Preferably browsed forage species by camels (Camelus dromedarius) and their mineral contents in Jijiga district, Eastern Ethiopia

Temesgen Desalegn and Y K Mohammed*

Madawalabu University, School of Agriculture, Department of Animal and Range Sciences
P.O. Box 247, Bale-Robe, Ethiopia. Mob. +251912159506
teme_desalegn1980@yahoo.com
* Haramaya University, School of Animal and Range Sciences,
P.O. Box, 138, Dire Dawa, Ethiopia. Mob. +251915740524

Abstract

The objectives of the study were to assess preferably browsed forage species of camels and their critical mineral contents. Data regarding feed resources were collected from 80 households using structured and semi structured questionnaires, and visual observations. Following the survey, samples of dominant and preferably browsed forage species were collected to determine chemical composition.  

The mean concentration of macro elements (%) Ca (1.91, 1.26); Mg (0.48, 0.32); K (2.03, 1.46); and micro elements (ppm) Fe (340, 97.6); Zn (73.6, 56.7); Mn (163, 82.9) and Cu (19.4, 12.2) in the sampled forages was higher than the lower recommended levels of these elements for camels in both the wet and the dry seasons, respectively. However, the mean concentration of Na (0.12, 0.09) and P (0.12, 0.04) were lower than the recommended level for camels in both the wet and the dry seasons. Effect of seasons was found significant for Ca, Mg, P,  Fe, Mn  Zn  and Cu with higher concentrations in the wet season.  It is concluded that the camels in the study area could get adequate amount of the mineral elements: Ca, Mg, K, Fe, Mn, Zn and Cu from browses except for P and Na. So there is a need for P and Na supplementation to the camels in the study district from other sources 

Key words: dry season, supplementation, wet season

Introduction

The one humped camel (Camelus dromedarius) in Ethiopia as elsewhere in dry lands of Africa and Asia are the main sources of milk for millions of pastoralists (Gebremariam 1989, Wilson 1998). They are important for the pastoralists to be recognized as a true member of the community (Kaufmann and Binder 2002). Camels not only sustain life on a day-to-day basis for many people living on the fringe of subsistence, but also serve as depository of wealth and a security against unknown future (Wilson 1998). 

In eastern Ethiopia, including the Somali Regional State and Eastern Hararghe, livestock production including camel rely on browse and grazing on open range lands. As pastoralism is the dominant feature in these areas, livestock are moved from place to place in search of grazing pasture and water as season changes. Natural pasture or vegetation therefore constitutes the sole diet of camels or livestock under pastoral systems where the pasture or the natural vegetation is often of poor quality.  

Information on the concentration of critical minerals in feeds is crucial pre-requisite for improvement of the mineral deficiencies or toxicities of animal diets for the improved performance. Although camel is an important domestic animal species in countries like Ethiopia that possess a large pastoralists and agro-pastoralist population, little has been done on the nutritional status of their feeds in general and that of mineral status in particular. Therefore, this study was designed to assess preferably browsed forage species and their mineral concentration in the study district.  

Materials and methods

The study was conducted in the Somali National Regional State in Jijiga district. Geographically, Jijiga district lies at 8^o 44’N longitude and 40^o 22’E latitude (NAE 1984). The average elevation of the district is 1803 meters above sea level (Hailu 2008). Temperature of the district is generally high all the year round where the mean minimum and maximum temperatures are around 20^oC and 35^oC, respectively. The mean annual rain fall is 660 mm and bimodal. The rainfall condition in the district is generally low, unreliable and with uneven distribution. 

Well structured and semi-structured questionnaires were prepared for interviewing purposively selected 80 camels’ herdsmen from four rural kebeles in the district to gather data on feed resources, dominant and preferably browsed forage species both in the wet and the dry seasons.  

Forage sample collection 

From the survey result, the forage species which are dominant and preferably browsed by camels in the study areas were ranked on the basis of frequency of the respondents for each forage species reported in the study area and then identified through the help of herdsmen and direct observation by the authors before the collection of samples. After ranking and identification, those forages species were sampled in two different seasons. The first round samples were collected in January to mid-February (dry season) and the second round samples were collected in July to mid-September (wet season) for laboratory analysis. During sampling, the plant parts which are consumed by camels (leaves, stems and pods) were harvested together carefully from each species of forage. Branches with flowers and/or pods of browse species were reserved in plant press for plant identification. 

Sample preparation and chemical analysis 

The forage samples were chopped into small pieces and allowed to be dried at 60^oC for 72 hours in forced draft oven.  Then all dried samples were ground separately to pass through 1mm sieve of the Willey mill. The dried and ground samples were allowed to equilibrate in air at room temperature over-night and stored in plastic bags awaiting analysis.

Forage samples were analyzed for DM and ash according to the AOAC (1995). The mineral concentrations (Ca, Mg, Fe, Mn, Zn, and Cu) in forages were analyzed by using an atomic absorption spectrophotometer (Model 210 VGP USA). Solutions were prepared by following the dry ashing method (AOAC 1995). Sodium and K were determined by using flame photometry and P was determined by using photometric method according to AOAC (1995). 

