Publikationsfonds der Universität Hohenheim

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A computer vision approach for quantifying leaf shape of maize (Zea mays L.) and simulating its impact on light interception
(2025) Otto, Dina; Munz, Sebastian; Memic, Emir; Hartung, Jens; Graeff-Hönninger, Simone
The precise determination of leaf shape is crucial for the quantification of morphological variations between individual leaf ranks and cultivars and simulating their impact on light interception in functional-structural plant models (FSPMs). Standard manual measurements on destructively collected leaves are time-intensive and prone to errors, particularly in maize ( Zea mays L.), which has large, undulating leaves that are difficult to flatten. To overcome these limitations, this study presents a new camera method developed as an image-based computer vision approach method for maize leaf shape analysis. A field experiment was conducted with seven commonly used silage maize cultivars at the experimental station Heidfeldhof, University of Hohenheim, Germany, in 2022. To determine the dimensions of fully developed leaves per rank and cultivar, three destructive measurements were conducted until flowering. The new camera method employs a GoPro Hero8 Black camera, integrated within an LI-3100C Area Meter, to capture high-resolution videos (1920 × 1080 pixels, 60 fps). A semi-automated software facilitates object detection, contour extraction, and leaf width determination, including calibration for accuracy. Validation was performed using pixel-counting and contrast analysis, comparing results against standard manual measurements to assess accuracy and reliability. Leaf width functions were fitted to quantify leaf shape parameters. Statistical analysis comparing cultivars and leaf ranks identified significant differences in leaf shape parameters (p < 0.01) for term alpha and term a . Simulations within a FSPM demonstrated that variations in leaf shape can alter light interception by up to 7%, emphasizing the need for precise parameterization in crop growth models. The new camera method provides a basis for future studies investigating rank-dependent leaf shape effects, which can offer an accurate representation of the canopy in FSPMs and improve agricultural decision-making.
Adapting wheat production to global warming in West Asia: facultative wheat outperforms winter and spring wheat at conventional nitrogen levels
(2025) Yousefi, Afsaneh; Koocheki, Alireza; Mahallati, Mehdi Nassiri; Khorramdel, Soroor; Trenz, Jonas; Malakshahi Kurdestani, Ali; Ludewig, Uwe; Maywald, Niels Julian
Global warming and weather anomalies pose significant threats to cereal production in West Asia. Winter wheat, which requires vernalization to trigger reproductive growth, is particularly vulnerable to heat, while spring wheat faces limitations due to short and hot vegetation periods. Facultative wheat, which does not require vernalization and can be planted in either fall or spring, offers potential flexibility and resilience to fluctuating temperatures. This study aimed to evaluate the development and grain yield of facultative, spring, and winter wheat varieties under different nitrogen fertilization rates in current climate conditions. Facultative wheat, grown as either facultative winter (FWW) or facultative spring (FSW), along with winter (WW) and spring wheat (SW) varieties, was cultivated over two consecutive seasons (2020–2022) at Ferdowsi University of Mashhad, Iran. Developmental stages were monitored, and grain yield, protein, and nutrient concentrations were measured at four nitrogen levels (0, 100, 200, and 300 kg N ha −1 ) in both shoots and grains. Crop modeling under the RCP 8.5 climate scenario supported the experiments and projections. Facultative wheat sown in autumn exhibited a shorter tillering stage and a longer early reproductive stage compared to winter wheat. While nitrogen fertilization delayed development, it significantly increased yield. Facultative wheat achieved higher grain yields at conventional nitrogen levels (100–200 kg N ha −1 ). Additionally, increasing nitrogen fertilization improved grain protein and nutrient concentrations (N, P, and K). Crop modeling indicated that facultative varieties sown in winter could offer greater yield stability and might benefit from a more consistent phenological development. Overall, facultative wheat performed better at conventional nitrogen levels, highlighting its potential in a changing climate in West Asia. Optimizing sowing dates and nitrogen fertilization could help mitigate some of the negative effects of rising temperatures, enhancing wheat resilience and productivity.
The adoption potential of extended lactation as a strategy to reduce excess calf numbers in dairy farming
(2024) Gresham, Josephine; Reiber, Christoph; Chagunda, Mizeck G. G.
