Livestock Research for Rural Development 27 (12) 2015 Guide for preparation of papers LRRD Newsletter

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Effect of maturity on chemical composition of edible parts of Ficus thonningii Blume (Moraceae): an indigenous multipurpose fodder tree in Ethiopia

Mulubrhan Balehegn and Kidane Hintsa

Department of Animal, Rangeland and Wildlife Sciences, Mekelle University, Post Box 231, Mekelle, Ethiopia
mulubrhan.balehegn@mu.edu.et   ,   mulubrhanbghz@yahoo.com

Abstract

Ficus thonningii is an important fodder species with multipurpose benefits to rural communities and many desirable qualities such as drought resistance, absence of allelopathic effects, lower anti-nutritive contents, easy propagation and fast growth rate. Despite its use, through lopping,  as a seasonal emergency feed for livestock in the drylands, the effect of maturity (season lopping) on the nutritive value or chemical composition of the different edible parts of the is not known. This study was undertaken to analyze the nutritive value of the different edible parts: leaves, twigs and bark. Samples were taken from young (< 6 months) and old (> 1 year) trees comprising different age ranges.

 

Most nutritive parameters: DM (dry matter), CP (crude protein), NFC (non-fibrous carbohydrates), NFE (nitrogen free extract), CF (crude fiber) and NDF (neutral detergent fiber), but Ca (calcium) and Mg (magnesium) varied significantly among three edible parts and two maturity levels. Most of the values were within the acceptable or tolerable range for ruminant and non-ruminant herbivores. Leaves were the most nutritious parts and bark was the least. It is concluded that  F. thonningii, an ever green drought resistant tree,  can be used as a ruminant fodder source during critical seasons, though farmers might need to  harvest leaves at young stage for optimum nutritional content.

Key words: browse, nutritive value, reforestation


Introduction

Ficus species are highly neglected and least studied indigenous fodder species (Bamikole et al 2004). Unlike their familiarity for being common home garden plants used in the form of live hedges, and fire breaks (Danthu et al 2002) and their reasonably higher nutritive value, Ficus species are rarely used as feed sources for ruminant animals (Bamikole et al 2004).

 

Ficus thonningii is one of such neglected and underutilized fodder plants.  In areas where it is used for feeding animals, it is  appreciated for its diverse merits including;  higher palatability to all species of animals (Balehegn and Eniang 2009), which is a reflection of reasonably good nutritive value (Berhe and Tanga 2013), higher biomass production (Balehegn et al 2012), fast growth rate and easy propagation (Mekoya et al 2008, Balehegn et al 2014a), demonstrable drought resistance and adaptation to diverse edapho-climatic conditions (Balehegn and Eniang 2009). It has also been demonstrated that F. thonningii leaf meal can replace costly commercial concentrates up to 50%, while improving animal productivity (Balehegn et al 2014a).

 

In areas where it is used for intensive livestock feeding, F. thonningii leaves are harvested by lopping branches and offering branches to animals, as the tree usually grows beyond heights accessible by most livestock types (Balehegn et al 2014b). For harvested forage, knowledge of right stage of harvesting is important for achieving optimum nutritional value of the harvested feed (Modi 2007). This is because harvesting season has been observed to significantly affect the nutritional value of harvest forage (Kamalak et al 2005). Inclusion of the nutritious and multipurpose fodder tree- F. thonningii in livestock diets, by a cut and carry system therefore requires understanding of the variation in nutritional content of the different edible parts at different levels of maturity. However, despite the importance of identification of the right time for harvesting in a cut and carry system, the effect of maturity level or stage of harvesting on the nutritive value of the different edible parts of F. thonningii is not yet known. Moreover, even if many herbivores browse on different parts of the plant, the nutritive value of different edible parts, apart from leaves, has not been analyzed. This study was undertaken with the objective of investigating the nutritive value of three edible parts of F. thonningii (leaves, twigs and bark) and the effect of age or stage of maturity on the nutritive value of the three edible parts.


