School of Agriculture and Fisheries Sciences

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African swine fever outbreak at a farm in central Namibia
(2019) Samkange, Alaster; Mushonga, Borden; Mudimba, Douglas; Chiwome, Bernard; Jago, Mark; Kandiwa, Erick; Bishi, Alec S.; Molini, Umberto
An outbreak of African swine fever (ASF) occurred at a farm in central Namibia in March 2018. Fourteen pigs died out of a herd of 59 animals over a period of 16 days between the first and sixteenth of March 2018. The clinical signs observed included sternal recumbency, fever, weakness, pain and reluctance to move, hyperemia of the skin and anorexia, followed by death. Necropsy findings included large amounts of unclotted blood in the pleural and peritoneal cavities, diffuse carcass congestion, splenomegaly, consolidation of both lungs, hemorrhagic and frothy airways and trachea, hepatomegaly and congestion, congestion of the gastric mucosa, enlarged and congested kidneys, ecchymotic epicardial, and endocardial hemorrhages, and very enlarged and congested urinary bladder. All the remaining pigs were euthanized, burned, and buried under state veterinary supervision. The authors concluded that the outbreak resulted from indirect transmission of the ASF virus due to lapses in biosecurity measures.
Analysis of marine biotoxins: Paralytic and lipophilic shellfish toxins in Mussels (Mytilus Galloprovincialis) along the Namibia coastline
(2015) Dijerenge, Kahe J.
The study was carried out along the Namibian coastline, this includes Henties Bay, Swakopmund, Bird Island, Walvis Bay and Lüderitz to assess presence of shellfish marine biotoxins in mussels, Mytilus galloprovincialis which are filter feeders and feed on some of the algal species that produces phycotoxins, that can negatively affect the mariculture industry and human health. Samples were analysed for Paralytic and lipophilic shellfish toxins; including environmental parameters and phytoplankton species composition. Samples were collected using randomized sampling techniques for the period of May 2012 to April 2013. Mussel toxin content was measured by liquid chromatography-mass spectrometry (LC-MS/MS) for lipophilic toxins and paralytic shellfish poisoning Mouse bioassay (PSP MBA). The diarrhetic shellfish poisoning (DSP) toxin profile was found to be primarily composed of Okadaic acid (OA) and dinophysistoxins-1 (DTX-1), with the highest concentration recorded at Walvis Bay area, each toxin accounted for at least 50% of the total toxin content, this is probably due to the Dinophysis species reported in this area during the sampling period. In addition, Yessotoxin (YTX) and its analogues 1a-Homoyessotoxin (homo-YTX) and 45- hydroxy-yessotoxin (45-OH-YTX) were all detected at concentrations below the regulatory limit of 1 mg YTX equivalents/kg with homo-YTX dominating at Swakopmund and Bird Island stations with the highest toxin content of 0.14 mg YTX equ./kg recorded at both stations. Furthermore, PSP toxin contents in mussels were only detected at Walvis Bay and Lüderitz, with highest toxin concentrations of 80 and 903 μg STX equivalents/100g respectively. This coincided with the time at which Alexandrium species cell concentration at Lüderitz were at maximum, and could be a source of the paralytic shellfish toxins (PST). Although the toxin content in mussels were generally low, it still highlights the importance of a continued monitoring of both shellfish toxicity and their causative phytoplankton species, in order to produce safe shellfish for both local and international consumers.
