National Repository :: Browsing by Issue Date

Browsing by Issue Date

Filter results by year or month

Now showing 1 - 20 of 1175

Factors Influencing Development of Farm Forestry in Lugari District, Kakamega County, Western Kenya
(Agricultural and Food Sciences, Environmental Science IOSR Journal of Agriculture and Veterinary Science, 0002) Otsieno Fredrick Sikuku; Apudo Musa Gweya; Ototo Gilbert O.
This study was conducted to establish the factors influencing the development of farm forestry in Lugari Division, Western Kenya. Data was collected between December 2007 to January 2008. Structured questionnaires/schedules, key informant interviewing, and secondary sources of data were used to collect data. All collected data were entered in SPSS 13.5 to facilitate statistical analysis using descriptive statistics such as frequency distributions and cross tabulations. Significant differences between expected and observed attributes were analyzed by non-parametric Chi- square tests. Farm sizes, species preferences, end use of tree products, access to and availability of preferred germplasm and planting materials, availability of resources for raising seedlings, access to extension services, and marketing constraints as well as biological and technical factors such as diseases, pests and planting methodologies were established as important factors influencing farm forestry and tree planting in general, in the division. This study has also demonstrated that farm forestry can be a useful tool for enhancing the livelihoods of many people and contributing to rural development in Lugari, and can be readily adopted if identified challenges can be comprehensively addressed. It is recommended that tree propagation techniques and distribution networks should be developed to enable affordable access to a wide range of appropriate germplasm. Small scale farmers should be assisted, through extension services, to manage and enhance the value of their tree crops. Institutional support through incentives such as credits, subsidies, technical support and creation of market opportunities including forest policy and legislation sensitization and implementation would boost farm forestry Collapse
A review of the impacts of invasive aquatic weeds on the bio- diversity of some tropical water bodies with special reference to Lake Victoria (Kenya)
(Biodiversity, 0020-12-30) Aloo, Peninah; Ojwang, William; Omondi, Reuben; Njiru, James Murithi; Oyugi, Dalmas
Aquatic weeds may be defined as troublesome or unsightly plants growing in abundance inaquatic situations where they are not wanted. These plants are either adapted to continuoussupplies of water or are at least tolerant to waterlogged soil conditions for substantial periodsof time. The wide range of adaptation to varying amounts of water, and the impossibility ofsharply distinguishing between aquatic and terrestrial environments, makes it difficult toprecisely define an aquatic plant. The menace of water weeds is reaching alarming proportions in many parts of the world, especially in tropical water bodies where they have led toserious ecological and economic losses. Lake Victoria, Kenya, which is the largest freshwaterbody in the tropics, has undergone serious ecological changes including over-exploitationof its fishery resources, degradation of the catchment area, introduction of exotic fish speciesand invasion by the water hyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae),among others. The presence of the weed in the lake has led to many problems includingblockage of water pumps, reduced fishing activities and increase in water borne diseasessuch as schistosomiasis. Positively, aquatic weeds constitute a free crop of great potentialvalue; they are a highly productive crop that requires no tillage, fertilizer, seed, or cultivation.Moreover, these plants have the potential for exploitation as animal feed, human food, sourceof food to some aquatic organisms, soil additives, fuel production, wastewater treatment,source of raw materials and habitat to many organisms. This paper reviews the effects ofaquatic weeds in aquatic systems with examples from some selected waterbodies and specialreference to Lake Victoria.
Rethinking pastoralism and African development: A case study of the Horn of Africa
(Research Gate, 28-10-2005) Kandagor, Daniel Rotich
astoralists in the Horn of Africa have become among the most marginalized and disadvantaged of minority groups. This is due to their wide dispersal, climatic and ecological conditions, state neglect, development plans that have excluded them, seizure of their land, land tenure laws, national borders that restrict their freedom of movement, internal strife and national conflicts. The corollary has been the neglect of gender issues in the pastoralist communities, where custom and religious teachings defining women’s role have been overtaken by rapid modern development. Consequently, the bulk of the land in the Horn of Africa, the pastoralist habitat, lies in the semi-arid and arid zone, home to the largest aggregation of traditional livestock producers in the world, estimated at 15 million people. While there is some non-pastoralist production, the pastoralist contribution is more important economically, providing significant employment and income opportunities seldom shown in official statistics. Traditional livestock production is becoming non-viable through the gradual erosion of access to land and water, as they are turned over to cultivation. This loss has been facilitated by the unwillingness of states to acknowledge and respect pastoralists’ rights to land. Loss of mobility of people and animals has disrupted the process of adjustment that maintains the balance between people, land and livestock. Pastoralist society has been adversely affected by state borders dividing ethnic groups, separating people from their kin, traditional leaders, places of worship, markets, pastures and watering places.