Dairy production relies predominantly on a few, selectively bred, high-yielding dairy breeds, resulting in a surplus of low-value male offspring. This situation leads to a conflict between a growing demand for milk and low appreciation for dairy calves. Extending lactation could reduce the number of calves born. This study aimed to assess the current use of extended lactation in dairy production in Southern Germany, identify the perceived potential, and determine the biological potential extended lactation has to reduce calf numbers. A survey from 2020 with 310 farmers was analysed. A total of 145 (46.8%) farmers used extended lactation. The use of extended lactation on farms correlated significantly with breed, milk yield, interest in continuing or implementing the use of extended lactation, and the indicated feasibility of extended lactation. The perceived potential was assessed by 39.8% of farmers as “high” to “very high”. A total of 17 (12.8%) farmers currently not using extended lactation were identified as potential adopters. Together with existing adopters, this could result in 52.3% of farms using extended lactation, which could biologically reduce calf numbers by 7.3% or 14.1% p.a., when extended by three or six months, respectively. This adoption potential shows that extended lactation can reduce calf numbers considerably, addressing both ethical and economic concerns in dairy farming and benefiting farmers as well as society.
AI-assisted tractor control for secondary tillage
(2025) Boysen, Jonas; Bökle, Sebastian; Stein, Anthony
Modern agricultural machinery requires skilled operators to optimally configure their complex machines, while autonomous machines without operators must already optimize their configuration themselves to achieve optimal performance. During secondary tillage multiple performance measures need to be monitored and maximized: Seedbed quality, area output and fuel consumption. The seedbed quality can be measured with the soil surface roughness coefficient which can be computed with 3D-cameras attached to the machine. For our work, such cameras are mounted in the front and back of a Claas Arion 660 tractor with an attached power harrow seeding combination. The soil-machine response model of our prior work is utilized to model the soil-machine interaction for the training of a reinforcement learning agent and the application of a decision-time planning agent to assist in controlling the working speed of the machine. The control agents are tested in real-world field trials and compared to good professional practice. The decision-time planning agent achieves comparable results to a gold-standard while reaching significantly higher performance in terms of area output (29.1%) and more efficient fuel consumption (8.4%) than a baseline while the reinforcement learning agent performed worse during the field trials. The seedbed quality and field emergence are not showing significant differences between the variants. Further analysis shows that model training and selection for the reinforcement agent could have led to performance loss and models that are performing better in simulation have been trained after the field trials. Furthermore, we analyze the models when tested under the field conditions in the field trials (out-of-distribution) that are different from the field conditions during training data collection. The out-of-distribution testing leads to a reduced performance in terms of rRMSE of the decision-time planning agent and to some extend reward of the reinforcement learning agent compared to in-distribution testing.
Can market fragmentation explain the limited success of political attempts to promote grain legume cultivation in Germany?
(2025) Mittag, Franziska; Hess, Sebastian
Grain legumes, such as field peas, field beans, sweet lupins and soybeans, are known to increase biodiversity within the appropriate crop rotation and are an important source of import-substituting feed protein. National and regional policy schemes have long tried to support the cultivation of grain legumes. Although many regions in Germany offer favourable conditions for grain legumes, previous subsidy schemes have failed to increase the area under cultivation and farmers report a lack of market incentives. Indeed, the available price data exhibit a substantial share of non-random missing values in weeks when grain legumes were not traded. We analyse these non-price periods using cointegration tests and single-hurdle Tobit models. The results indicate that regional price formation for grain legumes in German regions depends not only on a minimum quantity of the respective legume crop in supply but also on a favourable supra-regional soybean price: Regional grain legume markets are not integrated and show evidence of a fragmented market structure. This may explain why local grain legume value chains have failed to emerge in Germany, despite decades of policy attempts to support these crops.