Antimicrobial activity profiles of traditional fermented milk starter culture from north-eastern Namibia
(2014) Heita, Lusia
The aim of this study was to identify and examine the antimicrobial properties of Lactic Acid Bacteria (LAB) isolated from fermented milk collected from Ohangwena, Omusati, Oshana, Oshikoto, Zambezi and Kavango regions. Traditional fermented milk in Namibia are produced by spontaneous fermentation using traditional utensils. In this study, thirty homesteads from six regions that produce and process fermented milk were selected and interviewed using semi- structured questionnaires. Omashikwa and Mashini ghakushika have similar processing method whereby fermentation is achieved by accumulation of milk; mean while Mabisi is produced by allowing the milk to ferment naturally. The pH decreased logarithmically, nonlinearly over the fermentation period from 6.5 ± 0002 from first day of fermentation to 3.92±0.001 over 4 days.There was no significant difference (p<0.05) in the pH values between the three types of fermented milk preparations. Cell free supernatants (CFS) of 180 LAB isolated from traditional fermented milk were evaluated for antimicrobial activities against selected food borne pathogens; Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Candida albicans ATCC 14053, Bacillus cereus ATTC 10876 Geotrichum klebahnii (IKST F. Lab. isolate) Escherichia coli ATCC 25922 using the well diffusion method. Twenty LAB isolates that shown the highest inhibitory effects were selected for biochemical identification using API 50 CHL were identified as; Lactobacillus plantarum (53%), Lactobacillus rhamnosus (29%), Pediococcus pentosaceus (6 %), Lactobacillus paracasei ssp. paracasei (6%) and Lactococcus lactic ssp. lactis (6%), of which Pediococus pentosaceus showed the most inhibitory effect on all the indicator strains and they have potential to produce bacteriocin Pediocin and the most inhibited indicator strain belonged to yeast Candida famata. In addition to antimicrobial activities, the major organic acids in all three types of milk were found to be lactic acid 0.265±0.056 mg/L. However, the levels of volatile organic compounds in the naturally fermented samples varied from one sample to another but, butyric, acetic and propionic acid were found in trace amounts. Some of the volatile flavor compounds found in Omashikwa, Mabisi and Mashini ghakushika were acetic acid, 2,3 Butanediol and Lactic acid. Further genetic confirmation of species was carried out using the 16S rDNA sequences. The research outcome addressed the establishment of the newly identified starter cultures and contributes positively to the advancement of national LAB’s profiling. The study is also the first attempt that indicates probiotic potential and exceptional preservation properties of LAB from traditional fermented milk produced in North- Eastern Namibia.
Appropriate harvesting stage of sweet-sterm sorghum (Sorghum bicolor (L) Moench) cultivar for optimum bio-ethanol production in Namibia
(University of Namibia, 2017) Asuquo, Sylvester Okon
There has been growing global concern over dwindling fossil fuel supply. This development has led to increased interest in exploration of alternative energy sources, especially bio-fuel. Sweet sorghum (Sorghum bicolor), sugar cane (Saccharum officinarum), corn (Zea mays), wheat (Triticum aestivum), rape seed (Brassica napus), barley (Hordeum vulgare), sugar beet (Beta vulgaris), cassava (Manihot esculenta), oil palm (Elaies guineensis), sweet potato (Ipomoea batatas) and many more have been recognized as feedstock crops for bio-fuel production. Like most bio-fuel crops, sweet stem sorghum has the potential to reduce carbon emissions. In addition, this crop shows stronger tolerance than other crops under hot and dry climatic conditions. Its bagasse can be exploited as a by-product including burning, material for electricity generation, paper or fibre board manufacturing, silage for animal feed or juice for ethanol production. While there is abundant availability of sweet stem sorghum in Namibia, its potential as feedstock crop for bio-fuel has not been fully explored. One of the major problems associated with sorghum as a feedstock crop for bio-fuel is the issue of knowing the right harvesting stage for optimum brix sugar yield. In Namibia, great potentials exist for the development of the energy sector through adoption of bio-fuel production. Therefore, this study aimed at ascertaining appropriate harvesting stage of sweet-stem sorghum (Sorghum bicolor (L) Moench) cultivar for optimum brix sugar yield for bio-ethanol production in Namibia. Two trials (February to June 2014) and (October 2014 to February 2015) were conducted in the demonstration plot of the University of Namibia (UNAM), Hifikepunye Pohamba Campus. A total of six harvesting stages (booting stage, and one after every week for five weeks) were used to determine the following response variables: plant height, stem diameter, stem biomass, percentage juice extract, and percentage brix sugar. Data obtained were analyzed using SPSS statistical software and inferences were made at p = 0.05. Mean plant height at 50 % booting was 74.9 cm in trial I and 73.7 cm in trial II with respective coefficients of variation of 20.3 and 21.0. The t-test analysis for plant height was not significant (f = 22.5, p = 0.05). Mean stem weight was 71g in trial 1 (dry season) and 65g in trial 2 (raining season). Mean brix value of the extracted juice was 9.8 % in trial I and 11.8 % in trial II, with coefficients of variation of 5.0 % and 14.5 % respectively. The brix value increases significantly until it peaked at 5 weeks after booting. The study confirms that sweet stem sorghum IS 2331 cultivar could be grown in both dry and wet seasons in the study area. They could be harvested for optimum brix sugar yield for bio-ethanol production at five weeks after booting. Therefore, the study recommends that the Namibian government should raise awareness among crop farmers of the potential of growing sweet stem sorghum in both dry and wet seasons. Future studies should determine the brix sugar yield beyond 5 weeks after booting until possible grain harvest stage.
