School of Engineering and Technology

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Mechanisms of mechanical oil expression from rapeseed and cashew.
(University College Dublin, 1979-02) Mrema, Geoffrey C.
The conventional theory of oil expression from vegetable oilseeds suggests that before substantial oil expression can occur, the oilseed cellwalls have to be ruptured by a combination of physical (crushing) and thermal (cooking) pre-treatments. Results from oil expression tests using rapeseed and cashew on the Instron Universal Testing Machine have suggested an alternative mechanism in which up to 80% oil is expressed through a porous cellular microstructure under pressure without cellwall rupture and at ambient temperature. The porous mission electron microscopy. The cellwall pores (plasmodesmata) were of diameter 0.87 and 0.126 pm wall surface area for rapeseed and cashew respectively. The oil expression process has been successfully described by a mathematical model based on three modified form of Terr.aghi's equation for the consolidation of saturated soils., to describe the behaviour of the consolidating oilseed cakej the Hagen Poiseulle equation for flow of fluids to describe the flow of oil through the pores on the cellwall; and The model has Darcy 's law of flow of fluids through porous media to describe the flow of oil through the intra-kernel voids. in pipes, fundamental equations: a oil expression can occur, the oilseed cellwalls and average porosity of 0.093 and 0.171% of the cellnature of the cellwalls has been confirmed by trans been succeafully applied to experimental data which has revealed that the flow of oil across cellwalls in the seed kernel was the rate determining step. In addition the model was also used to analyse the performance of hydraulic and screw expellers. The study has suggested that the design of both hydraulic and screw expellers could be improved by incorporating an undrained compression pretreatment to rupture cellwalls 3 and by reducing the drainage area to 0.5% - 1.5%. Furthermore^ improved strategies for oil expression have been suggested in two cases, (a) For mechanical expression followed by solvent extraction it is proposed that the physical (pre-crushing) and thermal (cooking) pre-treatments be replaced by an undrained compression pre-treatment. are not r equired (b) where mechanical expression is the sole process^ the pre-crushing pre-treatment should replaced by an undrained compression pre-treatment.
Irrigation scheduling
(Sokoine University of Agriculture, 1984) Thadei, Simon y
This thesis deals with irrigation scheduling under rotational water supply. First, irrigation scheduling is defined and the general review of the principles, factors, methods, and scheduling techniques which must be considered before scheduling is given. This includes crop water requirements, factors affecting crop water requirements and methods for determining crop water requirements. Then soil waterholding capacity, irrigation requirements (efficiencies and leaching requirements), amount of water for irrigation, availability of water supply, and scheduling techniques are reviewed. Also, Tanzania's case study is given for two projects: Mbarali (a state farm) and Mombo (village owned farm). Finally, irrigation schedule is prepared for Mombo irrigation scheme.
Construction and evaluation of a modified multicrop thresher model irr1-pak
(Sokoine University of Agriculture, 1987) Kilasara,Wenceslaus George
ABSTRACT A modified IRRI-PAK Multicrop Axial-flow thresher has been manufactured at the International Rice Research Institute (1RRI), Engineering workshop, based on the blueprints of the IRRI-PAK-30 Multicrop Axial-flow Thresher from Pakistan.The modifications include, a piece of hollow shaft to the threshing cylinder shaft; bolted thresher stands; increased area of one of the cleaning screens, and omission of locks and hinges on the observation windows. Different models of four-wheel tractors were used.Three of the four crops used — sorghum variety casor 2; paddy varieties IR38, IR58 and 1917; and yellow corn were obtained from IRRI experimental plots. Wheat was found in Ilocos Region - Northern part of the Philippines.Settings which included increasing/decreasing aspirator air vents, varying the slope/pitch of the oscillating tray assembly, and varying the cylinder speed/peripheral velocity were the variables for the experiments conducted.A conveyor was used during sorghum threshing,An output of 1594 kgh 1 with 97.65% cleaning efficiency, 98.47% threshing efficiency, 1.27% grain loss were recorded.The paddy threshed, gave an output range of UJ7kgh”1■l,r"'r'’-“1 with cleaning efficiency of 93.39% 1569 kgh to 96.01%, and a threshing efficiency of above 99% and total grain loss of between 1.27% and 2.01%.The output of wheat varied from 790kghT1to 2110kgh cleaning efficiency of 76.60% to 96.57%. with Threshing efficiency increased with increased speed. The speed of 510rpm [17.81ms 1 ] gave 96.12% and 710rpm [24.79ms 1 ] gave 98.14%.The results for corn threshing were influenced by the concave bar clearance and or the design of the louvres which resulted to high grain losses from straw thrower (15.94% to 16.98%). The output ranged from 862 kgh -1 to 896 ,._^-lkgh with cleaning efficiency of 85.79% to 86.66% and threshing efficiency of above 99%.
