Institut für Tropische Agrarwissenschaften (Hans-Ruthenberg-Institut)

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Enhanced crop diversity but not smaller field size benefit bats in agricultural landscapes
(2025) Hiller, Thomas; Gall, Friederike; Grass, Ingo; Hiller, Thomas; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Gall, Friederike; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Grass, Ingo; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany
Context: Farmland biodiversity continues to decline due to the expansion and intensification of agriculture. Historically, efforts to conserve farmland biodiversity have focused on conserving habitats outside agricultural production areas. More recently, attention has turned to the conservation potential of the cropland matrix, where reducing field size and increasing crop diversity to promote crop heterogeneity can significantly benefit farmland biodiversity. Bats are one group of farmland species that have experienced dramatic declines over recent decades. Objectives: Here we investigated the effects of crop heterogeneity (crop diversity, field size) and landscape structural elements (e.g. length of linear structures, distance to forest, proportion of semi-natural habitat) on the activity of bat functional groups. Results: Increasing crop diversity led to greater bat activity, especially for open space foraging bats. However, contrary expectations, bat activity was not affected by heterogeneity in crop configuration, i.e. field edge density. Furthermore, structural landscape elements, including hedgerows and distance to forest, were important predictors of bat activity, especially for species that hunt in highly cluttered spaces. While crop diversity clearly benefited bat activity, the lack of effect of crop configurational heterogeneity on bat foraging activity may suggest heterogeneityarea trade-offs and intensive pesticide use in small-scale vegetable production. Conclusions: Therefore, in addition to maintaining high levels of crop diversity, promoting hedgerows and tree lines between farmland and woodland may facilitate bat activity across the agricultural landscape matrix. The combination of high crop heterogeneity and structural elements provides favorable hunting grounds for bats and may promote their conservation in agricultural landscapes.
Governance of land rehabilitation and remediation: case studies of Ghana’s small-scale mining sector
(2024) Adu-Baffour, Ferdinand Ababio; Birner, Regina
The artisanal and small-scale mining (ASM) sector is a complex and evolving industry that presents unique challenges within the global resource landscape. Despite its traditional labeling as artisanal, ASM operations are increasingly becoming mechanized, utilizing heavy machinery and hazardous chemicals such as mercury and cyanide for mineral extraction. Concurrently, the informal nature of most ASM operations limits effective top-down regulatory enforcements due to governance challenges. These developments have led to wide spreads of degraded, contaminated and abandoned rural community lands which also serve as valuable agricultural and forest lands for inhabitants of affected mining communities. While the existing literature has extensively analyzed the impacts of these developments on local, national, and global economies, ecologies, health, and welfare, there remains a notable gap in understanding the governance of rehabilitating and remediating affected environments post-mineral extraction. Furthermore, phytoremediation – a biological innovation which can help remediate contaminated sites and address the problem of soil degradation and erosion, with reported economic and environmental benefits – has only seen very limited global commercial adoption. In regions where traditional remediation approaches are financially untenable, like in the Global South, however, phytoremediation is argued to be a suitable and viable solution towards a greener future for remediation and environmental restoration. This thesis aims to address the knowledge gaps pertaining to the governance of rehabilitating and remediating affected environments affected by mineral extraction in the artisanal and small-scale mining (ASM) sector. Specifically, it focuses on systematically investigating the governance challenges in ASM, exploring community-based solutions for sustainable land restoration, and proposing a framework for the broader-based application of phytoremediation to address land contamination in the small-scale gold mining sector in Ghana. These research objectives are structured around three chapters, with the first two focusing on empirical case studies and the last chapter serving as a review of scientific and grey literature, as well as project reports on land rehabilitation and phytoremediation. Chapter 2, which addresses the first objective, delves into the obstacles hindering the implementation of the legal framework for artisanal small-scale mining (ASM) in Ghana. The first part conducts an institutional analysis of the legal and political framework governing Ghana’s small scale mining sector, with a particular focus on its implications for post-mined land rehabilitation efforts. This is followed by an assessment of the practical application of the legal framework in the context of small-scale gold mining (ASGM) value chain, using the Process Net-Mapping tool along with stakeholder interviews. The study reveals outdated legislation, formal licensing bureaucracies, land tenure issues, and ineffective collaboration among stakeholders as major bottlenecks. Drawing on these insights, the chapter discusses the broader implications of the findings for the effective running of the ASGM value chain and recommends, among other things, the adoption of collaborative governance systems, like co-management, to ensure sustainability. Chapter 3, which addresses the second objective, examines community-based solutions for sustainable mined land restoration through a case study of an NGO-initiated project in five active mining communities in Ghana's Amansie West district. The chapter utilizes a combination of qualitative methods including the participatory Net-Mapping tool to explore conditions under which local communities would engage in restoration efforts without financial incentives, revealing community support, using communal labor, dependent on factors like land tenure arrangements and local leadership influence. The study underscores the potential of community-led efforts for land rehabilitation, emphasizing the role of social networks, norms, and land tenure structures. Chapter 4, which addresses the third objective, introduces a conceptual framework for the effective and sustainable application of phytoremediation to clean contaminated lands resulting from mining activities. This is the result of insights drawn from existing phytoremediation literature, including case studies where the field application or/and commercialization of phytoremediation has been successful, and lessons gleaned from other real-world applications of the technology. The framework encompasses technical considerations across the phytoremediation process and identifies the socio-cultural, economic, political, and institutional conditions necessary for successful large-scale implementation. The paper provides valuable guidance for regions seeking to leverage phytoremediation to benefit society and the environment. In conclusion, this thesis contributes to understanding the challenges facing the ASM sector and proposes innovative solutions to address governance issues, promote community-based land restoration, and facilitate the scaling of phytoremediation initiatives for sustainable development in the mining sector, particularly in developing regions. The holistic approach advocated in this thesis underscores the importance of legal reforms tailored to the constantly evolving ASM sector, stakeholder collaboration, adaptive governance systems, and community engagement to effectively navigate the intricate ASM landscape and maximize its beneficial effects on local livelihoods and development worldwide.
Do regional-specific differences influence smallholder farmers’ climate information use? Evidence from Ghana
(2025) Owusu, Victor; Asravor, Jacob
Mounting evidence underscores the importance of improving smallholder farmers’ use of reliable climate information (CI) in sub-Saharan Africa (SSA). Previous studies have not examined the differences in region-specific climate information use, as well as predictors of the source, type and timing of climate information use. In this study, we provide empirical evidence on how location-specific differences influence the source, type and timing of CI use. Integrating cross-sectional data from 503 households in the Upper West Region (UWR) and Brong-Ahafo Region (BAR) of Ghana into a multivariate probit model, our results indicate that farm households in the two regions exhibit different preferences regarding the source, type and timing of CI use. We find that while households in the BAR are more interested in CI ahead of the season – given that rainfall is relatively secure in that region, CI use ahead of the season is of less interest to those in the UWR where rainfall is more erratic. Our results further show that while CI source, type and timing are considerably influenced by education, distance to the farm, access to credit and extension in the UWR, gender, farm size, education and tractor access tend to drive the source, type and timing of CI use in BAR. These findings underscore the need for a more downscaled and context-specific strategy in disseminating CI services in the various regions of SSA. Practical implications: Notwithstanding evidence that the adverse impacts of the changing climate on smallholder livelihoods continue to vary within and across communities, districts, regions and agro-ecological zones (Abbam et al., 2018) in sub-Saharan Africa, little is known about how location-specific distinctions in climate change impact, infrastructural endowments as well as socioeconomic and plot-level attributes of smallholder farmers influence farm households’ use of climate information (CI). Given that these location-specific distinctions can considerably influence the generation and dissemination of CI, and its subsequent uptake by farm households in various regions, the empirical findings from this study are relevant for policy formulation towards boosting the use of CI. Evidence from this study strongly suggests that the diverse locations of smallholder farmers tend to significantly influence the source, type and period of CI use; for example, farm households in the Brong-Ahafo Region, a relatively more infrastructurally developed region, have better prospects of accessing different types of CI from diverse sources. We further find that the period of the cropping season in which CI is used is considerably influenced by the location of the farmers; and we identify disparities in the plot-level, institutional and socioeconomic characteristics of rural households in these two study regions that significantly influence the types, sources and times of CI used by farm households. Consequently, there is a need to take into account the unique regional, agro-ecological, plot-level, institutional and socioeconomic attributes of farm households. Policy recommendations on CI use should be tailored to the needs of these specific locations rather than being wholesale. Investment in rural infrastructure may trigger economic opportunities in deprived regions such as the Upper West Region. This may motivate rural households in such regions to invest in different CI types and sources for enhanced uptake of climate information.
