 

which ranged between 41 - 53.5%. Dry matter digestibility values range widely 

from 60% for species like Gliricidia sepium and Leucaena leucocephala down to 

about 30% for fibrous species (Brewbaker, 1986).



The form in which the leaves are fed (fresh, wilted or dry) is known to affect 

both feed intake and digestibility in some species (Palmer and Schlink, 1992). The 

dry matter digestibility (DMD) of forages is known to decrease with advancing plant 

growth. Tilley and Terry (1963) showed that the in vitro digestibility o f lucerne 

stems declined from 85% when young to 56% at maturity.

2.7.5 In  sacco degradabilitv

In sacco degradability of DM and N involves placing samples o f ground 

forage in nylon bags and suspending them in the rumen of fistulated animals by the 

help of steel weights. The rates o f the digestion o f dry matter can then be 

determined by removing the bags at varying intervals. The technique provides a 

powerful tool for the initial evaluation o f feedstuffs and for improving our 

understanding of the processes of degradation which occur within the rumen (Orskov 

et al. 1980).

The pore size of the nylon bags is very important since it is known to regulate 

the passage o f solid particles from the bags. Uden et al. (1974) as cited by (Orskov 

et al., 1980) reported that material with pore size o f 20/x and 35/x have been found 

to give smaller dry matter losses than from bags with 5/i pores. Van Miellan and 

Ellis (1977) considered 10//, to be the maximum pore size if  loss o f solids was to be 

prevented. Rodriguez (1968) as cited by Kempton (1980) reported that the pore size 

of the material used for the manufacture o f the nylon bags apparently has no 

significant effect on dry matter disappearance from bags during a 72 hour incubation.

24



The optimum size o f the bag has been investigated by a number o f workers 

(Rodriquez 1968, as cited by Kempton 1980; Mehrez 1976 as cited by Orskov et al., 

1980). The optimum size o f the bag is essentially a compromise between two 

opposing factors. On one hand, it is necessary to have the bag large enough relative 

to the sample size used so as to ensure that rumen fluid can easily enter the bag and 

mix with the sample. On the other hand, it is necessary to have the bag small 

enough for ease o f withdrawal through the rumen canular.

Preparation o f the feed samples for incubation is very critical, as they should 

represent as far as possible the material as they would appear in the rumen had they 

been consumed by the animal (Bailey 1962 as cited by Orskov et al, 1980). Ideally, 

masticated ingesta from animals fitted with an oesophageal cannula can be collected 

but in practice the use of a laboratory hammer mill fitted with 2.5 3.0 mm screen

for dry feed is adequate. Erwin and Ellison (1959) as cited by Orskov et al, (1980)

found out that the fineness o f grinding o f the sample had less effect on the
|

disappearance o f dry matter as the period o f incubation was increased. Mohammed 

and Smith (1977) as cited by Kempton (1980) found out that with grains however, 

cracking o f the glumes increases degradability and with protein meals, degradability 

increases with reduction in particle size.

The basal diet of cannulated animals has major effect on dry matter 

disappearance. Kempton (1980) found out that the half time for dry matter 

disappearance from rice hulls is considerably less in sheep given a diet o f chopped 

lucerne chaff in comparison with sheep given a diet o f liquid molasses and lOOg

25



wheatened chaff. Orskov and Hovell (1978) found out that dry matter disappearance 

was 18% lower in bags incubated in the rumen of zebu cattle given chopped sugar 

cane diet after 40h incubation than animals given pangola hay. It is therefore 

important that cannulated animals be given standard ration when used to assess the 

rates o f degradation o f most feed material.

It has been suggested that the position o f the nylon bag in the rumen affects 

the dry matter disappearance o f feed from the bag. Balch and Johnson (1950) as 

cited by Orskov et al. (1980) showed that the position o f the bag in the rumen had 

little or no effect on the degradation o f the various feeds.

Orskov et al. (1980) reported that the total time for complete or partial 

degradation varies with the material being incubated. As a rough guide, concentrates 

require ,12-36 hours, good quality forages 24-60 hours, and poor quality roughages 

48-72 hours. These are the times required to reach the asymptote (potential 

degradation). Mehrez and Orskov (1977) found that the greatest source o f variation 

in the dry matter disappearance from the bags was betw een, (animal) component 

(6.2% of the mean) followed by that o f between days (4.9%). The least variation 

was found between the bags (3.3%) incubated together and withdrawn at the same 

time. They suggested that the use of one bag, two days (that is a repeat 

measurement, and three sheep was a reasonable combination). The number o f bags 

incubated is affected by the type of animal used. In cattle, which generally can have 

much larger rumen cannulae than sheep, the number of bags incubated at one time 

can be greater than with sheep, 12 in Balch and Johnson (1950) and 20 in Miles

26



(1951) as cited by Orskov et al. 1980). With sheep, Mehrez and Orskov (1977) 

found it preferable to incubate no more than five bags in the rumen at the same time 

in order to avoid the difficulties in their removal from the rumen.

