Newest publications
Effects of different dietary energy and essential amino acid levels on growing turkeys under organic farming conditions
(2025) Kirn, Anna Isabella; Rodehutscord, Markus
An adequate supply of dietary apparent metabolizable energy (AMEN) and essential amino acids (EAA) is crucial for turkeys to reach their genetic growth potential. However, optimizing diets in organic turkey production is challenging due to regulatory restrictions under EU Regulation 2018/848, which often lead to increased crude protein levels, potentially compromising animal health and environmental sustainability. To address this, targeted feeding strategies can be applied, leveraging compensatory growth through an initial qualitative feed restriction followed by a re-alimentation phase. Previous research showed that a consistent 10% reduction in AMEN combined with an initial EAA reduction of up to 20% (relative to commercial breeder guidelines), gradually restored to 90-100% during refeeding, effectively triggered compensatory growth, resulting in full catch-up growth. Nevertheless, as nutrient intake also affects welfare indicators such as plumage condition and injury prevalence, a balance between growth and welfare is essential.
The present thesis aimed to evaluate whether dietary EAA levels could be further reduced by up to 30%, maintaining a constant 10% AMEN reduction, in male and female turkeys of two genotypes (slow-growing Auburn and fast-growing B.U.T. 6) across various housing systems (indoor, indoor with silage, and mobile housing with free-range). The study focused on evaluating growth, slaughter performance, and welfare indicators. Additionally, the potential of a newly introduced scoring system for wing feather structure and depigmentation was examined as a sensitive indicator of dietary EAA supply status.
In the first study, 600 male day-old chicks from two genotypes (B.U.T. 6 and Auburn) were allocated to three feeding strategies differing in EAA levels across five 4-week phases: F1 (80/90/90/90/90%), F2 (80/80/90/100/90%), and F3 (70/80/90/100/90%). After rearing in indoor housing until week 8, the turkeys were transferred to one of three housing systems (indoor, indoor with silage, and mobile with free-range; weeks 9–20). Results showed that up to 30% initial EAA reduction followed by gradual re-alimentation triggered compensatory growth without affecting final body weight, total feed intake, or valuable cuts. No genotype by feeding interaction was observed. However, compensatory feed intake increased the feed conversion ratio and nutrient intake per kilogram of weight gain. While there was no housing by feeding interaction, housing significantly affected performance. Mobile housing with free-range and silage supplementation improved the feed conversion ratio and reduced abdominal fat. Additionally, mobile housing increased breast meat yield. Notably, a significant genotype by housing interaction suggested that B.U.T. 6 may demonstrate superior adaptability to the nutritional and environmental variability of the housing systems compared to Auburn.
Building on this, the second study tested a similar approach in 432 female turkeys across three feeding strategies (F1: 80/90/90/90%, F2: 80/80/90/90%, F3: 70/80/90/90%) over four four-week phases. After being reared indoors until week 8, birds were assigned to indoor or mobile housing with free-range access (weeks 9-16). While a 20% EAA reduction maintained growth and slaughter performance, a 30% reduction led to significant decreases in final body weight, slaughter weight, and dressing percentage. A significant genotype by feeding interaction suggested that B.U.T. 6 was more sensitive to the 30% reduction than Auburn. Mobile housing improved breast meat yield and reduced abdominal fat but increased feed conversion ratio, likely due to winter fattening conditions.
The third study examined the effects of dietary AMEN and EAA reductions on injuries, plumage damage, and the potential of a newly introduced scoring system for wing feather structure and depigmentation as an indicator of dietary EAA supply status. A total of 216 non-beak-trimmed female turkeys from the second study, housed indoors and subjected to the same feeding strategies, were evaluated. The most restrictive feeding strategy (30% EAA reduction) increased the prevalence of skin injuries, plumage damage, alterations in feather structure, and depigmentation. In contrast, the 20% EAA reduction preserved welfare and performance outcomes. Importantly, wing feather structure and pigmentation showed graded responses to varying EAA levels, supporting their potential as sensitive indicators of dietary EAA status in turkeys.
