Epidemiology of gastrointestinal helminthiasis of small ruminants in selected sites of North Gondar zone, Northwest Ethiopia

A cross-sectional study was conducted to determine the prevalence and risk factors associated with small ruminant helminthiasis in north Gondar zone, northwest Ethiopia from November-January, 2008. A total of 558 small ruminants (458 sheep and 100 goats) were examined using standard parasitological procedure. The study revealed that the overall prevalence of helminthiasis was 47.67%. The species level prevalence of helminthiasis was 46.07% and 55% in sheep and goats respectively. Strongyles were the most prevalent parasites encountered in the area followed by Fasciola. A statistically significant difference was found in prevalence between sheep and goat. Agroecology was found to be associated with prevalence rate and species of parasite found. Sex and age of the animals were shown to have association with prevalence but significant difference was not found. Therefore during the control and treatment of small ruminant helminthiasis agroecology, species, age and sex of the animals should be considered as potential risk factors for the occurrence of the disease in the study areas

Prevalence of bovine trypanosomosis in Wemberma district of West Gojjam zone, North West Ethiopia

A cross-sectional survey of bovine trypanosomosis was carried out in Wemberma district of west Gojjam zone, North West Ethiopia. From three peasant associations in the district (one from the midland and two from lowland), 384 cattle were randomly selected and examined for trypanosomosis. The prevalence of the disease as determined by buffy coat techinque was 7.81(95% CI = 5.11- 10.5%). Trypanosoma vivax and T. congolense were detected from buffy coat positive samples. Among the total of 30 cases of trypanosome infections detected 24(80%) of the infections were due to T.vivax and the rest 6(20 %) were due to T. congolense. No statistically significant associations(P>0.05) were observed between the disease and potential risk factors like age, sex and agroecology. However, when the different species of trypanosomes were considered, T. congolense infections were found only in the lowland. A significant association was observed (P<0.05) between the disease positivity and body condition score. When the mean packed cell volume of trypanosome infected animals was compared with that of non infected animals, it was significantly lower (P<0.05) in the infected animals, and the reduction was significantly lower (p<0.05) for T. congolense infection as compared with T. vivax infection. In conclusion, trypanosomsis was found to be important disease in the study area, and T. vivax was the more prevalent species and T. congolense with more negative impact in mean packed cell volume of affected animals

Assessment of strip tillage systems for maize production in semi-arid Ethiopia: effects on grain yield and water balance

International audienceThe traditional tillage implement, the Maresha plow, and the tillage systems that require repeated and cross plowing have caused poor rainfall partitioning, land degradation and hence low water productivity in Ethiopia. Conservation tillage could alleviate these problems. However, no-till can not be feasible for smallholder farmers in semi-arid regions of Ethiopia because of difficulties in maintaining soil cover due to low rainfall and communal grazing and because of high costs of herbicides. Strip tillage systems may offer a solution. This study was initiated to test strip tillage systems using implements that were modified forms of the Maresha plow, and to evaluate the impacts of the new tillage systems on water balance and grain yields of maize (Zea mays XX). Experiments were conducted in two dry semi arid areas called Melkawoba and Wulinchity, in the central Rift Valley of Ethiopia during 2003?2005. Strip tillage systems that involved cultivating planting lines at a spacing of 0.75 m using the Maresha plow followed by subsoiling along the same lines (STS) and without subsoiling (ST) were compared with the traditional tillage system of 3 to 4 times plowing with the Maresha plow (CONV). Soil moisture was monitored to a depth of 1.8 m using Time Domain Reflectometer while surface runoff was measured using rectangular trough installed at the bottom of each plot. STS resulted in the least surface runoff (Qs=17 mm-season?1), the highest transpiration (T=196 mm-season?1), the highest grain yields (Y=2130 kg-ha?1) and the highest water productivity using total evaporation (WPET=0.67 kg-m?3) followed by ST (Qs=25 mm-season?1, T=178 mm-season?1, Y=1840 kg-ha?1, WPET=0.60 kg-m?3) and CONV (Qs=40 mm-season?1,T=158 mm-season?1, Y=1720 kg-ha?1, WPET=0.58 kg-m?3). However, when the time between the last tillage operation and planting of maize was more than 26 days, the reverse occurred. There was no statistically significant change in soil physical and chemical properties after three years of experimenting with different tillage systems

Investigating the spatial variation and risk factors of childhood anaemia in four sub-Saharan African countries.