The chicken gut microbiome in conventional and alternative production systems
(2025) Cheng, Yu-Chieh; Krieger, Margret; Korves, Anna-Maria; Camarinha‑Silva, Amélia
The poultry gut microbiome plays a key role in nutrient digestion, immune function, and overall health. Differences among various farming systems, including conventional, antibiotic-free, free-range, and organic systems, influence microbial composition and function through variations in diet, genetic selection, environmental exposure, and antibiotic use. Conventional systems typically rely on formulated diets and controlled housing conditions, often with routine antimicrobial use. In contrast, organic systems emphasize natural feed ingredients, including roughage, outdoor access, and strict limitations on the use of antibiotics. These divergent practices shape the gut microbiota differently, with organic systems generally associated with greater exposure to environmental microbes and, consequently, greater microbial diversity. However, the implications of this increased diversity for poultry health and performance are complex, as organic systems may also carry a higher risk of pathogen exposure. This review summarizes current findings on the chicken gut microbiome across conventional and alternative production systems (antibiotic-free, free-range, and organic), focusing on microbial diversity, functional potential, and disease resilience. The need for standardized methodologies and consistent nomenclature in microbiome research is also discussed to improve comparability across studies. Understanding how production systems influence the gut microbiota is essential for improving poultry health and productivity while addressing challenges related to antimicrobial resistance and sustainable farming practices.
Classifying early-stage soybean fungal diseases on hyperspectral images using convolutional neural networks
(2025) Hsiao, Chieh Fu; Feyrer, Georg; Stein, Anthony
Using convolutional neural networks (CNNs) to detect plant diseases has proven to reach high accuracy in the classification of infected and non-infected plant images. However, most of the existing researches are based on RGB images due to the availability and the comparably low cost of image collection. The limited spectral information restricts the detectability of plant diseases, especially in the early stage where often symptoms of pathogen infection have not yet become visible. To this end, in this study, hyperspectral imaging (HSI) data are combined with deep learning models to test the classification ability of two soybean fungal diseases: Asian soybean rust (Phakopsora pachyhizi) and soybean stem rust (Sclerotinia scleroriorum). Different CNNs employing 2D, 3D convolution, and hybrid approaches are compared. The influences of the depth of the convolutional layer and the regularization techniques are also discussed. Besides, image augmentation methods are investigated to overcome the problem of data scarcity. The results indicate the 6-convolutional-layer depth hybrid model to have the best capacity in classifying Asian soybean rust in the early-mid to mid-late stage when there are over 2 % visible symptoms but a limited detectability in the early stages when there are below 2 % visible symptoms on leaves. On the other hand, the optimized CNN model shows a limited capability to detect both diseases when there are no visible symptoms observable. Overall, this study suggests a hybrid 2D-3D convolutional model with augmentation and regularization methods has a high potential in the early detection of fungal diseases. This research is expected to contribute to a new cropping system that vastly reduces the chemical-synthesis plant protection products, where a continuous pathogen disease monitoring plays a key to manage the crop stands.
Comparing hops and malt price transmission in the beer value chain: evidence from Germany
(2025) Hess, Sebastian; Bublik, Nikolas
The German beer value chain has received limited attention so far, despite the country’s central role in global beer production. This study investigates the price dynamics of its two key inputs—hops and malt—using monthly price data from 2015 to 2024 based on a unique dataset from a German hops cooperative. While contract farming is common for both raw materials, malt is traded via private firms, whereas hops are marketed almost exclusively through farmer-owned cooperatives. A vector error correction model (VECM) is estimated, incorporating structural break dummies identified through Bai–Perron tests, followed by forecast error variance decomposition (FEVD) and impulse response function (IRF) analysis. The results show that hop prices are largely self-driven and adjust more quickly to deviations from equilibrium than malt or beer prices. While malt and beer exhibit stronger interdependencies, the hop sector displays greater price stability. The findings further reveal that the malting sector responded significantly to the recent energy price crisis in Germany, whereas the hop sector did not.
A concept of a decentral server infrastructure to connect farms, secure data, and increase the resilience of digital farming
(2025) Bökle, Sebastian; Gscheidle, Michael; Weis, Martin; Paraforos, Dimitrios S.; Griepentrog, Hans W.
With the intensified use and integration of digital technologies in agriculture, dependencies and constraints occurred which weakened the adoption and reduced effectiveness of innovative technology due to lacking interoperability and resilience. As awareness of these problems increased concepts have been developed to meet this issue with decentralized IT- infrastructures. With the proposed concept the authors aim to refine these existing infrastructures with concrete suggestions for server infrastructures. Off-the-shelf hardware and open-source software, enable cheap access to digital technologies yet provide sufficient support by choosing open-source tools with big or active communities. With the involvement of the machinery rings the economic advantages scale up because of the interfarm use of expensive technology. The farmservers on the farmside are the edge nodes of a regional network. The local machinery ring is the next node which is supposed to offer remote services for the farmers, who have a trustful partner in the machinery rings. The concept orients on revised requirements enriched by the results of a survey, conducted by the authors, adding the focus on interfarm cooperations. The concept meets the main constraints farmers face in digitalization: Data sovereignty, resilience, interoperability, high costs, and trust.