In conclusion, this thesis demonstrated that reducing EAA levels by 20%, followed by a re-alimentation phase, alongside a 10% AMEN reduction, can be successfully applied in organic turkey production. This approach maintained final growth performance, slaughter performance, and welfare in male and female Auburn and B.U.T. 6 turkeys by effectively leveraging compensatory growth. Wing feather structure and pigmentation scoring proved to be a sensitive indicator of EAA supply status. External feed sources such as silage and free-range foraging contributed nutritionally, while mobile housing enhanced breast muscle yield and reduced abdominal fat. Overall, turkey growth and performance under organic conditions resulted from complex interactions between endogenous factors (sex, genotype, age) and exogenous factors (housing, environment, feeding), highlighting the need for integrated and adaptive management approaches.
Stakeholder perspectives on the contribution of digital technologies to improve the sustainability of fruit production – a case study on the Lake Constance region in Germany
(2024) Gaber, Kirsten; Bieling, Claudia
Fruit cultivation is facing numerous sustainability challenges including climate change, weather extremes, and societal pressures surrounding the use of agricultural inputs. The value of fruit cultivation extends beyond the production of food, as the places of production are regionally important for ecology, recreation, tourism, and socio-cultural values; thus, sustainability issues threaten not only the future production of fruit, but also the cultural landscape as such. Digitalization in agriculture is progressing at a rapid pace and is frequently heralded as a solution to the current pressures surrounding modern food production. Increased productivity, efficiency gains, and improved transparency along the food value chain, enabled through the implementation of digital technologies, may lead to environmental and socio-economic benefits. Meanwhile, a divide is growing between supporters of digitalization and skeptics who are concerned with the technologies and their short- and long-term impacts. Digital solutions are not always suitable across agricultural sectors and regions due to differences in crop management activities, land-use types (e.g. perennial crop area like orchards versus arable land area for temporary crops), and physical barriers and infrastructure.
At the face of these challenges and the rapid development of digitalization, stakeholder perceptions regarding the influence of digitalization on the sustainability of fruit cultivation must be understood in order to enable a sustainable further development of digital technologies. Particular to the case study region of this dissertation, the Lake Constance region in southern Germany, research on stakeholder perspectives at the interface of sustainability in fruit production and digitalization does not exist. There is a large knowledge gap regarding the attitudes and practical understandings of the stakeholders impacted by the digital transformation of fruit cultivation, as well as what measures are required to support a more user-oriented development. Technology development without the consideration of barriers, user abilities, and user expectations may lead to an imbalanced transformation that may favour certain agricultural sectors, farm sizes, or production systems over others, which may consequently create a regional, demographic, and/or sectoral digital divide.
To this end, this cumulative doctoral work sought to explore the knowledge and views of stakeholders regarding the contribution of digital technologies to improve the sustainability of fruit production by using an empirical and qualitative case-study approach within the setting of sustainability research. The case-study region was the Lake Constance region in Germany, characterized by organic and integrated production (IP) fruit production on small- to medium-sized family farms. This region is the second-largest fruit growing area in the country and plays a critical role in the regional, national, and international food supply. The research questions that have guided this doctoral thesis are as follows: (1) What is the state of the art on digital technologies in fruit production? (2) How do stakeholders perceive digitalized fruit production, adoption and barriers to adoption of the technologies, and do these perceptions differ based on production system or farm size? (3) Do farmers (and other stakeholders) believe that digital technologies can tackle the environmental and social/societal sustainability challenges of fruit production, in both conventional and organic production, and if yes, how? In order to answer these questions, the author comprehensively reviewed over 200 digital tools that can be used by farms in the context of fruit production and conducted a qualitative analysis of 34 interviews with stakeholders along the fruit value chain. The three research articles that form the basis of this cumulative dissertation synergistically answer these questions through the research findings and surrounding scientific literature-based discussions.