Legume-derived phenolic acids influence Fusarium oxysporum f.sp. strigae compatibility and biocontrol potential in a Striga push–pull system
(2025) Assena, Mekuria Wolde; Schöne, Jochen; Rasche, Frank
Biological control of Striga hermonthica (Del.) Benth. includes push–pull, intercropping using legumes, and soil-borne fungi such as Fusarium oxysporum f.sp. strigae (FOS). Efficacy of both technologies is compromised by various environmental factors. Combining them could potentially overcome their limitations and enhance control of S. hermonthica. It was hypothesized that FOS inoculation is compatible with push–pull intercropping, allowing consistent S. hermonthica suppression. Effects of selected phenolic acids and crude root exudates from three legume species (Mucuna pruriens, Desmodium uncinatum, Crotalaria juncea) on FOS mycelial growth and spore germination were studied. Bioassays showed that most phenolic acids (e.g., caffeic, p-hydroxybenzoic, syringic) had no effect on FOS development, except for piperonylic (80 %, 38 %) and t-cinnamic (53 %, 33 %) acids, which strongly inhibited growth at concentrations of 1 and 0.5 mM, respectively. Crude root exudates from Crotalaria inhibited FOS mycelial growth at 1 (44 %) and 0.5 (32 %) mg ml-1. Desmodium and Mucuna exudates showed no inhibition. Greenhouse results showed that legume intercropping and FOS inoculation reduced S. hermonthica emergence, with their integration achieving over 95 % suppression and boosting maize biomass. Legume presence enhanced FOS proliferation, with Mucuna and Desmodium increasing FOS gene copy numbers by over 44 %. LC-MS analysis identified nine phenolic acids, with p-coumaric (85–128 µg g−1) and p-hydroxybenzoic (50–97 µg g−1) acid being most abundant; the latter positively correlated with FOS abundance. In this setting, legume intercropping with maize did not impair FOS proliferation in rhizosphere soil and effectively suppressed S. hermonthica, demonstrating compatibility of FOS inoculation with push–pull for effective S. hermonthica management.
Diacetoxyscirpenol, a Fusarium exometabolite, prevents efficiently the incidence of the parasitic weed Striga hermonthica
(2022) Anteyi, Williams Oyifioda; Klaiber, Iris; Rasche, Frank; Anteyi, Williams Oyifioda; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Stuttgart, Germany; Klaiber, Iris; Core Facility Hohenheim, University of Hohenheim, Stuttgart, Germany; Rasche, Frank; Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Stuttgart, Germany
Background: Certain Fusarium exometabolites have been reported to inhibit seed germination of the cereal-parasitizing witchweed, Striga hermonthica , in vitro . However, it is unknown if these exometabolites will consistently prevent S. hermonthica incidence in planta . The study screened a selection of known, highly phytotoxic Fusarium exometabolites, in identifying the most potent/efficient candidate (i.e., having the greatest effect at minimal concentration) to completely hinder S. hermonthica seed germination in vitro and incidence in planta , without affecting the host crop development and yield. Results: In vitro germination assays of the tested Fusarium exometabolites (i.e., 1,4-naphthoquinone, equisetin, fusaric acid, hymeglusin, neosolaniol (Neo), T-2 toxin (T-2) and diacetoxyscirpenol (DAS)) as pre- Striga seed conditioning treatments at 1, 5, 10, 20, 50 and 100 µM, revealed that only DAS, out of all tested exometabolites, completely inhibited S. hermonthica seed germination at each concentration. It was followed by T-2 and Neo, as from 10 to 20 µM respectively. The remaining exometabolites reduced S. hermonthica seed germination as from 20 µM ( P < 0. 0001). In planta assessment (in a S. hermonthica -sorghum parasitic system) of the exometabolites at 20 µM showed that, although, none of the tested exometabolites affected sorghum aboveground dry biomass ( P > 0.05), only DAS completely prevented S. hermonthica incidence. Following a 14-d incubation of DAS in the planting soil substrate, bacterial 16S ribosomal RNA (rRNA) and fungal 18S rRNA gene copy numbers of the soil microbial community were enhanced; which coincided with complete degradation of DAS in the substrate. Metabolic footprinting revealed that the S. hermonthica mycoherbicidal agent, Fusarium oxysporum f. sp. strigae (isolates Foxy-2, FK3), did not produce DAS; a discovery that corresponded with underexpression of key genes (Tri5, Tri4) necessary for Fusarium trichothecene biosynthesis ( P < 0.0001). Conclusions: Among the tested Fusarium exometabolites, DAS exhibited the most promising herbicidal potential against S. hermonthica . Thus, it could serve as a new biocontrol agent for efficient S. hermonthica management. Further examination of DAS specific mode of action against the target weed S. hermonthica at low concentrations (≤ 20 µM), as opposed to non-target soil organisms, is required.
Arbuscular mycorrhizal fungi-based bioremediation of mercury: insights from zinc and cadmium transporter studies
(2023) Guo, Yaqin; Martin, Konrad; Hrynkiewicz, Katarzyna; Rasche, Frank; Guo, Y.; Faculty of Agricultural Sciences, Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, 70593, Stuttgart, Germany; Martin, K.; Faculty of Agricultural Sciences, Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, 70593, Stuttgart, Germany; Hrynkiewicz, K.; Department of Microbiology, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University, 87-100, Torun, Poland; Rasche, F.; Faculty of Agricultural Sciences, Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, 70593, Stuttgart, Germany
Phytoremediation, a sustainable approach for rehabilitating mercury (Hg)-contaminated soils, can be enhanced by arbuscular mycorrhizal (AM) fungi, which promote plant growth and metal uptake, including Hg, in contaminated soils. Hg, despite lacking a biological function in plants, can be absorbed and translocated using Zn and/or Cd transporters, as these elements belong to the same group in the periodic table (12/2B). In fact, the specific transporters of Hg in plant roots remain unknown. This study is therefore to provide fundamental insights into the prospect to remediate Hg-contaminated soils, with a focus on the role of AM fungi. The hypothesis posits that Hg uptake in plants may be facilitated by transporters responsible for Zn/Cd, affected by AM fungi. The Scopus database was used to collect studies between 2000 and 2022 with a focus on the ecological role of AM fungi in environments contaminated with Zn and Cd. Particular emphasis was laid on the molecular mechanisms involved in metal uptake and partitioning. The study revealed that AM fungi indeed regulated Zn and/or Cd transporters, influencing Zn and/or Cd uptake in plants. However, these effects vary significantly based on environmental factors, such as plant and AM fungi species and soil conditions (e.g., pH, phosphorus levels). Given the limited understanding of Hg remediation, insights gained from Zn and Cd transporter systems can guide future Hg research. In conclusion, this study underscores the importance of considering environmental factors and provides fundamental insights into the potential of Hg phytoremediation with the assistance of AM fungi.
Do we need post-tree thinning management? Prescribed fire and goat browsing to control woody encroacher species in an Ethiopian savanna
(2024) Abate, Teshome; Abebe, Tesfaye; Treydte, Anna; Abate, Teshome; College of Agriculture, Hawassa University, Hawassa, Ethiopia; Abebe, Tesfaye; College of Agriculture, Hawassa University, Hawassa, Ethiopia; Treydte, Anna; Department of Sustainable Agriculture and Biodiversity Conservation, The Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
Worldwide, bush encroachment threatens rangeland ecosystem services, including plant biodiversity and forage for livestock. Various control methods for encroaching woody species and restoring herbaceous vegetation exist but have rarely been explored experimentally. We assessed the impact of post-tree thinning management on tree mortality, the herbaceous community, and overall rangeland condition in Borana, an Ethiopian savanna ecosystem. At two 1.4 ha areas of encroached mono-specific Vachellia drepanolobium (whistling thorn) stands, we set up twenty-four 20 × 10 m experimental plots with four post-tree-thinning treatments (goat browsing only (1), prescribed fire (2), fire and goat browsing (3), and control (4) (i.e., no management after tree cutting), with three replications in a complete block design. Over two growing periods, we monitored resulting tree mortality, coppicing, seedling mortality and recruitment, as well as herbaceous layer attributes (diversity, biomass) and overall rangeland condition. All three post-tree thinning management scenarios significantly enhanced tree mortalities, reduced seedling recruitment and increased the abundance of the dominant desirable grass species. Prescribed fire and fire and goat-browsing treatments resulted in significantly greater grass and forb species richness, forb diversity, and biomass, as well as the overall rangeland condition compared to goat browsing only and the control treatment. However, grass species diversity did not respond to treatments. Post-tree management significantly increased tree mortality, reduced seedling recruitment, and increased the abundance of desirable grass species. Our findings strongly suggest that post-thinning management, particularly prescribed fire or a combination of fire and browsing, is highly effective in suppressing woody encroachment and improving biomass and overall rangeland condition.