Quality and quantity of maize and sorghum vegetative parts harvested at different stages of plant growth as fodder for livestock
(Sokoine University of Agriculture, 1994) Eligy J. M. Shirima
Two on-station research experiments were conducted at the Livestock Production and Research Institute, Mpwapwa and one at Pasture Research Center, Kongwa both in Central Tanzania from January to October, 1993. Four treatments in maize, grown in Mpwapwa station, were stripping (SR), topping (TP), stripping + topping (STP) at silking stage and whole plant stover (WPL or control) were assigned randomly within the four blocks of a complete randomized block design experiment. Only SR and WPL treatments were performed in sorghum trials in Kongwa under the same experimental design as in maize but each were replicated twice within each of the four blocks. Also three treatments replicated thrice for measuring the intake and digestibility of the SR, TP and WPL obtained from the maize trial were done at Mpwapwa center by using nine adult BHP male sheep. Complete block design was used by blocking the sheep on weight basis ranging from 29 to 37 kg live weights (mean 32.8 + 1.0). Both animals received equal amount of supplement diet (maize bran + sunflower cake). A village survey through questionnaire and physical body weight measurement of cattle every other fortnight was carried out in Berege village in Dodoma region from the start of the dry season (June) to mid- dry season (October). Sample collection of forage used by the animals was done on the same day after weighing the animals. Ten farmers with improved dairy cattle (Mpwapwa breed) were incorporated. An additional survey was also conducted in Kilimanjaro region among eight farmers to explore the farmer’s knowledge on the use of SR, TP and STP from maize. In maize the highest vegetative biomass production including the final residues after the grain harvest was gained with the STP treatment followed by TP with 5.44 t/ha and 5.35 t/ha respectively (p<0.05). Less fodder materials were collected from WPL (4.23 t/ha) due to field losses. No significant difference were found in sorghum fodder yields despite the leaf losses in WPL. Stripping in sorghum yield 2.2 t/ha and WPL as 1.8 t/ha. In maize total CP accrued from STP were (287 kg/ha) ), TP (234), SR (177) and WPL (138). The IVOMD of the fractions were in the order of 75%, 69%, 64% and 52% in SR, STP, TP and WPL fractions respectively. Seventy-three percent more CP was produced from SR of sorghum than WPL treatment with 123 kg/ha by 71 kg/ha respectively. Digestibility (IVOMD) of the SR leaves from sorghum was 79 % while 55 % from the WPL leaves. The feed intake of SR leaves in maize was more than twice (850 g/day) that of the WPL stover (361 g/day) when fed to sheep. The total digestible crude protein (DCP) from SR of maize was 51 % while the same from WPL was negative. With the supplement diets, the DCP of SR leaves improved slightly to 55 % but increased greatly in WPL to 51 %. From the village survey, the cattle in Berege suffered from lack of high quality feeds resulting in body weight losses during the later part of the dry season despite the bigger cultivated crop field farms than in Kilimanjaro region. With small areas of land in Kilimanjaro region, less than 1.5 ha, the maize fractions alone harvested before and after grain harvest accounted for over 39 % of the total annual cattle feed2 requirement while in Berege the combination of all dry residues after harvest (maize, sorghum and millet) formed 42 % of the total annual diet. This made the dependence of natural pasture in Kilimanjaro region to be only 28 % while in Berege village the cattle were still depending on 40 % natural pasture for the annual feed resources. Since the defoliation of maize and sorghum vegetative parts had no deleterious effects on the final grain yield, the technique should be introduced in Central Tanzania so as to make use of the enormous green materials lost in the wet season to be available in dry season. Their higher feeding value also will be an advantage to the farmers as they will buy less supplements to be added . to the forage to meet the animal requirements for maintenance and production.
Isolation and characterisation of yeasts and bacteria from Mbege- An opaque Beerr made from millet malt and banana juice
(Tanzania J. AgriC. Sc, 1998) Shayo, N. B; Nnko, S. A. M; Gidamis, B
The micro organism involved in the traditional fermentation process of "mbege ",an indigenous Tanzanian alcohol beverage prepared from malted millet and banana juice were isolated and identified saccharomyces cerrevisiae and lactobacillus plantarum whereidentified as yeast and bacteria responsible for the fermentantion process respectivelly. The main spoilage micro-organism of Mbege was identified as of Acetobacter species. A diverse range of micro-organisms were also identified in the mlliet malt .The coliforms were the predominant ones followed by pseudomonads, lactic acid bacteria(LAB) and yeasts. The presence of high numbers of coliforms (l.98+0.20x 107 ) in millet malt poses no health risk as they are destroyed during porridge preparation. In addition the low PH ( ph4.5 ) of mbege in hibits the growth of coliforms and other pathogenic bacteria. The diverse range of micro-organisms founds in millet malt was an indication of unhygienic handling of millet malt,
Evaluation of the water budget technique for the determination of the effective length of the growing season under different climatic conditions in Malawi
(Sokoine University of Agriculture, 1998) Majamanda, Ignatious Ives
A study was conducted in Malawi, with the objective of evaluating the potential of the water budget technique, for the determination of the effective length of the growing season under different soil and climatic conditions. Two criteria were used to achieve the objective. One was the rainfall criterion, where rainfall was the only input and the other was the water budget criterion, where climatic data, soil and plant characteristics were major inputs. Historical rainfall data were tested for homogeneity and statistical distribution using RAINBOW computer programme. All the stations, except Dedza, were homogeneous (P = 0.05). The coefficient of determination (R^) suggested that the onset and end of the growing season can be approximated by normal distribution whilst the annual rainfall can be approximated by lognormal distribution. Three years of historical rainfall data were used to calibrate IRSIS as a predictor of daily runoff. Very good and consistent performance (R2=0.86) was obtained in predicting runoff. The calibration of the rainfall criterion using the water budget criterion indicated that the onset of the growing season could be defined as, a day when a running total of 30mm of rain is accumulated in a decade with no dry spell of more than 10 days occurring in the following 30 days. The results of the start and end of the growing season indicate that the rainfall criterion used in this study can be adapted for Chitedze and Makoka. The water budget criterion predicted onset dates closer to when farmers usually plant maize than the rainfall criterion. Both criteria revealed that Mangochi, Ngabu, Makhanga and Chileka have short growing seasons and high occurrence of dry spells within the growing season. Water conservation measures and / or supplemental irrigation should be advocated in these areas for sustainable crop production. Using runoff plots, the study also showed that the Curve Number (CN) value in plain plot was higher than in contour plot. It is recommended that the rainfall criterion which does not require a lot of input data should be calibrated using a more accurate approach (water budget) to establish appropriate threshold and conditions for different stations.