Overall, the development of digital tools for this case study region appears to be unsuitable and knowledge on digitalization is uneven. Based on the findings, opportunities for technological development to overcome reported barriers and therefore support a user-oriented transformation include the development of tools that are cost-efficient, such as tools with multifunctionalities or that are hireable services, and that offer technical support in the local language. Marketing of technologies must be improved, as misguided marketing and inadequate information in the fruit sector may hinder implementation. Political frameworks should prioritize supporting the inclusion of small farms and equal efforts for development and implementation across production systems. The reduction of agricultural inputs and lack of societal acceptance of agriculture were the most frequently reported sustainability challenges for regional fruit production. Stakeholders believed both environmental and socio-economic challenges could be mitigated by digitalization in fruit production, particularly through increased efficiency and improved transparency. However, perceptions of digitalization’s chances and challenges varied among individuals, fruit production systems, and farm sizes. Furthermore, the majority of stakeholders believed that digitalization could change the public opinion about fruit production, either through on-farm use of the technologies or through improved transparency along the value chain. Both pathways were reported to potentially create positive or negative impacts; for instance, more transparency can lead to improved trust between farmers and consumers, but could also de-romanticize expectations or contradict the idea of naturalness in agriculture, especially in the case of organic farming. The discourse surrounding the use of digital technologies in fruit farming may be more influential on public opinion than their actual implementation.
According to stakeholders in the Lake Constance region, digitalized technologies can be used as tools to mitigate urgent sustainability challenges in fruit cultivation, but are not a cure-all solution. These technologies must be considered with caution, as they also risk worsening sustainability issues, particularly related to power inequalities and the growth paradigm of greater productivity and efficiency. Therefore, a reprioritization of digitalization focusing on mitigating urgent sustainability issues is required. This should include the supported development and implementation of user-driven technological design, hybrid (human-technological) intelligence for fruit cultivation tasks, and tools that prioritize building trust towards farmers and maintaining their autonomy. Future transdisciplinary research approaches are encouraged in order to meet many of the provided recommendations from this dissertation, such as enabling collaborative technology- and research design, improving foundational knowledge of involved groups through capacity-building measures like trainings, and building trust between actor groups. The results of this work will inform policy makers, researchers, and technology developers to support the fruit production sector to overcome current and future sustainability issues and enable fair, informed participation in the digital transformation of agriculture.
Herstellung von HMF aus Kartoffelschalen
(2025) Limbach, Nadine; Konnerth, Philipp; Kruse, Andrea
Die stoffliche Nutzung von Biomasse zur Herstellung von Plattformchemikalien gewinnt zunehmend an Bedeutung für eine nachhaltigere Chemie. Eine wichtige Verbindung in diesem Bereich ist 5-Hydroxymethylfurfural (HMF), das aus einfachen Zuckern gebildet werden kann. Ziel dieser Arbeit war es, HMF aus dem stärkehaltigen Nebenprodukt der Kartoffelschale zu synthetisieren. Dazu wurden die Einflüsse zweier Mineralsäuren – Schwefelsäure und Salpetersäure – in unterschiedlichen Konzentrationen (1 M, 1,5 M und 2 M) untersucht.
Die experimentelle Arbeit bestand aus zwei aufeinanderfolgenden Schritten. Zunächst wurde die Stärke der Kartoffelschalen hydrolytisch aufgeschlossen, um eine möglichst hohe Glucoseausbeute zu erzielen. Im anschließenden Versuch wurde diese Glucose über Isomerisierungs- und Dehydratisierungsschritte zu HMF umgesetzt. Hierfür wurden die Reaktionslösungen auf verschiedene pH-Startwerte (pH 2, pH 2,5 und pH 3) eingestellt.