Assessing the potential of Spirulina Platensis as a protein source and its effect on feed intake, growth performance, carcass yield, internal organs sizes and meat quality of boschveld and potchefstroom koekoek chicken breeds
(University of Namibia, 2024) Nambahu, Aino
The potential of Spirulina platensis (SP) as a protein source to replace soybean meal and its effect on feed intake, growth performance, carcass yield, internal organ sizes and meat quality was determined. A 12 weeks feeding trial was conducted using 72 unsexed Boschveld and Potchefstroom Koekoek chickens. The chickens were fed with commercial starter crumbles from day 1 to week 4. At week 5 of age, the chickens were randomly assigned to one of four dietary treatments which were as follows; 0%SP, 5%SP, 10%SP and 15%SP of dried Spirulina platensis powder as a replacement of soybean meal, with six replicates per treatment and three per breed. The feeding experiment excluding brooding period lasted for 12 weeks. Feed intake data were collected daily, and live weights were taken weekly for growth performance. The results showed that feed intake responded negatively to increase in Spirulina inclusion level. Chickens on treatment 0%SP had higher weights (P˂0.05) which was not affected (P˃0.05) by the breed. The breed significantly affected (P˂0.05) average daily gain (ADG) where BV had a higher ADG compared to PK. The feed conversion ratio was highest (P˂0.05) in chickens on diet 10% SP; with a mean value of 1.03 and the lowest in 0% SP with the value of 0.98. Birds on diet 0%SP recorded the highest (P<0.05) protein efficiency ratio PER (0.91) while those on diet 15%SP had the least PER (0.57). The results showed that dietary treatment x breed interactions did not (P˃0.05) affect the gizzard, spleen, heart, liver and intestines weights and carcass yield. However, the breed of the chicken affected the spleen size, in which Potchefstroom Koekoek chickens recorded heavy spleen weight (P˂0.05) than Boschveld. Treatment diets significantly ii influenced (P˂0.05) breast muscle and thigh weight of the chickens. The treatment diets affected (P˂0.05) the coliform and Lactobacillus counts of the cecum. The coliform counts decreased significantly with an increase in Spirulina inclusion in the diet while Lactobacillus counts increased significantly with increasing level of Spirulina in the diet. The inclusion of Spirulina in the grower diet did not (P˃0.05) influence the meat physiochemical quality of the chickens but compromised some eating quality parameters such as flavor and initial and sustained juiciness. A prominent chicken flavor (P˂0.05) was recorded in chickens fed the control diet while chickens fed Spirulina had less chicken flavor. In conclusion, increasing Spirulina level in the diets negatively affected feed intake, body weights, PER, breast muscle and thigh weights and chicken flavor of the meat. Increasing Spirulina in the diets also resulted in high FCR, increased Lactobacillus counts and reduced coliforms. Based on these results, it is therefore best if only up to 5% Spirulina can be included in the diets for indigenous chickens. However, Spirulina was found to have high protein content but its inclusion at high levels negatively affected feed intake, meat flavor and acceptability of the meat. There is need to further investigate lower inclusion levels of Spirulina platensis and their effect on chicken production parameters and meat quality
Assessing the potential of using nylon bags in batch analysis of crude fibre and ether extract of livestock feeds
(OMICS Group, 2012) Ncube, S.; Mpofu, I.
The objective of this study was to determine the potential of laboratory batch analysis and optimum number of bags to be used. Katambora, veld hay and maize stover were analyzed for Crude Fibre (CF) and Ether Extract (EE) using the proximate analysis procedure but with samples bagged in nylon bags of pore size 60 micron. A completely randomized block design was used with Treatment 1 as the control, Treatment 2 with 1 bagged sample, Treatment 3 with 2 bagged samples, Treatment 4 with 3 bagged samples and Treatment 5 with 4 bagged samples. Results showed that there is a potential to use nylon bags in CF and EE analysis on katambora, veld hay and maize stover. There was an interaction between block and treatment. EE analysis on Katambora showed no significant difference among all treatments but for maize stover and veld hay, treatment 4 and 5 were significantly different from all the other treatments. In CF analysis trial, treatment 2 and 3 did not differ significantly from the control, while treatment 4 and 5 were significantly different from the control for all the diets. It was concluded that there is a potential to do batch analysis with optimum number varying between forage type and component of analysis. The proposed batch analysis is more sensitive with EE than with CF analysis.