Dependence of the abundance of reed glass-winged cicadas (Pentastiridius leporinus (Linnaeus, 1761)) on weather and climate in the Upper Rhine Valley, Southwest Germany
(2025) Kakarla, Sai Kiran; Schall, Eric; Dettweiler, Anna; Stohl, Jana; Glaser, Elisabeth; Adam, Hannah; Teubler, Franziska; Ingwersen, Joachim; Sauer, Tilmann; Piepho, Hans-Peter; Lang, Christian; Streck, Thilo; Guo, Jianying
The planthopper Pentastiridius leporinus , commonly called reed glass-winged cicada, transmits the pathogens “ Candidatus Arsenophonus phytopathogenicus” and “ Candidatus Phytoplasma solani”, which are infesting sugar beet and, most recently, also potato in the Upper Rhine valley area of Germany. They cause the “Syndrome Basses Richesses” associated with reduced yield and sugar content in sugar beet, leading to substantial monetary losses to farmers in the region. No effective solutions exist currently. This study uses statistical models to understand to what extent the abundance of cicadas depends on climate regions during the vegetation period (April–October). We further investigated what influence temperature and precipitation have on the abundance of the cicadas in sugar beet fields. Furthermore, we investigated the possible impacts of future climate on cicada abundance. Also, 22 °C and 8 mm/day were found to be the optimal temperature and precipitation conditions for peak male cicada flight activity, while 28 °C and 8 mm/day were the optimum for females. By the end of the 21st century, daily male cicada abundance is projected to increase significantly under the worst-case high greenhouse gas emission scenario RCP8.5 (RCP-Representative Concentration Pathways), with confidence intervals suggesting a possible 5–15-fold increase compared to current levels. In contrast, under the low-emission scenario RCP2.6, male cicada populations are projected to be 60–70% lower than RCP8.5. An understanding of the influence of changing temperature and precipitation conditions is crucial for predicting the spread of this pest to different regions of Germany and other European countries.
Developing marginal‐land‐based bioeconomy systems — A design and development approach for bio‐based value chains and webs
(2025) Schlecht, Valentin; Vargas‐Carpintero, Ricardo; von Cossel, Moritz; Lewandowski, Iris
Industrial crops grown on marginal lands offer a potential source of low-iLUC feedstock for bio-based industries, supporting sustainable bioeconomic development. However, marginal-land-based bioeconomy systems face significant uncertainties at early stages, such as limited data, farmers' hesitancy to adopt novel crops, undeveloped markets and immature technologies. This study implements an integrated multi-criteria framework as a structured, multi-step approach to connect bio-based value chain components and stakeholders in marginal-land-based bioeconomy systems at the research level. The framework was applied within the EU Horizon project MIDAS to identify, evaluate and combine bio-based value chain components, with a case study in the Swabian Alb (southern Germany) demonstrating its potential for designing scalable bio-based value chains tailored to regional conditions. Key findings emphasise the importance of stakeholder collaboration, iterative design processes and context-specific criteria that address technical, economic, social and regulatory aspects. The approach, based on qualitative data and stakeholder input, offers critical insights into the feasibility of biomass-to-product pathways and serves as a foundation for advanced research. Future research needs to focus on expanding data availability, incorporating quantitative methods, and addressing economic and market factors, such as stakeholder willingness to produce feedstocks, to enhance the scalability and robustness of the findings and facilitate the establishment of sustainable bioeconomy systems on marginal lands.
