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Effects of pond fertilization and supplementary feeding on growth perfomance and economic return of Nile tilapia (oreochromis niloticus)
No full textM.Sc. DissertationNile Tilapia (Oreochromis niloticus) is the most cultured fish species in tropical and
subtropical countries. Desirable characteristics of farmed Nile tilapia include tolerance to a
variety of aquaculture environments and consumption of a wide range of natural food
organisms. In developing countries including Tanzania, Nile tilapia is cultured under semi-
intensive system. Under this system, supplementary feeding is imperative for optimum
growth. However, commercial feeds are very expensive and feed cost accounts for 40 to
70% of the culture operational costs. The best way to reduce production costs is
fertilization of ponds to stimulate natural food production that can be eaten by fish. This
minimizes the amount of supplementary feeds provided without significantly affecting the
growth of the fish, and hence, increases yield and profitability.
A study was carried out to evaluate the effects of pond fertilization alone (T 1 ), feeding
alone (T 2 ) and combination of pond fertilization plus supplementary feeding (T 3 ) on water
physico-chemical parameters, growth performance and profitability of pond cultured Nile
tilapia. The study also assessed the quantity and quality of periphyton found in the ponds
subjected to the three treatments. The experiment was conducted in nine earthen ponds,
each with an average size of 177 m 2 for 180 days. Sex reversed Nile Tilapia (O. niloticus)
fingerlings with an average size of 0.9 g were collected from Ruvu fish farm and stocked
at a density of 3 fish/m 2 seven days after initial fertilization of ponds. Urea and
Diammonium phosphate (DAP) were applied into the ponds under fertilization treatments
at a rate of 3 g/m 2 and 2 g/m2 one week before stocking and then weekly during the
experimental period. Mash feed containing 25.1% crude protein (CP) was fed twice daily
at 1000 and 1600 hours. During the first two months, the fish were fed at a feeding rate of
10% and 5% of fish body weight (FBW) for T 2 and T 3, respectively. After two months, the amount of feed was reduced to 5% and 2.5% for T 2 and T 3, respectively. The fish were fed
at these feeding rates up to the end of the experiment.
Pond water physico-chemical parameters i.e. dissolved oxygen (DO), pH, temperature,
total dissolved solids (TDS), conductivity and salinity were measured weekly at dawn
while Secchi disk readings were measured weekly after dawn hours. Diurnal
measurements were done at three hours intervals for 24 hours at the beginning of the
experiment and then at three months intervals up to the end of the experimental period. A
total of 500 ml of water samples were collected weekly for alkalinity, total nitrogen (TN),
nitrate and phosphorus determination. For periphyton collection, eight nets, each with 20
μm-mesh size and an area of 1250 cm 2 were placed full submerged in water in each pond
for periphyton to attach. The nets were taken out from pond water after every two months
and put in a bucket containing water and then scrubbed to collect periphyton and
zooplankton. The periphyton samples were stored in vials for determination of dry matter,
organic matter, crude protein, phosphorus and ether extract. Four ml of the periphyton
solution were taken and preserved at 4% concentration of formalin for species
identification. A random sample of 30 fish from each pond was taken biweekly and each
fish was measured individually for body weight and length. After being measured the fish
were returned back to their respective ponds. At the end of the experiment feed conversion
ratio (FCR), feed conversion efficiency (FCE), fish body weight gain, growth rate (GR),
specific growth rate (SGR), condition factor (K) and proximate chemical composition of
the fish body were determined.
The data were analysed using one-way ANOVA to assess the effect of treatment on water
physico-chemical parameters, fish body weight gain, growth rate, specific growth rate,
proximate chemical composition, survival rate and gross margin. R studio software version 3.5.0 (2018) was used to analyse the data. Duncan’s new multiple range test and
Tukey’s were used to assess the significance of the differences between pairs of the
treatment means at p = 0.05.
Results indicate that ponds subjected to fertilization alone (T 1 ) had significantly higher
(p ≤ 0.05) dawn dissolved oxygen (DO) (4.35 ± 0.04 mg/l), pH (8.24 ± 0.01) and Secchi
disk reading (25.3 ± 0.1 cm) than the ponds under feeding alone (T 2 ) and combination of
fertilization plus supplementary feeding (T 3 ). Ponds under fertilization alone had the
lowest values for water conductivity (1322 ± 3.28 mg/L), salinity (0.660 ± 0.0 mg/L) and
TDS (670 ± 1.70). Furthermore, the results show that phosphorous (0.33 ± 0.01 mg/L), TN
(20.82 ± 0.24 mg/L) and nitrate (11.85 ± 0.12 mg/L) concentrations were higher (p ≤ 0.05)
in the ponds under fertilization alone than in the ponds under other treatments. Water
alkalinity was lower (181.97 ± 3.25 mg/L) in the ponds under the combination of
fertilization plus feeding treatment than in other treatments. Higher values of water
alkalinity were observed under the ponds subjected to feeding alone (194.39 ± 2.43 mg/L)
and fertilization alone (191.82 ± 2.45 mg/L) treatments, but the difference of water
alkalinity between the two treatments was insignificant (p > 0.05). Mean water
temperature during the experimental period did not differ significantly among the
treatments. The values of DO, pH and temperature within 24 hours showed the peak
values at 1500 hours while the lowest values were observed at 0600 hours in all
treatments.