2.8 TOXIC PRINCIPLES IN BROWSE PLANTS

Apart from being low in digestibility, some tree species have low acceptability 

to livestock or contain deleterious principles (Duke 1981, Maslin et al. 1987; Ivory, 

1989). High levels o f phenolic compounds such as tannins in many tree species 

have been implicated as reducing acceptability (Hegarty et al. 1986; Brewbaker,

1986). Duke (1981) listed ninety-seven toxic substances found in some browse 

legumes. These principles limit the use o f the browse plants as livestock feed 

(Hegarty et ah 1964).

Hegarty et al. (1964) reported that it is not possible to add Leucaena at more 

than 30% of the diet of goat due directly or indirectly to its mimosine content. 

Mimosine is degraded by the action of saliva and above all by rumen microbial 

action to 3,4-dihydroxypyridine (DHP) and thence to 2,3 - DHP which have anti 

thyroid effects (Hegarty et al., 1986; Christie et al., 1979; Jones, 1979). However, 

in Indonesia a solution to the mimosine problem has been found in the presence of 

a gram negative bacterium capable o f metabolising DHP to innocuous substances 

(Jones, 1986). This microbe is transferable from ruminant to ruminant both 

artificially and by contact (Jones et al. 1985; Jones and Megarrity, 1986). Although 

low mimosine lines o f Leucaena have been bred, their low dry matter yield makes

27



them undesirable. Some Acacia species contain linamarine, a cyanogenetic glycoside 

that can kill instantly by disrupting the electron transport system. If  small doses of 

linamarine are taken in, thiocynate is rather formed and this is goitrogenous as it 

inhibits the formation o f thyroxine (Jones 1986). There are various ways by which 

the toxicity o f these browse plants can be reduced. Kang and Reynolds (1986) 

reported that a combination o f these tree/shrub fodder planted in alley farms and 

intensive feed gardens (IFG’s) could allow mixed foliage to be offered to livestock 

and this would minimise the possibility o f toxicity from high levels o f intake o f only 

one species. This idea has also been expressed by Lowry (1989) who reported that 

a simple approach to reducing toxicity is to feed the toxic plant in a mixture with 

other plants, thus diluting the effective level o f each compound. Toxicity can also 

be minimised through management practices as in many plants, the level of 

secondary compounds is higher in new or developing leaves than in matured leaves 

(Lowry 1989). Detoxification by rumen microbial activities is also a possibility 

(Jones 1986).

28



CHAPTER THREE

EX PERIM EN T ONE

TITLE: Seed germ ination in some browse plants.

3.1 INTRODUCTION

Throughout the developing tropical world, shrub and tree fodders are 

traditionally used in feeding livestock. This practice calls for studies into sustainable 

propagation and establishment to enhance their exploitation for the benefit o f  the 

livestock industry. Humphreys and Riveros (1986) advocated that successful pasture 

establishment occurs when good quality seed or cutting is given the right conditions 

to germinate or sprout and grow.

The objective of the study was to test in vitro, the most appropriate technique 

for breaking the dormancy o f the seed o f one adapted and nine native browse plants.

3.2 M ATERIALS AND M ETHODS

The study was carried out on the seed of the following 10 browse species in 

the laboratory o f the Department o f Animal Science, University o f Ghana, Legon 

(Lat. 5° 38’N and 60° O’N, Long. 0° 12’W and 0° 5’E)

i. Cajanus cajan (L) Millsp. 

ii. Dialium guineense Willd. 

iii. Afzelia africana Sm.

iv. Khaya senegalensis (Desr) A. Juss.

29



v. Grewia carpinifolia 

vi. Pithecellobium dulce (Roxb) Benth

vii. Albizia lebbek L (Benth)

viii. Milettia thonningii (Schum & Thonn) 

ix. Baphia nitida Lodd.

x. Griffonia simplicifolia (Vahl ex DC) Baill

The seeds were given the following treatments.

(a) Sowing without any treatment (control) (T,).

(b) Soaking in water at room temperature for 14 hours before sowing (T2).

(c) Immersing in hot water at 80°C for five minutes before sowing (T3).

(d) Scarifying with sand paper until their testa broke before sowing (T4).

The experiment, was a 10 x 4 factorial arranged in a completely randomised

design with four replicates, the factors being the ten browse species and the four 

treatment methods. Cotton wool was placed in petri dishes and the seeds were 

placed on the cotton wool in the dishes. There were five petri dishes per treatment 

and twenty seeds per dish for all the species with the exception o f Afzelia africana 

and Khaya senegalensis where there were ten petri dishes and ten seeds per dish as 

their seeds were so big that twenty could not be contained in one petri dish. Each 

treatment was replicated four times. The petri dishes were covered but occasionally, 

the lids were removed to flush in fresh air. Water was sprinkled on the seeds daily 

when necessary and germination counts made daily for each treatment over a period 

of 18 days. The appearance of the radicle was used as an index of germination. The

30



rate o f germination was calculated using the method of Maguire (1962). This was 

done by dividing the number of normal seedlings per 100 seeds obtained at each 

counting in the standard germination test by the number o f days seeds have been in 

the germinator. The values obtained at each count were then summed at the end o f 

the germination test to obtain the germination rate. This is expressed as follows:

Number o f normal seedings +— +—  + Number o f normal seedlings 
Days to first count Days to final count

Data obtained for the germination percentage were subjected to the arcsin percentage

transformation after which analysis o f variance was performed on the data. The

treatment means were compared, using the LSD procedure according to Steel and

Torrie (1980).

