The feed values of indigenous multipurpose trees for sheep in Ethiopia: The case of Vernonia amygdalina, Buddleja polystachya and Maesa lanceolata

Aynalem Haile** and Taye Tolemariam*

* Jimma University, College of Agriculture and Veterinary Medicine, P.O. Box. 307, Jimma, Ethiopia
**International Livestock Research Institute, P.O.Box 5689, Addis Ababa, Ethiopia
a.haile@cgiar.org

Abstract

The feed resources base, the feeding systems and feed values of three indigenous trees Girawa, Anfare and Kelewa (Local (Amharic), Ethiopian names ) were studied for sheep in sub humid, mid altitude area of south western Ethiopia. The study involved a survey of the feed resources base and assessment of the feeding systems, chemical analysis and in vitro dry matter digestibility. In addition, Girawa was selected to study its effect on growth performances using 32 lambs. The levels of Girawa used for the growth performance study in groups I, II, III and IV, respectively were 100 g/d, 200 g/d, 300 g/d and 400 g/d.

The main feed resources for sheep in Jimma area were found to be natural pasture, crop residues, crop aftermaths and indigenous multipurpose trees. Grazing on natural pasture constituted the main feeding system. The indigenous trees were cut and fed occasionally. The levels of CP ranged from 186.2 to 244.4 g/kg DM with minimum level in Anfare. Higher values were recorded for Girawa. Organic matter content was higher for Anfare (924.3 g/kg DM) and lower for Girawa (877.9 g/kg DM).  In vitro dry matter digestibility values were 0.448, 0.422 and 0.458 for Girawa, Anfare and Kelewa, respectively. Supplementation of Girawa had an effect (p<0.01) on live weight gains of lambs. Lambs that were offered 400 g/d of Girawa had a higher daily live weight gain (95.1 g/d) compared to those supplemented with 200 (43.3 g/d) and 300 g/d (50.5 g/d) of Girawa as well as the control group (34.0 g/d). Weight gains were not different between the control group and those supplemented with 200 and 300 g/d of Girawa.

It was concluded that these feed resources represent a great potential for sheep production in areas where the resources are available. It is also suggested that more studies are needed on higher level of Girawa than the present study on animal performances along with its anti-nutritional effects. 

Key words: growth performance, nutritional value, sub humid , supplementation

Introduction

Ethiopia has huge livestock and poultry resources. However, it was not possible to bridge the gap between the ever-increasing demand for animal products and the level of production. The major limiting factors, among others, include under nutrition and disease.

To mitigate the problem of feed availability, use of browse plants would be regarded as good options. Most browse plants have high crude protein content, ranging from 10 to more than 25% on dry matter basis; they may be considered as a more reliable feed resource of high quality to develop sustainable feeding systems and in increasing livestock productivity (Okoli et al 2003). Thus, there is a pressing need to evaluate the potential and feed values of the indigenous browse plants, i.e., multi-purpose trees and shrubs so that they could be used in developing sustainable feeding standards.

Indigenous multipurpose browse species are well known to farmers and are better adapted to the environments than exotic. Consequently, they are in common use in many parts of the country though not on scientific basis. They are also important feed resources in traditional animal agro-forestry systems through out the tropics but their potential as forage has been a subject of little research.

A variety of trees and shrubs are grown around Jimma, mainly due to the suitability of the environment and the need to use them as coffee shade. It is also common practice to use multipurpose tree and shrubs as a supplementary feed to cattle and sheep, which represent the largest livestock population of the region. The most commonly used multipurpose trees for animal feed in the area include Vernonia amygdalina  (Girawa), Buddleja polystachya (Anfare) and Maesa lanceolata (Kelewa). Girawa was known to have high saponin content which might decrease the feed intake (Bonsi et al 1995). Thus, it is imperative that multipurpose trees should be evaluated for their feed value. Moreover, reports are not available on evaluation of the performance of sheep with supplementation of local based fodder trees. This study was, thus, designed with the following objectives: (1) to assess the feed resources base and the feeding systems around Jimma with emphasis on multipurpose trees and shrubs; (2) to study in vitro dry matter digestibility and chemical composition of Girawa, Anfare and Kelewa; and (3) to study effects of different levels of Girawa on weight gains of lambs.