Results on growth performance indicate that fish cultured under the treatment of
combination of pond fertilization plus supplementary feeding (T 3 ) had significantly higher
daily weight gain (1.5 ± 0.1 g/day), feed conversion efficiency (FCE) (0.5 ± 0.0) and gross
margin (28 499 967 ± 3 173 413 TZS/ha/year) than the fish reared under the other treatments. The survival rate of the fish reared in ponds subjected to different treatments
did not differ significantly (p > 0.05). In addition, fish reared in ponds under feeding alone
showed higher FCR (4.1 ± 0.3) than those grown under combination of fertilization plus
supplementary feeding (2.0 ± 0.1). The cost of producing one kg for fish reared in ponds
under feeding alone (TZS 8 446 ± 380.6) was significantly higher (p < 0.05) than cost of
producing one kg for fish reared under fertilization alone (TZS 5 284 ± 327.4) or
fertilization plus supplementary feeding treatment (TZS 5 824 ± 166.7). However, the
costs of producing one kg of fish did not differ significantly (p > 0.05) between
fertilization alone treatment and combination of fertilization plus supplementary feeding.
Fish condition factor (K) differed significantly among the treatments. The fish cultured
under fertilization alone had the highest condition factor (2.54 ± 0.0) while those reared
under feeding alone showed the least value (2.05 ± 0.0). The highest periphyton biomass
(47.35 ± 7.64 g DM/m 2 ) was obtained in ponds under combination of fertilization plus
supplementary feeding treatment. Ether extract (EE) was significantly higher in fish body
muscles (18.33 ± 0.19%) and periphyton (1.84 ± 0.07%) in samples from ponds subjected
to fertilization alone than in the samples from ponds under feeding alone and combination
of fertilization plus supplementary feeding. Positive correlation was observed between CP
and EE of fish body muscle and those of periphyton. Higher values of CP for both fish
(69.14 ± 0.33%) and periphyton (11.40 ± 0.16%) were observed in ponds under the
combination of fertilization plus supplementary feeding than in other treatments.
The analysis of correlation between fish growth rate and periphyton quantity and quality
revealed that as periphyton quantity (biomass, OM) and quality (CP) increased, fish
growth rate also increased. Periphyton community composition differed (p ≤ 0.05) among
the treatments. Higher species abundance was observed in the ponds subjected to
combination of fertilization and supplementary feeding. The phytoplankton classes observed were Bacillariophyceae, Chlorophyceae, Cyanophyceae, Euglenophyceae and
Zygnematophyceae while zooplankton classes were Eurotatoria, Heterotrichea and
Oligohymenophorea. Therefore, from this study it is concluded that the combination of
weekly fertilization plus supplementary feeding at 2.5% of the fish body weight is the best
feeding strategy. This is because it results into higher periphyton quantity (biomass and
organic matter), quality (crude protein) and species composition which ultimately lead to
higher fish growth, carcass quality (crude protein) and gross margin compared to the other
treatments. The chemical composition of fish body muscles is closely related to
periphyton chemical composition
Uncertainity reduction in climate and hydrological models predictions at catchment scale in the upper great Ruaha river sub-basin, Tanzania
No full textA thesis 2019Water resources have become scarce in most tropical areas of Tanzania due to climate
change. Any changes to the hydrological cycle may have significant effects on the water
resources in the river basins of Tanzania. The impact of climate change on water resources
in Tanzania have been studied using General Circulation Models (GCM) which run at low
spatial resolutions of 100-300 km. The resolution is too coarse to provide useful
information about climate change impact in small catchments as many physical processes
which control local climate e.g.; vegetation, hydrology, topography is not fully
parameterized and hence results on uncertainty in model prediction.