3.3 R E S U L T S

Table 3.1 shows the percentage germination o f the seed o f the browse species 

given different treatments. Seeds of Baphia nitida and Griffonia simplicifolia did not 

germinate over the study period. The species differed significantly (P<0.05) in 

percentage seed germination. Cajanus cajan , Afzelia africana and Milettia 

thonningii had 83.8, 85.8 and 93.8% respectively which were significantly higher 

(P<0.05) than the rest of the species for the control. Grewia carpinifolia and 

Dialium guineense had very low germination (10.8% and 12.1% respectively).

For the warm water treatment, Milettia thonningii, Afzelia africana and 

Cajanus cajan had germination value of 90.4%, 77.5% and 69.6% and these were

31



significantly higher (P<0.05) than the rest o f the species. Germination was lowest 

for Grewia carpinifolia and Dialium guineense.

For mechanical scarification, Milettia thonningii, together with Albizia lebbek, 

Afzelia africana and Cajanus cajan were superior to the rest o f the species (P<0.05). 

Grewia carpinifolia and Khaya senegalensis were significantly very low (P<0.05).

Mechanical scarification did not affect the % germination but warm and hot 

water slightly depressed the germinability o f Cajanus cajan.

Table 3.1: Percentage germination of browse plants under different seed
treatments

SPECIES

T R E A T M E N T
LSD
(5%)Control

(T.)
Warm water 

(T2)
Hot 

water (T3)
Mechanical
scarification

(T4)

Cajanus 83.8 69.6 74.6 86.3 9.6

Albizia 26.7 30.4 86.3 94.6 9.1

Milettia 93.8 90.4 90.4 98.3 NS

Ajzelia 85.8 77.5 94.2 97.5 NS

Pithecellobium 65.4 47.5 65.4 65.8 NS

Grewia 10.8 10.4 2.9 15.5 5.0

Khaya 44.2 40.8 28.3 10.8 13.7

Dialium 12.1 5.0 8.8 53.8 5.7

LSD (5%) 15.0 10.2 11.4 17.5

NS = Not significant
LSD , Species x treatment = 9.1

32



Table 3.2: Effect of seed treatment on germination time of browse plants (Days)

SPECIES T R E A T M E N T LSD
(5%)

Control
(T,)

Warm water 
(T2)

Hot 
water (T3)

Mechanical
scarification

(T4)

Cajanus 3.5 3.4 3.4 3.4 NS

Albizia 13.8 14.3 12.8 2.3 4.2

Milettia 4.3 5.4 4.6 3.8 0.7

Afzelia 12.7 12.7 12.0 6.3 2.6

Pithecellobium 7.0 4.3 5.5 3.7 1.0

Grewia 6.7 8.8 9.6 6.4 NS

Khaya 9.0 8.4 7.8 6.8 2.0

Dialium 4.4 7.5 5.8 3.3 1.0

LSD (5%) 3.0 1.8 2.4 2.8

NS = Not signiJleant
LSD, Species x treatment = 1.5

For Albizia lebbek hot water treatment or mechanical scarification significantly 

(P<0.05) improved the germinability while warm water only slightly influenced it. 

There were no significant differences (P>0.05) among treatments for Milettia 

thonningii, Afzelia africana and Pithecellobium dulce. With regard to Grewia 

carpinifolia hot water treatment depressed % germination (P<0.05) while mechanical 

scarification increased it slightly. Warm water treatment did not affect it.

33



In Khaya senegalensis, whereas warm water treatment did not affect the % 

germination hot water treatment and mechanical scarification actually decreased the 

% germination (P<0.05). In Dialium guineense,hot water treatment did not affect 

the germination percentage, whereas warm water depressed it (P<0.05) and 

mechanical scarification increased it (P<0.05). There was a significant (P<0.05) 

species x treatment effect on percentage germination.

Table 3.2 shows the effect of seed treatment on germination time o f the 

browse plants in days. Significant differences (P<0.05) were observed among the 

species under all treatments. No matter what treatment method was adopted, 

Cajanus cajan and Milettia thonningii took the same time to germinate for all the 

treatments (3 and 4 days respectively). Mechanical scarification reduced the number 

of days to germination from 13.8 to 2.3 and 12.7 to 6.3 in Albzia lebbek and Afzelia 

africana respectively. For Grewia carpinifolia and Dialium guineense, warm and 

hot water treatments increased the number o f days to germination. The control and 

mechanical scarification were similar. There was a significant (P<0.05) species x 

treatment effect on days to germination.

The rate o f germination of the eight species o f browse plants under different 

treatments is presented in Table 3.3. The species differed significantly (P<0.05) in 

the rate of germination. Significantly higher (P<0.05) germination rates were 

recorded by Pithecellobium dulce, Milettia thonningii and Albizia lebbek in T4 (15.5,

31.1 and 42.0 respectively). With the exception of Khaya senegalensis in which the 

germination rate in T4 was significantly lower (P<0.05), (0.9) than in the others.

34



Mechanical scarification significantly increased (P<0.05) the germination rate in all 

other species more than the other treatments.