Modelling nitrogen use and excretion in dairy cattle herds grazing temperate, semi-natural grasslands
(2025) Perdana-Decker, Sari; Dickhöfer, Uta
Grazing-based dairy cattle systems exhibit several benefits, such as preserving biodiverse grassland habitats, improving animal welfare, or turning grassland protein into human-edible protein. However, grazing-based diets are prone to greater nitrogen (N) losses via urine than balanced stall-fed diets, leading to a greater risk for N emissions. Strategies for improving the N use in grazing-based systems are predominantly investigated on homogenous clover-ryegrass pastures with high yields and nutritional quality. In contrast, grazing-based systems reliant on less external inputs (e.g., synthetic fertilisers or concentrates) using semi-natural grassland as main feed source received less attention. The present thesis addressed the knowledge gap on the N use of such low-input grazing-based systems by adapting an existing dynamic, process-based herd model (i.e., the LIVestock SIMulator, LIVSIM) for simulating animal performance and N use and excretion of dairy herds. For this, a broad dataset was gathered on nine commercial organic dairy cattle farms in Baden-Württemberg during two grazing periods (2019, 2020). This dataset fulfilled two purposes: firstly, to get a basic understanding on N use and excretion of dairy cows under low-input grazing conditions (study 1); secondly, to serve as reference dataset for adapting and evaluating LIVSIM for such production systems (studies 2 and 3). The reference dataset represented the wide range of grazing and production factors found on commercial farms in South Germany using semi-natural grasslands for grazing. The dataset applied for study 1 covered n = 323 individual animal observations with mean (± one standard deviation) milk production, dry matter intake (DMI), and pasture DMI (PDMI) of 23.9 (± 5.35), 21.0 (± 3.21), and 11.3 (± 4.83) kg/d, respectively. Milk N use efficiency (MNE) averaged 24.7 g/100 g N intake (± 5.91), which is greater than observations in temperate, high-input grazing-based systems but lower than in cows receiving balanced stall-fed diets. Nevertheless, MNE and other indicators of N use and excretion varied greatly among farms and seasons, highlighting the need to identify the drivers for this variation. Supplement feeding had the greatest potential for manipulating the N use and excretion. Increasing shares of fresh forages as well as of hay of total supplement DMI increased N use (e.g., MNE) and decreased urinary N excretion (e.g., urinary N to creatinine ratio), while increasing shares of concentrates of supplement DMI were related to lower N losses via urine. Study 1 highlighted that using semi-natural grasslands for grazing can potentially reduce environmentally harmful N losses compared to high-input grazing systems. For future research endeavours, a modelling approach may simplify the investigation of more feeding scenarios, their interactions, different local conditions, and considering the spatial and temporal variation of pasture herbage quality and yield. Hence, studies 2 and 3 focused on adaptating LIVSIM for low-input grazing-based dairy farms. The DMI and N intake are among the most decisive factors for determining animal performance and N excretion. Therefore, a module for predicting the PDMI of cows grazing semi-natural grassland was identified in study 2, using a subset of the reference dataset (n = 233 individual animal observations). Among the thirteen tested models, behaviour-based and semi-mechanistic models specifically developed for grazing animals had the lowest prediction adequacy. Their underlying empirical equations likely did not fit the grazing and production conditions of farms employing semi-natural grasslands. Modelling performance of a semi-mechanistic model developed for stall-based feeding situations (Mertens II) with slight modifications was best (relative prediction error = 13.4%) when evaluated based on the mean observed PDMI (i.e., averaged across animals per farm and period (n = 28)). Consequently, the modified Mertens II model was integrated in LIVSIM in study 3. Additionally, the modules for energy requirements, lactation, N excretion, and herd management were adopted, and breed-specific model coefficients added to represent Simmental, Brown Swiss, and Holstein-Friesian cattle breeds. Dairy cow characteristics, herd composition, annual milk yield, and DMI were predicted accurately (i.e., with a relative difference ≤ 10 % between observed and predicted outputs for the majority of outputs). The absolute total N excretion (g/d) was underpredicted by 23 % (= relative difference between observed and predicted values) mainly due to the underprediction of urinary N excretion by 43 %. The relative differences in N excretion between farming systems, in contrast, were predicted reliably. The observed faecal, urinary, and total N excretion (in % of N intake) differed by 30, -23, and -7 %, respectively, between the two reference herds, which is similar to the respective relative differences for the predicted faecal, urinary, and total N excretion of 32, -36, and -4 %. Further model improvements should focus on increasing the prediction accuracy of N excretion and its partitioning due to the varying degree of susceptibility of faecal or urinary N to volatilisation and leaching. The scenario and sensitivity analyses further confirmed that the adapted LIVSIM plausibly simulated differences in animal performance and nutrient excretions based on differences in supplement feeds and pasture herbage. Core input and model coefficients are the dietary ME, CP, and rumen-undegradable CP concentrations, as well as the available herbage biomass on pastures, for which precise measurements are thus needed. The findings of studies 2 and 3 demonstrate that existing models can be adopted for low-input grazing-based dairy production systems. There is further potential for adapting LIVSIM for production systems beyond the ones investigated in the present study, and/or for adding more outputs (e.g., enteric methane) and scales (e.g., grassland) to better capture the multifaceted aspects determining farm sustainability.
Exploring the plausibility of inoculated cowpeas as a climate adaptation strategy for Namibian smallholder farmers
(2025) Rasche, Livia; Katjana, Johannes; Jantke, Kerstin; Uchezuba, David; Schneider, Uwe A.; Rasche, Livia; Research Unit Sustainability and Climate Risks, Center for Earth System Research and Sustainability (CEN), Universität Hamburg, 20144 Hamburg, Germany; Katjana, Johannes; School of Agriculture and Natural Resource Sciences, Namibia University of Science and Technology, Windhoek 10005, Namibia; Jantke, Kerstin; Research Unit Sustainability and Climate Risks, Center for Earth System Research and Sustainability (CEN), Universität Hamburg, 20144 Hamburg, Germany; Uchezuba, David; School of Agriculture and Natural Resource Sciences, Namibia University of Science and Technology, Windhoek 10005, Namibia; Schneider, Uwe A.; Research Unit Sustainability and Climate Risks, Center for Earth System Research and Sustainability (CEN), Universität Hamburg, 20144 Hamburg, Germany; Lombardi, Mariarosaria
Increased cultivation of cowpeas is a possible adaptation option for Namibian farmers under changing climatic conditions. Using inoculated cowpeas can potentially double the yields under favorable climate conditions. But is such a potentially beneficial agricultural adaptation technique likely to be adopted? We surveyed 90 cowpea farmers from 30 villages in the Kavango region of northern Namibia on their households and farms, access to institutions and services, food consumption and preferences, and perceptions of climate change. Our survey reveals that smallholder farmers will not readily adopt the new technology. At most, about 50% of farmers can be convinced by new information to change their agricultural activities. When specifically asked about their willingness to grow inoculated cowpeas, almost all farmers responded that they would be willing to do so. However, the farmers are reluctant to allocate more land for cowpea cultivation, mainly because harvesting is very time and labor-intensive. The study shows that technology assessments should be conducted in combination with socio-economic assessments to realistically assess the potential success of proposed adaptation measures, as the extent to which a new technology may be adopted is an essential indicator for justifying funding of new technologies or adaptation programs.
Scenario analysis of global food security within CGE models: The role of caloric equivalents
(2023) Korovin, Vladimir; Boysen-Urban, Kirsten
In the last decade, the topic of food security attracted significant attention from the research community, politicians, and the general public. This is not surprising, as every person should have a guaranteed physical and economic access to safe, nutritious and a sufficient amount of food all year round. Including the aim to eradicate all forms of malnutrition, each of these food security elements is an integral part of the agenda for Sustainable Development defined by the UN in 2015. Nonetheless, full achievement of the agenda’s ambitious goals is far from being easy in the near future. On the contrary, recent years have shown an increasing number of undernourished people around the globe. This is certainly a worrying sign. The future socio-economic development, rising population, resource scarcity, changing demand patterns, diminishing increase of agricultural yields; each of these aspects further exacerbate the uncertainty of food security. They underline how important it is to assess the prospect challenges to feeding the world. Within the broad spectrum of methodological approaches used for projection studies, the computable general equilibrium (CGE) models occupy a strong position. However, as CGE models are essentially economic models and use monetary indexes by default, the direct application of CGE models for the evaluation as well as communicating results on dietary and food security issues remains fundamentally challenging. With this in mind, this thesis provides a state-of-the-art overview on the design and implementation of the forward-looking exercises within the CGE modeling framework with an explicit focus on food and nutrition security. As a part of this work, the author elaborates whether and how caloric equivalents can be included in CGE models, underlining their relevance for the modeling framework in general, as well as defining plausible scenarios for the future global and regional food security trajectories in particular. The centerpiece of this thesis is a comprehensive modeling framework that is capable of analyzing the development of future regional food security and facilitating discussions on various aspects of long-term projections within CGE models. An important element of this framework is the integrated calorie module that contributes to the reporting as well as the validation of the model’s results. The empirical analysis conducted with the help of this extended modeling framework underlines the importance of such caloric metrics and identifies benefits of their application in scenario analysis. It also shows the advantages for intercomparison of modeling outcomes at the stage of sensitivity analysis as well as across different studies. The simulation results reveal the potential for further elevation of the average consumer’s energy intake in all regions under the central scenarios. However, the expected increase in calorie availability is neither regionally uniform nor scenario specific. Some regions do not show a substantial improvement in energy intake though, indicating that a substantial share of their population could remain food insecure. Both central scenarios emphasize a tendency in emerging and industrialized countries toward more energy-dense diets, containing more animal-based products, sugars, and oils. This, in turn, imposes the risk of unbalanced diets and overconsumption. This thesis and the presented method of integrating caloric information into the CGE model provides a solid basis for further research. It makes a substantial contribution to the discussion of scenario analyses and application of CGE models in the area of food security modeling. In this regard, the calorie module has proven itself to be a valuable diagnostic tool and a central element for food security assessment. The approach of integrating caloric equivalents presented in this work is very general and can easily be extended to include other macronutrients, such as fats, proteins, and carbohydrates. The free accessibility of the data sources used and the transparent implementation process are evident strengths of the approach that might further motivate its use. Moreover, the proposed modeling framework offers an interesting and effective tool for analyzing various research questions concerning dietary trajectories and food security policies in long-term scenario analyses. The study of policy mechanisms targeting the adverse developments of dietary shifts might be one such interesting research direction.