Materials and Methods

The study was conducted in Ahferom district of Tigray, northern Ethiopia. The site lies at an altitude ranging from 1300 to 3200 masl and at 14o 7’00” to 14o 38’30” N and 38o 56’0” E. The district is characterized by very rugged topography and has altitude-based agro-ecological divisions: the high altitude “Dega”, medium altitude or semi-highland “Woinadega”, and low altitude “qola”. The area experiences a uni-modal rainfall pattern, typically between June and August, with a mean annual rainfall range of 350 to 650 mm (BOARD 2011). Mixed crop-livestock agriculture is the main livelihood of communities in the study area; with an overall 1533 ha of land, with 711 ha cultivable (686 ha rain-fed and 25 ha under irrigation), 357 ha area exclosure, 120 ha grazing land (including F. thonningii silvopastures), and 180 ha waste land (BOARD 2011). Common vegetation types that grow in the area include; Ficus thonningii, Croton macrostachyus, Cordia africana, Olea europae, Juniperus procera, Dodonaea angustifolia, Euclea schimperi and Allo spp (Balehegn 2011).

 

Edible fodder parts; leaves, twigs and bark of F. thonningii were collected from 25 trees comprising all age ranges. Two different samples with age or maturity level of young (< 6 months or new out growths) and old (> 1year or old plant parts) were collected for the three edible parts (leaves, twigs and bark). The samples for young and old of the three edible parts were mixed separately and three samples were taken for analysis from each of the mixtures. Samples were weighed and dried at ambient temperature, and ground to pass through a 1mm screen pending laboratory analysis.

 

Dry matter (DM) content was determined by oven drying at 105oC for 24h, and ash was determined by ashing samples in a muffle furnace at 600 oC for 16 hours (AOAC 1990). Ether extract (Okoli et al) using fat extractor apparatus, crude protein (CP) using Kjeldhal apparatus, crude fiber (CF) using Ankom fiber analyzer, neutral detergent fiber (NDF) using Ankom fiber analyzer, and Ca and Mg using atomic absorption spectrophotometer were all analyzed using the formal procedures of (AOAC 1990).Non fibrous carbohydrate (NFC) was calculated by difference: NFC= 100-(NDF+ CP+ EE+ Ash) (NRC 2001). The Nitrogen Free Extract was also calculated by subtraction as; NFE= 100-(CP+EE+CF+Ash).

 

The data were subjected to one-way analyses of variance (ANOVA) using the General Linear Model (GLM) procedures of JMP7 (SAS Institute 2002). Comparison of treatment means was performed using Fisher’s least significant difference test at p < 0.05.


Results

Proximate components of edible parts (Leaf, twig and bark) of Ficus thonningii

 

The proximate principles - DM, CP, EE, NFC,  NDF, CF, NFE and Mg - varied among edible parts, with most of the values being highest in leaves and lowest in bark, except for EE, CF and NDF which were highest in bark and lowest in leaves (Table 1).

 

Effect of stage of maturity on proximate components in edible parts of Ficus thonningii

 

While CP and Mg were higher in young leaves, DM and CF were higher in older leaves. Neither age nor its interaction with edible parts showed significant effect on the NFC, NFE and NDF content of edible parts (Table 2).

 

Ash content of the different edible parts did not show significant variation between the two age categories. The Ca contents in the old age groups for leaves and twigs were significantly higher than the young age groups. Similarly, Mg content also showed significant variation between age groups for leaves and twigs, but, higher values recorded in young than in the old edible parts (Table 2). However, there was no significant difference in the Mg content of bark among maturity stages (Table 2).

 

Higher CF was observed in old leaves than young ones (Table 2). NDF did not vary with stage of growth (Table 2), though there was a tendency towards increased NDF in older samples than younger ones for all edible parts (Table 2).  

 

Table 1. Average values of different proximate components of bark, leaf and twig of F. thonningii in Sefeo, central Tigray.

