The study was conducted in the Somali region of eastern Ethiopia, with an arid to semiarid
climate. The study aimed at the characterization of the rangeland resources, assessing
the current condition of the rangeland, understanding pastoral perceptions on rangeland
degradation and developing drought feeding strategies for livestock.
Three experimental sites, representative of the three predominant vegetation types of
eastern Ethiopia were selected. They were the arid Asbuli grassland (used as grazing
area for large and small ruminants), the arid Aydora open savanna (bush-grassland:
entirely used for grazing/browsing by all types of livestock), and the semi-arid Hurso
closed savanna (bushland: selected for its importance as browsing for camels and goats). A degradation gradient was identified in each of the three vegetation types, where the
botanical composition was surveyed and the rangeland condition assessed. The
perceptions of the pastoralist on rangeland degradation were also quantified. The dry
matter production of both the herbaceous and woody layer was determined, while the
grazing and browsing capacity calculated. Key forage species were identified and the
grazing pattern of various livestock species along the degradation gradient studied. The
soil seed bank regeneration potential was assessed in a greenhouse experiment and the
response of cattle, sheep and goats to a simulated drought, in terms of reduced fodder,
was conducted under controlled conditions.
The results of the study confirmed the existence of severe rangeland degradation that
occurred since 1944 and which was aggravated after the 1974 drought. This contributed
to an increase in the number of poor households. The average livestock holding per
household declined from 809 Tropical Livestock Units (TLU) before 1974 to 483 TLU
after 1974. Livestock holding shifted from a predominance of cattle to small ruminants,
which are able to utilize the degraded rangeland more effectively. Camels are now the
most important livestock species in terms of milk and meat production, mainly due to
their ability to tolerate drought.
The abundance of herbaceous plants, basal cover, dry matter production and grazing
capacity was found to be higher in the benchmark sites compared to the other rangeland
conditions. There was also a corresponding increase in percentage bare ground, soil
compaction and soil erosion along the degradation gradients. Over-grazing and overutilization
through continuous grazing of the herbaceous layer were identified as the main
causes of these differences.
Rangeland condition was observed to significantly influence the grazing behaviour of
livestock in terms of plant species selection, grazing intensity and intake per animal.
When forage sources were adequately available, animals selected fever plant species. As
forage resources declined the animals spend more time grazing and more species
selected, including less palatable species. The number of bites, intake per bite and intake as a percentage of the animalâs body mass also increased as the rangeland become more
degraded.
Acacia nubica and A. mellifera were identified as aggressive encroaching species in the
Aydora open savanna and Hurso close savanna. The Aydora open savanna experienced
extensive encroachment by woody plants with increasing plant densities across the
degradation gradient. The Hurso closed savanna experienced an opposite trend where
severe deforestation and a loss of valuable browse species occurred, mainly as a results of
over cutting of the woody plants for firewood, charcoal making, construction and the
clearing of the land for planted crops.
The study on the soil seed bank of soil collected along the various degradation gradients
showed a high abundance of plant seed present in the soil, confirming the potential of the
area for rangeland restoration.
As expected the body weight losses of all livestock species in the controlled feeding trial
were highly correlated with the reduction in daily dry matter feed. More than 50% of the
animals showed pronounced emaciation and physical weakness and 25% of the cattle and
goats collapsed and died within ten weeks after the trial started. This explained the large
scale mortalities of livestock during prolonged droughts.
Drought must be accepted as part of the pastoral life and there should be an adequate
early warning system regarding livestock feed availability and strategies of appropriate
mitigation strategies. More realistic stocking rates is the obvious solution to the
avoidance of stock losses during droughts, but in view of the well established culture of
the pastoralists it is highly doubtful if they will be willing to reduce their animal numbers.
In conclusion, the experimental results indicated the existence of genetic variability
among the various Somali livestock breeds regarding the tolerance to feed shortages and
in rates of compensatory growth. This demonstrates the opportunity for improving the
genetic composition of the Somali herds through selection.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-07302007-151852 |
| Date | 30 July 2007 |
| Creators | Gezahegn, Amaha Kassahun |
| Contributors | Prof GN Smit, Prof HA Snyman |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-07302007-151852/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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