Win-win opportunities combining high yields with high multi-taxa biodiversity in tropical agroforestry
(2022) Wurz, Annemarie; Tscharntke, Teja; Martin, Dominic Andreas; Osen, Kristina; Rakotomalala, Anjaharinony A. N. A.; Raveloaritiana, Estelle; Andrianisaina, Fanilo; Dröge, Saskia; Fulgence, Thio Rosin; Soazafy, Marie Rolande; Andriafanomezantsoa, Rouvah; Andrianarimisa, Aristide; Babarezoto, Fenohaja Soavita; Barkmann, Jan; Hänke, Hendrik; Hölscher, Dirk; Kreft, Holger; Rakouth, Bakolimalala; Guerrero-Ramírez, Nathaly R.; Ranarijaona, Hery Lisy Tiana; Randriamanantena, Romual; Ratsoavina, Fanomezana Mihaja; Raveloson Ravaomanarivo, Lala Harivelo; Grass, Ingo; Wurz, Annemarie; Conservation Ecology, Department of Biology, Philipps-University Marburg, Marburg, Germany; Tscharntke, Teja; Centre for Biodiversity and Sustainable Land Use (CBL), University of Göttingen, Göttingen, Germany; Martin, Dominic Andreas; Department of Geography, University of Zurich, Zürich, Switzerland; Osen, Kristina; Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany; Rakotomalala, Anjaharinony A. N. A.; Entomology Department Faculty of Science, University of Antananarivo, Antananarivo, Madagascar; Raveloaritiana, Estelle; Plant Biology and Ecology Department, University of Antananarivo, University of Antananarivo, Antananarivo, Madagascar; Andrianisaina, Fanilo; Department of Tropical Agriculture and Sustainable Development, Higher School of Agronomic Science,University of Antananarivo, Antananarivo, Madagascar; Dröge, Saskia; Division of Forest, Nature and Landscape, KU Leuven, Leuven, Belgium; Fulgence, Thio Rosin; Natural and Environmental Sciences, Regional University Centre of the SAVA Region (CURSA), Antalaha, Madagascar; Soazafy, Marie Rolande; Doctoral School of Natural Ecosystems (EDEN), University of Mahajanga, Mahajanga, Madagascar; Andriafanomezantsoa, Rouvah; Zoology and Animal Biodiversity, Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar; Andrianarimisa, Aristide; Zoology and Animal Biodiversity, Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar; Babarezoto, Fenohaja Soavita; Diversity Turn in Land Use Science, coordination office, Sambava, Madagascar; Barkmann, Jan; Department of Agricultural Economics and Rural Development, Research Unit Environmental- and Resource Economics, University of Göttingen, Göttingen, Germany; Hänke, Hendrik; Department of Agricultural Economics and Rural Development, Research Unit Environmental- and Resource Economics, University of Göttingen, Göttingen, Germany; Hölscher, Dirk; Tropical Silviculture and Forest Ecology, University of Göttingen, Göttingen, Germany; Kreft, Holger; Biodiversity, Macroecology and Biogeography, University of Göttingen, Göttingen, Germany; Rakouth, Bakolimalala; Plant Biology and Ecology Department, University of Antananarivo, University of Antananarivo, Antananarivo, Madagascar; Guerrero-Ramírez, Nathaly R.; Biodiversity, Macroecology and Biogeography, University of Göttingen, Göttingen, Germany; Ranarijaona, Hery Lisy Tiana; Doctoral School of Natural Ecosystems (EDEN), University of Mahajanga, Mahajanga, Madagascar; Randriamanantena, Romual; Natural and Environmental Sciences, Regional University Centre of the SAVA Region (CURSA), Antalaha, Madagascar; Ratsoavina, Fanomezana Mihaja; Zoology and Animal Biodiversity, Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar; Raveloson Ravaomanarivo, Lala Harivelo; Entomology Department Faculty of Science, University of Antananarivo, Antananarivo, Madagascar; Grass, Ingo; Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany
Resolving ecological-economic trade-offs between biodiversity and yields is a key challenge when addressing the biodiversity crisis in tropical agricultural landscapes. Here, we focused on the relation between seven different taxa (trees, herbaceous plants, birds, amphibians, reptiles, butterflies, and ants) and yields in vanilla agroforests in Madagascar. Agroforests established in forests supported overall 23% fewer species and 47% fewer endemic species than old-growth forests, and 14% fewer endemic species than forest fragments. In contrast, agroforests established on fallows had overall 12% more species and 38% more endemic species than fallows. While yields increased with vanilla vine density and length, non-yield related variables largely determined biodiversity. Nonetheless, trade-offs existed between yields and butterflies as well as reptiles. Vanilla yields were generally unrelated to richness of trees, herbaceous plants, birds, amphibians, reptiles, and ants, opening up possibilities for conservation outside of protected areas and restoring degraded land to benefit farmers and biodiversity alike.
A low-tech approach to mobilize nutrients from organic residues to produce bioponic stock solutions
(2024) Heintze, Sebastian; Beckett, Marc; Kriem, Lukas Simon; Germer, Jörn; Asch, Folkard; Heintze, Sebastian; Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstr. 12, 70569 Stuttgart, Germany; (S.H.); (L.S.K.); Beckett, Marc; Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstr. 12, 70569 Stuttgart, Germany; (S.H.); (L.S.K.); Kriem, Lukas Simon; Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstr. 12, 70569 Stuttgart, Germany; (S.H.); (L.S.K.); Germer, Jörn; Hans-Ruthenberg Institute for Tropical Agricultural Sciences, University of Hohenheim, Garbenstr. 13, 70599 Stuttgart, Germany; (J.G.); (F.A.); Asch, Folkard; Hans-Ruthenberg Institute for Tropical Agricultural Sciences, University of Hohenheim, Garbenstr. 13, 70599 Stuttgart, Germany; (J.G.); (F.A.); Liu, Guodong
Organic residues, as a nutrient source suitable of producing solutions for hydroponic crop production, have the potential to reduce the dependence on mineral fertilizers. Especially in remote and resource-constrained regions, organic residues might be the only option to produce hydroponic nutrient solutions. However, nutrient solutions made from organic residues, called bioponic solutions, are usually unbalanced in their nutrient composition, which leads to deficiencies and poor plant growth. This study aimed to experimentally develop a low-tech approach to produce bioponic stock solutions rich in NO3−, P, and K, to create a balanced bioponic solution. The mixed bioponic solution contained 58 mg L−1 NH4+-N, 43 mg L−1 NO3−-N, 50 mg L−1 PO43−-P, and 246 mg L−1 K+. This approach resulted in satisfactory levels of P, K and micronutrients. The solution was tested pure and spiked with Ca(NO3)2 on lettuce in comparison with a mineral Hoagland nutrient solution. Neither the bioponic nor the spiked bioponic solution achieved comparable lettuce yields to the Hoagland solution. The poor growth of the plants in the bioponic solution was attributed to an unfavorable NH4+:NO3− ratio, high microorganism load, and elevated pH levels. However, the approach of preparing bioponic stock solutions could be promising for future research into the production of balanced bioponic nutrient solutions from organic residues.
