Thursday, July 18, 2013

The Effect of Purified Condensed Tannins of Forage Plants from Botswana on the Free-living Stages of Gastrointestinal Nematode Parasites of Livestock

The effect of condensed tannins (CT) extracted from forage plants from Botswana on the free-living stages of a number of species of gastrointestinal nematode parasites derived from infected sheep were investigated using in vitro assays. Fresh samples of five different plants (Viscum rotundifolium, Viscum verrucosum, Tapinanthus oleifolius, Grewia flava and Ipomoea sinensis) were collected over two summers (February 2009 and 2010). Fractionation of each crude extract on a Sephadex LH-20 column yielded low molecular weight phenolics and CT-containing fractions. The effect of each purified CT fraction on parasites was evaluated using either egg hatch, larval development or larval migration inhibition assays. Three gastrointestinal nematode species (Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta) derived from infected sheep were evaluated in the study. CT from V. rotundifolium and I. sinensis fractions from samples collected in 2009 and 2010 did not inhibit larval development. However, CT isolated from V. verrucosum, T. oleifolius and G. flava collected in 2009 completely inhibited the development of all parasite species. These CT fractions were more potent in inhibiting larval development of H. contortus than fractions from the same plant species collected in 2010. However, a slight effect on larval migration was observed with some CT extracts. The results suggest that CT extracts of some forage plants from Botswana have anti-parasitic properties in vitro, and that further research is required to determine any in vivo efficacy from feeding the plants to goats in a field situation.

Effects of gut passage by kudu (Tragelaphus strepsiceros) and pericarp on the germination percentage of morula (Sclerocarya birrea) seeds

The study was conducted to determine the effects of gut passage of Sclerocarya birrea (morula) seeds by Tragelaphus strepsiceros (tholo) and pericarp of S. birrea fruits on the germination time and percentage of S. birrea seeds.  The S. birrea seeds used in this study were distributed into three sets of thirty.  These were the gut passed seeds (GP), mechanically extracted seeds (ME) and seeds in intact fruits (IF).  The GP and IF seeds served as treatments while ME seeds served as a control.  The seeds were planted into black nursery bags filled with soil and kept in the shade.  They were watered daily and the date on which seedlings appeared and the number of seedlings recorded as the seeds germinated.  The duration of the study was 60 days.  There was a statistically significant difference between seed percentage germination of different treatments (P < 0.0001).  Gut passage of S. birrea seeds by T. strepsiceros enhanced seed germination percentage and time while seed pericarp inhibited S. birrea seed germination. Conservationists may introduce T. strepsiceros in areas where S. birrea is needed and may be decreasing in numbers.

Thursday, May 02, 2013

Vegetable growers perception of pesticide use practices, cost, and health effects in the tropical region of Cameroon

Pesticide use practices of vegetable farmers were investigated during surveys conducted in major vegetable production zones of the humid tropics of Cameroon. The surveys aimed to elucidate farmers’ crop calendar, pesticide spray schedule and frequency. Farmers’ knowledge was determined on pest targets, quantities and major active ingredients used, and training received in vegetable production. It was found that weekly spray of pesticides was the most common practice; 40% of farmers sprayed insecticide, 28% sprayed fungicides. However, 45 and 59% could not identify the insect pests and diseases respectively they were attempting to control. Farmers applied 0.5-9 liters of pesticide per year, 10-49 kg, and 10 to 49 packets of chemicals depending on farm size. Prices of pesticide range from 5000 to 13000 FCFA per liter of insecticide, 6000 to 8500 FCFA per kg of fungicide and 300 to 12000 F per packet. Ninety percent of farmers used a knapsack sprayer and 20% of farmers noticed that their health was affected by pesticides. About 25% of farmers store chemicals at home. Seventy-five percent receive information about agricultural production from other farmers, and have never received any training on pesticide use practices and health effects. The absence of farmer training further increases the danger of pesticide misuse and cost of vegetable production. Less expensive pest management options that are less hazardous to the environment and human health need to be introduced to farmers, and create awareness regarding hazards of mishandling pesticides if the products are to be used by vegetable farmers in Cameroon. Keywords: Pest and diseases, pest management, chemical spray.

Saturday, January 12, 2013

Phytochemical and antioxidant analysis of wild and ex situ cultivated shoots and tubers of Harpagophytum procumbens (Burch) DC ex.Meisn from Botswana

Comparative phytochemical analysis [TLC method] and antioxidant activity of wild and  ex situ cultivated
shoots and tubers of  Harpagophytum procumbens were done. Total phenolic content [Folin-Ciocalteu
method] and free radical scavenging activity [1,1-diphenyl-2-picryl-hydrazyl assay] of both chloroform and
methanol extracts were determined. Analysis of ex situ cultivated plant material showed presence of phytochemicals comparable with those found in the wild plants. The total phenolic contents (mg GAE/L) of
methanolic tuber extracts from wild plants (3366±22.68) were comparable to the methanolic tuber extracts
(3297.00±54.56) from ex situ cultivated plants. The total phenolic contents of methanolic leaf extracts from
wild (2562±158.77) plants were also not significantly different from the  ex situ (2686.00±10.49) cultivated
H.procumbens. Similar trends were observed in the chloroform extracts of both wild and ex situ cultivated
H.procumbens. The free radical scavenging activities also correlated well with the total phenolic contents of
both wild and ex situ cultivated plants. At all tested concentrations, the methanolic extracts of both wild and
ex situ cultivated plants were ≥80%. The scavenging potencies of chloroform extracts were consistently
lower than the methanol extracts in both ex situ cultivated plants and wild species. The consistency in presence of phenolic compounds in these plant materials is of interest from both the pharmacological and conservation point of view given the role played by these compounds in oxidative stress. These results indicate
that ex situ cultivation can be both a conservation strategy and can provide an alternative and sustainable
source of therapeutically active compounds.