The main aim of this research was to quantify the uncertainty in model predictions for the
Mbarali River Sub-catchment of the Upper Great Ruaha River Sub-basin in the Rufiji
River Basin, Tanzania. Three research objectives were analyzed; the first objective was to
evaluate the performance of the Coordinated Regional Downscaling Experiment Regional
Climate Model (CORDEX, Regional Climate Models) in simulating rainfall
characteristics of the Mbarali River Sub catchment. The area weighted average method
was used to calculate the average rainfall from the CORDEX RCMs and from
ERA-Interim reanalysis over the entire Mbarali River sub-catchment. Comparison
between rainfall data from CORDEX RCMs and ERA-Interim reanalysis was done to test
the ability of the CORDEX RCMs to reproduce the annual cycles, interannual variability,
annual total and trends of rainfall as presented by the ERA-Interim reanalysis.
The second objective assessed the impact of climate change on hydrological
characteristics using the Soil and Water Assessment Tool (SWAT) model. The ability of
the SWAT model to simulate catchment processes was assessed through a calibration and validation process, which was a key factor in reducing uncertainty and increasing user
confidence in its predictive abilities. The SWAT model was driven by high resolution
climate simulations for historical climate condition (1971-2000) as well as future climate
projections (2011-2040, 2041-2070 and 2071-2100) for two Representative concentration
Pathways (RCPs): RCP 4.5 and RCP 8.5. Furthermore, Ensemble of RCMs was applied
into SWAT to simulate water resources availability and the results were compared with
individual models (HIRHAM5, CCLM4, RACMO22T, RCA4). The Rainfall and
Temperature data were obtained from the selected four CORDEX RCMs driven by three
different General Circulation Models (GCMs). Inverse Distance Weight Average (IDWA)
was used to interpolate model gridded climate simulation to the location of weather
station. The third objective assessed the impacts of land use and land cover change on the
hydrology using integration of remote sensing data, QGIS and SWAT model. The land
use and land cover (LULC) maps for three window period snapshots, 1990, 2006 and
2017 were created from Landsat TM and OLI_TIRS. Supervised classification was used
to generate LULC maps using the Maximum Likelihood Algorithm and Kappa statistics
for assessment of accuracy.
The findings of the first objective are that CORDEX RCMs were able to capture well the
seasonal and annual cycles of rainfall. However, they underestimated the amount of
rainfall in March, April and May (MAM) and overestimated in October, November and
December (OND) respectively. CORDEX RCMs reproduce interannual variation of
rainfall. The source of uncertainties was revealed when the same RCMs driven by
different GCMs and when different RCMs driven by the same GCM in simulating
rainfall. It was found that the error and biases from RCMs and driving GCMs contribute
roughly equally. Overall, the evaluation found reasonable (although variable) model
capability in representing the mean climate, interannual variability and rainfall trends.The results suggest that CORDEX RCM is suitable in simulating rainfall, maximum
temperature and minimum temperature.
The findings of the second objective showed that SWAT model simulated stream flow
and water balance components differently when two different RCMs were forced by the
same GCMs as well as when the same RCMs were forced by different GCMs. The
differences are related to the formulation of the RCMs themselves. For example,
RACMO22T and HIRHAM5 driven with the same GCM (ICHEC-EARTH) simulate
different amount of stream flows, surface runoff, water yield and groundwater yield in
historical (1971–2000) as well as in present century (2011-2040), mid-century (2041-
2070) and end century (2071-2100). Ensemble RCMs projected decrease in stream flows
by 13.67% under RCP 8.5. However annual rainfall was shown to increase in averages by
1.62% under RCP 4.5 and by 1.96% for RCP 8.5 relative to the 1177.1mm of the baseline
period (1971-2000).
The results also showed that, temperature will slightly increase relative to the baseline
during present century (2011-2040) for RCP 4.5 and RCP 8.5. The ensemble average
project that the minimum temperature will increase by 14% (1.9 0 C) under RCP 8.5 and
maximum temperature by 7.68% (1.8 o C) under RCP 4.5
The findings of the third objective showed that there were significant changes in land use
and cover for the three-time periods (1990, 2006 and 2017). The cultivated land and built
up area increased from 25.69% in 1990 to 31.53% in 2006 and 43.57% in 2017 compared
to other land classes. Increase of cultivated land and built up area led to decrease in forest
cover. Forests occupied 7.54% in 1990, but decreased to 5.51% in 2006 and 5.23% in
2017. This decrease in forest cover has resulted in increased surface runoff for the same periods (2006-2017). The increase in surface runoff in the study area could be attributed
to deforestation and poor land husbandry, where during land preparation much of the
vegetation is cleared, hence decreasing canopy interception and allowing water to drain
off. Also, poor farming practices including cultivation on hillslopes without soil
conservation, reducing soil compaction, hence allowing more water to drain as surface
runoff.