There was a significant (P<0.05) species x treatment effect on rate o f 

germination.

Table 3.3: Rate of germination of browse plants under different seed
treatments

Species

T r e a t m e n t

LSD 5%Control
(T.)

Warm
water
(T2)

Hot
water
(T3)

Mechanical
scarification

(T4)

Cajanus 2.3 1.0 1.4 4.8 0.13

Albizia 2.1 2.7 8.3 42.0 0.43

Milettia 22.0 11.9 22.8 31.1 0.36

Ajzelia 6.4 6.0 6.7 7.8 0.16

Pithecellobium 7.1 11.0 8.1 15.5 0.36

Grewia 1.8 1.6 0.3 4.8 0.13

Khaya 3.6 3.9 3.0 0.9 0.45

Dialium 3.9 0.8 1.6 18.5 0.32

LSD (5%) 0.92 0.13 0.17 0.52

LSD Species x treatment = 0.19

35



3.4 D I S C U S S I O N

The differences in the germination o f the browse species as influenced by the 

different treatments adopted seem to agree with the findings o f other workers 

(Whiteman, 1980; Grant and Clatworthy 1984). Although seed treatment generally 

promotes germination, the actual method used would depend on the browse species 

and the feasibility o f the seed treatment method. The high germination obtained in 

the scarified seed agree with the findings o f other workers (Viliers, 1972; Ellis et al. 

1985). Such treatments are known to improve germination by enhancing 

permeability to moisture and gases (Milthorpe and Moorby, 1986; Tybirk 1991). It 

may also increase the seeds sensitivity to temperature and light as well as result in 

the removal or destruction o f some o f the inhibitory substances (Ellis et al. 1985) 

thus improving germination. On the contrary, comparatively lower germination with 

scarification have also been reported in other studies (Clark et al. 1968; Bewley and 

Black, 1978). Scarification damaged the seed coat o f such seeds and led to the loss 

of cell contents stimulating the growth o f fungal pathogens. The low germination 

given by the scarified seeds o f Khaya senegalensis might be attributed to the fact 

that mechanical scarification led to the peeling off o f a greater part o f the embryo 

and subsequent build up o f fungal pathogens..

Dell (1980) reported that different treatments gave different water uptake 

curves for Albizia lophanta. This gives an indication that the various treatments 

adopted in the trial might have affected the imbibition o f water by the seeds 

differently hence some o f the species recording higher germination than others.

36



Tybirk (1991) reported that seed coat dormancy o f legumes in semi-arid climate has 

many important ecological advantages such as endozooic dispersal, recolonisation 

after fire and escape in terms o f time. This is seen in the differential germination 

of hard seeded legumes o f a population under the same stimulus.

Seeds with no pretreatments have been found to germinate in spurts if  kept 

moist over long periods o f time (Halevy, 1974; Coe and Coe, 1987). This explains 

why appreciable germination was recorded in some of the untreated species. Even 

though most o f the species obtained their lowest germination in the untreated groups, 

some of them germinated after long periods as was exhibited by Albizia lebbek and 

Afzelia africana.

Freshly harvested seeds have been reported to germinate differently from 

seeds that have been stored for some period. For example, fresh seeds o f Cassia 

siberiana, Albizia gummifera, Acacia hockii, Acacia milifera and Acacia tortilis had 

germination of 67-100% after hot water treatment, whilst the same treatment gave 

germination of 3-31% for old stored seeds (Schmidt 1988 as cited by Tybirk, 1991). 

This might explain the differences found in the various treatments as some of the 

seeds for the study were collected after their dispersal from the plant whilst other 

seeds were collected whilst still on the plant.

Ellis et al., (1985) have observed imbibition injury and subsequent destruction 

of the embryo o f forage sorghum (Sorghum vulgare) when immersed in warm water. 

In the same way Rudrapel and Basu (1980) also observed soaking injury resulting 

from rapid imbibition when soybean was immersed in warm water. These findings

37



might explain why Dialium guineense seeds for both warm and hot water treatments 

were very low. Tybirk, (1991) reported that the kind of treatment and the duration 

of the treatment is very important and this should be considered in each case and 

depends mainly on species, duration o f storage o f the seed and moisture content o f 

the seed.

Maguire (1962) reported that seedlots with similar total gemination often vary 

in the rate o f seedling emergence and rate o f growth. This finding seems to explain 

the differences that were observed in both the percentage germination as well as the 

rate of germination. For example, Milettia thonningii and Afzelia africana had 

similar germination percentages (98.3 and 97.5) respectively for mechanical 

scarification, their rates o f germination were 31.1 and 7.8 respectively. Also 

Cajanus cajan recorded a high % germination (86.3) for mechanical scarification but 

a low rate of germination o f 3.4. This might also be explained by varietal 

differences (Craddock and Vogel, 1960 as cited by Allen et al., 1961) who reported 

that large varietal differences in rate o f seedling emergence occur in nature. The rate 

of germination has also been found to decrease with decreasing available moisture 

but the rate of decline varies with species (Evans and Stickler, 1961; Nyborg 1961).

