Institut für Tropische Agrarwissenschaften (Hans-Ruthenberg-Institut)

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/21

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Genetic and non‐genetic factors influencing KLH binding natural antibodies and specific antibody response to Newcastle disease in Kenyan chicken populations
(2022) Miyumo, Sophie; Wasike, Chrilukovian B.; Ilatsia, Evans D.; Bennewitz, Jörn; Chagunda, Mizeck G. G.
This study aimed at investigating the influence of genetic and non‐genetic factors on immune traits to inform on possibilities of genetic improvement of disease resistance traits in local chicken of Kenya. Immune traits such as natural and specific antibodies are considered suitable indicators of an individual's health status and consequently, used as indicator traits of disease resistance. In this study, natural antibodies binding to Keyhole Limpet Hemocyanin (KLH‐NAbs) was used to measure general disease resistance. Specific antibodies binding to Newcastle disease virus (NDV‐IgG) post vaccination was used to measure specific disease resistance. Titers of KLH‐NAbs isotypes (KLH‐IgM, KLH‐IgG and KLH‐IgA) and NDV‐IgG were measured in 1,540 chickens of different ages ranging from 12 to 56 weeks. A general linear model was fitted to determine the effect of sex, generation, population type, phylogenetic cluster, line, genotype and age on the antibody traits. A multivariate animal mixed model was fitted to estimate heritability and genetic correlations among the antibody traits. The model constituted of non‐genetic factors found to have a significant influence on the antibody traits as fixed effects, and animal and residual effects as random variables. Overall mean (±SE) concentration levels for KLH‐IgM, KLH‐IgG, KLH‐IgA and NDV‐IgG were 10.33 ± 0.04, 9.08 ± 0.02, 6.00 ± 0.02 and 10.12 ± 0.03, respectively. Sex, generation and age (linear covariate) significantly (p < 0.05) influenced variation across all the antibody traits. Genotype effects (p < 0.05) were present in all antibody traits, apart from KLH‐IgA. Interaction between generation and line was significant (p < 0.05) in KLH‐IgM and NDV‐IgG while nesting phylogenetic cluster within population significantly (p < 0.05) influenced all antibody traits, apart from KLH‐IgA. Heritability estimates for KLH‐IgM, KLH‐IgG, KLH‐IgA and NDV‐IgG were 0.28 ± 0.08, 0.14 ± 0.06, 0.07 ± 0.04 and 0.31 ± 0.06, respectively. There were positive genetic correlations (0.40–0.61) among the KLH‐NAbs while negative genetic correlations (−0.26 to −0.98) were observed between the KLH‐NAbs and NDV‐IgG. Results from this study indicate that non‐genetic effects due to biological and environmental factors influence natural and specific antibodies and should be accounted for to reduce bias and improve accuracy when evaluating the traits. Subsequently, the moderate heritability estimates in KLH‐IgM and NDV‐IgG suggest selection possibilities for genetic improvement of general and specific immunity, respectively, and consequently disease resistance. However, the negative correlations between KLH‐NAbs and NDV‐IgG indicate the need to consider a suitable approach that can optimally combine both traits in a multiple trait selection strategies.