Erosion hazard assessment in the upper Ewaso Ng’iro basin of Kenya: application of gis, usle and eurosem
(Sokoine University of Agriculture, 1999) Mati Bancy Mbura
A methodology was developed for assessing soil erosion hazard in the Upper Ewaso Ng’iro basin of Kenya, using Geographic Information Systems (GIS), the Universal Soil Loss Equation (USLE) and the European Soil Erosion Model (EUROSEM). The USLE was used in a GIS environment by creating thematic maps of R, K, L, S, C and P and then calculating soil loss by raster-grid modelling with Arc/Info GRID. The rainfall erosivity factor (R) was derived from relationships between rainfall amount and erosivity using erosion plot data from within the catchment. The nature of the relationship was found to be a function of agi o-climatic zones of the region. Mean annual erosivities ranged from 145 to 990 J m'2 hr'1. For a given amount of rainfall, erosivity was higher in zone IV than in the wetter zones 11-111. The soil erodibility factor (K) was estimated using the USLE nomograph and data from laboratory analysis of field samples collected from representative major soil mapping units. The K-values were low to medium, ranging from 0.10 to 0.25 over 84 percent of the basin. The topographic factor (LS) was obtained by creating Digital Elevation Models (DEMs) of the basin with TOPOGRIDTOOL of Arc/Info. These were then used to determine the slope steepness and length factor values, calculated with raster-grid modelling. Although DEMs proved a useful tool, maximum values of both steepness and length had to be set in this reconnaissance study to achieve reasonable results. A finer resolution of input data and a smaller grid cell size are needed for accurate determination. The cover and management factors (C) were obtained by determining the land cover types within the basin using remotely sensed data (SPOT 1 colour composite prints) and ground truthing studies. The factor values were estimated from USLE guide tables and measurements of cover from plots and test sites. Some 70 percent of the basin is covered by rangelands. The conservation practice (P) factor values were estimated from USLE guide tables and then applied to areas where soil conservation had been introduced /?. M. Mali PM > Thesis 1999 Silsoe College Cranfield .■Ihstract •'university II according to maps obtained from the Ministry of Agriculture. The USLE was validated using data from erosion plots. A value of R2 = 0.645 was obtained between predicted and measured values but the standard error was rather high (e = 5.745 t ha'1 yr'1). Using an annual soil loss of 9.0 t ha'1 yr'1 as tolerance level, some 36 percent of the basin was found to experience unacceptably high erosion rates. Most of this area was communal grazing land and cropland where soil conservation measures had not been applied. A critical land cover type within the grazing land is shrubland, where vegetation cover is less than 40 percent and high erosion risk was predicted and confirmed by field surveys. EUROSEM could not be integrated within a GIS in the time available for research. It was therefore simulated outside GIS environment, where it was applied to Embori and Mukogodo plot data using separate data sets for calibration and validation. Calibration was used to obtain input parameters for saturated hydraulic conductivity, cohesion and Manning’s roughness coefficients. Validation gave correlation coefficients of 0.907 and 0.840 for predictions of storm runoff and soil loss respectively at Embori; the corresponding values for bare soil plots at Mukogodo were 0.895 and 0.577. However, EUROSEM predicted runoff poorly (R2 = 0.570) and failed to predict soil loss at all the vegetated plots at Mukogodo. The model was applied to simulated vegetation covers of barley, maize, grass and forest for a 36.7 mm rainstorm at Embori. The simulated soil losses showed an exponential decrease with increasing cover. At a threshold cover of 70 percent, soil loss diminished to zero under grass and forest and decreased to a minimum value under barley and maize. These results support the USLE simulations, which showed that areas with more than 70 percent cover (such as forest) had a low erosion hazard, even with steep slopes and high rainfall erosivities. This research has demonstrated that GIS can be used with the USLE to assess and quantify erosion hazard, giving results that can be used for conservation planning. EUROSEM can be applied successfully to bare soil and cropland, but application to other land covers requires further investigation. Land cover and topography are the main factors controlling the spatial distribution of soil loss in the Upper Ewaso Ng’iro basin. Future conservation activities should be concentrated on the rangelands.
