|Livestock Research for Rural Development 27 (4) 2015||Guide for preparation of papers||LRRD Newsletter||
Citation of this paper
The study took place in five selected districts from central and north-western zones of Tigray, Ethiopia, in order to identify the major browse trees, analysing their chemical composition and developing the base line information for future use. A list of 18 browse trees was described from the whole study location of which 12 browses were selected based on their abundance, livestock preference, growth rate, coppicing, biomass production, ease to use and propagate, length of foliage production, suitability to agro-forestry and acceptance by the community. Foliage samples were collected during the end of rainy season and these samples were dried and milled for chemical analysis.
Most of the identified browses were distributed in almost all districts, while some of them were specific to certain localities. The abundance of browse at Laelay-Maichew was found to be least compared to other districts followed by Ahforem. The CP contents of the browse species ranged fom 10.9% to 23.0% whilst NDF and ADF values ranged from 31.5% to 66.5% and 16.3% to 45.3% respectively. In general, the nutritional value of most browse species was high and they could be use as a source of protein. Therefore, they need special attention on their potential use as a livestock feed, agro-forestry and natural resource conservation.
Keywords: abundance, agro-forestry, biomass, coppicing, foliage, growth rate, preference, propagation and utilization
The main constraint to increased livestock production in Ethiopia, specifically in the Tigray region, is the low availability of feed, in terms of quality and quantity. Natural pasture and crop residues are reported to be the major feed sources, although they are highly dependent on good climatic conditions during the growing season. Erratic and unreliable nature of rainfall hampers the availability of crop residues and forages, especially pastures, leading to prolonged periods of undernourishment for livestock.
The use of local resources (browse trees and pastures) with nutritional potential, multipurpose use, easy to propagate, desirable evergreen and fast growing species, should be encouraged, rather than introduced species. Among the indigenous browse plants of Tigray, some of them are traditionally well known as a good source of animal fodder. Livestock, especially goats, browse directly when these are accessible or when they are offered by herders through lopping the branches of the trees; this is a long tradition that local farmers have followed for centuries. However, there is a lack of knowledge about their nutritional value and adequate use. This study was planned to document and test the nutritional content of foliage from different indigenous trees in the Central and North Western Zones of Tigray.
The study was carried out in Mereb-lekhe, Ahforem, Laelay-Maychew, Medebay-Zana and Asgede-Tsimbla districts. Asged-Tsimbla is located bordering the Tekeze River with many sharp gorges and undulating topographies while Mereb-Lkhe borders the Mereb river. In these districts many lowland browse plant species are found supporting huge numbers of small ruminants.
These areas represent all agro-ecological features of the two zones. Asged-Tsinbla and Mereb-Lekhe represent the lowland areas in North Western and Central zones respectively. Ahferom and Laelay-Maichew represent the mid-altitude areas in the central zone and Medebay-Zana for the North Western zone. Most of the districts for this research, except Laelay-Maichew, were selected due to the presence of indigenous browse species which contribute significantly to animal nutrition and also for their relatively good vegetation coverage. In these areas the advantage of agro-forestry is clearly observable. Laelay-Maichew area was considered purposely due to the severe shortage of feed sources. Check-lists were developed and distributed to each Peasant Association (PA) through the district office of agriculture and rural development (DAs). The district office DAs had discussions with the communitiees to identify and prioritize the major browse types in their localities. The communities listed the species in order of the criteria and the most frequently selected plants were taken into account for further study.
Each Peasant Association set the browses in their order of importance and the most frequently selected (12 browse plants) were considered. The criteria included abundance, livestock preference, growth rate, coppicing ability, biomass production, ease of utilization and propagation, suitability to agro forestry and acceptance by the community.
The leaves and twig samples of the 12 selected browse species were collected in October and air dried in a well-ventilated room. After that, the samples were ground in a Willey mill to pass through a 1 mm sieve for chemical analysis. The samples were then stored in plastic bags for analysis.