Agromorphological and Phenological Variability of 10 Bambara Groundnut [Vigna subterranea (L.) Verdc. (Fabaceae)] landraces cultivated in the Ivory Coast

The objective of this study was to investigate the agro-morphological and phenological characteristics often Bambara groundnut landraces that originated in the Ivory Coast. The study was conducted on an experimental plot at the University of Abobo-Adjame. The trial was set up according to a randomized complete block design with five replications. Twenty variables were used to identify the landraces. Landraces Ci1, Ci3, Ci10 and Ci12 exhibited high emergence percentages, early maturity within 90 DAS (days after sowing) and low vegetative/floral development. A high seed yield (388 to 495 kg/ha) was also obtained from these landraces. In contrast, a low seedling emergence rate, high vegetative development and yield (80 kg/ha) could be observed with landrace Ci9. This landrace reached maturity within 180 DAS. Landraces Ci2, Ci4, Ci5, and Ci8, on the other hand, reached maturity between 120-150 DAS. The principal component analysis conducted on the data obtained showed that the landraces with a high seed yield were early in terms of flowering and maturity, but presented low vegetative development, with limited foliage, secondary roots, leaf area and biomass. The physiological and agronomical traits presented by landraces that originated in the Ivory Coast could be exploited in Bambara groundnut varietal improvement programmes.

Monday, January 07, 2013

Cattle Productivity and Nutritional Limitation in the Semi-Arid Makgadikgadi Region of Botswana

Cattle growth and reproductive performance in the semi-arid Makgadikgadi region of Botswana was
investigated. Calving Rates (CR) and Growth Rates (GR) of Brahman beef cattle breed were used as
indicators of productivity and covered the periods of 2005-2009. Animal nutritional status involved
collection of faecal samples from rectums of 20 randomly selected cattle while the clipping method was
used to collect herbaceous samples from 1m
plots randomly located both in the Nata  ranch and
adjacent communal grazing areas. The herbaceous sampling period covered the wet season, late wet
season, dry season and late dry season. The mean calving rate for Brahman cattle in the study area was
relatively low (46.37 ± 3.45%). The  growth rate prior to weaning and post-weaning for both male and
female calves were poor compared to the national average productivity indicators. Faecal samples
indicated significantly low N levels (P<0 .05=".05" animal="animal" below="below" dry="dry" during="during" fell="fell" nbsp="nbsp" p="p" season="season" the="the" weight="weight" which="which">maintenance requirements, but peaked during the wet season. Faecal P significantly varied between
sampling periods, which was associated with rainfall distribution. The lowest faecal P was observed
during the late wet season whilst the highest amounts were observed during the late dry season.
Forage nutritive value (especially CP, P and Ca) varied significantly (P<0 .05=".05" nbsp="nbsp" p="p" seasons.="seasons." study="study" the="the" with="with">concluded that cattle performance in Makgadikgadi region could be limited by nutritional deficiency.
Thus, appropriate supplementation strategies can be developed to address mineral imbalances
observed especially during the dry seasons.

Essential and toxic metals in cow’s whole milk from selected sub-cities in Addis Ababa, Ethiopia

The level of essential (Fe and Zn) and non essential (Cd and Pb) metals in whole cow milk was
determined by Flame Atomic Absorption Spectrophotometer (FA-AAS).Whole cow milk was sampled (n
= 32) from dairy farms of Akaki-kality, Bole, Kolfe- keraniyo, and Yeka subcities in Addis Ababa.
Statistical analysis was performed using SPSS version 17. Significant differences between means were
subjected to one way ANOVA using Duncan’s multiple range test (P < 0.05). The average concentrations
of the elements were Fe (1.213±0.077 mg/kg), Zn (4.923±0.277 mg/kg), Cd (0.100±0.006 mg/kg) and Pb
(0.998±0.251 mg/kg). The levels of toxic metals (Cd and Pb) were beyond the acceptable limit which can
be a potential health concern for consumers.

Implications of Climate Change and Water Resources in Botswana

Climate variability (and /or change) continues to be recognized as the major threat to development of
the southern African region particularly in Botswana, where the major impact has been felt on the water
resources among others. This study, therefore attempts to analyze changes in key climatic variables
(rainfall and temperature) and their impacts on river flows. Mann-Kendal trend analysis was carried out
for four major meteorological stations (Gaborone, Gantsi, Francistown  and Maun). The results show
that  annual rainfall has been decreasing  while temperature  has been increasing, all insignificantly.
Through homogeneity tests, the study revealed that no country-wide statement can be made about
trend direction in  annual rainfall while for temperature a country-wide statement can be made that
temperatures are generally increasing. An attempt to study the linear relationships between rainfall and
river flows at Francistown and Gaborone revealed poor and insignificant correlations of 0.21 and 0.14
respectively. Projections of temperature and rainfall up to the year 2050 were undertaken through the
MAGICC/SCENGEN at which precipitation will decrease by 5% while temperature will increase by 2.5°C
with likely impacts of 7.9 and 4.4% reduction in river flows respectively. The findings have revealed that
rainfall and temperature have to be re-evaluated across the whole country with consideration of
modeling approaches that can handle non-linearity and complex inter-plays of other factors if water
resources management and planning are to be improved for semi-arid Botswana