Made in Africa – how to make local agricultural machinery manufacturing thrive
(2024) Daum, Thomas; Adegbola, Ygué Patrice; Kamau, Geoffrey; Kergna, Alpha Oumar; Daudu, Christogonus; Adebowale, Wahab Akeem; Adegbola, Carine; Bett, Charles; Mulinge, Wellington; Zossou, Roch Cedrique; Nientao, Abdoulaye; Kirui, Oliver; Oluwole, Fatunbi Abiodun
Manufacturing has the potential to drive economic growth, job creation and poverty reduction, but African manufacturers face challenges in competing with global markets. Agricultural machinery manufacturing may be one niche where African manufacturers can succeed. This paper examines the challenges and opportunities facing local agricultural manufacturers in Africa based on a survey of 386 manufacturers in four countries and qualitative methods. Results show that small, dedicated entrepreneurs have created vibrant local machinery markets. These manufacturers have several comparative advantages, in particular, the ability to develop machinery adapted to local agroecological conditions but face challenges related to financing, human resources, utilities, raw materials, production equipment and the regulatory environment. The paper offers recommendations on how to support local manufacturers to make “Made in Africa” the first choice for African farmers and agro-food processors.
Combining improved mungbean cultivars with plant growth promoting rhizobacteria inoculation and regulated deficit irrigation to increase crop productivity
(2024) Pataczek, Lisa; Cadisch, Georg
The cultivation of legumes provides an approach to sustainably intensify agricultural production, since short-duration legumes can fit into existing cereal-based cropping systems, diversifying farm incomes and farmers diets, as well as providing environmental benefits through the fixation of atmospheric N2 and, thus, enhancing yields of following crops. Mungbean is a legume, which plays already an important role in the traditional nutrition of people in the Global South. Its nutritious seeds can improve food security and the short growing duration facilitates the diversification of mainly cereal-based crop rotations. However, yields are low and may even become lower in future in the face of climate change. Main constraints of mungbean cultivation include pest and diseases, as well as heat, drought and soil salinity due to inappropriate irrigation techniques or saline ground water. The main aim of this thesis was therefore to analyse the effects of more advanced cultivation techniques, i.e. the use of plant growth promoting rhizobacteria (PGPR) and regulated deficit irrigation (RDI), on the productivity and nitrogen (N) fixation capacity of improved mungbean (Vigna radiata L.) cultivars, resistant and/or tolerant to pests, diseases, heat and soil salinity. An extended literature review was conducted to summarize the current understanding of the use of PGPRs and the effect on crop productivity, especially on marginal land (Chapter 2). The use of PGPRs can on the one hand side increase plant growth through direct and indirect mechanisms, such as BNF, hormone production and nutrient solubilization or the production of antibiotics to suppress phytodiseases. Especially 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity plays a significant role to reduce the negative impact of stress environments. On the other side PGPRs can be used to remediate decontaminated sites, through metabolic capabilities, transforming for instance aromatic compounds into less toxic compounds, or the biodegradation of pesticides and organic pollutants. Since ACC deaminase-producing bacteria are also supposed to enhance root growth, it is assumed that they can potentially increase soil N uptake and/or infection sites for rhizobia to biologically fix atmospheric N2 (BNF). In order to test the effect of ACC deaminase-producing PGPRs on mungbean productivity and N accumulation, three strains were tested as single- or multistrain inoculation in the field: Rhizobium phaseoli, Bacillus subtilis and Pseudomonas fluorescens (Chapter 3). Their effect on one improved mungbean cultivar (NM11, resistant to the Mungbean Yellow Mosaic Disease) was assessed on two research sites in Faisalabad, Pakistan. The impact of the strains differed significantly, with no effect on productivity (total biomass, seed yield) or total N accumulation (BNF and soil-N uptake) with multi-strain inoculation of all strains and single-strain inoculation of P. fluorescens. Inoculation with B. subtilis did, however, result in significantly increased dry matter (roots: +211 kg ha-1, total dry matter: +1.7 t ha-1), and total plant-N (+36 kg ha-1), while R. phaseoli inoculation enhanced BNF (+24%). The results suggested that only the single strain inoculation of B. subtilis and R. phaseoli was promising in terms of productivity increase, however, the choice of the strain should be made according to the soil-N status: low soil-N favors R. phaseoli inoculation, while medium to high soil-N would rather point towards the use of B. subtilis. The improved mungbean cultivar NM11 was additionally tested together with three other improved cultivars (AVMU 1604, AVMU 1635 and KPS2, resistant/tolerant to powdery mildew, bruchids and heat and salt, respectively), in combination with RDI in a greenhouse trial at the University of Hohenheim (Chapter 4). The aim was to identify differences in drought adaptation strategies between the cultivars in terms of dry matter partitioning, yield, harvest index, pod harvest index, water use efficiency and carbon-13 isotope discrimination. Levels of water deficit as depletion fractions (%) of total available soil water were set to 0.45, 0.65 and 0.8, corresponding to recommended irrigation, moderate and severe water deficit, respectively. The cultivars differed in their drought resistance strategies, exhibiting either drought escape, avoidance, tolerance or a combination of several strategies. The cultivar KPS2 showed mainly a drought escape mechanism through faster development, stable yields and greatest harvest index/pod harvest index (36%/69%) across all RDI treatments and cultivars. The cultivar AVMU 1604 displayed mainly a mixture of drought avoidance and escape through increased remobilization of assimilates from vegetative plant parts to pods/seeds, resulting in greater yield under water deficit by 52%. The choice of a cultivar for the field should be based, thus, on the prevailing climatic conditions (season and region): KPS2 can grow in areas with terminate drought conditions, whereas AVMU 1604 can tolerate intermittent drought conditions. The results of this thesis showed that ACC deaminase-producing PGPRs can substantially affect N uptake, although this effect is barely discussed in literature. Moreover, improved mungbean cultivars, exhibiting already a range of tolerances and resistances to certain pests and diseases, showed a great potential in adapting to drought conditions, representing a viable option for cultivation under increasing abiotic and biotic stress factors in the face of climate change.
Genetic relationships among resilience, fertility, and milk yield in dairy cattle performing in sub-Saharan Africa
(2025) Oloo, Richard Dooso; Chagunda, Mizeck G. G.
Despite the relevance of dairy production in the fight against food insecurity in sub-Saharan Africa (SSA), the negative effects of climate change and general changes in the production environment pose tremendous challenges to its profitability. Genetic improvement of resilience, the capacity of animals to be either minimally affected by an environmental disturbance or rapidly recover from a disturbance in their environment, is deemed as a part of the solution to low dairy productivity and poor cattle adaptability in SSA. However, to breed for resilience, reliable and practical methods for quantifying and analyzing resilience in SSA need to be described and undertaken. This thesis explored the measurement of resilience using different indicators and examined the relationships of resilience with fertility and milk production in dairy cows performing in SSA. Chapter two of this thesis reviewed potential solutions to enhance the sustainability and productivity of the dairy sector in SSA with an emphasis on breeding for resilience. It described the dairy production in SSA, and environmental challenges cattle have to weather in this region. The chapter further discussed different forms of resilience (general resilience and specialized resilience), indicators for measuring resilience, and provided insights into the data that can be utilized to quantify resilience in SSA’s dairy production systems. It is concluded that improving resilience of dairy animals in SSA would contribute to poverty alleviation, animal welfare improvement, and better preparedness in lieu of climate change in this region. In chapter three, the potential of quantifying general resilience using indicators based on deviations in milk yield was examined. Three indicators of general resilience were defined: variance (LnVar), lag-1 autocorrelation (rauto), and skewness (Skew) of deviations in milk yield based on actual and standardized deviations of observed milk yield from predicted milk yield. The heritability estimates of all resilience indicators except Skew were significant and ranged from 0.05 to 0.19. Weak to moderate genetic correlations were observed among indicators of general resilience, suggesting that these indicators captured different aspects of resilience. LnVar indicators indicated that resilient cows are genetically associated with better longevity. The use of actual deviations and standardized deviations to define indicators yielded identical traits except in LnVar. Standardization of deviations or correcting for the milk production potential of animals ensures that the resultant LnVar indicator does not inaccurately categorize low-producing animals as inherently resilient. The study concluded that LnVar holds a significant potential as a robust resilience indicator for dairy animals performing in SSA. The fourth chapter investigated the response of milk production at varying heat loads as an indication of heat tolerance, which is a specialized resilience. Random regression models, including reaction norm functions, were fitted to derive two resilience indicators: the slope of the reaction norm (Slope), and its absolute value (Absolute), reflecting changes in milk yield in response to varying heat load. Heritability estimates for these indicators ranged from 0.06 to 0.33 and were mostly significantly different from zero. The correlation analysis between these indicators and average milk yield revealed that high- producing cows are more vulnerable to heat stress and have less stable milk production under heat-stress conditions. The study demonstrated the possibility of using the slope of the reaction norm and its absolute value to measure the specialized resilience of dairy cattle to heat stress conditions in SSA. Chapter 5 examined the genetic parameters and relationships among resilience, fertility, and milk production traits. The heritability estimates of age at first calving (AFC), calving interval (CI), and test-day milk yield (MY) were 0.17, 0.06, and 0.35 respectively, and were all significantly different from zero. AFC was negatively correlated with both CI and MY, showing that animals that attain sexual maturity earlier exhibit longer calving intervals and higher milk production. A positive correlation between CI and MY showed that high-yielding cows faced challenges in maintaining shorter calving intervals. There was a generally positive correlation between resilience and fertility, implying that resilient animals might have better fertility. All indicators, except the variance of actual deviation corrected for milk production and variance of standardized deviations, revealed an antagonistic relationship between resilience and milk production. This thesis showed the potential for quantifying and breeding for resilience in dairy cattle performing in SSA. Cows with more than 50% Zebu genes and those performing in semi-arid environments had higher resilience, higher AFC, shorter CI, and lower MY. This suggests that zebu genes confer resilience advantage to animals and exposure of animals to various disturbances in semi-arid environments improved their resilience capacity. Different directions of relationship observed among the traits studied imply that developing a multi-trait selection index that combines all these traits could strike the right balance among resilience, fertility, and milk production. The implications of these findings are valuable in improving the productivity of dairy cattle through selective breeding for resilience to environmental stressors, particularly in low-income countries situated in tropical regions.