A review of the changes in phytoplankton community structure and ecology in lake naivasha, kenya
(Academic Journals, 1970-01-01) Argwings Owino Omondi, Steve Opiyo Balaka, George Ogendi Mokua, James Onchieku Mokua, Steve Oduor Omondi
Phytoplankton community structure plays a vital role in freshwater ecosystems. Besides the provision of dissolved oxygen through photosynthesis, they also form an important diet for several fish and zooplankton species. Plankton are also used as biological indicators of water quality. The objective of this paper is to provide a comprehensive review on the changes in phytoplankton community structure and their ecological functional roles. Phytoplankton are the primary producers in Lake Ecosystem. The diversity, distribution, and abundance of phytoplankton are influenced by both abiotic and biotic factors. Lake Naivasha has undergone drastic ecological changes due to the growth in human population, horticultural and floricultural developments and changes in its fisheries. Lake Naivasha is surrounded by horticultural farms that are greatly influencing its ecosystem health and the major fish species in the lake are of introduced species. These anthropogenic activities together with hydrological changes are expected to play a role in the changes in phytoplankton community structure. Previous investigations indicate that there are more than 143 species of phytoplankton and seasonal shift in phytoplankton dominance overtime between Chlorophyta, Bacillariophyta, and Cyanophyta. Due to various limnological, hydrological, and ecological changes being witnessed in the Lake, there is need for the monitoring of phytoplankton community structure. Such information would be useful in the Lakeâ€™s management and conservation.
My Roots and Their Importance in Understanding Abagusii History
(Africa Bib, 1986) Kiriama, Herman O.
Using his own family as an example, the author shows how a synthesis of a single family tree can help to understand the general history of a society. The genealogy, which extends from 1638 up to 1983, indicates that by the early years of the 17th century, the Abagusii (descendants of Mogusii) had not yet moved from their cradleland somewhere in northern/southern Uganda. They were part of a large congregation of people who were later to separate and become distinct groups. Within the spell of one century, they had migrated to their present homeland in western Kenya. The author examines how the Abagusii moved from their cradleland and under whose leadership, as well as the relationship between different groups of Abagusii. Bibliogr., ref.
Preliminary Study on The Food and Feeding Habits of Schilbe Mystus (Linn., 1762) in River Nyando
(ICIPE SCIENCE, 1994) Reuben Omondi; James Ogari
Schilbe mystus (Butlerfish) is one of the "endangered species" of Lake Victoria, whose fishery was once of commercial importance. The annual landings have declined from about 400 mt in 1968 to a bare 15 mt in 1991. The average size of the species is smaller than that reported by Greenwood (1 966). During the study, the size range sampled was 11.2 to 25.6 cm. fork length with the majority measuring 14.0-15.0 cm FL. The food and feeding habits of the fish are discussed. Study on the gut content shows that Schilbemystuspreys mainly on insects with chironomid larvae as the dominant Prey.
Generalized characteristics of intense rainfall and peak discharges in Athi basin, Kenya
(JSHWR Committee on Editorial and Publication Affairs, 1995) Nyadawa, Maurice O.; Kobatake, Shigeki; Ezaki, Kazihiro
Presented in this paper is a study clarifying any distinctions or similarities in trends of extreme value statistics of rainfall and discharges recorded at stations sampled all over a basin traversing three distinct climatic zones in Kenya. It is found that in Athi basin, difference in seasonal rainfall pattern affect general characteristics of intense rainfall more significantly than spatial variation of mean annual rainfall. Survey of flood potential of the basin revealed zones which are considered hydrologically homogeneous and heterogeneous cases.