The reason why Baphia nitida and Griffonia simplicifolia failed to germinate 

is not quite clear. However, it was observed that the seeds got mouldy within 24 

hours after sowing in the petri dishes and some greenish liquid was found in them 

especially in Griffonia simplicifolia. This greenish liquid may contain inhibitors to

38



germination and the seed may as well need "after ripening" period since they were 

freshly collected from the plants.

39



CHAPTER FOUR

EXPERIMENT TWO 

TITLE: GROWTH AND DEVELOPMENT OF SELECTED BROWSE

PLANTS OF GHANA

4.1 INTRODUCTION

According to Noggle and Fritz (1986) the term growth in the broad sense is 

used to denote an increase in size by cell enlargement and cell division together with 

the synthesis o f new cellular material and the organisation o f sub cellular organells. 

Development however is used to encompass the activities resulting from growth and 

differentiation.

Growth can be measured in many different ways. These include plant height 

measurement, individual leaf size (length, width, area), plant fresh weight and dry 

weight partitioned among organs such as roots, stems, leaves and fruits, cell numbers 

in tissues and organs, and concentration o f specific chemical constituents (nucleic 

acid, soluble nitrogen, protein nitrogen, lipids, carbohydrate) in tissues and organs.

The growth and development o f browse plants is affected by genetic, 

nutritional, environmental and hormonal factors. How these factors affect the growth 

and development o f the plant would ultimately determine its yield. The leaf with its 

axilliary bud is the smallest module of organised structure in higher plants and it 

plays a vital role in the construction of the crown structure o f the tree (Harper and 

White, 1974). Many strategies of leaf display and variation in leaf life span have

40



been evolved to maximize production in higher plants (Chabot and Hicks, 1982). 

Thus total leaf area is primarily determined by the pattern o f production, leaf fall and 

longevity of leaves (Watson, 1956) along with seasonal variation in leaf size 

(Kozlowski, 1971). Many investigations related to plant growth processes such as 

photosynthesis, net assimilation rate (NAR), transpiration and response to 

management practices require an estimation o f leaf area (Ndawula-Senyimba, 1972).

The objective o f this experiment was to study the changes in plant height 

with time, the relative growth rate (RGR), net assimilation rate (NAR) and leaf area 

ratio (LAR) of the browse plants.

4.2. MATERIALS AND METHODS

Soil collected from Pokoase Agricultural Station, 15km from Legon, was 

autoclaved at 2.11 kg/cm2 pressure and put into perforated polythene bags o f size 

18cm x 25cm. The bags were then put under a 2xh  m high shed behind the Animal 

Science Department, University of Ghana, Legon, and planted with the following 

eight browse species.

1. Cajanus cajan (L) Millsp.

2. Dialium guineense willd.

3. Afzelia africana sm.

4. Khaya senegalensis (Desr) A Juss

5. Grewia carpinifolia

6. Pithecellobium dulce (Roxb) Benth.

41



7. Albizia lebbek (L) Benth.

8. Milettia thonningii (Schum and Thonn).

The experimental design was a completely randomised design with 8 

replicates. Four seeds o f each species were planted in each o f the polythene bags. 

After emergence, the plants in the polythene bags were thinned to one plant per bag. 

Data collected included weekly height o f the plant from the soil surface to the tip of 

the terminal bud. The leaf area of the plants was determined every five weeks by 

using the cork borer method (Edje and Osiru, 1987). Two plants were used at a time 

for the leaf area determination. One of the two plants (A) was used to get the cork 

bored leaves and the leaves from the remaining plant (B) was bulked together with 

the leaves from (A) that was left after the cork bored leaves had been taken. The 

cork bored leaves as well as the other bulked leaves were dried in an oven to 

constant weight, and used to estimate the leaf area. The leaf area o f the leaf discs 

is related to the bulk leaf area as follows.

Area of leaf discs (cm2') = leaf area o f the bulk leaves ('em2)
weight (g) of leaf discs weight (g) of the bulk leaves

From this relationship, the leaf area of the bulked leaves was calculated.

For the determination of the growth rates o f the browse plants, the graphical 

method as described by Noggle and Fritz (1986) was used. Growth curves (Fig. 4.1) 

were plotted, a straight line, touching the curves at approximately 30 and 60 days 

after planting were drawn. Triangles were then constructed and the growth rates

42



calculated from the units o f the coordinates o f the graph. The calculated leaf area 

for the plants together with their dry matter accumulation for, 5, 10, 15 and 20 

weeks were used to calculate Net assimilation rate (NAR) and leaf area ratio (LAR) 

while the dry matter accumulation alone was used to calculate the relative growth 

rate (RGR) by using the following formulae (Noggle and Fritz, 1986).

RGR = 2.303 (log.n Wo - log,„ W,)
*2 ‘ t]

NAR = fWo - W ,) 2.303 (log10A? - loglp A ,)
(k - *i) (A2 A,)

LAR = (An - A ,) 2.303 (logl0 W2 - log10 W.)
2.303 (log10A2 log,0 A,) W2 W,)

where W „ A„ W2, A2 represent dry weights and leaf areas at time intervals t, and

tj respectively.