Identifying governance challenges in scaling biofortification programs and the potential of training: a case study of Uganda
(2025) Alioma, Richard; Zeller, Manfred; Birner, Regina; Bosch, Christine; Muayahoto, Bho; Zeller, Manfred; Department of Rural Development Theory and Policy, Hohenheim University, Stuttgart, Germany; Birner, Regina; Department of Social and Institutional Change in Agricultural Development, Hohenheim University, Stuttgart, Germany; Bosch, Christine; Department of Social and Institutional Change in Agricultural Development, Hohenheim University, Stuttgart, Germany; Muayahoto, Bho; HarvestPlus, International Food Policy Research Institute, Washington, DC, United States
Introduction: Biofortification initiatives can significantly help reduce micronutrient deficiencies in developing countries. However, when hidden hunger affects a large segment of the population, large-scale implementation is necessary to achieve the desired results. We aimed to identify governance challenges in biofortification, and potential remedies based on a conceptual framework that considers low demand and the invisible nature of micronutrient traits in crops. Methods: Using process net maps and quantitative methods, this paper explores how farmer training can address governance issues. Results: Results show that, in addition to common agricultural marketing issues, sweet potato vine multipliers struggle with vine supply, value chain actors adulterate iron beans, and consumers are hesitant to pay higher prices for biofortified crops. These problems may result from information asymmetry, merit goods, collective action issues, and free riding. Furthermore, training had little impact on reducing the governance challenge arising from information asymmetry. Discussion/conclusion: One of the key solutions was investing in subsidies to increase production and raise awareness of the importance of nutritious foods. With governance problems, there is a need to take them into consideration when planning and expanding biofortification programs.
Improving accuracy, stability, and practicability of poverty-targeting tools in the context of vietnamese ethnic minorities
(2025) Duong, Be Thanh; Zeller, Manfred
Poverty-targeting tools (PTTs) are essential tools used globally to identify households below established poverty benchmarks, such as food consumption or monetary standards, through simple and verifiable indicators. These tools enable social programs, ranging from cash transfers to healthcare and educational supports, to effectively and quickly deliver urgent support to the households most in need. However, despite the significant improvements made over time, current PTTs face some critical limitations that undermine their accuracy performance in both laboratory and field conditions. First, current efforts to enhance PTT accuracy through algorithmic improvements appear to be reaching a plateau. The Weight of Evidence (WOE) transformation technique has demonstrated success in optimizing the predictive power of input variables and potentially improving the accuracy of the prediction model across other domains, but this methodology remains underexplored in the poverty targeting field. Additionally, most existing PTTs lack transparent and user-friendly scoring systems. The score-scaling technique, doubling-the-odds, commonly paired with WOE in credit scoring, provides a logical and interpretable relationship between scores and outcome probabilities, yet it is rarely applied to the development of PTTs. Second, although the performance stability of PTTs is critical for ensuring their reliability and robustness in different datasets and real-world applications, this aspect remains insufficiently addressed in current research. Most existing studies rely on hold-out validation, which assesses the model’s performance based on a single random draw of a training-testing split. This approach offers limited insight into performance variability and restricts developers from making timely model adjustments. While k-fold cross-validation, a technique widely adopted in machine learning, offers a more comprehensive assessment of model stability and facilitates the fine-tuning of prediction models, this technique remains underutilized in poverty-targeting research. Third, the predictive accuracy of PTTs in the real world is significantly impacted by their practicability, namely the simplicity and verifiability of their indicators, but this aspect is often assumed rather than empirically validated. Currently, developers select indicators based on theoretical assumptions about simplicity and verifiability, without systematically validating these assumptions with frontline users. In addition, various contextual factors may influence the practicability of PTTs, ultimately affecting their overall predictive accuracy in practice. Despite this, no studies have thoroughly explored this dimension. To address these critical gaps, this dissertation aims to enhance the predictive performance of PPTs in both controlled research environments and real-world implementation settings. The research focuses on advancing fundamental dimensions of PTT effectiveness: technical accuracy, performance stability, transparency, and practicability. The