Performance evaluation of an indigenous irrigation system at towero village, western Uluguru mountains, Tanzania
(Sokoine University of Agriculture, 2000) Kongola, Malongo John Mussa
Indigenous irrigation methods in mountainous areas are a result of people’s efforts to survive on limited land resource bases. The adoption of an irrigation method depends on whether it does not affect the soil. While surface methods are common in the Uluguru Mountains, drag hose sprinkling is receiving wide use at Towero. Drag hose sprinkler irrigation refers to the local use of sprinklers where water pressure is obtained by gravity flow. Effects of indigenous irrigation systems’ practices on soil erosion were evaluated using field data and aerial photographs. Field data were obtained from six slopes, ranging from 6 to 84%. Two versions of aerial photographs were used to produce land-use maps for 1964 and 1992, respectively. Traversing produced the land-use map of 1999. Land-use analysis revealed that between 1964 and 1999, the area under indigenous irrigation increased by 0.81 ha/ycar. Between 1964 and 1999 the settlement area increased by 0.83 ha/year. Deforestation rate was 6.48 ha/year. Mean crop yields for leeks ranged between 9.65 — 13.53 tonne/ha. Mean specific yields ranged between 0.65 - 1.09 kg/m3. Mean water conveyance, application and storage efficiencies were 83.72%, 86.20% and 99.64%, respectively. All fields wereii over-irrigated based on soil moisture data which were taken daily. Over-irrigation caused inequitable water distribution. Daily sediment load transport in canals A, B and C were 22.2 kg, 187.6 kg and 54.7 kg, respectively. Total sediment loss was 264.6 kg per day. Net downslope splash loss at 84, 70, 65, 24 and 15% slope was 28.9, 19.1, 12.0, 6.0, and 1.0 kg/ha, respectively. The effects of indigenous irrigation systems’ practices at Towero were: soil loss in the form of splash erosion and sediment load transport, and acceleration of deforestation in pursuit for more agricultural land. Hence, efforts to promote soil conservation practices at Towero are essential.
Modelling the water balance of a small catchment: a case study of Muhu catchment in Southern highlands of Tanzania
(Sokoine University of Agriculture, 2000) T. Shiba, Sipho Simeon S.
I'he water balance ol'Muhu catchment located in the Southern Highlands of Tanzania in Iringa region was modelled by establishing the empirical relations that exist between storage parameters, rainfall parameters and runoff components. Storage parameters included soil moisture storage and interception. Rainfall parameters included rainfall amount, intensity, duration. throughfalL stemflow and evaporation. Runoff components included total runoff, direct runoff and base How. The catchment's physical and hydrological characteristics that affect these parameters were determined. 1 he assessment of hydrological and physical properties showed that the soils were predominantly sandy clay, having high organic matter content, with a moderately rapid hydraulic conductivity (Ks) of 4.2 cm/h and infiltration rale of 3.8 cm/ h. The bulk density was generally low with an average of 0.9 g/cnT for 0-15 cm depth: 1.1 Ig/cm5 for 15-30 cm depth and 1.30 g/cm’ for 30 - 45 cm depth. The catchment had a slope steepness of 35 % and a varying vegetal percentage cover of about 56 %. The 1997/98 waler year was exceptional with high rainfall (1934 mm) mainly due to the El-nino phenomenon. Sixty-seven percent of the rainfall received in the catchment penetrated the canopy to reach the forest floor as throughfalL On average 3.3 % of the rainfall reached the forest floor as stem flow' while 25.5% of the rainfall was intercepted by the canopy. ThroughfalL stemflow and interception were linearlyIll related to rainfall. Die regression coefficients of all the relationships were significantly different from zero al 1% level (fteO). With increasing percentage surface cover, interception increased while throughfall decreased. The storage capacity of the forest cover was estimated to be 0.7 mm. Il has been found in this study that stream flow and runoff have gradually been increasing since the 1994/95 season. However the rainfall trend docs not support this development. A consideration of runoff curve numbers showed that the observed trend was partly due to catchment degradation, farming activities in the area have gradually been substituting the forest with arable land, thus reducing surface cover. Records indicated that the lowest recorded daily mean How was 0.27 m'/s. while the highest was 1.6 m'/s. I he water balance was positive during the first five months of the wet season. The highest water balance was in April. During this period there was more recharge to the soil moisture and ground water storage. Water balance was negative in the remaining seven months of the water year, with the lowest in September. The developed direct runoff model and water balance model were found to be valid and useful in estimating the respective parameters in forested catchments of the southern highlands of Tanzania.
Repair costs of tractors and comparison of mechanization strategies under Tanzanian conditions
(University of Munich, 2000-08) Mpanduji, Sylvester Michael
Influence of quality attributes on the market value of fresh sweet potato tubers and processed cassava.