43



Pl
an

t 
h

ei
g

h
t 

(c
m

)

L S D (P < 0 '0 5 ) 

I  LSD

5 10 15 20

No. of weeks after emergence

(P <  0 05)

Cajanus

Albizia

Milettia

Afzelia

Pithecellobium —■—
Grewia

Dialium

Figure 4.1: Height (cm) of seven browse species 

during 20 weeks of growth

44



4.3 RESULTS

Khaya senegalensis seeds did not emerge in the test and Dialium guineense 

and Grewia carpinifolia had very poor emergence (Table 4.1).

Table 4.1: Number of seeds of browse species that emerged from the soil

Species
Replicates Total %

Emergence
1 2 3 4 5 6 7 8

■ Emergence

Cajanus 4 4 3 4 4 4 3 2 28 87.5

Albizia 4 4 4 3 4 3 2 3 27 84.4

Milettia 4 4 3 4 3 3 4 4 29 90.6

Afzelia 3 3 4 4 4 2 3 3 26 81.3

Pithecellobiu
m

2 3 2 2 2 1 2 2 16 50.0

Grewia 1 0 0 1 1 0 0 0 3 9.4

Khaya 0 0 0 0 0 0 0 0 0 0

Dialium 2 0 0 1 0 1 0 1 5 15.6

In view of this, after taking the height measurements o f these two species subsequent 

measurement on them were discarded hence the species that were used to continue 

the study were, Cajanus cajan, Afzelia africana, Pithecellobium dulce, Albizia lebbek 

and Milettia thonningii.

The growth rates o f the plants are shown in Table 4.2. The growth rate of 

Cajanus cajan was the highest at both 30 and 60 days of growth. This was followed 

by Grewia carpinifolia, Albizia lebbek and Pithecellobium dulce in that order. These 

also had increases in growth rates at 30 and 60 days o f growth. On the contrary, 

Afzelia africana, Millettia thonningii and Dialium guineense had low growth rates

45



and their growth rates fell at 30 and 60 days o f growth.

46



Table 4.2: Growth rates (cm d'1) of browse plants to 30 and 60 days after

planting

Species 30 days 60 days

Cajanus cajan 2.80 4.20

Grewia carpinifolia 1.75 1.86

Albizia lebbek 1.63 1.75

Pithecellobium dulce 1.40 1.75

Afzelia africana 0.70 0.20

Milettia thonningii 0.46 0.07

Dialium guineanse 0.35 0.11

The leaf area development o f browse plants for 5, 10, 15 and 20 weeks o f growth 

is presented in Table 4.3.

Table 4.3: Leaf area development of browse to 20 weeks of growth (cm2)

Species W e e k s X SE

5 10 15 20

Pithecellob
ium

744.4 1486.7 1211.7 1982.8 1356.43 259.0

Cajanus 4768.6 37562.7 39854.7 128660.8 52711.7a 26554.3

Afzelia 461.0 2481.0 2362.3 2022.4 1831.73 467.1

Albizia 586.7 1811.8 4450.2 6160.6 3252.3a 1260.7

Milettia 568.9 1524.2 2125.9 3429.6 1912.23 598.8

X 1425.9a 8973.3A 10001.0A 28451.3A

SE 836.9 7149.6 7482.2 25063.9
Means bearing the same superscript are not significantly different (P>0.05).

47



Table 4.3 shows that the leaf area o f Cajanus cajan, Albizia lebbek and 

Milettia thonningii continuously increased from week 5 through to week 20.

Table 4.4: Dry matter yield of browse plants to 20 weeks of growth (g)

Species W e e k s X SE

5 10 15 20

Pithecellobium 0.30 6.2 2.9 5.1 3.6a 1.3

Cajanus 5.5 38.3 65.6 279.9 97.3a 62.1

Afzelia 0.8 4.2 4.8 4.3 3.5a 0.9

Albizia 0.5 8.3 10.3 13.4 8 . r 2.6

Milettia 0.3 6.4 8.5 9.2 6.1a 2.0

X 1.5a 12.7A 18.4a 62.4a

SE 1.0 6.4 11.9 54.4
Means bearing the same superscript are not significantly different (P>0.05).

The highest yield o f dry matter was recorded by Cajanus cajan from week 5 

through to week 20 (Table 4.4). Similarly Albizia lebbek and Milettia thonningii 

also increased in dry matter accumulation from week 5 through week 20 but these 

increases were not as large as in Cajanus cajan. Pithecellobium dulce increased in 

dry matter accumulation from week 5 till week 10, decreased in week 15 and rose 

again in week 20. Afzelia africana on the other hand, had increases in dry matter 

from week 5 till week 15 and then decreased in week 20.

Relative growth rate (RGR), Net assimilation (NAR) and Leaf area ratio (LAR) of 

5 browse plants to 70 days of growth are presented in table 4.5.