research is situated in the context of ethnic minority communities in Vietnam, which experience the highest poverty rates and are a major concern for national poverty reduction programs. To achieve this overarching goal, this dissertation pursues the following interconnected sub-objectives: (1) Examine the efficacy of applying the WOE transformation method to improve the accuracy of PPTs; (2) Explore the combination of k-fold cross-validation with the WOE technique to ensure high and consistent performance PTTs with transparent and interpretable scoring systems; (3) Evaluate the practicability (simplicity and verifiability) of the PPTs and identify the key determinants impacting their practicability in field conditions, particularly in the context of Khmer communities in Southern Vietnam. These objectives are addressed through three scientific articles, presented respectively in Chapters 2 through 4 in this dissertation. The first research component of this dissertation is presented in Chapter 2, which examines the adaptation of the WOE technique in constructing high-accuracy PTTs. This research introduces a comprehensive approach, called the WOE (Logit) method, to develop PTTs based on international and national poverty lines. The WOE (Logit) method integrates the WOE technique with other techniques such as logistic regression, the indicator selection approach based on c-statistic value, and a score-scaling technique of doubling the odds. The resulting PTTs are evaluated against well-known methods such as the Simple Poverty Scorecard, Proxy Means Test, and Poverty Assessment Tool. The results show that the WOE (Logit) method yields higher accuracy, specifically improving identification rates by 1.9–5.9 percentage points for households and 1.5–3.3 percentage points for individuals. This finding contributes a valuable alternative methodology for more accurate poverty targeting. Chapter 3 explores the effectiveness of integrating k-fold cross-validation into the WOE (Logit) method in constructing high-accuracy and stable-performance PTTs with transparent scoring mechanisms for ethnic minorities in Vietnam (EMP tools). This research integrates a 5-fold cross-validation technique into the WOE (Logit) method to assess predictive performance and its variation. Two indicator selection strategies are compared based on the results of 5-fold cross-validation to find out the best prediction models, high-predictive power, and low performance variation, to develop EMP tools: one based on the highest c-statistic value (MaxC) and the other on the smallest Akaike Information Criterion (MinAIC). The results indicate that both indicator selection approaches yield high predictive power with minimal differences between them. However, the MinAIC approach shows a significantly lower performance variation in small urban datasets and remains slightly more stable in large rural datasets. Based on these results, MinAIC-based models are selected to design the EMP tools by applying the score-scaling technique of doubling-the-odds. Independent testing further validates this choice: the MinAIC models outperform their MaxC counterparts in terms of predictive power and standard error across rural and urban settings. When tested out-of-sample, EMP tools outperform the Vietnamese government’s current models while using one-third the number of indicators. Crucially, the EMP tools also feature a transparent and user-friendly scoring mechanism, which the government's tools lack. These results underscore the value of incorporating k-fold cross-validation to assess both accuracy and stability during model selection. Moreover, this study demonstrates that this integrated strategy effectively develops transparent PTTs with high accuracy and stable performance. The third article in Chapter 4 evaluates the practicability of the EMP tools developed in Chapter 3 through a field study in Khmer communities in the Vietnamese Mekong Delta. Employing both quantitative and qualitative methods, this study examines enumerators’ perceptions of indicator simplicity and verifiability. Quantitative data are analyzed using Likert scales, Factor Analysis, and Ordinary Least Squares regression, while qualitative data are analyzed using a thematic approach. The findings reveal a complex landscape of practicability that challenges conventional assumptions about indicator simplicity and verifiability. While EMP tools are generally perceived as practical, with over half of enumerators affirming the straightforwardness and verifiability of most indicators, significant variations exist across different types of indicators. Some commonly assumed simple indicators (e.g., cellphone ownership, job type) are rated low in verifiability, while more complex indicators (e.g., land ownership) are seen as more practical than anticipated. Qualitative insights highlight the vital role of local knowledge, particularly from village managers, in verifying high-risk indicators. The characteristics of enumerators (such as ethnicity, age, authority level of enumerators, and prior poverty-targeting experience) are significant determinants of overall tool practicability. These findings contribute a mixed-methods framework for pre-assessing PTT practicability