Assessment of bycatch species in the Namibia Hake directed bottom trawl fishery (1997-2014)
(University of Namibia, 2021) Mbaimbai, Greg Limbo
One of the main problems faced by fisheries management, is how to manage and mitigate bycatch caught during commercial fishing. The Namibian hake-directed bottom trawl fishery has been an important component of the Namibian fishing industry for decades. Due to the low selectivity of the bottom trawling method, bycatch has been a common feature of this hake-directed fishery. This study examines the spatial distribution of bycatch; monthly and inter-annual variations in the bycatch catch per unit effort (CPUE) (kg/hr); and factors that influence bycatch catch rate of Namibian hake bottom trawl bycatch species. The specific objectives were: to assess the spatial distribution of the bycatch species in the hake-directed bottom trawl fishery; to assess monthly variations of hake bycatch species/ species groups based on catch rate data that spans over 18 years; to assess inter-annual variations of hake bycatch species’/ species groups, catch rate over a period of 18 years and to identify and assess the relative importance of factors (latitude, month and year ) that best explain the variation in catch rates of hake bottom trawl bycatch species. Data were extracted from the database: Fisheries Information Management System (FIMS) at Namibia’s Ministry of Fisheries and Marine Resources, where all commercial information is captured and stored by scientists. The data extracted and used in the study was from 1997-2014. The study covered the whole fishing grounds within the Namibian Economic Exclusive Zone (EEZ), from the Kunene River to the Orange River. Data analysis methods used in this study included: mapping and density plots; Hierarchical Cluster Analysis (HCA); Multidimensional Scaling (MDS); Similarity Percentage (SIMPER) and Analysis of similarity (ANOSIM) to tackle the following objectives: spatial distribution of bycatch and monthly variations of the Namibian hake bottom trawl bycatch species. These analyses are used to find natural groupings and to give statistical significance in groups. In addition, Generalized Additive Models (GAMs) analyses are used for: monthly and inter-annual variations in the bycatch catch per unit effort (CPUE) (kg/hr); and for the significance of factors that influence bycatch catch rates of Namibian hake bottom trawl bycatch species. These analyses are done by incorporating various factors (latitude, month and year) that may have had an influence on bycatch. In this study twenty-four species are recorded as bycatch in the hake-fishery, with a combined catch amounting to about 9120.90 metric tons for the period 1997-2014. Among all bycatch species, the species that had the highest total catch rate was ribbonfish (Trachipterus trachypterus), while blacktail (Diplodus capensis) was the species with the lowest catch rates in the study period. Most bycatch species were caught along the entire Namibian coast, with some species having higher catch rates in the Northern (17°S - 20°59’59” S), Central (21°S - 24°59’59”) and the majority in Southern regions southern (25°S - 29°59’59”). Blacktail (Diplodus capensis) and silver kob (Argyrosomus inodorous) were only encountered in the Northern parts of Namibia while, yellowfin tuna (Thunnus albacores) was only caught in Northern and Central Namibia. Three major bycatch assemblages/groups were identified along latitudes. The three bycatch groups were mostly distributed at around 29°S (A), 22°S (B) and 17°S (C). Kingklip (Genypterus capensis), west coast sole (Austroglossus microlepsis), species belonging to the family Raja (Skates) and large-eye dentex (Dentex macrophthalmus) were the species that contributed most to the dissimilarity in groups for spatial distribution for A, B and C respectively. Variations in monthly CPUE were observed in all bycatch species. Some species had noticeable variations in the trends increasing /decreasing. CPUE was explained by various factors: latitude; month and year that had an influence on it. This was done for all bycatch species. The common factor that influenced the CPUE of most species was latitude while month and year had the least influence on CPUEs of species. Overall, this study shows that bycatch varies considerably between different species. It also shows that hake fishing has the potential to negatively influence the functioning of the Benguela ecosystem on the basis of the number of species that it has an influence on. Bycatch management measures will, therefore, need to be species-specific in order to tackle specific factors that may have an influence on the different bycatch species. Each species has an influence on the structure and function of food web and the ecosystem at large.