The calibrated SWAT model using the three different land use and land cover change of
1990, 2006 and 2017 indicate that during the wet season, the mean monthly flow
increased by 1.48% relative to the 28.09 m 3 /s of the baseline 1990 while during the dry
season, the mean monthly flow decreased by 16.7% relative to the 0.20 m 3 /s baseline
flow. Assessment of the impacts of land use and land cover changes on catchment water
balance component revealed that surface runoff increased by 3.9% in 2006 and 9.01% in
2017 while groundwater contribution to stream flow decreased by 6.3% and 12.86% in
2006 and 2017, respectively. The decrease in stream flow could also be attributed to
abstraction of water for irrigation activities upstream of the Igawa gauge station.
The findings of the study may help basin water officers, planners in water sector and
agriculture sector in addressing uncertainty in policy and decision-making specifically
when preparing strategies and adaptations plans for river catchment. The science used in
this study can be applicable to another river basin in Tanzanian in a climate change
impact study
Provitamin a carotenoids, tocopherols, ascorbic acid and minerals in indigenous leafy vegetables from Tanzania
No full textFoods 2019, 8, 35; doi:10.3390/foods8010035The essential micronutrients in indigenous leafy vegetables (ILVs) could substantially
contribute to the micronutrient supply in rural communities in Tanzania, but concentrations differ
between species. Provitamin A carotenoids, tocopherols, ascorbic acid, minerals, and phytate were
analysed in 13 different species using HPLC-, ICP-OES, and photometric techniques. Eight of the
13 ILVs, including Amaranthus ssp. and Sesamum angustifolium, had high -carotene concentrations
(2.91–4.84 mg/100 g fresh weight), which could provide 50% of vitamin A’s recommended
nutrient intake (RNI). Six ILVs including Cleome hirta and Sonchus luxurians had high iron contents
(34.5–60.4 mg/100 g, >50% RNI); Amaranthus ssp. represented the ILV with high calcium, magnesium
and zinc contents (85%, 207% and 21% of RNI per 100 g); Cleome hirta and Cleome gynandra had high
ascorbic acid contents (>15 mg/100 g, 34–35% of RNI), while Sesamum angustifolium was the only
ILV with a high tocopherol content (7.34 mg -TE/100 g). The highest phytate concentration was
found in Amaranthus ssp., which could negatively affect its role as a very good source of minerals.
Results indicate that the analysed ILVs could make a substantial contribution to the vitamin A and
iron supply in the diets of rural Tanzanian populations
Synergy between local government authorities and corporates for social service delivery: a case of district councils and sugar companies in Morogoro, Tanzania
No full textThesis 2019This study examined synergy between Local Government Authorities (LGAs) and
corporates for social service delivery in Kilombero and Mvomero District Councils in
which Kilombero and Mtibwa sugar companies are situated, respectively. Specifically, the
study aimed at examining the environmental forces challenging LGAs and corporates for
social service delivery; assess planning interface between LGAs and corporates for social
service delivery; and examine resource complementarity between corporates and Local
Government Authorities for social service delivery. A case study design was used in which
42 key informants and participants of four Focus Group Discussions were the sources of
data. Content analysis was used to analyse data. The study found that LGAs and
corporate’s response to the environmental forces including community needs for social
services, policies such as employment policy as well as corporates response to
competition and market situation contributed to social service delivery to communities.
The study also found that LGAs planning process for social services was found to be
inclusive and transparent enabling corporates to decide on kind of services to be provided
to communities. On the other hand, Mtibwa Sugar Company was not transparent to share
their planning decisions with the LGA because the decision on the social service to be
implemented was made by the owner of the company in absence of LGAs leaders. On the
other hand, Kilombero Sugar Company planning process for social service delivery was
transparent because their planning decisions were shared with the LGA. This is because
the LGA representative was among decision makers on the kind of social service to
implement to communities through Corporates Social Responsibility (CSR). The study
further found that, despite resources complemented by sugar companies to enable social
service delivery, there were no reports at the district councils showing the amount used by
corporates in financial terms to complement the LGAs budget in the study area. It was