Estimating Transmission Losses in the Main Channel of River Tana, Kenya
(J-Stage, 1997) Nyadawa, Maurice O.; Kobatake, Shigeki; Ezaki, Kazuhiro
This study has presented correlation equations thought to define channel loss in River Tana in Kenya. Modified Tank Model is used to transfer runoff information from gaged basins to ungaged ones in the study area. The study has revealed that channel loss has two step functions corresponding to flow rates below 800m3/s and larger values.
Effect of Drying Lactic Acid Bacteria Fermented Uji on Its Pasting Properties and Content of Carboxylic Acids
(University of Nairobi Department of Food and Nutrition Technology, 1999-01-01) Onyango, Calvin; Okoth, Michael; Mbugua, Samuel
The effect of fermentation and drying on the pasting properties and carboxylic acids of pure flours of maize, finger millet and cassava and of composite flours of maize-finger millet and cassava-finger millet were studied. The pasting properties were measured between 30°C and 96°C in a Brabender Amylograph while carboxylic acids from the uji slurries were determined on thin layer chromatography plates coated with 0.25 mm silica gel. Irrespective of the treatment given, the cereal flours of maize, finger millet and the composite of maize-finger millet consistently had higher onset and peak gelatinization temperatures than pure cassava or the composite of cassava-finger millet. Also the latter two flours developed higher peak viscosities and disintegrated more rapidly after attaining the peak than either pure maize, finger millet or the composite of maize-finger millet. The higher viscosities of the root flours was also reflected in the higher swelling powers and solubility values at 85°C. Fermentation increased the viscosity of the slurries. The greatest increases were recorded by maize (500BU) and the composite of maizefinger millet (780 BU). Fermentation did not affect gelatinization temperatures except for the maize-finger millet composite whose gelatinization temperature decreased by 10°C. Fermentation and drying resulted in increased viscosity when compared to the non-fermented flours, except for the drum dried cassava-finger millet composite. For all the drum dried flours there was a spontaneous increase in viscosity at 30°C when the Brabender Amylograph was switched on. The drum dried flours absorbed about four times their own weight of water; and since the starch granules were pregelatinized, reconstitution in cold water was difficult, as the flour particles tended to lump together, getting wetted on the surface and inhibiting the penetration of water into the interior. In contrast, sun and cabinet dried flours absorbed about 1.9 times their own weight of water and formed smooth slurries in cold water. Fermentation increased total titratable acidity and fixed acidity of the slurries to about 3.9% and 3.6% respectively, while the pH declined from 5.5 to 3.9. On drying there were no significant changes in (p0.05) from the uji prepared from fermented and nondehydrated slurries.
Importance of Indeginous Macrophytes in Control of Water Hyacinth in the Nyanza Gulf of Lake Victoria, Kenya.
(Aquadocs, 2000) Omondi, Reuben; Gichuki, John
Observation of macrophytes dynamics in the Nyanza gulf of Lake Victoria is ongoing since the early 1990s. A checklist of the macrophytes and their distribution in the study area is provided. Occurrence of macrophytes before and after the invasion of water hyacinth is highlighted. The dynamics of water hyacinth, control measures employed for its control and macrophyte succession are also mentioned.
Flavour Compounds in Backslop Fermented Uji (An East African Sour Porridge)
(ResearchGate, 2000-12) Onyango Calvin; Heike Raddatz; Bley Thomas
The potential of Lactobacillus plantarum, Pediococcus acidilactici, Pediococcus pentocaceus, Lactobacillus cellobiosus, different mixtures of these lactic acid bacteria and backslop starter cultures to acidify and form flavour compounds in uji was investigated. The bacteria chosen are the most prevalent species in fermented uji. Flavour compounds were analysed using GC-MS and GC-FID with HP5 non-polar column and DB-Wax polar columns respectively. Use of pure single or mixed cultures did not improve the flavour profile of fermented uji. On the basis of peak areas of unfermented and fermented uji aromagrams, pentanal, hexanal and hexadecanoic, 9,12-octadecadienoic, oleic and octadecanoic acids were found to be native to the flours, while 3-methyl-1-butanol, octanoate, nonanoate, hexadecanoate, linoleate, oleate and hexanoic, heptanoic, octanoic and nonanoic acids were synthesised during submerged culture fermentation. Ethanol, 1-pentanol, 1-hexanol, lactic acid and ethylacetate were synthesised prior to fermentation and synthesis of these compounds continued during fermentation.