Genetics and breeding for humoral immunity and feed efficiency in indigenous chicken population in Kenya
(2024) Miyumo, Sophie; Chagunda, Mizeck G. G.
Indigenous chicken (IC) population contribute to food, nutrition, livelihood and economic security in many rural households in developing countries in the tropical regions. Despite their contribution, IC are predominantly raised under challenging free-range systems which limit their optimal production potential and utilization. Of significance, are disease morbidity and scarcity of feed resources. Indigenous chicken are exposed to a myriad of pathogens that cause various poultry diseases which result to massive production and economic losses. Among these diseases is Newcastle disease (NCD) which is endemic in the tropics and is considered important because of high prevalence and mortality rates. Seasonal variation in availability and quality of feed resources have a negative impact on production costs and performance of chicken. Furthermore, with climate change effects, environmental conditions are expected to significantly impact feed availability and pathogen epidemiology. Selective breeding for disease resistance and feed efficiency traits is an avenue through which individuals that are adaptative to disease-prone production environments, with ability to efficiently convert available feed resources into products and support their maintenance requirements can be sustainably produced. Therefore, this thesis aimed to generate information that can guide breeding decisions on selection for improved health and efficient production to enhance the overall performance of the indigenous chicken population in Kenya. Chapter 1 presented an overview on the relevance of indigenous chicken genetic resources in developing countries with respect to their proportion among chicken population, contribution at household and national levels, and adaptive capacity to local environments. The challenges experienced in IC production systems in developing countries and their impacts on productivity and profitability, with a focus on diseases and scarcity in feed resources were addressed in this chapter. Management strategies practiced on-farm to control diseases and cope with seasonal availability of feed resources and the limitations of these strategies were also discussed. Proposed alternative strategies related to selective breeding for traits that can be utilized to manage diseases and scarcity in feed resources in IC production systems were presented in this chapter. Finally, the chapter gave a justification for this study, and objective and outline of the thesis. Literature estimates of genetic parameters are considered resourceful in instances where estimates for traits of interest are not available or insufficient. Estimates obtained from different studies, however, may vary due to differences in population among other factors. The choice of which estimate from sampled studies to use, is in most cases subjective and this may lead to either underestimation or overestimation of potential genetic progress. Chapter 2 assessed the robustness of literature estimates of genetic parameters for traits of economic importance in chicken performing in the tropical and sub-tropical environments using meta-analysis. Additive genetic, maternal environment and residual variances, and heritability estimates for traits related to immunity, reproduction, survival, growth, egg production and feed efficiency from 70 studies were considered. Heterogeneity index showed that published estimates of the genetic parameters sampled from different studies significantly varied in each of the traits. Based on total variance, a higher proportion of the variation in genetic parameters were more due to random effect of study than sampling error. Reliability estimates (relative standard error) of the genetic parameters varied across the traits considered in this study, in which, traits well represented in terms of number of published estimated had lower levels of variation compared to traits with low published estimated. Study characteristics related to population, production system, estimation methods, sex, age and antigen (only for immune traits) significantly influenced variation in the sampled genetic parameters across the traits. Pooled genetic parameters estimated in this study using the inverse of sampling variance as a weighting factor indicate that the weighted averages of genetic parameters can be utilized where estimates are not available or insufficient. The significant variation among sampled studies and low reliability estimated in some of the traits imply that genetic parameter estimates from literature should be applied with caution to prevent negative impacts on breeding decisions and genetic progress. In addition, differences in study characteristics should be considered in order to use estimates from studies with population and production conditions characteristics that closely resemble the intended population and production system. Antibody response to challenging conditions is suggested a suitable indicator trait that can be utilized for indirect improvement of disease resistance. However, prior to selection, understanding the genetic background of antibody response in the population of interest is a prerequisite in setting up an effective selection strategy. Chapter 3 investigated non-genetic and genetic sources of variation in natural antibodies binding to keyhole limpet hemocyanin antigen (KLH-NAbs) and specific antibodies binding to NCD virus (NDV-IgG). Non-genetic factors related to sex, population, phylogenetic cluster, generation, line, genotype and age significantly influenced the antibody traits, and should therefore be accounted for in genetic evaluations to reduce bias and improve accuracy of selection. Considerable amount of additive genetic variation was observed in the KLH-NAbs and NDV-IgG traits, implying possibilities of improvement of the antibody traits through selective breeding. However, the low to moderate heritability estimated in the antibody traits indicate that relatively low accuracy levels would be expected and hence, reduced rate of genetic gains if mass selection would be used. Positive genetic correlations observed among KLH-NAb isotypes (KLH-IgM, KLH-IgG and KLH-IgA) suggest that the isotypes can be improved simultaneously. In contrast, KLH-NAbs were negatively correlated with NDV-IgG implying that genetic improvement of natural antibodies would be associated with low specific antibodies binding NDV. These findings provide a better understanding of factors affecting antibody traits in a heterogeneous chicken population and may enable effective decisions prior to inclusion of immune parameters in breeding programs intended for tropically adapted chicken. Considering that an effective immune system is heavily dependent on metabolic resources for maintenance and deployment of various immune responses, improved antibody levels is expected to compete for nutrients and energy with other functions, such as production. Besides, given the scarcity in feed resources in production systems in Kenya, competition for nutrients and energy among biological functions is likely to influence the efficiency of feed utilization. Therefore, it is pertinent to also determine the pleiotropic nature between the immunity, production and feed efficiency traits. Chapter 4 estimated genetic and phenotypic correlations among antibody, feed efficiency and production traits measured pre- (nine to 20 weeks of age) and post- (12 weeks from on-set of lay) maturity. Results revealed that improved feed efficiency would be associated with high growth rates, early maturing chicken, high egg mass and reduced feed intake. In contrast, improved general (KLH-IgM) and specific (NDV-IgG) immunity would result in lower growth rates and egg mass but associated with early sexual maturation and high feed intake. Negative genetic correlations estimated between feed efficiency and antibody traits imply that chicken of higher productivity and antibody levels will consume more feed to support both functions. These associations indicate that selective breeding for feed efficiency and immune competence may have genetic consequences on production traits and should therefore be accounted for in IC improvement programs. Based on marketable end products, a breeding goal targeting simultaneous improvement of meat and egg production to develop a dual-purpose (ICD) breed that can perform in low to medium input systems is recommended for the IC population. However, due to the dynamics in market forces over time, goals targeting specialized production to develop a meat (ICM) and a layer (ICL) breed that can perform in medium to high input systems are also recommended as alternatives. Prior to defining the selection criteria across the goals, it is necessary to determine optimal combination of traits in an index because this has an impact on the overall genetic merit of an individual and total index response. Chapter 5 evaluated various selection strategies for adoption in ICD and ICL and ICM goals in indigenous chicken breeding with respect to total index response, accuracy of selection, rate of inbreeding and number of generations of selection required to achieve pre-defined genetic gains. Selection strategy targeting only production traits in a goal had the highest total index response, highest index accuracy (only ICM goal) and lowest inbreeding rate per generation, and least number of generations of selection required to achieve pre-defined gains. The index was, however, associated with unfavorable correlated responses in feed efficiency and antibody traits. Addition of both feed efficiency and antibody response in a goal indicated favorable genetic gains could be achieved in these traits. Conversely, this strategy reduced total index response and increased the rate of inbreeding per generation and required additional number of generations of selection to achieve desired gains pre-defined in each of the goals. Inclusion of either feed-related traits or antibody traits in a goal showed that feed-related traits had a more negative impact on the total index response per generation but improved selection accuracy in the ICD and ICL goals compared to antibody traits. Based on these results, choice of whether to include feed efficiency or/and antibody response in the ICD, ICM and ICL goals should depend on targeted production system, resource availability to support additional number of generations of selection and magnitude of correlated responses on these traits when not included in the goals. Lastly, a synthesis of the thesis is presented in Chapter 6 where practical relevance and utilization of findings of the thesis in designing a breeding program for indigenous chicken population is demonstrated.