also found that LGAs planning process preceded that of corporates which resulted into
failing of including corporates plans for social service provision through CSR. The study
recommends that there should be measures to ensure that resources used by corporates
and LGAs to respond to environmental forces are tapped and properly allocated to render
social services to communities. Moreover, there should be budget review by the LGA to
relocate resources that corporates use to support community activities. The study
recommends further that, there is a need to improve information system within LGAs on
the resource complemented by sugar companies for social services delivery. Such
improvement should encompass production and submission of reports on resources and
social services provided through CSRs by development stakeholders to the District
Councils
Effect of liming acid soils on physico-chemical characteristics of the soils and coffee seedling vigor in Mbozi District, Tanzania
No full textA Dissertation 2019Soil acidity is one of the most important soil factors affecting crop growth and ultimately
yield and profitability of coffee in Mbozi District Tanzania. Soils tend to be naturally
acidic in areas where rainfall is sufficient to cause substantial leaching of basic ions such
as calcium and magnesium, which are replaced by hydrogen ions. Most soils in Mbozi
District are acidic due to high rainfall and/or the use of soil acidifying fertilizers over a
long period of time. Low soil pH causes aluminium and manganese toxicities while
calcium, phosphorus and magnesium become deficient. In order to counteract the
situation, liming is inevitable. This study was conducted on Ultisols of Mbimba sub-
station, located in Mlowo Ward, Mbozi District, Songwe Region Tanzania. The study area
is located within latitudes 9 0 05’35.97”S and 9 0 05’13.10”E and longitudes 32 0 57’14.51”E
and 32 0 57’22.32”E. The area experiences mean annual rainfall ranging between 1 000 and
1 500 mm with a monomodal distribution pattern. The study aimed at increasing soil
productivity for coffee through the use of agricultural lime and ultimately improve
livelihoods of the coffee farmers in Mbozi District. Different levels of dolomite lime at 0
kgha -1 , 1 000 kgha -1 , 2 000 kgha -1 and 2 500 kgha -1 were used whereby NPK (22.6.12
+3S) at 150 kgha -1 was used at basal application rate. The field layout was set in a
randomized complete block design with three replications. The results indicated that lime
at 1 000 kgha -1 and 2 000 kgha -1 increased soil pH between 0.22 and 0.97 units and the
increase of P was significant at P<0.001. Lime applied at a rate of 2 000 kgha -1 increased
available P concentration by 5.73 - 7.28 mgkg -1 while exchangeable Potassium
concentration increased by 0.14 - 6.01mgkg -1 in all 3 levels of lime and K increase was
significant at P = 0.05. Soil Ca and Mg increased between 0.19 and 6.82 cmol(+)kg -1 and 0.54 - 1.98 cmol(+)kg -1 respectively after application of dolomitic lime. Plant height
increased between 60.4 and 67.1 cm, branches between 29-31, internodes between 23 and
27, canopy width between 74.7 and 79.5cm and stem girth between 8.2 and 9cm. A very
strong positive correlation was found between lime and Mg (R 2 = 0.8643), moderate
positive correlation between lime and N (R 2 = 0.4453), between lime and P (R 2 = 0.7064),
between lime and K (R 2 = 0.4043), between lime and Ca (R 2 = 0.5288) while weak
correlation between lime and Na (R 2 = 0.2007. Correlation value of < 0.4 is considered as
weak, 0.4 - 0.8 moderate correlation and 0.8˃ as very strong correlation. Thus, the study
recommends the use of 2 000 kgha -1 of CaMg(CO 3 ) 2 lime to be used by Mbimba Mbozi
farmers in coffee farms
Safety of selected vegetables grown in urban areas; Case of heavy metals in Dar Es Salaam City
No full textA Dissertation 2019A study was carried out to assess the safety of selected vegetables grown in urban areas,
focusing on a case of heavy metals in Dar es salaam, Tanzania. The study investigated the
concentration of three heavy metals, namely Lead (Pb), Cadmium (Cd) and Copper (Cu)
in the edible portions of selected leafy vegetables, and the effect of blanching on the
possible reduction of heavy metals concentration. The study also compared the levels of
metal in selected matured leafy vegetables across their sampling sites and their associated
uptake rates of the metals from soil. The selected leafy vegetables were Chinese cabbage
(Brassica rapa), Spinach (Spinacia oleracea), Amaranthus (Amaranthus spp), and
Pumpkin leaves (Curcubita moschata). The heavy metals concentration was measured
using an Atomic Absorption Spectrophotometer. The results showed that, Pb and Cd in
dry weight (mg/kg) ranged from 4.46 to 10.09 and 0.49 to 0.79 respectively.