Management and Ecology of Lake and Reservoir Fisheries | Wiley
(Wiley, 2002-02) G.Cowx, Ian
In this comprehensive edited book, international experts in fisheries management and ecology review and appraise the status of lake and reservoir fisheries, assessment of fisheries yields, trophic ecology, rehabilitation and conservation, including a special section on African lakes where so much information of huge relevance to fisheries managers is now available . Contributions from around the world. Carefully edited by internationally respected editor. Has been generated from acclaimed HIFI Symposium.
Production of High Energy Density Fermented Uji using a Commercial Alpha-Amylase orby Single-Screw Extrusion
(ScienceDirect, 2003) Onyango Calvin; Henle Thomas; Hofmann Thea; Bley Thomas
The effects of alpha-amylase and extrusion on the viscosity and energy density of uji, a spontaneously fermented thin porridge from different combinations of maize, finger millet, sorghum and cassava, were investigated. Fermentation alone was not able to reduce the viscosity of uji, but addition of 0.1–2.1 ml/100 ml alpha-amylase to the fermented slurry or extrusion of the fermented and dried flour at 150–180°C and a screw speed of 200 rpm reduced the viscosity of 20 g/100 ml uji from 6000–7000 to 1000–2000 cP, measured at 40°C and a shear rate of 50 s−1. The amount of flour required to make uji could thus be increased by a factor of 2.0–2.5 and consequently it was possible to produce uji with acceptable energy densities (0.6–0.8 kcal/g) for child feeding.
Digestibility and Antinutrient Properties of Acidified and Extruded Maize–Finger Millet Blend in the Production of Uji
(ScienceDirect, 2004) Onyango Calvin; Noetzold Horst; Ziems Annette; Hofmann Thea; Bley Thomas; Henle Thomas
Lactic and citric acids were used as alternatives to backslop fermentation in the manufacture of extruded uji (a thin porridge from eastern Africa). Acidity of the blends was reduced by fermentation or progressively lowered with 0.1, 0.5 and 1.0 mol/l lactic or citric acids before extrusion. The absence of ethanol soluble starch in the extrudates indicated that extrusion solubilizes starch without formation of maltodextrins. In vitro starch digestibility increased from 20 mg maltose/g starch in the raw blend to about 200 mg/g after extrusion. Extrusion reduced total dietary fibre by 39–68%, redistributed soluble to insoluble fibre ratios and had a negligible effect on the formation of resistant starch (less than 1 g/100 g). In vitro protein digestibility increased after fermentation or acid treatment followed by extrusion. Nitrogen solubility index decreased by 40–50% when the unfermented, lactic or citric acid treated blends were extruded, but increased by 20% when the blend was fermented before extrusion. Amino acid analysis showed that histidine, lysine and arginine contents were lowest in the fermented-extruded blends. Tannin content decreased from 1677 mg/100 g in the raw blend to between 551 and 1093 mg/100 g in the extrudates whereas phytate content remained unaffected by extrusion (248–286 )
Proximate Composition and Digestibility of Fermented and Extruded Uji From Maize– Finger Millet Blend
(LWT - Food Science and Technology, 2004) Onyango Calvin; Noetzold Horst; Bley Thomas; Henle Thomas
The proximate composition, amino acid profile and in vitro starch and protein digestibilities of raw; fermented; fermented and cooked; unfermented and extruded; and fermented and extruded maize–finger millet blend was studied. Aspartic acid, glycine,cystine, methionine, tyrosine and lysine increased after fermentation, while contents of all other amino acids showed no significant changes. Greater losses of amino acids occurred when the fermented blend was extruded than when cooked. Fermentation improved protein and starch digestibilities, whereas cooking or extruding the fermented blend reduced the digestibilities. Extruding the unfermented blend increased protein and starch digestibilities and reduced nitrogen solubility index by 50%. Raw flour had 0.41 g/100 g water-soluble starch which declined to 0.05 g/100 g on fermentation but increased to 20–34 g/100 g after extrusion