48



Table 4.5: RGR, NAR and LAR of five browse plants to 70 days of growth

Species RGR (g g'd- ' ) NAR (g cm'2d_1) LAR (c m V 1)

Pithecellobium dulce 0.026 435.24 x 10-6 59.89

Cajanus cajan 0.052 153.46 x lO"6 339.40

Afzelia africana 0.021 189.06 x 10'6 108.45

Albizia lebbek 0.030 491.05 x lO'6 61.58

Milettia thonningii 0.027 439.72 x lO'6 60.32

Values o f RGR and LAR were highest in Cajanus cajan whilst its value for 

NAR was the lowest. Pithecellobium dulce had the fourth highest value in RGR, 

third in NAR and lowest in LAR. Afzelia africana had the lowest value for RGR 

and fourth value for NAR and and second in LAR. Albizia lebbek had the highest 

value in NAR, second in RGR and third in LAR. Milettia thonningii was second in 

NAR, third in RGR and fourth in LAR.

4.4 DISCUSSION

Based on the results o f the RGR, NAR and LAR, it was obvious that Cajanus 

cajan was able to increase its dry weight at a faster rate than the rest o f the species. 

That Albizia lebbek had the highest value for NAR could be explained in terms of 

species differences. Watson (1952) explained that the NAR measures the net result 

of photosynthetic gain over respiratory loss and this may vary according to the 

magnitude of respiration. For example, if  the total respiration o f an entire plant is 

expressed in terms o f leaf area, then NAR is likely to increase with age but LAR 

will decrease, as an older plant is not as leafy so that NAR could fall irrespective of

49



change in photosynthetic activity.

The lowest NAR value obtained from Cajanus cajan suggests that it was the 

poorest in putting up dry material. This was not the case since Cajanus cajan 

accumulated the highest dry matter. This discrepancy could be explained by the 

findings of Watson (1952) that precautions should be taken when comparing species 

by using their NAR values. Watson (1952) noted that because NAR gives no direct 

indication of respiratory losses, it does not necessarily serve as a direct measure of 

inherent photosynthetic capacities. Watson (1952) reported that while NAR indicates 

a plant efficiency at producing dry matter, economic yield is subject to additional 

controls and it is not necessarily related to photosynthetic efficiency. The 

differences in NAR observed in the species agree with the findings o f Hunt (1978) 

that wide variation in NAR may occur between species.

50



CHAPTER FIVE

EXPERIMENT THREE 

TITLE: PROPAGATING NATIVE BROWSE PLANTS USING STEM

CUTTINGS. 

5.1 INTRODUCTION

Propagation by stem cuttings is one o f the means o f establishing browse plants 

(Le Houerou 1980c, Adegbola 1985, Ivory 1989). In some plant species, this is the 

surest way of their establishment as the seeds produced by these plants may not be 

viable, or seedling growth from germinated seeds may be very slow.

Establishing cuttings in the nursery improves the survival rates o f stem 

cuttings: Growth regulators such as hormones are very important in the

establishment o f stem cuttings as they may help to improve root development so that 

the cuttings could easily be established.

The objective o f this experiment was to study the sprouting ability as well as 

the growth rate o f some native browse plants using hardwood stem cuttings and with 

the help o f a rooting hormone.

5.2 MATERIALS AND METHODS

Soil collected from Pokoase and treated as in Chapter 4 was used. The 

polythene bags were put under a two and half metre

high shed to provide shade for the cuttings. The browse species used in the study 

were Cajanus cajan, Dialium guineense, Afzelia africana, Khaya senegalensis,

51



Grewia carpinifolia, Pithecellobium dulce, Albizia lebbek, Milettia thonningii, 

Baphia nitida, Grijfonia simplicifolia, Ficus exasperata and Spondias mombin. These 

were treated with a rooting hormone before planting.

The hormone, Biozyme TS (manufactured by Bioenzymas S.A. De Cu of 

Mexico) was used together with an adherent - Bionex (manufactured by the same 

company).

There were four treatments as follows:

1. No hormone application (control treatment) (T,).

2. Application o f the hormone and adherent based on the manufacturer’s 

recommendation (i.e. 5cc Biozyme TS plus lcc Bionex in one litre of 

water) (T2).

3. Twice the normal concentration o f the hormone (i.e., lOcc Biozyme TS 

plus 2cc Bionex in one liter o f water) (T3).

4. Three times the normal concentration o f the hormone (ie 15cc 

Biozyme TS plus 3cc Bionex in one litre o f water) (T4).

Mean diameter and length o f the cuttings were 15mm and 30cm respectively. 

The base o f the cuttings were dipped in the hormone solution for 10-15 minutes 

before planting. The experiment was a 12 x 4 factorial arranged in a completely 

randomised design with four replicates, the factors being the twelve browse plants 

and the four treatment methods.

Data were collected on the number of sprouts on every cutting at two and four 

weeks after planting. The plant height (cm) taken from the base to the tip o f the

52



sprout from each cutting was recorded at monthly intervals for a period o f six 

months.

5.3 R E S U L T S

Table 5.1 shows the sprout check on cuttings 2 and 4 weeks after planting. 

Sprouting did not occur in Griffonia simplicifolia, Afzelia africana, Dialium  

guineense and Albizia lebbek in any o f the treatments while Cajanus cajan, Grewia 

carpinifolia, Khaya senegalensis and Spondias mombin sprouted in all the four 

treatments but died within 2 to 4 weeks after sprouting. A close look at the base of 

the cuttings which died after sprouting as well as those that never sprouted indicated 

that no roots developed in them. Thus the species that actually survived were: 

Baphia nitida, Milettia thonningii, Pithecellobium dulce and Ficus exasperata.