Data collected from the survey were analyzed using the descriptive statistics of the Statistical Package for Social Science (SPSS) version 13. T-test was employed to evaluate the effect of seasons on the mineral composition of forages.  

Results and discussion

The principal sources of camel feeds in the study areas constitute of browse species. The leaves, twigs, seeds and pods of browses are consumed by camels. During the survey more than 100 forage species consumed by camels were reported in the study district. This shows that the camels in Jijiga district have wider choices for browse and /or grazing forages.  

According to the pastoralists, twenty dominant and preferably browsed forage species were ranked and sampled for determination of mineral concentration (Table 1). Sixty five percent of the sampled forage species were also reported as the common type of range forages consumed by camels in Jijiga in a previous study (Tezera 1998).  Dessalegn (1984) in his study reported that in the Southern rangelands of Ethiopia the most important browse plants used by camels in different seasons are Acacia brevispica, Commiphora africana, Rhus natalensis, Grewia spp., Balanites spp., Boscia minimifolia, Cadaba glandulosa, Euphorbia spp., and Solanum tembensis.

Chemical composition

Ash content 

The ash contents of browses (Table 2) ranged (%) from 7.1 to 23 with a mean of 13.4 in the wet season and 4.5 to 20.4 with a mean of 10.3 in the dry season.  In the wet season, the ash content of forages was higher than the ash content in dry season. In a similar study, Alia et al (2007) also reported that the ash content of the plant parts browsed by camels during the wet season was higher compared to those browsed during the dry season.  

Macro mineral concentration in forages 

Calcium concentration in the browses (Table 2) ranged from 0.5 to 3.6% with a mean of 1.9±0.26% in the wet season and 0.3 to 3.4% with a mean of 1.3±0.26% in the dry season. Based on the lower limits of ruminant requirements (McDowell and Arthington 2005), all browse samples contained higher concentration of Ca in both the wet and the dry seasons. There were seasonal difference for Ca (Table 3), with concentration in the wet season being higher than that of the dry season. High Ca value in browses implies that the browsing and/or grazing camels of different classes including lactating camels in the study areas could get adequate amount of Ca in both seasons. El Shami et al (1990) also reported that the mineral content of the browse plants is adequate in Ca, Mg and K for browsing animals. Over 80% of preferred forage species by camels had Ca concentrations above the recommended levels during both the dry and the wet seasons at all the study sites in western Marsabit, Kenya (Kuria et al 2004).

Concentration of Mg in the browses ranged from 0.15 to 0.98% with a mean of 0.48±0.04% in the wet season and ranged from 0.14 to 0.7% with a mean of 0.32±0.04% in the dry season. In the wet and the dry seasons, 10 and 25% of the samples were below the suggested critical level of 0.2% (McDowell and Arthington 2005), respectively. Mean Mg concentration in browses sampled were higher than the critical levels for ruminants in both seasons signifying adequate amount of Mg for different classes of camels. Seventy five to 90% of the sampled forages had Mg concentration above the recommended levels during both the dry and the wet seasons. Similarly, Kuria et al (2004) reported that over 80% of preferred forage species by camel had Mg concentration above the recommended levels during both the dry and the wet seasons. Higher Mg concentration (Table 3) was found in the wet season compared to the dry season.  

Concentration of K in the browses ranged from 0.19 to 3.95% with a mean of 2.03±0.22% in the wet season and ranged from 0.04 to 3.75% with a mean of 1.46±0.22% in the dry season. In the dry season, 15% of sampled browses contained less than 0.6% K and 80% of the samples had greater concentration than 0.8% K and in the wet season only 5% of the sampled forages contained less than 0.6% K and 90% of the samples had greater concentration than 0.8% K. Mean K concentration in forages in both seasons were well above the critical level established (McDowell and Arthington 2005), indicating that the forage plants adequately supply K for browsing and/or grazing camels of different classes in the study area. McDowell and Valle (2000) reported that there are very few confirmed reports of K deficiency for ruminants grazing exclusively forages. The concentration of K in the wet season was higher than the dry season.  

Concentration of Na in the browses ranged from 0.049 to 0.24% with a mean of 0.12±0.01% in the wet season and ranged from 0.03 to 0.24% with a mean of 0.09±0.01% in the dry season. In this study, the recommended critical level of 0.18% Na (McDowell and Arthington 2005) in feed was used as reference to compare the Na status of sampled browses as camels highly need salt (Wilson 1984).  In the wet and the dry season, 65-85% of the sampled browses contained less than 0.18% Na recommended for ruminants, respectively. Considering the critical level (0.18%) already established for ruminants, the mean concentration of Na in browses in both seasons were lower than the established critical level signifying deficiency of Na in browses for camels in the study areas. French (1955) from his study concluded that NaCl is the most needed nutrient for livestock throughout East Africa. Natural forage low in Na has been reported in numerous tropical countries throughout the world (McDowell and Valle 2000). In contrast, Kuria et al (2004) reported that over 80% of preferred forage species of camels had Na concentration above the recommended levels during both the dry and the wet seasons at all the study sites in western Marsabit, Kenya. This could be due to high botanical composition of salty plants in the study sites in Kenya. In the present study, no difference was found on mean concentration of Na between the wet and the dry seasons. 