Assessment of farmer preferences, constraints and angro-morphological variation among Bambara groundnut (Vigna subterranea (L.) Verdc.) accessions as a basis for seed yield selection index
(University of Namibia, 2020) Valombola, Johanna Shekupe
Bambara groundnut (Vigna subterranea (L) Verdc) is an orphan, underutilised and less exploited crop in Africa and beyond, Yet, it is an essential traditional crop for the majority of local farmers. The first step in preparing such local germplasm for possible pre-breeding is to undertake a needs assessment study to find out what farmers have on their farms and what they would rather have as an improvement. After that, a pre-breeding program with appropriate breeding goals and objectives can be formulated. Currently, in Namibia, a pre-breeding or breeding program is yet to be put in place. Thus, objective one of this study was to investigate, using a survey instrument, constraints encountered by Bambara groundnut farmers and the farmers’ preferred morpho-types that can be used in the breeding program. The ethnobotanical study was first done across five regions, targeting some key constituencies. Data were collected on varieties, descriptors, uses, preferences, crop improvement status, seed source, and production challenges. Chi-square test showed significant differences among farmers’ preferences (P ≤ 0.05) and crop improvement status (P ≤ 0.05). The results also showed that farmers faced challenges, including susceptibility to insects and the use of low yielding, unimproved cultivar. Results further indicated that many farmers had different Bambara groundnut preferences, such as large seed size and high yield cultivar. The second objective focused on the evaluation of local and exotic Bambara groundnut germplasm. Twenty-five Bambara groundnut germplasm accessions were characterised and evaluated for diversity, using qualitative and quantitative traits. The experimental design was square lattice design replicated three times. For qualitative descriptors, data collected included seed eye colour pattern, seed coat colour, seed pattern, pod shape, pod colour, and pod texture. The Shanon Weiner Index showed high diversity, with an average value of 0.92. Also, a dendrogram indicated five clusters of similarity. Quantitative data were analysed using multiple analysis of variance, Pearson correlation moment, Principal Component Analysis (PCA), and dendrogram. Analysis of variance (ANOVA) indicated significant differences (P ≤ 0.05) among accessions for the number of pods with two or more seeds, seed length, seed width, fresh pod weight per plant, dry pod weight per plant, 100 seed weight, shelling percentage, and harvest index. Other variables that were highly significant (P ≤ 0.01) included the number of pods per plant, pod yield, seed yield, plant height, terminal leaflet width, terminal leaflet length, number of branches, fresh biomass, and dry biomass. Dendrogram sub-criterion indicated three clusters suggesting that few accessions were dissimilar, which was confirmed with Principal Component Analysis, showing that germplasm accessions with common traits were grouped into the same quadrant. For meaningful progress, crop breeding hardly focuses on a single trait at a time. Since crop yield is a polygenic traits, some breeders nowadays use a selection index technique for yield improvement. In this study, a selection index was constructed using yield traits as seed yield, biological yield, dry pod weight per plant, and fresh pod weight per hectare. The index based on three traits, namely seed yield, dry pod weight per plant, and fresh pod weight that had a GA of 41.23% and selection efficiency of 376%. This selection method for seed yield appears to be more effective and efficient compared to the conventional method, the straight selection method.
Assessment of normal mortalities, biosecurity and welfare of Lohmann Brown layers at a farm in central Namibia
(2020) Samkange, Alaster; Mushonga, Borden; Kandiwa, Erick; Kambode, Josephina Ndamonako; Mbiri, Pricilla; Gorejena, Brighton; Madzingira, Oscar
Objective: The current study investigated the causes of mortality and evaluated the biosecurity situation and welfare conditions of Lohmann Brown layer chickens reared for 12 months, from point-of-lay, at farm A in central Namibia. Materials and Methods: Necropsies, standard biosecurity appraisal and on-farm welfare assessment tools were used. A standard protocol was used for post-mortem examinations of dead birds. The Chi-square test was used for analysis of causes of mortality whilst linear regression was used for analysis of the temporal distribution of mortality. Results: The overall mortality rate throughout the study period was 18.7% (N = 1000). There was a very strong negative correlation between duration of birds in lay and proportion of live birds [r (162) = 0.97, p<0.05]. The proportion of live birds decreased by an average of 2.98% for every 50 days of the laying period. Overall, the proportional mortalities due to undetermined causes (31.6%) were greater than those due to inflammatory conditions, trauma, cannibalism and retained eggs (20.9,19.3,16.6 and 11.8% respectively, p<0.05). Conclusion: The high mortality rates reported in this study have an obvious negative impact on productivity and thus there is a need to improve the biosecurity and welfare conditions for these layers in order to improve profitability.
Assessment of the impact of chemical de-bushing on herbaceous vegetation and ground-dwelling invertebrate communities at Neudamm farm
(University of Namibia, 2020) Zeriua, Justine N.