Effect of Extrusion Variables on Fermented Maize–Finger Millet Blend in the Production Of Uji
(ScienceDirect, 2004) Onyango Calvin; Henle Thomas; Ziems Anette; Thea Hofmann; Thomas Bley
The effects of screw speed, feed moisture, glucose, fructose, sucrose and maltose on extrusion of lactic fermented and dried maize–finger millet blend was investigated. Fermentation caused a reduction in sectional expansion index, flour bulk density and water absorption index (WAI) but increased specific volume, water solubility index and darkened the extrudates. Increase in feed moisture (13–25%) reduced sectional expansion index, specific volume and yellowness but increased extrudate moisture content, bulk density and darkness of the extrudates. Increasing screw speed (158–242 rpm) had a negative correlation only with specific volume and lightness (P<0.05). An increase in the content of any of the sugars reduced extrudate moisture content, sectional expansion index, WAI and specific volume but increased bulk density and water solubility index. Extrudates treated with monosaccharides were darker than extrudates treated with disaccharides.
Effects of Zinc, Lead and Copper Concentration Levels on the Distribution of Macro Invertebrates: A case Study of River Sosian, Eldoret Town, Kenya
(journal of the kenya chemical society, 2004-08) Osano, Aloys; L.L., Cheruiyot
The relationship between zinc and copper concentration levels and the distribution of benthic macro-invertebrates in river Sosiani, Eldoret has been investigated. Atomic Absorption Spectrophotometry (AAS) and the Dip-net method have established the concentration of zinc and copper and the number of macro-invertebrates respectively. The study showed that the concentration of both copper and zinc were higher than the threshold levels and that the macro-invertebrate species were fewer in the more polluted regions of the river. Thus, zinc and copper concentration levels play a role in the distribution of macro-invertebrates.
Macrophytes of Lake Victoria and succession after invasion of Water Hyacinth
(AQUA DOCS, 2006) Omondi, Reuben; Kusewa, Mwende
The distribution of Lake Victoria macrophytes is described. Succession of macrophytes in the lake became more dramatic and dynamic after invasion of water hyacinth. The weed pushes and smothers other free-floating macrophytes like Pistia stratiotes. It then provides substrates for the emergent Vossia cuspidata, which later reduces its population by competition for light and nutrients. The noxious weed is believed to have led to extinction of Azolla nilotica in the lake.
Systematics and distribution of zooplankton in Lake Victoria basin, Kenya
(AQUA DOCS, 2006-01) Mutune, Masai; Omondi, Reuben; Owili, Monica
Zooplankton samples were collected, using a 60µm nansen net, from Lake Victoria and adjacent water bodies with emphasis being placed on the different habitats within the ecosystems. A total of 116 species were identified, 63 rotifers, 24 cladocerans and 29 copepods. A number of these were new records for the zooplankton fauna for the country.
Groundwater overdraft vulnerability and environmental impact assessment in Arusha
(Springer, 2006-07-11) Ong’or, Basil T. I.; Cang, Shu Long
A simple approach is proposed for identifying areas vulnerable to groundwater overdraft. The methodology utilizes GIS techniques to analyze and evaluate controlling factors in areas with little data. The proposed methodology was applied in Arusha. Water demand in Arusha Municipality and its environs has increased to about 5.3% annually since 1999. Groundwater levels have declined. The aquifer hydrogeological variables were evaluated for impact to potential groundwater overdraft by overlay and index techniques. The spatial distribution of overdraft vulnerability was discussed. The northwestern part of Arusha is the most vulnerable to overdraft and possible serious environmental impacts. The Loruvani area has the most potential for aquifer development due to its permeability, high recharge rate, massive aquifer thickness and low drawdown.

Browsing by Issue Date

Results Per Page

Sort Options