Edible Part

DM

CP

EE

CF

NFE

NDF

Ash

NFC

Ca

Mg

Bark

21.41±2.35

3.31±1.57a

6.30±0.32 a

24.67±0.77 a

65.72±1.99

47.52±0.77 a

20.36±2.72

22.51±1.58

0.22±0.05

0.12±0.02

Leaf

35.21±10.46

14.37±1.59 b

3.76±2.62

16.59±2.74

70.28±3.59 a

35.12±1.84

19.12±4.50

32.63±5.15 a

0.21±0.16

0.46±0.07 a

Twig

47.69±13.72

6.39±0.99 c

4.05±1.23

23.17±1.27 b

66.39±1.31

39.59±1.60

19.07±2.96

30.89±3.62 b

0.34±0.14

0.38±0.09 b

p- value

<0.0001

<0.0001

0.017

<0.0001

0.005

<0.0001

0.669

<0.0001

0.054

<0.0001

Values are mean± standard error. a, b, c value with in a column separated by different superscripts show differ at p < 0.05


Table 2. Effect of stage of maturity on the proximate contents of bark, leaf and twig of F. thonningii in Sefeo tabia of central Tigray

Composition

Edible parts

p - value

Leaf

Bark

Twig

Edible part

Age group

Edible Part*
Age group

Young

Old

Young

Old

Young

Old

DM

28.76±4.32 b

41.66±1.20a

21.3±2.39

21.51±2.68

37.82±8.25 b

57.56±10.56 a

<0.0001

0.00

0.05

CP

14.45±1.11 b

12.29±1.24 a

4.14±1.90 b

2.48±0.54 a

6.96±0.56

5.82±1.07

<0.0001

0.00

0.69

EE

4.28±3.471 b

3.24± 1.81 a

6.31±0.42

6.30±0.26

4.69±1.24

3.41±0.94

0.017

0.29

0.74

CF

14.34±1.93 b

18.83±0.59 a

24.36±0.76

24.98±0.75

22.56±1.04

23.78±1.30

<0.0001

0.00

0.01

NFE

70.94±4.68

69.63±2.68

65.19±2.27

66.25±0.95

65.79±1.33

66.98±1.12

0.051

0.77

0.06

NDF

33.96±1.65

36.28±1.27

47.31±0.73

47.74±0.85

38.54±0.76

40.66±1.55

0.669

0.19

0.11

ASH

20.18±3.98

18.07±5.35

19.04±3.15

21.68±1.65

16.65±1.69

21.50±1.40

0.669

0.19

0.11

NFC

31.14±5.25

34.12±5.33

23.21±0.94

21.81±1.90

33.16±1.56

28.61±3.78

<0.0001

0.51

0.14

Ca

0.12±0.10 b

0.31±0.16 a

0.20±0.06

0.23±0.04

0.28±0.08 b

0.40±0.16 a

0.054

0.02

0.03

Mg

0.53±0.01 b

0.40±0.02 a

0.13±0.02

0.12±0.01

0.44±0.08

0.32±0.08

<0.0001

0.00

0.03

Values are mean± standard error. a, b, c values for maturity levels (young and old) with in an edible part separated by different superscripts are different at p <0.05


Discussion

Proximate components of different edible parts of Ficus thonningii

 

The 35.2% DM content for F. thonningii leaves reported in the current study is higher than the 17% reported by Bamikole et al (2004). This value is also lower than values reported by Tegbe et al (2006) and Jokthan et al (2003). The lower DM% of the bark, in spite of its higher CF content as compared to the other edible parts can be explained by the fact that it contains 78.5% water, and need for water in the dry landscape might explain why it is readily peeled by wild and domestic animals. However, most reported values of DM for other Ficus species indicate lower values than results in this study (Devendra 1992, Joshi 1992, Bamikole et al 2004).   This inter-species difference can be explained by inherent variation in the physiology of the different species, but the large intra species variation indicate that other factors including age, agro-ecology and climatic conditions or season might have a role in explaning the variation.

 

The CP content of leaves (14.3%), and twigs (6.39%) (Table 1) are generally in agreement to the crude protein content of many indigenous fodder trees and shrubs in Africa (Le Houérou 1980) and are higher than the minimum tolerable percentage of 6% for tropical forages (Minson 1990). However, the bark has a very low (3.3%) CP content (Table 1). CP content of leaves observed in this research was also comparable to the results for F. thonningii  obtained by other researchers (Jokthan et al 2003, Tegbe et al 2006, Mekoya et al 2008).