and suggest solutions for improving tool practicability through more targeted enumerator selection. In sum, the dissertation achieves its three sub-objectives by demonstrating that: (1) the WOE (Logit) method enhances the predictive accuracy of PTTs; (2) Incorporating the k-fold cross-validation alongside the WOE (Logit) method reduces performance variation, enabling the development of high-accuracy and stable PTTs with transparent and use-friendly scoring systems; (3) Practical field assessments confirm that while the EMP tools are generally practical, conventional assumptions about indicator simplicity may require re-examination. Furthermore, enumerator characteristics significantly impact the practicability of the tools, suggesting their consideration in enumerator recruitment processes to optimize the tool’s practicability during implementation. This dissertation makes substantial theoretical and empirical contributions to poverty targeting research and practice through three key aspects. First, it provides compelling empirical evidence demonstrating how techniques so far have been underutilized in poverty identification; that is, the WOE technique and the k-fold cross-validation can enhance both the accuracy, transparency, and stability of poverty targeting, while highlighting the critical importance of field-based practicability assessments before implementing PPTs. Second, the research contributes an integrated methodological framework that integrates the WOE (Logit) method with the k-fold cross-validation and a mixed-methods approach of practicability assessment. This framework serves as a robust foundation for developing transparent PTTs that consistently deliver high accuracy and stable performance across diverse contexts. Third, the study not only delivers high-accuracy, stable-performance, and practical PTTs with a transparent and user-friendly scoring mechanism for ethnic minorities in Vietnam, but also offers actionable insights and strategies to maximize these tools’ practicability in real-world settings, ultimately supporting their accuracy performance during implementation. While focused on ethnic minorities in Vietnam, the broader implications of this research extend beyond this context, offering a replicable framework for constructing context-appropriate PTTs that perform accurately and reliably across diverse conditions while remaining practically feasible for frontline implementation.
A multifaceted analysis of Myanmar’s rice sector: gender perspectives, international competitiveness, and farmers’ emotional well-being
(2025) Chan, Nandar Aye; Zeller, Manfred
The agricultural sector is vital to Myanmar’s economic development, food security, and poverty reduction. However, recent global shifts in commodity markets, combined with local crises such as climate change, the COVID-19 pandemic, conflicts, economic instability, and rising fertilizer prices and operational costs, have significantly affected Myanmar’s agri-food sector. These challenges threaten the performance of the agricultural sector, particularly the rice sector, which is essential for many livelihoods, rural employment, and export earnings. The sector faces declining productivity, reduced incomes, rising debt burdens, and increased vulnerability, especially among smallholder farmers, including women. Therefore, the Ministry of Agriculture, Livestock, and Irrigation (MOALI) is dedicated to strengthening the rice sector through promoting inclusive gender roles, enhancing competitiveness in the domestic and international rice markets, and safeguarding the socio-economic well-being of all farmers. Addressing Myanmar’s key agricultural challenges and aligning with the objectives of MOALI, this dissertation investigates three critical areas (Chapters 2 to 4) to make a modest knowledge contribution to the sustainability and long-term development of the country’s rice sector. Despite government initiatives and extensive research on Myanmar’s rice sector, three important aspects remain underexplored: the gender gap in productivity, cost competitiveness, and the role of productivity in mediating shocks to farmers’ well-being. Specifically, this dissertation has three main objectives: 1) to estimate the magnitude of the gender gap in rice productivity and identify the factors contributing to this gap; 2) to analyze the cost competitiveness of rice production by examining production costs, cost efficiency, and the potential effect of improving cost efficiency on the country’s global competitiveness; and 3) to examine the effects of shocks on farmers’ well-being and explore how rice productivity mediates this relationship. Understanding these issues is crucial for designing policies that improve the performance of Myanmar’s rice sector and strengthen farmers’ resilience. The dissertation employs a quantitative approach, using household survey data and other secondary data sources. Particularly, data for Chapters 2 and 3 originate from the 2014 Area-Based Farm Household Survey in the Ayeyarwady Delta Region, administered by the International Rice Research Institute (IRRI) under the Metrics and Indicators for Tracking in the Global Rice Science Partnership project. Chapter 3 also incorporates nationwide phone survey