The concentrations were higher than the permissible levels as per WHO, FAO and TBS
for green leafy vegetables. Except for Pb, blanching had no significant reduction effect
(p>0.05) in the heavy metals concentration in the vegetables. The mean concentration of
Pb varied across sites and vegetables (p< 0.05), the mean concentration of Cd did not vary
across sites but varied across vegetables (p>0.05), where the difference was observed
between Chinese cabbage and Spinach. The mean concentration of Cu varied across sites
and vegetables (p<0.05) where the difference was observed between Chinese cabbage and
Amaranthus, Pumpkin leaves and Spinach. The uptake of Pb, Cd and Cu concentrations
among vegetable varieties was not significantly different (p>0.05). This showed that all
selected vegetable varieties up took the metals at a similar rate
Effects of pond fertilization and supplementary feeding on growth perfomance and economic return of Nile tilapia (oreochromis niloticus)
No full textA Dissertation 2019Nile Tilapia (Oreochromis niloticus) is the most cultured fish species in tropical and
subtropical countries. Desirable characteristics of farmed Nile tilapia include tolerance to a
variety of aquaculture environments and consumption of a wide range of natural food
organisms. In developing countries including Tanzania, Nile tilapia is cultured under semi-
intensive system. Under this system, supplementary feeding is imperative for optimum
growth. However, commercial feeds are very expensive and feed cost accounts for 40 to
70% of the culture operational costs. The best way to reduce production costs is
fertilization of ponds to stimulate natural food production that can be eaten by fish. This
minimizes the amount of supplementary feeds provided without significantly affecting the
growth of the fish, and hence, increases yield and profitability.
A study was carried out to evaluate the effects of pond fertilization alone (T 1 ), feeding
alone (T 2 ) and combination of pond fertilization plus supplementary feeding (T 3 ) on water
physico-chemical parameters, growth performance and profitability of pond cultured Nile
tilapia. The study also assessed the quantity and quality of periphyton found in the ponds
subjected to the three treatments. The experiment was conducted in nine earthen ponds,
each with an average size of 177 m 2 for 180 days. Sex reversed Nile Tilapia (O. niloticus)
fingerlings with an average size of 0.9 g were collected from Ruvu fish farm and stocked
at a density of 3 fish/m 2 seven days after initial fertilization of ponds. Urea and
Diammonium phosphate (DAP) were applied into the ponds under fertilization treatments
at a rate of 3 g/m 2 and 2 g/m2 one week before stocking and then weekly during the
experimental period. Mash feed containing 25.1% crude protein (CP) was fed twice daily
at 1000 and 1600 hours. During the first two months, the fish were fed at a feeding rate of
10% and 5% of fish body weight (FBW) for T 2 and T 3, respectively. After two months, amount of feed was reduced to 5% and 2.5% for T 2 and T 3, respectively. The fish were fed
at these feeding rates up to the end of the experiment.
Pond water physico-chemical parameters i.e. dissolved oxygen (DO), pH, temperature,
total dissolved solids (TDS), conductivity and salinity were measured weekly at dawn
while Secchi disk readings were measured weekly after dawn hours. Diurnal
measurements were done at three hours intervals for 24 hours at the beginning of the
experiment and then at three months intervals up to the end of the experimental period. A
total of 500 ml of water samples were collected weekly for alkalinity, total nitrogen (TN),
nitrate and phosphorus determination. For periphyton collection, eight nets, each with 20
μm-mesh size and an area of 1250 cm 2 were placed full submerged in water in each pond
for periphyton to attach. The nets were taken out from pond water after every two months
and put in a bucket containing water and then scrubbed to collect periphyton and
zooplankton. The periphyton samples were stored in vials for determination of dry matter,
organic matter, crude protein, phosphorus and ether extract. Four ml of the periphyton
solution were taken and preserved at 4% concentration of formalin for species
identification. A random sample of 30 fish from each pond was taken biweekly and each
fish was measured individually for body weight and length. After being measured the fish
were returned back to their respective ponds. At the end of the experiment feed conversion
ratio (FCR), feed conversion efficiency (FCE), fish body weight gain, growth rate (GR),
specific growth rate (SGR), condition factor (K) and proximate chemical composition of
the fish body were determined.
The data were analysed using one-way ANOVA to assess the effect of treatment on water
physico-chemical parameters, fish body weight gain, growth rate, specific growth rate,
proximate chemical composition, survival rate and gross margin. R studio softwareversion 3.5.0 (2018) was used to analyse the data. Duncan’s new multiple range test and
Tukey’s were used to assess the significance of the differences between pairs of the
treatment means at p = 0.05.