Phosphorus concentration in the browses ranged from 0.01 to 0.19% with a mean 0.12±0.008% in the wet season and ranged from 0.01 to 0.13% with a mean of 0.04±0.008% in the dry season. The mean P concentration in browses in both the wet and the dry seasons was below the recommended critical concentration (0.25%) required in forages to satisfy the requirements of ruminants (McDowell and Arthington 2005). This shows that browse species in the study areas are deficient in P. Similarly, in a review by McDowell et al (1984), P deficiency was reported in 46 tropical countries of Latin America, South-East Asia and Africa. Phosphorus concentration in forages was higher in the wet season than in the dry season. 

Trace elements composition in forages 

Iron concentration in browses ranged (ppm) from 93 to 693 with a mean of 340±22.1 in the wet season and 51.3 to 188 with a mean of 97.8±22.1 in the dry season (Table 4 and 5). The Fe content in all sampled browses was well above the recommended level for ruminants in feeds in both the wet and the dry seasons with  higher concentration in the wet season than the dry season (Table 5). The forages in the study areas adequately supply the requirements of Fe for different classes of camels. Sousa et al (1981) reported high concentration of Fe in forages in both the wet and the dry seasons in northern Mato Grosso, Brazil. Most forage contains Fe concentration considerably in excess of the requirements of herbivorous animals (McDowell 1992). McDowell (1992) reported that Fe contents of most feed ingredients is highly variable, reflecting differences in soil and climatic conditions as well as differences in variety or processing procedures.

Manganese content in browses ranged from 9.52 to 371 ppm with a mean of 162±21.1 ppm in the wet season and 17.2 to 325 ppm with a mean of 82.8±21.1 ppm in the dry season (Table 4 and 5). In the wet and the dry seasons, 5 and 40% of the sampled browses contained below the recommended concentration of Mn (McDowell and Arthington 2005) in feeds for ruminants. The mean concentration of Mn in forage plants is well above the minimum requirement indicated in both wet and dry seasons with higher concentration in the wet than in the dry season (Table 5). The mean concentration of Mn in browses is adequate to different classes of camels in the study areas in both seasons. Concentration of Mn in crops and forages is dependent on soil factors, plant species, and stage of maturity, yield, crop management, climate, and soil pH (McDowell 1992).

Zinc concentration in browses ranged from 38.1 to 171 ppm with a mean of 73.6±6.08 ppm in the wet season and 14.3 to 130 ppm with a mean of 56.7±6.08 in the dry season (Table 4 and 5). In the dry season, 10% of the sampled browses contained below the recommended (McDowell and Arthington 2005) concentration for ruminants. Mean concentration of Zn in sampled browses were higher than the critical level for ruminants in both the wet and the dry seasons indicating adequate concentration of Zn in forages for different classes of camels. Higher concentration of Zn was obtained in the wet season compared to the dry season (Table 5). Mtimuni et al (1990) also reported a variation on Zn concentration of forages with high concentration in wet seasons in Malawi. 

Concentration of copper in sampled browses ranged (ppm) from 8.91 to 30.8 with a mean of 19.4±1.38 in the wet season and 3.64 to 23.9 with a mean of 12.2±1.38 in the dry season (Table 4 and 5).  In the wet and the dry seasons, 10 and 45%, respectively of sampled browses contained Cu in a concentration lower than the critical level suggested for ruminants (McDowell and Arthington 2005). Based on the critical level of Cu in feeds established for ruminants, forages in the study areas could supply adequate amount Cu for camels of different classes in both the wet and the dry seasons. Copper deficiency is a severe limitation in grazing ruminants and has been observed in many parts of the world (McDowell 1992). However, the current result and that of Woldu (1984) indicates that browse forages can supply adequate amount of Cu for browsing camels. This could be due to differences in soil factors, plant species and stage of maturity, climate, and soil pH (McDowell 1992). Copper concentration in the wet season was higher than that in the dry season (Table 5). 

Conclusions

• In Jijiga district, the major sources of feeds for camels are browse species. Leaves, twigs, seeds and pods of the browses are consumed by camels.

• Based on the lower limits of ruminants’ requirements, the mean concentrations of Ca, Mg, K, Fe, Mn, Zn, and Cu in forages were higher than the lower recommended levels in both the wet and dry seasons signifying adequacy for different classes of camels.

• However, the mean concentration of Na and P were lower than the established recommended levels for ruminants, signifying deficiency of these minerals in forages in the study areas. Thus, camels in the study district should be supplemented with sodium and phosphorus from other sources.

Acknowledgements

The authors wish to acknowledge the Haramaya University for its support during data collection and for the provision of facilities; they also acknowledge the Agricultural Research and Training Section of the Ethiopian Agricultural Research Organization for funding this study; and all those who have contributed to the study. 

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Received 8 September 2011; Accepted 7 February 2012; Published 4 March 2012

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