Die Ergebnisse zeigen, dass beide Säuren die Stärkehydrolyse in ähnlicher Weise katalysieren und vergleichbare Ausbeuten an Glucose, Fructose und Zucker-Dimeren bei gleicher Verweilzeit liefern. In der nachfolgenden HMF-Synthese traten jedoch deutliche Unterschiede zwischen den Säuren auf: Schwefelsäure führte zu einer schnelleren Zuckerumwandlung und zu höheren HMF-Ausbeuten bei kürzerer Reaktionszeit. Mit sinkendem pH-Wert stiegen die HMF-Ausbeuten bei beiden Säuren an.
Neben HMF entstanden weitere Neben- und Abbauprodukte wie Levulinsäure, Ameisensäure und Huminstoffe. Dabei bildete sich bei Verwendung von Schwefelsäure eine höhere Menge an Huminstoffen als bei Salpetersäure. Insgesamt zeigt sich, dass Schwefelsäure die beteiligten Reaktionen bei gleichem pH-Startwert stärker katalysiert.
Participatory research at scale: a comparative analysis of four approaches to large-scale agricultural technology testing with farmers
(2024) Oberson, Nathalie; Moussa, Hannatou O; Aminou, Ali M; Kidane, Yosef Gebrehawaryat; Luo, Juliet Nangamba; Giuliani, Alessandra; Weltzien, Eva; Haussmann, Bettina IG
Tailoring agricultural technology options to the diverse conditions of smallholder farmers requires innovative approaches for testing these technologies with farmers across varied contexts, while incorporating their feedback into learning and decision-making processes. This study compares four such approaches: the Farmer Field School on Participatory Plant Breeding (FFS-PPB), Farmer Research Network (FRN), Crowdsourcing–Triadic comparisons of technologies (Tricot), and adapted Mother–Baby Trial (MBT) as implemented by four concrete projects. The objectives are to provide detailed descriptions of these approaches and their project-specific implementations, identify and analyze common aspects and differences, and derive insights to guide future farmer-inclusive projects aiming at contextual scaling of agricultural technologies. A literature review, key informant interviews, and a systematic content analysis were conducted for the analysis. Common features include cascade training models, simple farmer-managed experiments, and the use of digital tools for data collection. Major differences lie in the extent of farmer–researcher collaboration and decision-making, as well as how technology option-by-context interactions are addressed. The FRN, FFS-PPB, and adapted MBT approaches involve farmers in decision-making throughout most stages of research, including co-learning cycles that adapt the research design and technology options to farmers’ needs. Although these approaches require more training and expertise, they increase the likelihood of achieving relevant results that farmers can implement in practice. In contrast, more standardized approaches like the Crowdsourcing–Tricot streamline the implementation, data management and analysis of large-scale trials, but have limitations in capturing the underlying reasons for farmers’ preferences. Among the studied approaches, the FRN as implemented by the Women's Fields project in Niger is particularly effective in identifying which options best suit specific farming contexts.
Seeds in rocky soil: the interactive role of entrepreneurial legacy and bridging in family firms’ organizational ambidexterity
(2023) Wilmes, Rolf; Brändle, Leif; Kuckertz, Andreas
Existing research on family firms emphasizes the importance of entrepreneurship across generations but leaves the role of entrepreneurial transmissions between predecessors and successors relatively unexplore. Building on the concept of entrepreneurial legacy, we ask how interactions of entrepreneurial mindsets and resources influence organizational ambidexterity in family firms. The study’s central argument (and metaphor) is that organizational ambidexterity thrives in multigenerational family firms if successors’ awareness of the family’s entrepreneurial legacy (the right seed) interacts with predecessors’ provision of entrepreneurial resources during succession (the fertile soil), also known as entrepreneurial bridging. We analyze a unique sample of successors from 296 multigenerational family firms in the agricultural sector. Our results point to the relevance of entrepreneurial resources in predecessor-successor collaborations to unlock the family firm’s ability to balance entrepreneurial exploration and exploitation.