Results indicate that ponds subjected to fertilization alone (T 1 ) had significantly higher
(p ≤ 0.05) dawn dissolved oxygen (DO) (4.35 ± 0.04 mg/l), pH (8.24 ± 0.01) and Secchi
disk reading (25.3 ± 0.1 cm) than the ponds under feeding alone (T 2 ) and combination of
fertilization plus supplementary feeding (T 3 ). Ponds under fertilization alone had the
lowest values for water conductivity (1322 ± 3.28 mg/L), salinity (0.660 ± 0.0 mg/L) and
TDS (670 ± 1.70). Furthermore, the results show that phosphorous (0.33 ± 0.01 mg/L), TN
(20.82 ± 0.24 mg/L) and nitrate (11.85 ± 0.12 mg/L) concentrations were higher (p ≤ 0.05)
in the ponds under fertilization alone than in the ponds under other treatments. Water
alkalinity was lower (181.97 ± 3.25 mg/L) in the ponds under the combination of
fertilization plus feeding treatment than in other treatments. Higher values of water
alkalinity were observed under the ponds subjected to feeding alone (194.39 ± 2.43 mg/L)
and fertilization alone (191.82 ± 2.45 mg/L) treatments, but the difference of water
alkalinity between the two treatments was insignificant (p > 0.05). Mean water
temperature during the experimental period did not differ significantly among the
treatments. The values of DO, pH and temperature within 24 hours showed the peak
values at 1500 hours while the lowest values were observed at 0600 hours in all
treatments.
Results on growth performance indicate that fish cultured under the treatment of
combination of pond fertilization plus supplementary feeding (T 3 ) had significantly higher
daily weight gain (1.5 ± 0.1 g/day), feed conversion efficiency (FCE) (0.5 ± 0.0) and gross
margin (28 499 967 ± 3 173 413 TZS/ha/year) than the fish reared under the othertreatments. The survival rate of the fish reared in ponds subjected to different treatments
did not differ significantly (p > 0.05). In addition, fish reared in ponds under feeding alone
showed higher FCR (4.1 ± 0.3) than those grown under combination of fertilization plus
supplementary feeding (2.0 ± 0.1). The cost of producing one kg for fish reared in ponds
under feeding alone (TZS 8 446 ± 380.6) was significantly higher (p < 0.05) than cost of
producing one kg for fish reared under fertilization alone (TZS 5 284 ± 327.4) or
fertilization plus supplementary feeding treatment (TZS 5 824 ± 166.7). However, the
costs of producing one kg of fish did not differ significantly (p > 0.05) between
fertilization alone treatment and combination of fertilization plus supplementary feeding.
Fish condition factor (K) differed significantly among the treatments. The fish cultured
under fertilization alone had the highest condition factor (2.54 ± 0.0) while those reared
under feeding alone showed the least value (2.05 ± 0.0). The highest periphyton biomass
(47.35 ± 7.64 g DM/m 2 ) was obtained in ponds under combination of fertilization plus
supplementary feeding treatment. Ether extract (EE) was significantly higher in fish body
muscles (18.33 ± 0.19%) and periphyton (1.84 ± 0.07%) in samples from ponds subjected
to fertilization alone than in the samples from ponds under feeding alone and combination
of fertilization plus supplementary feeding. Positive correlation was observed between CP
and EE of fish body muscle and those of periphyton. Higher values of CP for both fish
(69.14 ± 0.33%) and periphyton (11.40 ± 0.16%) were observed in ponds under the
combination of fertilization plus supplementary feeding than in other treatments.
The analysis of correlation between fish growth rate and periphyton quantity and quality
revealed that as periphyton quantity (biomass, OM) and quality (CP) increased, fish
growth rate also increased. Periphyton community composition differed (p ≤ 0.05) among
the treatments. Higher species abundance was observed in the ponds subjected to
combination of fertilization and supplementary feeding. The phytoplankton classesobserved were Bacillariophyceae, Chlorophyceae, Cyanophyceae, Euglenophyceae and
Zygnematophyceae while zooplankton classes were Eurotatoria, Heterotrichea and
Oligohymenophorea. Therefore, from this study it is concluded that the combination of
weekly fertilization plus supplementary feeding at 2.5% of the fish body weight is the best
feeding strategy. This is because it results into higher periphyton quantity (biomass and
organic matter), quality (crude protein) and species composition which ultimately lead to
higher fish growth, carcass quality (crude protein) and gross margin compared to the other
treatments. The chemical composition of fish body muscles is closely related to
periphyton chemical composition
Contribution of non-governmental organizations in promoting girls’ education in secondary schools in Morogoro District council, Tanzania
No full textA DisssertationThe gap between girls and boys in education still exists in Tanzania despite the sustained
efforts made by the Government and NGOs. Due to this, several studies on NGOs and
girls education were conducted and revealed different supports and activities done by
NGOs to solve the problem. But the question on how the NGOs’ support and activities
have contributed to girls’ education is not yet answered. Therefore, a cross sectional study
was conducted to assess the contribution of NGOs a case of CAMFED in promoting girls’
education in secondary schools. Specifically, the study aimed to examine the support
provided by CAMFED in promoting girls’ education among secondary school students, to
determine the contribution of CAMFED support to girls’ access to education and to
examine challenges encountered by CAMFED in promoting girls’ education in the study
area. A total of 108 respondents were involved in the study. Data were collected through
questionnaires, in depth interviews, observation and documentary review. The findings