(Sokoine University of Agriculture, 2001) Ndunguru,Gabriel t.
Cassava (Manihot esculenta Crantz} roots and sweet potato (Ipomoea batatas (L) Lam) tubers are important staple food crops in several areas of Tanzania. Studies were conducted in Mwanza and Dar es Salaam markets in order to assess the factors that influence the quality and market value relationship of fresh sweet potato tubers and processed cassava roots. Consumers and traders in Mwanza preferred sweet potato tubers which are wholesome and free from infestation. White processed cassava root products were preferred by traders and consumers in Mwanza. Valuation assessment made on sweet potatoes showed that, broken, cut and weevil infested tubers sold were at 12.1, 14.2 and 36.6 percent discount respectively. Average valuation discount of processed cassava roots were 10 to 15 for yellow, 20 to 25 for greenish and 35 to 40 percent for dark product. Causes of losses in quality of sweet potato tubers were due to operations related to handling and transportation. Occurrence of broken tubers, skinning injury and cuts increased significantly with handling and transportation (P < 0.001). The largest loss in quality occurred between the lakeshore and the port at Mwanza when sacks were loaded and unloaded from the ship and handled at the port.iii Broken sweet potato tubers and skinning injury increased significantly ( P < 0.001) during handling and transportation from Gairo to Da es Salaam Impact shock loggers provided a low cost method for comparing the handling of sacks during transportation. Shock impact record increased with increase in the height form which sweet potato sacks were dropped (R2 adjusted = 0.875). Multiple linear regression analysis indicated that the number of impact in the category between 0.2 and 2 g significantly correlated with skinning injury (P=0.001), (R2 adjusted =0.651) and broken tubers (P=0.001), (R2 adjusted = 0.407) respectively. Weight loss during storage increased significantly (P=0.01) with shock impact and skinning injury. Dropping sacks of sweet potato tubers significantly (P < 0.01) increased the occurrence of broken tubers The use of cardboard boxes filled with fewer tubers instead of overfilled polypropylene sacks and adoption of improved management procedures in the handling and transport are recommended.
An examination of alternative fertilizer transportation, warehousing and application systems for agricultural cooperatives
(Sokoine University of Agriculture, 2004) Kilima Fredy Timothy Mlyavidoga
The difficulty of controlling cost in a dynamic industry where competitiveness and costs are changing over time has long been recognized. Conventional wisdom suggests that players who succeed in such an industrial setting are those who capture the opportunities presented by a new business environment while maintaining economic efficiency (Bello, Lohtia and Sangtani; Flint). In recent years, one of the business challenges for fertilizer suppliers in the United States has been to keep pace with the changing business environment. The changes arise from changing demand, growing global competition, increased regulations in the industry for environmental and safety reasons, and improvements in the transportation and application methods. The improvement in fertilizer distribution and application methods is by and large a reflection of changes in the physical condition and operating characteristics of highways, and changes in farm transportation and application equipment (USDA, Agricultural Cooperative Service). Changes in fertilizer demand and increased market competition are attributable to changes in farm application systems, and consolidation of farming business that has decreased the number of farms and increased the average farm size (Norton).
Infant feeding practices and prevention of vertical transmission of HIV in Mvomero district, Morogoro
(Sokoine University of Agriculture, 2005) Kessy, Margaret
HIV infected mothers arc currently advised to avoid all breastfeeding where replacement feeding is acceptable, feasible, affordable, safe and sustainable in response to breastmilk transmission of HIV. However, in Tanzania where most women do not know their HIV status, exclusive breastfeeding and access to safe replacement feeding is unachievable. This study examined the impact of social, economic and cultural constraints on the development of infant feeding interventions to prevent vertical transmission of HIV, in order to inform a successful infant feeding improvement initiatives in the era of HIV and AIDS. The hypothesis of the study was that knowledge of breastmilk transmission of HIV and awareness of HIV status affect infant-feeding practices. Seventy infected and uninfected mothers with children below IS months were interviewed. The results show that respondents’ knowledge of breastmilk transmission of HIV was high, 100?4> of the infected and 97.1% of uninfected mothers knew about the possibility of transmission'oT^IIV through breastmilk. The mean duration of exclusive breastfeeding was 3.48 and 2.97 months for infected and uninfected mothers respectively. Knowledge of HIV status was not associated with breastfeeding practices. Although infected mothers stopped to breastfeed earlier than uninfected mothers, mean age for cessation of breastfeeding was 6.4 months, far above the recommended age for cessation of breastfeeding to prevent vertical transmission of HIV. The age of the mother was associated with the duration of exclusive breastfeeding (p<0.05) but did not contribute to cessation of breastfeeding (p=0. 3979). Health workers as source of infomiation regarding vertical transmission of HIV was significantly associated with exclusive breastfeeding for four months (p<0.05) and to cessation ol breastfeeding (p<0.05). Number of children below five years contributed to cessation of breastfeeding (p<0.05). Factors influencing the attitude of feeding interventions included mis-information, and myth about vertical transmission of HIV, lack of purchasing power to infant feeding interventions and stigma. Factors influencing breastmilk practices included mothers’ health (p<0.00l), fear of infecting the child (p<0.001), insufficient breastmilk (p<0.001), beliefs about breastfeeding such as clearance of child’s throat (p< 0.001) and child cry (p=0.112). Integrated approaches to increase awareness of vertical transmission of HIV, change health care seeking behaviour and counteract harmful beliefs about infant feeding may improve attitude and infant feeding practices to prevent vertical transmission of HIV.