 

Ether extract values ranging from 3.75 in leaves to 6.30 in bark are comparable to the values for leaves obtained by other researchers (Jokthan et al 2003, Tegbe et al 2006, Berhe and Tanga 2013). The higher EE content in bark as compared to that in leaf and twigs (Table 1), could be due to the protective waxy exudates in the bark that is commonly observed oozing when a branch or a stem is cut. 

 

The 32.6% (Table 1) non-fibrous carbohydrates or NFC of the leaves is generally lower than the optimum recommended range of 36-44% (NRC 2001). The  NFE (Nitrogen Free Extract), a common expression of carbohydrate content also varied with average values of 70.3% for leaf, 66.4% for twigs and, 65.7% for bark, indicating that most of the sugar content of the plant is concentrated in the leaves. These values are higher than the 42.4% NFE for F. thonningii recorded by Jokthan et al (2003) and Berhe and Tanga (2013). 

 

The ash content of leaves in this study (19.2%) is comparable to the 17.3% obtained by Jokthan et al (2003) but different from values reported by other researchers (Tegbe et al 2006, Berhe and Tanga 2013). This variation in ash content among results of different studies is probably caused by variations in edaphic environmental factors, which have direct bearing to mineral contents of plants.  

 

The values of CF for leaves and twigs are comparable to the results reported for other Ficus species (Bamikole et al 2004). The lower value of CF in leaves is perhaps one of the reasons for the ready acceptability and higher palatability of F. thonningii compared with other herbivorous species (Balehegn and Eniang 2009).  The NDF values of F. thonningii ranging from 35% for leaves and 45% for bark (Table 1) are comparable to the results for other Ficus species (Verma 1995) and can be considered as typical of tropical forages (Van Soest 1994), due to the high environmental temperatures in which the forages grow in this zone.

 

Generally, the small variation in content of different proximate components of edible parts of F. thonningii obtained by different researchers could be attributed to within species difference, plant parts, season, harvesting regimen, location, soil type, age and method of analysis (Yayneshet et al 2009).

 

Effect of stage of maturity on proximate components of edible parts of F. thonningii

 

Increase in DM with maturity, as observed for leaves and twigs in the currebt study (Table 2) has been observed in other studies (Oduntan et al 2012). The almost similar DM content of bark in the two age groups explains the fact that the bark is very watery even at an old age while the leaves and twigs become hardened with age.

 

Crude protein content of the different edible parts was higher in younger samples than the old ones, as is observed and well documented for other species (Tolera et al 1998, Roothaert 2000). It was also observed  there were differences in CP values between seasons (comparable effect to maturity as there is always new growth in the wet season and matured foliage in the dry season). This implies that local farmers who utilize F. thonningii trees for feeding their animals have to lop the trees before a significant decrease in CP occurs as a result of maturity of the edible parts, which in this case, is before the new outgrowths are one year old.

 

Ash content did not vary with age or level of maturity for all edible parts in the current study (Table 2). However, Roothaert (2000) found in Kenya that ash concentration increased during the dry season or with age in many indigenous fodder trees and shrubs. The Ca contents of leaves both at young (0.12%) and old (0.31%) stages were lower than the optimum requirement for lactating animals (NRC 2001). Therefore, lactating animals which depend on F. thonningii as a basal feed should obtain Ca supplementation.

 

An increase in CF as a result of maturity (Table 2), implies leaves get more fibrous with age compared to other edible parts. Increase in the values of CF with maturity in the different edible parts indicate that fibrousness of F. thonningii increases with age. Thus it is necessary for farmers to identify the point at which a significant increase in fibrousness takes place, in order to identify the right age for lopping branches for optimum nutritive value.


Conclusions


Acknowledgements

This research was funded by Mekelle University Research and Publication Office.


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Received 26 September 2015; Accepted 1 November 2015; Published 1 December 2015

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