Figure 5.1 shows the effect o f hormone application on the growth o f the 

browse species during 6 months of growth. The species differed significantly 

(P0.05) in the growth o f the sprouts.

Pithecellobium dulce gave significantly higher (P<0.05) growth than the rest o f the 

species for all the treatments. For T, Pithecellobium dulce was highest (15.5 cm), 

followed by Baphia nitida (7.3 cm) with Ficus exasperata being the lowest (2.3 cm).

For T2, Pithecellobium dulce was the highest (53.9cm) followed by Baphia 

nitida (6.5 cm), then Ficus exasperata (2.5 cm) with Milettia thonningii being the 

lowest (1.0 cm). In T3, Pithecellobium dulce was again the highest (31.2 cm)

53



followed by Milettia thonningii (22.3 cm). Ficus exasperata and Baphia nitida were 

similar (2.9 cm and 2.3 cm respectively). In T4, Pithecellobium dulce was highest 

(33.1 cm) followed by Ficus exasperata (20.0 cm) then Milettia thonningii (11.1 cm) 

and then Baphia nitida (2.8 cm).

Baphia nitida in T, was the highest (7.3 cm) whilst that in T3 was the lowest 

(2.3 cm). For Milettia thonningii T3 was the highest (22.3 cm). This was followed 

by T4 (11.1 cm) whilst T2 was the lowest (1.0 cm). With regards to Pithecellobium  

dulce, T2 was the highest (53.9cm). This was followed by T4 (33.1cm) whilst T, 

was lowest (15.5cm). Ficus exasperata had a significantly higher (P<0.05) growth 

(20.0cm) for T4 compared to all the other treatments.

54



Table 5.1: Sprout check on cuttings 2 and 4 weeks after planting

Species

Period 1 (2 weeks) Period 2 (4 weeks)

T, t 2 T3 T4 T, t 2 T3 t 4

Cajanus cajan + + + + - - -

Albizia lebbek - - - - -

Pithecellobium dulce + + + + + + + +

Milettia thonningii + + + + + + + +

Afzelia africana - - - - - - -

Grewia carpinifolia + + + + - - -

Khaya senegalensis + + + + - - -

Baphia nitida + + + + + + + +

Griffonia simplicifolia - - - - - - -

Dialium guineense - - - - - - -

Ficus exasperata + + + + + + + +

Spondias mombin + + + + - - -

Normal concentration of hormone 
Twice the normal concentration o f hormone 
Thrice the normal concentration o f hormone 
Presence o f sprouts (roots or buds)
Absence of sprouts (roots or buds)

55



Figuro 
5.1: 

E
ffect 

of 
H

orm
one 

A
pplication 

on 
the 

G
row

th 
o

f 

4 
brow

se 
p

lan
ts

Height (cm) Height (cm)

o3

O
U1

Height (cm) 
3 8

Height (cm)
« 8 8

Ao
ou\

(S
O'

O 
> 

d)
 Q

S"
I



5.4 DISCUSSION

The differences in growth among the browse species is in agreement with the 

findings of Larbi et al (1993) who classified Baphia nitida together with Dialium

guineense as very slow growth rate types o f browse plants and Leucaena

leucocephala together with Alchornea cordifolia as fast growth rate types. These 

differences may also have been influenced by the age, diameter and length as well 

as the depth o f planting. Since stem cuttings were taken from plants whose ages 

could not be determined, it could be that the cuttings were taken from plants o f

different ages, resulting in the differences in growth. Falvey, (1982) has

recommended that cuttings should be taken from stems which are at least six months 

old and from the lower part o f the tree, and should be matured. They should be of 

diameter of 7.0cm and o f length 0.5-2m. The diameter and length o f the cuttings 

used in the study were 15mm and 30cm respectively which is in contrast with the 

7cm in diameter and 0.5-2m in length as recommended by Falvey (1982) and Glover 

(1989) as cited by Shelton (1994a).

It was not clear why some of the cuttings failed to develop roots since the 

basis of choosing the hormone was to help the cuttings to develop roots quickly so 

that the sprouts could easily survive. Here, it could be said that the hormone is 

likely to be effective for some species and not others. The failure of some of the 

cuttings to develop roots may also be attributed to the depth o f planting. Glover 

(1989) as cited by Shelton (1994a) recommended that cuttings should be planted 20- 

50cm deep into the soil and since a planting depth of less than 6cm was adopted in

57



the study it might be possible that the shallow depth o f planting affected the root 

development of some of the species.

Environmental conditions have been found to modify the pattern o f shoot 

development in stem cuttings (Noggle and Fritz, 1986) and it is possible that the 

ambient temperature and relative humidity provided during the study period were not 

all that conducive for the development of the shoot system, hence the differences in 

growth.

58



CHAPTER SIX

EXPERIMENT FOUR

TITLE: FORAGE YIELD OF SOME NATIVE BROWSE PLANTS
ESTABLISHED ON THE FIELD

6.1 INTRODUCTION

The importance o f browse trees and shrubs is acknowledged throughout the 

world and much work is being carried out under various disciplines (Le Houerou 

1980a). The major value o f such plants is that they provide protein, vitamins and