The impacts of frozen storage and fatty acid oxidation on silver carp myofibrillar protein functionality
(Jiangnan University, Wuxi, JiangsuProvince, P.R., 2006) Mlyuka, Erasto
Silver carp (Hypophthalmichthys molitrix) is a freshwater species living in temperate conditions (6-28 °C) and its natural distribution is in Asia. It is generally cultured and marketed locally alive or fresh in most of the producing countries. China is the largest producer of silver carp in the world; however, its market price is relatively low compared to most other species, normally costs 8-10Yuan/kg. In order to keep the product longer and further extend the markets instead ofjust consuming it fresh, processing technologies for adding value and frozen storage are of significantly important for this fish species. In this thesis, the report is mainly focused on the study done on isolation of myofibrillar protein from silver carp; exposing the isolated myofibrillar protein to oxidative environment simulated using an iron oxidation model system to mimic the oxidative stress during processing and frozen storage. Also the impacts of the iron oxidation model system, fatty acid oxidation and frozen storage on protein functionality of silver carp myofibrillar protein isolate were evaluated. Oxidative damage to silver carp myofibrillar proteins isolate (MPI) was investigated by measuring changes in physico-chemical, and functional properties after exposure to iron-catalyzed oxidation system (IOS). Iron oxidized MPI exhibited an increase in carbonyl content and dityrosine, which were significant and negatively correlated with protein solubility (PS) (r=0.85), (r=0.80) and gel strength (GS) (r=0.95), (0.93), respectively, however the decrease in total thiol group content was significantly and positively correlated with PS (r=0.77) and GS (r=0.89). These led to significant changes (P<0.05) observed in the protein and functional properties of oxidized MPI. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis demonstrated that IOS resulted in a major loss of myosin and actin associated with formation of protein polymers as supported by gel-permeation chromatography (GPC) results. The total fat content of silver carp MPI was 0.6%, it is mainly composed of unsaturated fatty acids of which about 34% constituted by eicosapentaenoic acid, ( 2O:5co-3), docosahexaenoic acid, ( 22:6co-3), and linolenic, ( 18: 3m-3) as the main co-3 poly-unsaturated fatty acids (PUFAs) as well as linoleic acid, (18:2co-6) and arachidonic acid, (20:4co-6), the main co- 6 PUFAs in fish , unfortunately PUFAs are prone to oxidation producing reactive oxygen species capable of modifying protein structure. This study suggests that the decreased functionality of proteins in muscle foods exposed to an oxidative environment could be due to chemical and physical changes resulting from oxidation reactions. It was found that silver carp myofibrillar protein is susceptible to an iron-catalyzed oxidation causing a significant loss of its functionality, thus a study was carried out to iii Jianenan University, M.Sc Thesis, 2010 Abstract determine the susceptibility of silver carp protein to natural oxidants (fatty acids or fatty acids oxidation products) in frozen storage with respect to its functionality. Frozen stored myofibrillar protein isolate with 0.6M NaCl or myofibrillar protein isolated from previous frozen stored whole fish and fish mince of silver carp at -18°C for 90 days were assessed for protein and lipid oxidation with regard to protein functionality. The addition of sodium chloride to 0.6M at pH6.5 improved protein functionality especially water holding capacity of frozen stored myofibrillar protein isolate from 5.3 to 6.4mL/g MP1 after 90 days of frozen storage. However, the differential scanning calorimeter results showed that, sodium chloride significantly increased thermal susceptibility of myosin from 48.12 to 46.40°C with 0.1M NaCl and 0.6M NaCl frozen stored for 90 days, respectively. Whole fish frozen storage was more susceptible to oxidation compared to fish mince and myofibrillar protein isolate due to their different lipid content. On contrary, myofibrillar isolated from frozen whole fish showed significant changes in protein functionality may be due to great loss of amino acid such as cysteine, lysine, histidine and methionine during frozen storage. On the other hand investigation was done on stabilization and oxidation protection of silver carp MP1 stored at -18 °C, 90 days and composed of MPI, 8% cryoprotectants (4% sucrose and 4% sorbitol) with or without antioxidants (0.2% ascorbate, 0.2% a- tocopherol, or their combination) and packed in a polyethylene bag, sealed under air. MPI without cryoprotectants and antioxidants was the control. Compared with the control, cryoprotectants increased PS (protein solubility), WHC (water holding capacity), OHC (oil holding capacity), EC (emulsification capacity) and GS (gel strength), also, the cryoprotectants and/or antioxidants decreased MPI oxidation susceptibility as well as susceptibility of myosin to thermal denaturation. After 30 days of frozen storage, there were no significant differences ((P>0.05) of storage time on alteration of protein functionality and actin susceptibility to thermal denaturation between cryoprotectants and the control. Antioxidants minimized oxidation effects on MPI frozen storage. Therefore, the present study reveals that, improvement in the functional properties of silver carp MPI were greatly influenced by cryoprotectants and antioxidants, this reflect a great role played by sucrose/ sorbitol and antioxidants in protecting native protein structure to a greater extent owing to impact of frozen storage and oxidation respectively.