Materials and methods 

Study location

The experiment was conducted in Jimma College of Agriculture and three districts around Jimma (Yebu, Dedo and Seka), Ethiopia. Jimma is located at 335 km South West Ethiopia at elevation of 1720 m above sea level with an average rainfall of 1000 mm. The area experiences 8 to 10 months of rainfall. The main rainy season extends from May to September and the small rainy season takes in February, March and April. The temperature of Jimma vary from maximum of about 28 ⁰C in the hottest month to as low as 8 ⁰C in the coolest month. The annual average temperature is 20 ⁰C.

Feed resources base survey

Three districts (Yebu, Dedo and Serbo), which are found in a radius of 30 km from Jimma city, were purposely selected based on their feasibility for the study. Twenty-five farmers from each district were then selected for an interview. A formal survey using a semi-structured questionnaire was conducted. The information collected included: livestock (type, number); uses of livestock; main feed (by livestock); feed availability by season (natural pasture, crop residues, industrial by products, cultivated forages, browse trees and others); methods of feeding; cultivation and utilization of Girawa, Anfare and Kelewa; distribution of the multipurpose trees per household; and relation to crop production.

Analytical methods

In the analysis of chemical composition and in vitro dry matter digestibility studies, edible parts (leaves and tips of twigs) of the three trees (Girawa, Anfare and Kelewa) were collected in different seasons. Samples of the trees were randomly selected from the three sites. The leaves and tips of twigs were separated from branches, mixed thoroughly and representative samples taken, weighed and oven dried at 105 ^oC. 

The dried samples were ground to pass through 1 mm sieve size of a Wiley mill. The dried and ground samples were subjected to proximate analysis per AOAC (1980) procedure, NDF fractions according to Van Soest et al (1991), ADF fractions using AOAC (1990) and in vitro dry matter studies at International Livestock Research Institute (ILRI) analytical laboratories.

Growth study

Girawa was selected among the three common fodder trees due to its wider availability and common use by the farmers as has been revealed from the survey. Thirty-two lambs of similar weight (average of 19.7 kg) were purchased and treated against internal and external parasites at the start of the experiment. Sheep were then randomly divided into 4 groups (8 per treatment). The lambs were housed indoors in 4 pens with concrete floors which were cleaned regularly. The randomisation of the treatment groups followed initial blocking by weight. The feeding treatments were allocated in the following way:

Hay ad lib + 100 g/d of Girawa (control),
Hay ad lib + 200 g/d of Girawa (II),
Hay ad lib + 300 g/d of Girawa, (III) and
Hay ad lib + 400 g/d of Girawa (IV).

Hay was prepared from locally available varieties of grass and legume mixes mainly composed of Bermuda grasses and lablab spp. Girawa was fed fresh, twice a day (at 9:00 AM and 2:00 PM). The sheep were fed weighed quantities of the feed from troughs and the 24 hours refusals were recorded every morning. Water was provided ad lib. The sheep were allowed two weeks to adjust to their respective diets before the commencement of data collection. Data were collected for 10 weeks. Daily feed intake, and weekly body weight changes were monitored.

Statistical analysis

The survey data were analysed using descriptive statistics. The feeding experiment data were analysed using the General Linear Model (GLM) procedures of SAS (SAS 2002). The dependent variables analysed were daily live weight gains and total weight gain over a space of ten weeks. Fixed effects fitted in the model include the effect of feed, measurement dates (weeks) and the interaction between the two. Tukey Kramer test was used to separate means (SAS 2002).

Results and discussion   

Feed resources base

Jimma area is characterized as one of the densely populated regions in the country. Consequently, there exists shortage of cropland. Livestock are an integral part of the agricultural activity. However, they had to depend on the limited natural grazing land and crop residues for their feed. Results of the questionnaire designed to assess the feed resources base is summarized in Table 1.