This study aimed at assessing the impacts of chemical de-bushing on herbaceous plants and ground-dwelling invertebrates at Neudamm farm. Three experimental sites (camp’s 5, 6 and 7) treated in 2015, 2016 and 2017 respectively with a general purpose arboricide were selected alongside one (camp 4) untreated site. Pitfall traps were placed under 15 Senegalia mellifera trees which were strategically selected in each site. Three quadrates, two placed contiguous under the canopy and one outside the canopy of fifteen Senegalia mellifera trees were used to identify and record the herbaceous plants. The herbaceous species diversity was higher in the control camp than in the other camps (H=29.285, d.f = 3, p < 0.000), while the ground- dwelling invertebrate diversity (H= 2.497, d.f = 3, p < 0.5) and Family richness (H = 0.285, d.f = 3, p =0.963) did not differ significantly between the camps. However, species richness was higher in camp 5 (treated in 2016) than in the control camp (H= 13.085, d.f = 3, p < 0.000). The HCA on binary data separated the herbaceous plant species into 6 clusters and the pitfall traps into 7 clusters indicating the significant changes in herbaceous species and invertebrate family composition due to chemical treatment, among other factors. Grass biomass was higher in camp 5 (p < 0.001) and the control camp had the highest ground cover (H= 8.5 and p- value= 0.037). This study has shown that arboricides have significant direct negative effect on herbaceous vegetation and, to a lesser extent, on the ground- dwelling invertebrates.
An assessment of the role of research and extension services for small-scale crop farmers in North-Central Namibia
(2012) Thomas, Benisiu
The aim of this study was to assess agricultural research and extension services that are aimed at improving rural household livelihoods in the changing environment in the north-Central Regions of Namibia. The study reviewed various secondary sources or publications and unpublished sources comprising technical reports, books, review papers and maps, all of which were deemed useful based on the role of agricultural research and extension services in north-Central Namibia. The presentations of the results were illustrated by examples from the area of crop production including seed multiplication, animal draught power and crop improvement schemes. The study found sufficient evidence that some research-extension strategies being employed are moderately successful. The main challenge, however, remains to strengthen national farming research or extension systems with an appropriate institutional and coordinating structure, focusing on decentralised participatory and adaptive research and on farm trials.
Assessment of trace metals pollution along the Central Namibian marine coastline: using Choromytilus Meridionalis (Black Mussel) as indicator organisms.
(2014) Vellemu, Emmanuel C.
This study was carried out at four stations along the Central Namibian marine coastline towns (Walvis Bay, Swakopmund, Henties Bay and Cape Cross) to assess trace metals pollution using Choromytilus meridionalis as indicator organism. Samples were collected using randomized sampling techniques during winter and summer months of 2012. EPA 3050B and ICP-OES protocols were used to digest and assimilate the samples. Data were analysed using a 4x2x3 factorial model of a completely randomised design and results showed there was a significant interaction (p < 0.05) of only Pb and Fe levels between stations, seasons and substrates studied. However, there was no significant interaction (p > 0.05) between Cu and Zn levels between stations, substrates and seasons respectively. Metal levels in mussels and sediments ranked in the order: Fe > Zn > Cu > Pb. Walvis Bay recorded increased metal levels (P < 0.05) than other stations probably due to factors like port activities e.g. ship repairs, urban and residential settlements, tourism and recreation as well as run-off water from catchment areas. Sediments exhibited significantly higher mean trace metals than mussels and water (P < 0.05). In addition, clear-cut significant correlation (p < 0.05) of metals was observed between some stations and substrates. Maximum Fe, Zn, Cu, and Pb mean values in mussels were 483.7, 79.3, 6.50, and 2.30 ppm of sample dry weight respectively while maximum Fe, Zn, Pb; and Cu values in sediments were 44, 749.90, 100.0, 79.30 and 50.50 ppm of sample dry weight respectively. All metal values recorded in this study were lower or within those reported elsewhere. Overall, mussels grown in this part of the coastline could be regarded safe for human consumption; however, levels observed in samples from Walvis Bay are of health concerns. Findings from this study have stressed the need for continued monitoring of these metals along the Namibian marine shoreline for regulatory purposes.