The dry mater (DM) content of the samples was determined by oven drying the samples at 105°C for 24 hours. Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were analysed following the procedure described by Van Soest et al (1991). The contents of N, OM, ash and DM were determined as described by AOAC (1990) and CP was calculated as N x 6.25 and OM by deducting ash from 100.
Many trees were reported to be browsed by livestock and distributed abundantly (Table1).
|Table 1. Major browse trees identified in the central and western zones of Tigray|
|Vernacular name (Tigrigna)||Botanical name|
Distribution of the plants in every surveyed district is shown in Table 2.
|Table 2. Availability of the browse species in the five representative districts of central and north western zones of Tigra|
|Name of plant (Tigrigna)||D1(TS)||D2(M)||D3(L)||D4(A)||D5(M)||Niches|
|+ = available; - = not available; D1= District Asgede-Tsimbla; D2= District Medebay-zana; D3= District Laelay-Maichew; D4= District Ahferom ; D5= District Mereb-Lekhe|
Browse species distribution was not uniform across locations. Most of the browses were abundantly found in Medebay-Zana, Asgede-simbala and Mereb-Lekhe, while in Laelay-Maichew and Ahferom, these species were found in smaller amounts, in regard to their current use as animal feed. The difference in distribution could be mainly due to their niches and human-made conditions. In this case, all the study districts, except Laelay-Maichew, have two agro-ecological zones (lowland and midland). However, some districts have only few browse species caused mainly by deforestation. The case of Laelay-Maichew is clearly an evidence to such a scenario, since deforestation is severe, due to population pressure. The result agrees with the report of Brinkman et al (1976), which suggested that the existence of different types of browse species between and within localities, and their distribution tendencies with any spatial arrangement, could be explained by lack of proper management and by the characteristics of their reproductive structures. Distribution of plants generally is influenced by their reproduction, regeneration, fast growing ability and resistance to drought, as well as to browsing.
Crude protein contents of eight plants ranged between 15.3 and 23.0 % (Table 3). In this case, Acacia bussei had the highest CP content followed by Faidherbia albida; Carissa edulis showed the least CP content. These CP values are similar with those in the report of Teferi (2006) for browses of Abergelle. However, a difference was observed in the CP value of Acacia lehai (17.2% in this study) compared with 12.5% found in Teferi′s research. The CP contents of the selected browse species of this study are similar to the results of Osga et al (2008), which are in the range of 10 to 25%. Mtengeti and Mhelela (2008) reported that CP content ranged from 12.6 % in Lannea schweinfurthii to 28.1% in Acacia polyacantha. The research of Sibanda and Ndlovu (1992) showed that crude protein content of leaves ranged from 7.9 to 22.3%, NDF values were between 31.5 and 66.5% and ADF ranged from 16.3 to 45.3%.
|Table 3. Chemical composition of twelve indigenous browse plants of central and north western zones of Tigray|
|Browse name||as % of DM|
Browses with lowest NDF and ADF values were Acacia abyssinica, Securinega virosa and Acacia lehai.
AOAC (Association of Official Analytical Chemists) 1990 Official methods of Analysis, 15thed. AOAC, Washington DC.
Brinkman W L and De Leeuw P N 1976 The nutritive value of browse and its importance in traditional pastoralism. Mimeo, Agricultural research station, Shika, Ahmodou Bello University, Zaria, Nigeria.
Osga I M, Wambui C C, Abdulrazak S A, Ichinohe T and Fujihara T 2008 Evaluation of nutritive value and palatability by goats and sheep of selected browse foliages from semiarid area of Kenya. Journal of Animal Science, 79:582-589.
Mtengeti E J and Mhelela A 2006 Screening of potential indigenous browse species in semi-arid central Tanzania. A case of Gairo division. Livestock Research for Rural Development. Volume 18, Article #108. Retrieved March 11, 2015, from http://www.lrrd.org/lrrd18/8/mten18108.htm
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Received 21 July 2014; Accepted 14 March 2015; Published 1 April 2015
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