Nutritional status of underfive Children in a Pastoral Community in Simanjiro District, Tanzania
(Tanzania Health Research Bulletin, 2006) Nyaruhucha, C. N. M; Mamiro, P. S; Kerengi, A.J; Shayo, N.B
A study was conducted in Simanjiro district in northern Tanzania to determine the nutritional status of underfive children in a pastoral community. Weight and height measurements were carried out on 250 children and that of mean upper arm circumference (MUAC) on 226 children. The z-scores of weight-for-age, weight-for-height and height-for-age indicated that 31.2% of the children were underweight and 6.0% were severely underweight. Wasting was observed in 17.2% children of whom 3.2% were severely wasted. Severely stunted children were 3.2% while 14% were moderately stunted. Measurements of MUAC indicated that 35% and 3.5% of the children were moderately and severely undernourished, respectively. The nutritional status of the children under study was slightly lower than the national average. In conclusion, malnutrition in Simanjiro district is prevalent, and therefore, appropriate multidisciplinary approach on nutrition education, environmental sanitation and hygienic practices at family and community level need to be promoted to reduce childhood illnesses thereby increasing child health and nutritional status.
Physical-chemical properties, storage stability and sensory evaluation of pumpkin seed oil
(2006) Lyimo, M. E.; Shayo, N. B.; Kasanga, A.
Physico-chemical properties, storage stability and sensory evaluation of pumpkin seed oil was carried out and compared with other vegetable oils commonly used in Tanzania in order to evaluate its potential as an edible oil with the aim of promoting its utilization in rural areas. Pumpkin seeds were collected from different farmers in three villages in Morogoro Region, Tanzania. The proximate composition of the seeds was determined using standard methods. Storage stability of the oil was evaluated by monitoring the physicalchemical properties of the oil for 15 weeks following the standard procedures. Acceptability of the oil was determined using a 5 point hedonic scale. Pumpkin seeds contained 34.7%, 15.9%, 3.85% and 44% protein, fat, fibre and carbohydrates, respectively. The specific gravity of the pumpkin seed oil was 0.92; peroxide value 4.6 meq/kg; iodine value 108.4; saponification value 173.0 and acid value of 0.5 mg KOH/g. The pumpkin seed oil was organoleptically acceptable in terms of flavour, taste and odour. The pumpkin seed oil conforms very well with other common edible vegetable oils in Tanzania in terms of physical-chemical properties and sensory evaluation. Farmers should be encouraged to utilize pumpkin seed oil for household consumption
Physico-Chemical and grain cooking characteristics of selected rice cultivars grown in Morogoro
(2006) Shayo, N. B.; Mamiro, P.; Nyaruhucha, C. N. M; Mamboleo, T
A study was carried out at Sokoine University of Agriculture to characterize the local rice varieties grown in Morogoro Region basing on their physical-chemical characteristics and cooking quality parameters. Five cultivars of rice were analyzed and these included Kaling’anaula, Kihogo Red, Salama M17, Supa and Salama. The samples were collected from Crop museum, SUA. The chemical analysis was done to determine the proximate composition, gelatinization temperature and gel consistency as main determinants of cooking quality, sensory evaluation tests was done as determinants for consumer acceptance. The proximate composition results indicated protein content values between 7.94 and 9.46%, ash content between 0.55 and 0.97%, fat content between 0.57 and 0.85%, fiber content between 0.29 to 0.73%. The amylose content values were between 18.25 and 19.25%. The gel consistency results showed that all cultivars analysed were hard with the gel length values between 27.50 and 31.80 mm There was a significant differences in composition as well as acceptability between the varieties. In all aspects, Supa cultivar appeared to be the most superior with mean score of 4.30 while Kihogo Red was the least superior with mean score of 2.93. The differences in the cultivars could be from environmental as well as genetic factors. This pauses a need for more studies to be directed to these factors in order to come up with useful alternatives on how to manipulate them so as to improve the cooking quality parameters, improve production of the local rice cultivars and increase the market demand for local rice.