Etablierung und Vernetzung digital-gestützter Systeme auf Pferdebetrieben unter Berücksichtigung der betriebswirtschaftlichen Optimierung
(2024) Speidel, Linda Thurid; Dickhöfer, Uta
Das Management eines pferdehaltenden Betriebs umfasst eine Vielzahl arbeitswirtschaftlicher Herausforderungen. Dazu zählen unter anderem die zeitintensiven Arbeitsabläufe, das notwendige Kundenmanagement in Pensions- und Schulpferdebetrieben sowie die begrenzte Verfügbarkeit von Fachkräften. Auf Ackerbau- und Veredelungsbetrieben wird der Nutzen der Digitalisierung bereits wahrgenommen, da deren Einsatz unter anderem Potenzial zur Zeitersparnis und Arbeitserleichterung bietet. Obgleich des genannten Potenzials sind Pferdebetriebe bisher wenig digitalisiert und technisiert, die Grundversorgung erfolgt meist manuell. Im Rahmen dieser, im Projekt „Digitale Wertschöpfungsketten für eine nachhaltige kleinstrukturiert Landwirtschaft“ (DiWenkLa) angefertigten, Forschungsarbeit wurde daher untersucht, welche Möglichkeiten der Digitalisierung bisher genutzt werden und unter welchen Voraussetzungen die einzelnen Systeme in Pferdebetrieben etabliert werden können. Des Weiteren wurde analysiert, welche Auswirkungen der Einsatz dieser Systeme auf den Arbeitszeitbedarf im Pferdebetrieb hat und welche Informationen über Schnittstellen zwischen den Systemen ausgetauscht werden können. Dafür wurden von März 2020 bis Oktober 2023 Experteninterviews, (Arbeitszeit-)Beobachtungen und Online-Befragungen durchgeführt. Zunächst wurden die vorhandenen Möglichkeiten der digitalen Technisierung auf Pferdebetrieben in der Fütterung von Rau- und Krippenfutter, der Entmistung und Einstreu, der Gesundheits- und Sicherheitsüberwachung sowie der Kommunikation und dem Betriebsmanagement untersucht. Der Schwerpunkt lag auf den Voraussetzungen, die erfüllt sein müssen, um ausgewählte digital-technische Systeme auf den Betrieben zu etablieren. Zu diesem Zweck wurden Beobachtungen und Befragungen bei pferdehaltenden Betrieben (N=1235) und den Kooperationspartnern aus der Industrie des Projekts DiWenkLa durchgeführt. Die Ergebnisse zeigen, dass die Einbindung digital-technischer Systeme von der Investitionsbereitschaft der Betriebsleitenden, der stabilen Internetverbindung, einer verfügbaren Stromversorgung in den Stallgebäuden (Steckdosen) und dem vorhandenen Haltungssystem (z. B. Einzel- oder Gruppenhaltung sowie Gliederung der Haltung in Funktionsbereiche) abhängt. Auf den an einer Online-Befragung teilnehmenden Pferdebetrieben (N=451) wurden Kameras zur Sicherheits- (30,8 %) und Gesundheitsüberwachung (22,6 %) sowie Software für die Kundenkommunikation (24,8 %) und das Betriebsmanagement (13,7 %) eingesetzt. Die automatisierte Fütterung von Krippenfutter (9,3 %) und Raufutter (7,3 %) war selten vorhanden. Eine Gliederung der Haltung in Funktionsbereiche führte zu einem vermehrten Einsatz digital-technischer Systeme. Als Gründe gegen den Einsatz neuer digital-technischer Systeme wurden von den 207 teilnehmenden Betriebsleitenden die fehlenden Finanzmittel, der unbekannte wirtschaftliche Nutzen sowie der Kontaktverlust zu den Tieren genannt. In Anlehnung an die vorliegenden Ergebnisse erscheint eine erneute Erhebung der vorhandenen Systeme auf Pferdebetrieben sinnvoll, um etwaige Veränderungen im Verlauf der Zeit abzubilden und die Gründe für die Investition in neue digital-technische Systeme zu ermitteln. Des Weiteren sollte untersucht werden, ob Einsteller bei einem höheren Digitalisierungsgrad im Pferdebetrieb bereit sind, einen höheren Pensionspreis zu bezahlen. Zu diesem Zweck könnte die Zahlungsbereitschaft beim Einsatz von z. B. Futterautomation und intelligenten Kameras zur Gesundheitsüberwachung abgefragt werden. Des Weiteren wurde analysiert, welche betriebswirtschaftlichen Vorteile die auf den Pferdebetrieben etablierten, digital gesteuerten Systeme mit sich bringen können. Dazu wurden die möglichen Auswirkungen der Digitalisierung auf den Arbeitszeitbedarf für verschiedene Arbeitsabläufe wie die Fütterung, Entmistung und Hütesicherheit untersucht. Dies wurde durch Zeiterfassungen mit und ohne den Einsatz der Systeme sowie mit Hilfe von Online-Befragungen (N=1014) und Experteninterviews (N=16) realisiert. Die Ergebnisse der Untersuchungen zeigen bei der Einzelhaltung von Pferden eine potenzielle Arbeitszeitersparnis in der Fütterung und Entmistung von bis zu 65 % durch eine automatisierte Fütterung von Rau- und Krippenfutter und den Einsatz von mobiler Technik, wie beispielsweise einem Hoflader. Zudem kann der Einsatz dieser Systeme auch dazu führen, dass die benötigte Arbeitszeit in anderen Arbeitsabläufen sinkt. Ein Beispiel hierfür ist der Einsatz einer automatisierten Fütterung, welcher zu einer geringeren Arbeitszeit in der Kundenkommunikation führte. Dies wurde in den durchgeführten Datenerhebungen dadurch begründet, dass gewünschte Änderungen in der Rationsgestaltung automatisiert erfolgen und somit nicht persönlich kommuniziert werden müssen. Darüber hinaus lassen sich durch eine digitale Absprache und die Dokumentation wesentlicher Arbeitsschritte und Änderungen in den Abläufen sowie Kundenwünschen Fehler reduzieren und Missverständnisse vermeiden. Auf Basis der Ergebnisse sollten die Abfragen der Arbeitszeitbedarfe der Arbeitsabläufe mit exakten und vorgegebenen Werten wiederholt und teilweise ergänzt werden. Dies betrifft z. B. den Zeitbedarf für das Betriebsmanagement, die Tierkontrolle und den Weidegang. Dadurch können die vorhandenen Kalkulationsgrundlagen aktualisiert und das Bewusstsein der Betriebsleitenden für teils unbeachteten Arbeitszeitaufwand geschärft werden. Dieser kann wiederum durch den Einsatz von digital-technischen Systemen reduziert werden. Darüber hinaus wurde ein Konzept für eine Schnittstelle für digitale Systeme für Pferdebetriebe entwickelt, um den Datenaustausch zwischen Systemen zu vereinfachen und somit die Übersichtlichkeit der verschiedenen Informationen aus den eingesetzten Technologien zu optimieren sowie zusätzliche Zeitersparnis zu gewährleisten. Dazu wurden mittels Experteninterviews (N=20 Experten) die auszutauschenden Informationen zwischen Systemen für die Fütterung, die Entmistung und Einstreu, die Gesundheits- und Sicherheitsüberwachung sowie das Betriebsmanagement und die Kommunikation identifiziert, um eine verbesserte Übersicht für die Betriebsleitenden zu gewährleisten. In diesem Kontext wurde der Datenaustausch zwischen Futterautomationen und Kommunikationssoftware als besonders relevant hervorgehoben. Je nach Bedarf können die Informationen aus dem Datenaustausch transparent an die Kunden (z. B. Einsteller) weitergegeben werden. Eine Online-Befragung ergab, dass die Mehrheit (57,2 %) aller Teilnehmenden (N=451) Interesse an einer Vernetzung der Systeme zeigt. In zukünftigen Untersuchungen könnten zum einen die Gründe für das Interesse an einer Vernetzung analysiert werden, da bisher lediglich die Gegenposition untersucht wurde (d.h. Gründe gegen das Interesse an der Vernetzung). Zum anderen könnte die Einbindung weiterer Systeme neben den genannten geprüft werden, insbesondere die Anbindung der vorhandenen Hardware (z. B. Solarien, Aquatrainer) an das Internet und die (standardisierte) Programmierung der Schnittstelle, um z. B. eine unkomplizierte und transparente Abrechnung der Nutzung zu ermöglichen. Die Etablierung und Vernetzung digital-technischer Systeme in Pferdebetrieben ist bei erfüllbaren Voraussetzungen als sinnvoll anzusehen, da sie eine Arbeitszeiteinsparung generieren, eine Entlastung der Arbeitskräfte ermöglichen, die Kommunikation verbessern und das Betriebsmanagement sowie die Sicherheits- und Gesundheitskontrolle der Tiere vereinfachen. Diese Faktoren sind neben der Beachtung und Verbesserung des Tierwohls für eine nachhaltige, zukunftsfähige Pferdehaltung unabdingbar.