datasets, including the Myanmar Household Welfare Survey (MHWS) and the Myanmar Agricultural Performance Survey (MAPS), conducted by the International Food Policy Research Institute (IFPRI) during 2021-2022. This cumulative dissertation consists of five chapters. Chapter 1 presents the introduction. Chapter 2 examines the gender gap. Chapter 3 focuses on the cost competitiveness of Myanmar’s rice sector. Then, Chapter 4 investigates the mediating role of rice productivity in the shocks-happiness relationship, and Chapter 5 concludes the dissertation and provides policy recommendations. Chapter 2 presents an analysis of the gender productivity gap in Myanmar’s rice sector. The analysis focuses on the Ayeyarwady Delta region, one of the three major agroecological zones for rice cultivation in Myanmar, using IRRI regional plot-level data. The study addresses seasonal variation and assesses jointly managed plots. The Oaxaca-Blinder mean decomposition approach is used to identify the causes of gender differences in monsoon and summer paddy productivity. The empirical findings show that women managers are 7 percent less productive than men in monsoon paddy production, with 95 percent of this gap explained by structural effects. Plots jointly managed by women and men outperform those managed by either women or men alone in summer paddy production. The results show that seasonality affects the disparity in gender productivity. Divorced women account for a large portion of the productivity differential among non-married women managers. Initiatives to eliminate the gender yield gap in Myanmar should pay attention to the unique requirements and obstacles that women encounter throughout different seasons and tailor their interventions accordingly. Chapter 3 conducts a comparative analysis of production costs among major rice-producing countries and estimates the cost efficiency of rice farming in Myanmar using a stochastic frontier cost function model. Moreover, this study examines the link between cost efficiency and domestic resource costs (DRC), a key indicator of global competitiveness in rice production. The study also considers the seasonal variations in Myanmar during both the dry and wet seasons. The findings show that Myanmar ranks as the second least expensive rice-producing country among selected Asian countries. The mean cost efficiencies are 89% and 86% for the dry and wet seasons, respectively. Both dry and wet seasons of rice production demonstrate a comparative advantage. The results also show that cost efficiency positively contributes to global competitiveness in both seasons. Focusing on education, farm size, seed procurement strategies, and training programs can increase cost efficiency, thereby further improving global competitiveness in rice production. Chapter 4 examines the effects of shocks on farmers’ happiness in Myanmar and explores the mediation role of rice productivity in this relationship. The study uses nationwide phone survey datasets from Myanmar, provided by the IFPRI, specifically focusing on the rice sector to assess productivity. The study applies the mediation analysis outlined by Acharya et al. (2016) and estimates the average controlled direct effect (ACDE) of shocks while accounting for rice productivity as a mediator. To ensure robustness, additional causal mediation analysis is employed. The results indicate that rice productivity partially mediates the shock-happiness relationship. This suggests that shocks influence happiness through additional pathways beyond productivity. Moreover, farmers’ happiness is more directly influenced by recent productivity than by past agricultural performance. However, past shocks continue to have a significant and lingering effect on their happiness. These findings highlight the need for policymakers to mitigate the impact of shocks on well-being not only by improving rice productivity but also by addressing other factors that influence farmers’ happiness. The findings of this dissertation contribute to the literature on the development of Myanmar’s rice sector. Firstly, providing the first empirical evidence of the gender gap in productivity can help inform targeted policy interventions to increase rice productivity while addressing the specific needs of men and women in rice production. Secondly, it provides scalable insights to promote the competitiveness, sustainability, and efficiency of rice production, which not only benefits Myanmar but also contributes to the broader global rice market. Finally, given the importance of understanding the relationship between shocks and well-being through rice productivity, this insight provides valuable guidance for designing interventions to strengthen productivity and improve well-being in vulnerable agrarian communities facing climate-related shocks. All these chapters contribute to the understanding of seasonality, which is vital for highlighting the importance of seasonal production dynamics in Myanmar’s rice sector. Overall, Myanmar’s rice sector can achieve greater sustainability and development by promoting gender equality, enhancing competitiveness, and supporting resilience-building measures for rice-farming communities, ultimately improving farmers’ well-being.