Natural pasture and crop residues were ranked as major (81%) feed resources for livestock in general and sheep in particular.  Improved forage development is generally considered to be very limited. On average improved forage represent 4.3% of the feed resource for livestock (dairy animals specifically). However, the respondents complained of unavailability of continuous supply of forage seed. 

Ninety five percent of the respondents indicated that they grow indigenous multipurpose trees.  The most common of all in order of importance are: Girawa, Anfare and Kelewa. These feed items are being used during the dry period of the year when other feeds are in short and as a supplemental feed for lactating ewe and fattening sheep (particularly Girawa).  Indigenous multipurpose tree species have naturally regenerated and are growing in homesteads, on croplands, along farm boundaries, and on communal hillside grazing areas.

Feeding systems

Grazing on natural pasture was found to be the main system of feeding sheep in Jimma area. Particularly, during the rainy season, when pasture availability is fairly good and sheep are not allowed to stay on the cropland, grazing on the pasture constituted the main feeding system.  After the cropping season, however, sheep are let to graze on crop aftermaths. Crop residues from different sources are sometimes prepared in different ways. The stovers of the most common crops (maize and sorghum) are chopped before feeding. The leaves of the indigenous multipurpose trees are cut and fed to the sheep. In some instances there are observations that people are processing differently (soaking, chopping, pounding, etc.) before supplementing the fodder trees to the animals. Bonsi et al (1995) have observed the role of supplementation (120 g/d) and processing Vernonia (boiling, soaking) compared to the fresh with or without molasses on feed intake and digestibility. The report indicated boiling for 30 minutes, but not soaking, enhanced the acceptability of vernonia, suggesting that pre-treatment may enhance the feed value of vernonia.  However, many reports agreed on stringent taste by Girawa (Vernonia) lowering its intake by animals (Buttler and Bailey 1973; Hindricksen 2000) due to its anti-nutritional factors such as alkaloids, saponins, tannins and glycosides. Boiling the Girawa during dry period supplementation was suggested to decrease the content of secondary plant compounds and make the feed more palatable (Bonsi et al 1995).

Feed chemical composition and in vitro dry matter digestibility

The chemical composition of the indigenous multipurpose trees is presented in Table 2.

The levels of CP ranged from 186.2 to 244.4 g/kg DM with minimum level in Anfare. Higher values were recorded for Girawa. These values thus indicate the fodder trees can serve as protein supplement when animals are based only on crop residues and pasture grazing. Organic matter content was higher for Anfare (924.3 g/kg DM) and lower for Girawa (877.9 g/kg DM).  These values are higher or comparable with results from other multipurpose trees (Okoli et al 2003; Melaku et al 2004).  However, both the NDF and ADF contents of these indigenous multipurpose trees were generally higher than those reported for vernonia by Bonsi et al (1995) as well as other multipurpose trees (Sesbania sesban, Leucaena  pallida, Leucaena leucocephala and Faidherbia albida) by Melaku (2004), but closer to the results obtained by Okoli et al (2003) under tropical condition. Thus, although the indigenous multipurpose trees have fairly good feed composition, the higher fibre content could greatly limit feed intake (Van Soest 1965).

The mean in vitro dry matter digestibilities obtained given in Table 2 are lower possibly due to the higher fiber contents. However, in vivo study by Bonsi et al (1995) depicted digestibilities of DM, OM and the fiber fractions were marginally higher (P<0.05) in the Girawa supplemented diets than the control.

Effect of supplementation on weight gain

Least square means (and standard errors) for the effects of supplementation of different levels of Girawa on live weight gains of lambs were summarised in Table 3.

Supplementation of Girawa had an effect (P<0.01) on live weight gains of lambs. Lambs that were offered 400g/dof Girawa had a higher daily (95.1 g/d) live weight gain compared to the rest of the groups. Weight gains were not different between the control group and those supplemented with 200 and 300 g/head of Girawa. Thus supplementation of Girawa at lower levels (100, 200 and 300 g/d) to hay had no impact in improving significant growth unless the quantity is increased up to 400 g/d.