indicate that CAMFED offered learning materials, hostel fees, sanitary protection,
uniforms, school contributions, school fees, bicycles, solar lamp and pocket money in
supporting girl students. The support contributed to the increased number of the girls who
were enrolled in secondary schools and in lowering their dropout rates. Despite the
positive contribution in enrollment and dropout the study shows a non-positive change in
academic performance of girls in the surveyed schools. However, it was noted during the
study that CAMFED face nepotism challenges, misuse of funds, lack of cooperation from
parents, inadequate financial resources to attend all students in need and lack of
commitment among the beneficiaries of the programme. The study suggests to the
Government, NGOs, TASAF, institutions and other stakeholders to complement
CAMFED’s efforts by bringing in other services such as building hostels, motivational
and counseling seminars to students and improving teaching environment in schools
Income diversification of rural households in Nigeria: implications for poverty reduction
No full textMasters Dissertation 2019Income diversification is becoming the norm in developing countries and is regarded as a
key factor in reducing the incidence of poverty especially among rural households. It is on
this premise that this study focused on assessing how rural households in Nigeria diversify
their income sources in relation to their poverty trajectories, using data from two waves of
the Nigeria General Household Survey Panel (GHS- Panel) conducted by the National
Bureau of Statistics in 2012/13 (wave 2) and in 2015/16 (wave 3). Specifically, this study
identified and classified the various income diversification options of the households into
two broad categories; (i) farm income and (ii) off-farm income. Results shows that the
rural households earn a higher share of their total income from off-farm sources than from
farm sources. The income earned from off-farm was positively and significantly
influenced by covariates such as education level of household head, education level of
other members of the household, the household size, the household assets and the total
livestock units owned by the household. Findings of this study further showed that off-
farm income has a positive relationship with agricultural intensification although this
relationship is not significant. Also, the nexus between income diversification and poverty
reduction in the study area is such that the incidence and depth of poverty (25%)
experienced by the undiversified household is relatively higher than the depth of poverty
(20%) experienced by the diversified households. The multidimensional poverty index
(MPI) is also higher for households without off-farm than the MPI for households with
off-farm income. This suggests that income diversification is a key factor in reducing the
incidence of poverty among rural households in Nigeria. This study recommend as a
policy measure that households should be encouraged to diversify their economy and
transmit productivity gains from income diversification into the rural economy for the
betterment of agriculture and for sustainable poverty reduction
Modelling rainfed pearl millet yield sensitivity to abiotic stresses in semi-arid central Tanzania, Eastern Africa
No full textDrought and heat-tolerant crops, such as Pearl millet (Pennisetum glaucum), are priority
crops for fighting hunger in semi-arid regions. Assessing its performance under future climate
scenarios is critical for determining its resilience and sustainability. Field experiments were conducted
over two consecutive seasons (2015/2016 and 2016/2017) to determine the yield responses of the crop
(pearl millet variety “Okoa”) to microdose fertilizer application in a semi-arid region of Tanzania.
Data from the experiment were used to calibrate and validate the DSSAT model (CERES Millet).
Subsequently, the model evaluated synthetic climate change scenarios for temperature increments
and precipitation changes based on historic observations (2010–2018). Temperature increases of
+0.5 to +3.0 ◦C (from baseline), under non-fertilized (NF) and fertilizer microdose (MD) conditions
were used to evaluate nine planting dates of pearl millet from early (5 December) to late planting
(25 February), based on increments of 10 days. The planting date with the highest yields was subjected
to 49 synthetic scenarios of climate change for temperature increments and precipitation changes (of
−30% up to +30% from baseline) to simulate yield responses. Results show that the model reproduced
the phenology and yield, indicating a very good performance. Model simulations indicate that
temperature increases negatively affected yields for all planting dates under NF and MD. Early and
late planting windows were more negatively affected than the normal planting window, implying
that temperature increases reduced the length of effective planting window for achieving high yields
in both NF and MD. Farmers must adjust their planting timing, while the timely availability of
seeds and fertilizer is critical. Precipitation increases had a positive effect on yields under all tested
temperature increments, but Okoa cultivar only has steady yield increases up to a maximum of 1.5 ◦C,
beyond which yields decline. This informs the need for further breeding or testing of other cultivars
that are more heat tolerant. However, under MD, the temperature increments and precipitation
change scenarios are higher than under NF, indicating a high potential of yield improvement under
MD, especially with precipitation increases. Further investigation should focus on other cropping
strategies such as the use of in-field rainwater harvesting and heat-tolerant cultivars to mitigate the
effects of temperature increase and change in precipitation on pearl millet yield