BACKGROUND: The causes of childhood anaemia are multifactorial, interrelated and complex. Such causes vary from country to country, and within a country. Thus, strategies for anaemia control should be tailored to local conditions and take into account the specific etiology and prevalence of anaemia in a given setting and sub-population. In addition, policies and programmes for anaemia control that do not account for the spatial heterogeneity of anaemia in children may result in certain sub-populations being excluded, limiting the effectiveness of the programmes. This study investigated the demographic and socio-economic determinants as well as the spatial variation of anaemia in children aged 6 to 59 months in Kenya, Malawi, Tanzania and Uganda. METHODS: The study made use of data collected from nationally representative Malaria Indicator Surveys (MIS) and Demographic and Health Surveys (DHS) conducted in all four countries between 2015 and 2017. During these surveys, all children under the age of five years old in the sampled households were tested for malaria and anaemia. A child's anaemia status was based on the World Health Organization's cut-off points where a child was considered anaemic if their altitude adjusted haemoglobin (Hb) level was less than 11 g/dL. The explanatory variables considered comprised of individual, household and cluster level factors, including the child's malaria status. A multivariable hierarchical Bayesian geoadditive model was used which included a spatial effect for district of child's residence. RESULTS: Prevalence of childhood anaemia ranged from 36.4% to 61.9% across the four countries. Children with a positive malaria result had a significantly higher odds of anaemia [AOR = 4.401; 95% CrI: (3.979, 4.871)]. After adjusting for a child's malaria status and other demographic, socio-economic and environmental factors, the study revealed distinct spatial variation in childhood anaemia within and between Malawi, Uganda and Tanzania. The spatial variation appeared predominantly due to unmeasured district-specific factors that do not transcend boundaries. CONCLUSIONS: Anaemia control measures in Malawi, Tanzania and Uganda need to account for internal spatial heterogeneity evident in these countries. Efforts in assessing the local district-specific causes of childhood anaemia within each country should be focused on

Evaluation of mixed-effects models for predicting Douglas-fir mortality

We examined the performance of several generalized linear fixed- and mixed-effects individual-tree mortality models for Douglas-fir stands in the Pacific Northwest. The mixed-effects models accounted for sampling and study design overdispersion. Inclusion of a random intercept term reduced model bias by 88% relative to the fixed-effects model; however, model discrimination did not substantially differ. An uninformed version of the mixed model that used only its fixed effects parameters produced predicted mortality values that exceeded the fixed-effects model bias by 31%. Overall, we did not find compelling evidence to suggest that the mixed models fit our data better than the fixed-effects model. In particular, the mixed models produced fixed-effects parameter estimates that predicted unreasonably high mortality rates for trees approaching 1 m in diameter at breast height.Keywords: Douglas-fir, Mortality, Generalized linear model, Mixed mode

Analysis and comparison of nonlinear tree height prediction strategies for Douglas-fir forests

Using an extensive Douglas-fir data set from southwest Oregon, we examined the (1) performance and suitability of selected prediction strategies, (2) contribution of relative position and stand-density measures in improving tree height (h) prediction values, and (3) effect of different subsampling designs to fill in missing h values in a new stand using a regional nonlinear model. Nonlinear mixed-effects models (NMEM) substantially improved the accuracy and precision of height prediction over the conventional nonlinear fixed-effects model (NFEM) that assumes the observations are independent, particularly when a few trees are subsampled for height. The predictive performance of a correction factor on a NFEM with relative position and stand-density measures was comparable to that of a NMEM when four or more trees were subsampled for height. When two or more heights were randomly subsampled, the NMEM efficiently explained the differences in the height–diameter relationship because of the variations in relative position of trees and stand density without having to incorporate them into the model. When only one height was subsampled, selecting the largest diameter tree in the stand would result in a lower predicted root mean square error (RMSE) than randomly selecting the height, regardless of the model form or fitting strategy used.A` l’aide d’une banque de donne´es exhaustive sur le sapin Douglas du sud-ouest de l’Oregon, nous avons examine ´ (1) la performance et la pertinence des strate´gies de pre´diction se´lectionne´es, (2) la contribution de la position relative de l’arbre et de la densite´ du peuplement pour ame´liorer la pre´diction de la hauteur des arbres et (3) l’effet de diffe´rents dispositifs d’e´chantillonnage pour imputer la hauteur manquante dans un nouveau peuplement a` l’aide d’un mode`le non line´aire re´gional. Les mode`les non line´aires a` effets mixtes (MNLEM) ame´liorent substantiellement l’exactitude et la pre´cision des pre´dictions de la hauteur comparativement au mode`le non line´aire a` effets fixes conventionnel (MNLEF). Ce dernier suppose que les observations sont inde´pendantes, particulie`rement lorsque peu d’arbres sont e´chantillonne´s pour e´valuer la hauteur. La performance pre´dictive d’un facteur de correction pour le MNLEF base´ sur la mesure de la position relative de l’arbre et de la densite´ du peuplement est comparable a` celle du MNLEM lorsque quatre arbres ou plus sont e´chantillonne´s pour e´valuer la hauteur. Lorsque deux hauteurs ou plus sont e´chantillonne´es ale´atoirement, le MNLEM explique efficacement les diffe´rences dans la relation hauteur-diame`tre dues aux variations de la position relative des arbres et de la densite´ sans avoir a` les incorporer formellement dans le mode`le. Lorsqu’une seule hauteur est e´chantillonne´e, le choix du plus gros arbre dans le peuplement pourrait entraıˆner une erreur de pre´diction plus faible que lorsque la hauteur est se´lectionne´e au hasard, peu importe la forme du mode`le ou la strate´gie d’ajustement utilise´e

Fodder and fertilizer trees action research in Africa RISING sites

United States Agency for International Developmen