Agricultural research online system: an approach to promote collaboration and sharing of agricultural research knowledge in Tanzania
(University of Dar es salaam, 2006) Lwoga, Edda
The purpose of this study was to develop a prototype of an agricultural research online system in order to promote collaboration and sharing of knowledge among researchers in Tanzania. Major focus was on the application of the open access (OA) and community of practices (CoP) concepts in order to improve the process of capturing and sharing of the agricultural technologies and knowledge to researchers, subsistence and commercial fanners and other stakeholders for the sustainable development of agriculture in Tanzania. An exploratory survey, system analysis and ICT-based design were the used methodologies to convey the current state and challenges of knowledge sharing activities among agricultural researchers, as well as to assess the user requirements and develop the Agrinet-Tz prototype. Survey results revealed that the current state of knowledge sharing activities in agricultural research institutes is still not satisfactory within the country. This is mainly due to poor knowledge sharing culture, poor ICT infrastructure, inadequate funds, lack of awareness about rhe OA issues and inadequate knowledge management support by the research institute management. Major features to be included in the proposed system were also identified in the survey with a greater emphasis on both intrinsic and interpersonal motivational factors in order to stimulate researchers to share their knowledge online. Prototype (i.e. Agrinet-Tz) of the agricultural research online system in Tanzania was therefore developed with the application features geared at both intrinsic and interpersonal motivational factors. This was done in order to resolve some of the revealed challenges such as poor knowledge sharing culture among agricultural researchers. The selected open source software (i.e. Dspace, SMF forum and Joomla portal software) were re-designed to develop the Agrinet-Tz prototype. Additionally, the system was also tested in order to assess the system usability, where the positive feedback was received from the respondents. User roles for the developed prototype were also defined in various categories in order to ensure the system sustainability
Evaluation of drip irrigation system of a commercial tea {Camellia sinensis l.) Estate: a case study of Kibena Tea Estate in the southern highlands of Tanzania
(Sokoine University of Agriculture, 2007) Sinda,Mabvuso Christopher
A study was carried out at Kibena Tea Estate (KTE) to evaluate the performance of drip irrigation in commercial tea production. The undertaking of this study was necessitated by the need for a more water efficient method of water application given the water scarcity problems faced by KTE. The main objective of the study was to evaluate the performance of drip irrigation system at KTE. Specific objectives were to evaluate water use efficiency of drip irrigation. The second objective was to assess the yield response to water of four tea clones (i.e. SI5/10, PC81, 207 and K35) and thirdly, to investigate if water savings would be attainable through employing drip irrigation in commercial tea. Six irrigation application levels representing four water replenishment levels of 25% evapotranspiration (ETC). 50% ETC, 75% ETC and 100% ETC and two variations of drip lateral placement (i.e. one drip lateral placed in each of the inter row spaces and one lateral placed every after each of the inter row spaces) were adopted. No significant differences were observed on tea yields among the 6 irrigation application levels. Clone SI5/10 had the highest yield of 284 kg ha'1, followed by clone PC81, 207, K35 which had made tea yields of 207 kg, 184 kg and 116 kg ha' respectively. Irrigation application 1 had the best performance in terms of IE. and WUE. Irrigation application levels 1, 2 and 5 had acceptable range ofIE for drip irrigation systems. Whereas, irrigation application levels 3, 4, and 6 were below IE acceptable standards. Emission uniformity, for all irrigation application levels was within acceptable standards. The highest WUE for irrigation application level 1 was under clone SI5/10 with 1.46 kg mm followed by PC81 with 1.07 kg mm i'1, clone 207 had 0.95 kgmm. The least perfonning clone, K35, had 0.60 kg mm The cumulative depth of ,3 irrigation water application under irrigation application level 1 was 194 mm (1940 m; ha'j.while irrigation application level 2, 3, 4, 5 and 6 received 350 mm, 467 mm, 623 mm, 208 mm and 659 mm respectively. The optimum level of irrigation water application under the prevailing conditions was irrigation application level 1. The recommendations from this study were that study should be repeated using proper drip scheduling methodology. Furthermore, the study should be done using irrigation requirements computed from recognised empirical methods such as Penman Monteith, Radiation with adherence to guidelines for scheduling of trickle systems. Possible research could be done to consider appropriate Kp and K< combination for drip in’igation scheduling at Kibena.
Root-zone soil moisture redistribution in cropping systems under freeze-thaw conditions
(University of Manitoba, 2008) Kahimba, Frederick Cassian
The availability and distribution of soil moisture within the root zone is a key factor in ensuring better crop growth performance and attaining improved yield. The soil moisture is influenced by farm management practices such as cover cropping that affect the freeze-thaw processes during the fall. This in turn may influence accumulation and redistribution of soil moisture during the winter, and thereafter, the soil’s response to thawing during spring, and availability of soil moisture for the subsequent season. The impact of cover cropping systems on soil temperature, infiltration, and soil moisture redistribution due to soil freezing and thawing was investigated. In addition, the effect of cover crop on the within-season and subsequent-season crop performance and yield was also investigated. Time Domain Reflectometry (TDR) and Neutron Scattering (NS) methods were used to measure the unfrozen and total water contents, respectively. Soil temperature was measured using thermocouples embedded in the soil profile. Soil moisture and soil temperature data were collected from August 2005 to September 2007. Laboratory calibration of the TDR miniprobes indicated the maximum cable length for the RG-58 50 Q coaxial cable to be 40.0 m when 35 mm TDR miniprobes were used. Since the TDR was found to overestimate the liquid water content at soil temperatures below 25°C, a method to correct the field measured TDR soil moisture for temperature effects was developed. During soil freeze-up, water from unfrozen soil layers below the freeze front migrated towards frozen layers above. Compared to non-cover crop treatment, the cover crop treatment did not freeze earlier during the fall, froze to a shallower depth during the i

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