Supplementation of multipurpose trees to small ruminants improved growth performance in a number of independent studies (Reed et al 1990; Melaku et al 2004).  In a study that involved feeding of Calliandra calothyrsus and Leucaena leucocephala to goats, supplemented group gained 11-15% more body weight than the control group.  Sheep fed leaves of S. sesban as a protein supplement also had higher body weight gain compared to un-supplemented group (Reed et al 1990). These studies were based on multipurpose trees of temperate origin. Evaluation of the feed value of indigenous multipurpose trees in Ethiopia is generally scanty. This study could, thus, be used as a base for further research into the feed value of other indigenous trees. Multipurpose trees were also complained of anti nutritional factors (Reed et al 1990; Melaku et al 2004), which could significantly limit their utilization. Thus, further studies should be carried out to evaluate the anti nutritional factors that may hinder their full utilization. 

Conclusion 

• Jimma area is endowed with diverse flora, huge livestock population and suitable climatic condition for production of crops and rasing of livestock. Unfortunately, the contribution of livestock to the livelihood of the people has not had its share.

  
  

• Lack of adequate feed, both in terms of quality and quantity, are acclaimed as the major constraints. 

  
  

• Indigenous multipurpose trees including Girawa, Anfare and Kelewa have great potential in this endeavour. The availability, feed chemical constituents, digestibility of the feeds and their multipurpose role opens avenue for better utilization of the resources.

  
  

• Supplementation of the tree leaves was also found to improve the weight gains of the sheep.

  
  

• It is concluded that these feed resources represent a great opportunity for sheep production in areas where the resources are available.

Acknowledgements  

The authors wish to acknowledge the Ethiopian Agricultural Research Organization for funding this study.  Jimma University College of Agriculture also provided different materials and facilities for the study. The contribution of Mr Anteneh Belachew is acknowledged.

References 

AOAC 1980 Official method of analysis 12^th edition. Association of Official Analytical Chemists, Washington, DC.

AOAC 1990 Official method of analysis 15^h edition. Association of Official Analytical Chemists, Washington, DC. Index no. 973.18

Bonsi M L K, Osuji P O, Tuah A K and Umunna N N 1995 Vernonia amygdalina as a supplement to teff straw (Eragrostis tef.) fed to Ethiopian Menz sheep. Agroforestry Systems 31(3: 229 – 241

Buttler G W and Bailey R W 1973 Chemistry and Biochemistry of Herbage. Academic Press, London and New York.

Hindricksen I K 2000 Multipurpose trees and shrubs as supplements to low quality roughage feed to ruminants in tropical countries. MSc. Thesis, Department of Animal Science and Animal Health. The Royal Veterinary and Agricultual University Copenhagen

Melaku Solomon, Kurt J Peters and Azage Tegegne 2004 Supplementation of Menz ewes with dried leaves of Lablab purpureus or graded levels of Leucaena pallida 14203 and Sesbania sesban 1198: effects on feed intake, live weight gain and estrous cycle. Animal Feed Science and Technology 30: 39–50

Okoli I C, Anunobi M O, Obua B E and Enemuo V 2003 Studies on selected browses of southeastern Nigeria with particular reference to their proximate and some endogenous anti - nutritional constituents. Livestock Research for Rural Development 15 (9). Retrieved December 24, 2007, from http://www.lrrd.org/lrrd15/9/okol159.htm

Reed J D, Soller H and Woodward A 1990 Fodder tree and stover diets for sheep: intake, growth, digestibility and effects of phenolics on nitrogen utilization. Animal Feed Science and Technology 30: 39–50

SAS 2002 Statistical Analysis Systems for mixed models. SAS Institute Inc., Cary, NC, USA.

Van Soest P J 1965 Symposium on factors influencing the voluntary intake of herbage by ruminants: voluntary intake in relation to chemical composition and digestibility. Journal of Animal Sciences 24: 834-843 http://jas.fass.org/cgi/content/abstract/24/3/834

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

Received 5 December 2007; Accepted 26 December 2007; Published 1 March 2008

Go to top