Rumen fermentation, microbial protein synthesis, and nitrogen balance in tropical cattle fed cultivated forages
(2024) Sainz-Sanchez, Pedro Alan; Dickhöfer, Uta
Over the past decade, extensive research has focused on the role of cultivated forages in cattle diets and their effects on animal performance, particularly in terms of milk yield and daily live weight gain. Despite this progress, there remains a scarcity of information regarding the dietary factors influencing the efficiency of ruminal microbial crude protein (MCP) synthesis and nitrogen (N) balance in tropical cattle fed on cultivated forages. In the Tropics and Subtropics, a variety of non-structural carbohydrate (NSC) sources are commonly used as energy supplements for tropical cattle. Current advancements in ruminant nutrition highlight the need for a deeper understanding of the complex interactions between the type of NSC, the kinetics of starch degradation, and the timing of supplementation, particularly in the context of high-quality forage diets. Hence, the overall objective of the thesis was to comprehensively understand the dietary factors influencing the rumen MCP synthesis and N balance in tropical cattle fed on high-quality and low-quality cultivated forages. This doctoral thesis hypothesized that the rumen MCP synthesis and the N balance in tropical cattle are mainly affected by the crude protein (CP) and fiber concentrations of cultivated forages. It was further hypothesized that dietary factors such as the supplementation of NSC, type of NSC, and time of supplementation influence the nutritional quality of cultivated forages and affect the rumen MCP synthesis and excretion in tropical cattle. Overall, one in vitro and two in vivo studies were conducted to investigate the proposed hypotheses. In the first in vivo study (Chapter 2), three forage grass species (Cenchrus purpureus, Chloris gayana, and Urochloa brizantha), grown alone or intercropped with a forage legume (Dolichos lablab), were evaluated to determine feed intake, digesta passage rates, rumen MCP synthesis, and N balance in Boran steers. The results showed similar duodenal MCP flow, MCP synthesis efficiency, and digesta passage rates in steers fed different forage grasses, whether grown alone or intercropped. Minor variations in dry matter (DM) intake largely drove increased N intake, fecal N excretion, and N balance, particularly when no significant differences in the chemical composition of the forage grass species were observed. The in vitro study (Chapter 3) evaluated the interactions between tropical forage grasses (Urochloa humidicola and Urochloa mutica) and forage legumes (Desmodium uncinatum, Stylosanthes guianensis, and Mucuna pruriens) and their effects on in vitro total gas production (TGP), short-chain fatty acids (SCFA) concentration and profile, and MCP synthesis. For this, various forage-legume mixtures were prepared by varying the ratios of forage legume to forage grass (75:25 or 25:75 on DM basis). Results indicated that in vitro TGP, short-chain fatty acids concentration and profile, and MCP synthesis were influenced by CP concentration, CP degradation extent, and the fermentation of both structural and NSC of the forages. Additionally, supplemental CP and NSC, influenced in vitro TGP and MCP synthesis. The second in vivo study (Chapter 4) evaluated the use of corn and oat, differing in extent and rate of ruminal starch degradation as NSC sources (i.e., corn- and oat-based concentrate mixtures), supplemented to lactating Brown Swiss cows before or after grazing on an alfalfa-ryegrass sward. The study measured feed intake, rumen MCP synthesis, nutrient digestibility, N partitioning, and milk performance. Supplementing corn-based concentrate mixture after grazing and oat-based concentrate mixture before grazing improved the efficiency of MCP synthesis, milk performance, and efficiency of N use in grazing lactating dairy cows. The effects of NSC supplementation were influenced by the interdependent interactions of starch concentrations of NSC sources, their ruminal degradation kinetics, and the timing of supplementation. The findings of the present thesis, supported by existing literature, demonstrate that cultivated tropical forages can provide sufficient N compounds to support rumen MCP synthesis, meeting the CP requirements of tropical cattle without negatively affecting DM intake, nutrient digestibility, N balance, or overall animal performance. Although CP concentration of the cultivated forages is a key factor influencing rumen MCP synthesis and N balance in tropical cattle, this perspective overlooks important aspects such as the distinction between rumen degraded protein and rumen undegraded protein which provide a clearer representation of CP degradation and utilization at both, the ruminal and post-ruminal levels. The CP concentration in cultivated tropical forages is not the only factor affecting N balance; other nutritional factors, such as energy concentration, neutral detergent fiber, and acid detergent fiber concentrations, also play a crucial role. Specifically, the energy concentration of the forage affects the capture of N by ruminal microbes, while the concentrations of neutral detergent fiber and acid detergent fiber influence the available energy in the forage, thereby impacting overall N utilization in tropical cattle. The interaction between the time of supplementation and the type of NSC source influences the synchronization of N and energy in the rumen. The response to NSC supplementation is influenced by the timing of supplementation and the degradation rates of CP and carbohydrates in both the forages and NSC sources. In the context of the results presented in the present thesis and the existing literature, cultivated tropical forages not only enhance protein nutrition and performance in tropical cattle but may also contribute positively to environmental sustainability. For instance, reducing urinary and fecal N excretion helps limit excessive N release into the environment. Additionally, intercropping forage legumes with grasses can enhance soil fertility and improve soil structure. However, further research is required to assess overall system sustainability and to develop comprehensive feeding strategies for tropical cattle in the Tropics and Subtropics.
Relationship between nutritional composition and fibre digestibility in tropical forages compared to temperate forages
(2024) Nurdianti, Risma Rizkia; Dickhöfer, Uta; Castro-Montoya, Joaquín Miguel
The study aimed to analyse variability in nutrient concentration and fibre digestibility in forage legumes and grasses from tropical and temperate regions and identify forage species with similar fibre concentration and digestibility. Forty-five samples comprised 22 tropical forage legumes, four temperate forage legumes, eleven tropical grasses, and eight temperate grasses were analysed for their proximate nutritional composition, as well as fibre digestibility by 240-h of in vitro incubation in buffered rumen fluid. All data were analysed using SAS (SAS Institute Inc., USA). Pearson correlations and multiple linear regressions were determined using CORR and GLM procedures, respectively. Cluster analyses were done using CLUSTER procedures. Tropical forage legumes had greater ash-corrected neutral detergent fibre (aNDFom) concentrations compared to temperate forage legumes, but lower aNDFom concentrations compared to tropical and temperate grasses. Tropical forage legumes had greater undigested neutral detergent fibre estimated after 240 h in vitro incubation (uNDF240) concentrations compared to other forages. In tropical forage legumes, aNDFom and lignin concentrations correlated with uNDF240 concentration (p < 0.001). Meanwhile, there were no relationships between explanatory variables and fibre digestibility (p > 0.100). Four clusters of forage species varying in fibre concentration and fibre digestibility were identified. Peanut, lima bean, and cowpea forages might have low fibre concentration and medium fibre digestibility similar to those of alfalfa and red clover. Despite differences in environmental conditions, tropical forage legumes might compete with temperate species in terms of nutrient and fibre quality. This information allows tropical farmers to improve forage quality by choosing appropriate species.
Metabolome fingerprinting reveals the presence of multiple nitrification inhibitors in biomass and root exudates of Thinopyrum intermedium
(2024) Issifu, Sulemana; Acharya, Prashamsha; Schöne, Jochen; Kaur-Bhambra, Jasmeet; Gubry-Rangin, Cecile; Rasche, Frank
Biological Nitrification Inhibition (BNI) encompasses primarily NH4 +-induced release of secondary metabolites to impede the rhizospheric nitrifying microbes from per- forming nitrification. The intermediate wheatgrass Thinopyrum intermedium (Kernza®) is known for exuding several nitrification inhibition traits, but its BNI potential has not yet been identified. We hypothesized Kernza® to evince BNI potential through the presence and release of multiple BNI metabolites. The presence of BNI metabolites in the biomass of Kernza® and annual winter wheat (Triticum aestivum) and in the root exudates of hydroponically grown Kernza®, were fingerprinted using HPLC-DAD and GC–MS/MS analyses. Growth bioassays involving ammonia-oxidizing bacteria (AOB) and archaea (AOA) strains were conducted to assess the influence of the crude root metabolome of Kernza® and selected metabolites on nitrification. In most instances, significant concentrations of various metabolites with BNI potential were observed in the leaf and root biomass of Kernza® compared to annual winter wheat. Furthermore, NH4 + nutrition triggered the exudation of various phenolic BNI metabolites. Crude root exudates of Kernza® inhibited multiple AOB strains and completely inhibited N. viennensis. Vanillic acid, caffeic acid, vanillin, and phenylalanine suppressed the growth of all AOB and AOA strains tested, and reduced soil nitrification, while syringic acid and 2,6-dihydroxybenzoic acid were ineffective. We demonstrated the considerable role of the Kernza® metabolome in suppressing nitrification through active exudation of multiple nitrification inhibitors.

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