Assessment of vegetation diversity and rangeland condition in the Highveld communal grazing lands of Swaziland
(2011) Mapako, Leslie
Determination of correct stocking rate based on current rangeland condition still remains a big challenge to livestock farmers. Assessment of vegetation diversity and current rangeland condition was carried out in four communal rangelands, namely Siphocosini, Hawane, Motshane and Nkhaba. The rangeland condition assessment method employed in this study was the ecological condition index (ECI) method. Grass species composition and dry matter were estimated using the point-intercept method and the direct harvest method using a metal frame (quadrat) respectively. Vegetation diversity was high. A total of 16 grass species were identified. Of these, 9 species were strong perennials and the remaining 7 were annuals. In addition, 5 species were identified as highly palatable, 6-moderately palatable and 4-less palatable species
Bifidobacterium in human GI tract: Screening, isolation, survival and growth kinetics in simulated gastrointestinal conditions
(InTech — Open Access Company, 2013) Shigwedha, Nditange; Jia, Li
Bovine rumen impaction caused by ingestion of Gonometa postica cocoons in eastern-central Namibia
(2019) Samkange, Alaster; Hausiku, Magrecia; Kandiwa, Erick; Mbiri, Pricilla; Muradzikwa, Erdwin N.; Mushonga, Borden
Cases of rumen impaction caused by ingestion of Gonometa postica cocoons occurred at a farm in eastern-central Namibia. Ten animals died on the farm over the previous 5 months. Rumenotomies were successfully performed on three affected animals. The authors were of the opinion that the affected animals ingested the cocoons around the time of weaning, which then resulted in tangled masses that gradually stretched and enlarged because of entrapment of ingesta, eventually causing impaction of the rumen in the young adult animals. These are the first reported cases of ruminal impaction attributable to G. postica cocoon ingestion in Namibia.
Cadmium and lead levels in three freshwater fish species from the Zambezi region, Namibia
(2020) Madzingira, Oscar; Lifumbela, L.Z.; Kandiwa, Erick; Kandjengo, Lineekela; Mushonga, Borden
Muscle tissue from three-spotted tilapia (Oreochromis andersonii) (n = 11), sharp tooth catfish (Clarias gariepinus) (n = 14) and tigerfish (Hydrocynus vittatus) (n = 12) were sampled from a market in the Zambezi region, Namibia in June 2018 and analysed for cadmium and lead. Cadmium was not detected in the three fish species. Mean lead levels in all three fish species (0.09–0.19 mg kg−1) were below the recommended safe level of 0.3 mg kg−1. Catfish had the highest mean lead concentrations, followed by tigerfish and tilapia in descending order. However, the differences in mean lead concentrations between the three fish species were not statistically significant (ANOVA, p = 0.18). These results show that the fish tested were safe for human consumption with respect to the metals tested. It is recommended that more metals and other contaminants, such as pesticides, be monitored robustly in water, sediment and fish, using the recommended protocols, in order to generate data that can be reliably used for human health risk assessments in the future.
Challenges facing communal farmers to improve cattle production and marketing systems in Namibia
(2011) Hangara, Gabriel N.; ; ;
Climate-growth relationships of Argyrosomus spp. found along the Namibian coast
(University of Namibia, 2024) Jagger, Charmaine Eleonora
Understanding how fish growth responds to changing environments is critical for monitoring and predicting the impacts of climate change on fish populations. The ocean warming hotspot in the northern part of the northern Benguela provides an excellent opportunity to examine the responses of fishes to rapid environmental change. This research focused on the congeneric Argyrosomus inodorus and Argyrosomus coronus as these are commercially and recreationally important fishery species in Namibia. Standard otolith age determination techniques were used to determine if the age and growth of A. inodorus had changed from the 1990s to 2019. The results showed that there was a significant difference (Likelihood-ratio chi square test, χ 2 = 33.36, df = 4, p < 0.001) for the historical (1994-1996) and contemporary (2018-2019) period, thus indicating that A. inodorus stock used to grow older and faster in the historical period when compared to the contemporary. Kruskal Wallis test showed that there was a significant difference between A. inodorus and A. coronus lengths at age 4 (H (1) = 8.264, p = 0.004 < 0.05). The linear mixed-effects models fitted to the A. inodorus otolith biochronology indicated that a best linear unbiased predictor (BLUP) of growth was significantly positively correlated (r = 0.580, n = 25, p < 0.05) with mean SSTs (July, year of formation) and significantly negatively correlated (r = -0.473, n = 25, p < 0.05) with mean spring-summer SSTs (October y-1 to December y-1) in the area 20-24◦S, 12-14◦E. Thus, faster annual growth was observed during cooler periods (above 15℃) and slower growth was noted when exposed to warmer temperatures >17℃. These findings suggest that changes in A. inodorus growth was associated with a change in temperature and that its growth and productivity will be negatively affected with the increasing frequency of extreme climate events and ocean warming