Reclaimed water driven lettuce cultivation in a hydroponic system: the need of micropollutant removal by advanced wastewater treatment
(2021) Kreuzig, Robert; Haller-Jans, Jaqueline; Bischoff, Cornelia; Leppin, Johannes; Germer, Jörn; Mohr, Marius; Bliedung, Alexa; Dockhorn, Thomas
For a novel approach of resource-efficient water reuse, a municipal wastewater treatment plant was extended at pilot scale for advanced wastewater treatment, i.e., ozonation and biological activated carbon filtration, and a hydroponic system for reclaimed water driven lettuce cultivation. The treatment specific wastewater lines with the corresponding lettuce plants, differentiated into roots and shoots, were monitored for priority wastewater micropollutants, i.e., acesulfame (sweetener), caffeine (stimulant), carbamazepine, diclofenac, ibuprofen, sulfamethoxazole with acetyl-sulfamethoxazole (human pharmaceuticals), 1H-benzotriazole, and 4/5-methylbenzotriazole (industrial chemicals). As clearly demonstrated, conventional tertiary treatment could not efficiently clean up wastewater. Removal efficiencies ranged from 3% for carbamazepine to 100% for ibuprofen. The resulting pollution of the hydroponic water lines led to the accumulation of acesulfame, carbamazepine, and diclofenac in lettuce root systems at 32.0, 69.5, and 135 μg kg−1 and in the uptake of acesulfame and carbamazepine into lettuce shoots at 23.4 and 120 μg kg−1 dry weight, respectively. In contrast, both advanced treatment technologies when operating under optimized conditions achieved removal efficiencies of > 90% also for persistent micropollutants. Minimizing the pollution of reclaimed water thus met one relevant need for hydroponic lettuce cultivation.
Why are toilets not used? Using system effects modelling to understand stakeholder perceptions on the impacts and barriers to Taenia solium control in Eastern and Western Uganda
(2025) Ngwili, Nicholas; Ahimbisibwe, Salaviriuse; Sentamu, Derrick N.; Craven, Luke; Thomas, Lian F.; Roesel, Kristina
Taenia solium taeniasis/cysticercosis in humans and pigs remains endemic to Uganda. Although, looking at the lifecycle of the parasite, the risk factors are well known, and many biomedical control options exist – no substantial progress has been made in the eradication of T. solium infections in Uganda to date. Contextual factors including socioeconomic, cultural and infrastructural factors, may influence the adoption of interventions. A community-based study using mixed methods and relying on system effects modelling approach was carried out between March and April 2021 in Kamuli district, Eastern Uganda, and Hoima district, Western Uganda. System effects modelling is a non-linear methodology that captures the varied nature of the unique, individually lived experiences and aggregates them to reflect what is experienced at a population level. The aim of the study was to capture individual stakeholder perceptions on the consequences of T. solium infections and barriers to practice known control options. Overall, 27 factors were identified by 192 participants as consequences of being infected with neurocysticercosis (NCC). For taeniasis, 35 factors were identified with 700 edges/connections made by the participants. Enlargement of stomach, weight loss, diarrhoea, weakness, and stunted growth were the most important consequences. Although porcine cysticercosis (PCC) seemed to be poorly understood by the participants, 14 factors were identified which included poor pig growth, loss of market for pig/pork, and poor pork quality. The study also identified important barriers hindering the adoption of control practices, including lack of knowledge on transmission, sociocultural factors, and resource constraints. For women, lack of knowledge on the mode of transmission and lack of a toilet in the compound ranked highly as important barriers with a weighted degree of 31 and 21, respectively, meaning they were identified by more participants unlike men who ranked lack of a toilet first with a weighted degree of 39, followed by lack of knowledge at 24. Different barriers are associated with the adoption of T. solium control practices among community members, stakeholders, and farmers. Despite efforts to address T. solium infections, misconceptions and limited understanding persist among stakeholders, particularly regarding NCC and its associated consequences. The system effects approach supports developing contextualized interventions to help in the control of the diseases associated with this parasite.

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