Comparing efficiencies of flood and drip irrigation methods in onion production under farmer's production conditions in Omusati region, Namibia
(University of Namibia, 2018) Kandongo, Hortensia
The study was conducted in 2015 at Ogongo Campus of the University of Namibia (UNAM) to compare efficiencies of flood and drip irrigation methods, normally used by small scale farmers in the Omusati Region of Namibia, at three different irrigation levels of 100, 80, and 60% Crop evapotranspiration (ETo). Irrigating at lower levels than full irrigation is also referred to as deficit irrigation. Furthermore, the study compared gross margins and assessed yield and growth indicators under the two irrigation systems using onion as the crop. A split-plot in a randomized complete block design (RCBD) experiment was carried out on a 43 m*34 m plot with soil physical and chemical characteristics analyzed before cultivation. The results indicated that 60% of ETo had a higher water use efficiency (WUE) of 4.6 kg m-3 in drip irrigation than 2.8 kg m-3 for the flood. At 80% level, water use efficiency of drip was 3.6 kg m-3 compared to 2.1 kg m-3 for the flood. At 100% levels, the water use efficiency was 2.9 kg m-3 for drip compared to 1.8 kg m-3 for the flood irrigation method. WUE is significantly different at all three levels of irrigation (p =0.008) and also significantly different for the irrigation type (p = <.001).The total volume of water used under the drip irrigation system was less compared to flood irrigation system by 32.3%. Results also show that there was a saving of water in drip irrigation by a margin of 30.7% for the 100% levels, by 33.3% each for the 80 % and 60% levels. As for moisture content, drip irrigation at 100% was better than flood at 100% by 0.74% whist at 80% drip was better than flood by 1.14%, and at 60% drip was better than flood by 0.03%. The yield productions of all treatments were highly significant at 0.4, 0.29 and 0.19 eta squared. The irrigation type was highly significant (p< 0.001). Irrigation level at 20wt is (p=0.008), irrigation level at 10 wt. is significantly different at (p <0.001) and at 5wt, it is also highly significantly different at (p<0.001). However, the interaction between level of irrigation and irrigation type are not significantly different at 20wt (p=0.415) and 10wt (p=0.224). Results show that more yields were obtained in drip irrigation by a margin of 5% for the 100% levels, by 9.4% for the 80 % levels and 9.5 % for the 60% levels. However, plant height/growth rate was not significantly different at all the three levels (p =0.397) of irrigation. A higher growth rate was obtained in drip irrigation treatment by a margin of 28.36% for the 100% levels, by 3.65% for the 80 % levels and 22.38 % for the 60% levels. In addition, the results showed that the gross margin for drip at 60 ETo was higher than for flood by 44.7%, while at 80 of ETo, the gross margin for drip was more than for flood by 64.6%. The gross margin is highly significantly different at all three levels of irrigation (p =0.001) and also significantly different for the irrigation type (p = <.001). The present study suggests that the small scale Namibia farming community should adopt deficit drip irrigation method instead of the old traditional flooding methods.
Comparison of the rehabilitative effects of mechanical and chemical methods of bush control on degraded highland savanna rangelands in Namibia
(2010) Kahumba, Absalom; ;
The study was carried out at Spes Bona 207 farm in Hochfeld district, and Neudamm 63 farm in the Khomas Hochland district,Highland savanna in Namibia. The objective of this study was to investigate the rehabilitative effects of mechanical and chemical methods of bush control of an invasive bush species Acacia mellifera for achieving long term rehabilitation of a degraded highland savanna rangelands in Namibia. At farm Spes Bona, three belt transects (50 x 5m2) were laid in chemical treatments and another three belt transects (50 x 5m2) were laid in mechanical treatments. Moreover, the same method was used in the control experiment. At Neudamm farm, a 200 x 100m2 plot with 495 Acacia mellifera treated stumps were divided into 3 sub-plots for each treatment (mechanical, chemical and control). Each sub-plot was further divided into 3 replicates. In each replicate, stumps were randomly assigned key-tags with sequential numbers from 1-55 per sub-plot, for assessment purpose. At Spes Bona farm, the grass tuft density of species Aristida congesta, Cenchrus ciliaris, Chloris vigata, Eragrostis rigidior, Eragrostis viscosa, Melinis repens and Melinis villosum was significantly higher (P0.05) in chemical and mechanical than in control treatment. Similarly, the total grass density had greater values (P0.05) high in chemical (36.1 ± 9.6a), and mechanical (31.7 ± 9.7a) than in control (25.7±9.0b) treatment. The soil condition did not show significant difference (P0.05) between treatments. Total density of woody plants was significantly greater (P0.05) in the control than chemical and mechanical treatments. At Neudamm farm exmortality of stumps was significantly higher (P0.001) in chemical than in mechanical and control treatments. On the contrary, coppicing of stumps was significantly lower (P0.001) in the chemical method than in the control and mechanical treatments. Tuft greater values outside the canopy than underneath the canopy

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