Development and testing of a precision hoeing system for re-compacted ridge tillage in maize
(2024) Alagbo, Oyebanji O.; Saile, Marcus; Spaeth, Michael; Schumacher, Matthias; Gerhards, Roland
Ridge tillage (RT) is a conservation practice that provides several benefits such as enhanced root growth and reduced soil erosion. The objectives of this study were to develop an autosteered living mulch seeder and hoeing prototype for RT systems using RTK-GNSS (real-time kinematic global navigation satellite systems) created ridges as a guide. It was also aimed to compare weed control efficacy and crop response of ridge-hoeing compared to conventional hoeing in flat tillage (FT). It was further aimed to investigate the impact of a new RT technology (with ridge re-compaction) on maize root development, yield, soil temperature, and moisture compared to FT. Field experiments were conducted with maize in 2021 and 2022 in a two-factorial split-plot design with tillage (RT and FT) as main treatment and weed control (untreated, herbicide, twice hoeing, hoeing + living mulch) as sub-treatment factors. Weed density, coverage, biomass, crop density, weed control efficacy (WCE) and maize silage yield were assessed. Temperature loggers were installed within RT and FT to take temperature readings at 20 min. Soil moisture and root penetrability were measured every two weeks in each plot using soil samples and a penetrometer. The WCE and yield did not differ significantly between the tillage systems. Twice hoeing resulted in 71–80 % WCE, which was equal to herbicide treatment. Hoeing + living mulch achieved 70–72 % WCE. Different from previous studies with ridge tillage, temperatures in the compacted ridges did not consistently differ from the ridge valleys and flat seedbeds. Root penetration (against 1.4 MPa penetrometer cone index) was 40 % higher in RT than in FT. On average, RT maize produced more (53.6 g m−2) root biomass compared to FT. In summary, re-compacted ridges built along RTK-GNSS lines can allow post-emergent hoeing and living mulch seeding along ridges and also provide good growing conditions for maize.
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.
Effects of dietary phosphorus and myo-inositol supplementation on NaPi-IIb and TRPV6 protein expression in duodenal apical membranes of laying hens from two strains
(2026) Shomina, Nataliia; Sommerfeld, Vera; Hanauska, Anna; Oster, Michael; Rodehutscord, Markus; Huber, Korinna
Phosphorus (P) and calcium (Ca) absorption in the intestine is mediated by apical brush border membrane (BBM) transporters, including the sodium-dependent phosphate (Pi) transporter NaPi-IIb and the Ca²⁺-selective channel TRPV6. Both are highly expressed in the duodenum and exhibit dietary adaptability; yet little is known about how this adaptability varies with strain and age in laying hens. The present study examined the effects of dietary mineral P renunciation and myo-inositol (MI) supplementation on NaPi-IIb and TRPV6 protein expression in the duodenal BBM of Lohmann Brown-Classic (LB) and Lohmann LSL-Classic (LSL) hens. Two independent feeding trials were conducted: hens received diets either with or without mineral P supplementation (wk 15 - 19 and 20 – 24), or with graded MI levels (0 - 3 g/kg; wk 26 – 30). At the end of each period, hens were euthanized and protein expression of NaPi-IIb and TRPV6 in duodenal BBM was studied by western blotting. Statistical correlation with additional traits of mineral metabolism was analyzed. An immunoreactive NaPi-IIb band was detected at ∼ 45 kDa; therefore, all results reported here refer to this NaPi-IIb fragment. Mineral P renunciation did not affect NaPi-IIb fragment or TRPV6 expression in either hen strain. In LSL hens NaPi-IIb fragment expression increased from wk 19 to wk 24, whereas in LB hens it remained unchanged. NaPi-IIb fragment expression was positively associated with duodenal phosphatase activity and plasma estradiol. TRPV6 expression tended to reduce in LB hens from wk 19 to wk 24, but remained stable in LSL hens. TRPV6 expression was positively associated with duodeno-jejunal P content. MI supplementation upregulated NaPi-IIb fragment expression in LB, but downregulated it in LSL hens with high dietary MI levels, without affecting TRPV6. These findings demonstrate strain-dependent regulatory patterns of duodenal expression of NaPi-IIb fragment and TRPV6 in response to physiological stage and MI supply, indicating that mineral feeding strategies may benefit from genotype-specific consideration, whereas the mechanisms underlying MI-related effects require further clarification.
Effects of feeding diets without mineral P supplement on intestinal phytate degradation, blood concentrations of Ca and P, and excretion of Ca and P in two laying hen strains before and after onset of laying activity
(2024) Sommerfeld, Vera; Bennewitz, Jörn; Camarinha-Silva, Amélia; Feger, Martina; Föller, Michael; Huber, Korinna; Oster, Michael; Ponsuksili, Siriluck; Schmucker, Sonja; Seifert, Jana; Stefanski, Volker; Wimmers, Klaus; Rodehutscord, Markus
The objective of this study was to characterize intestinal phytate degradation and mineral utilization by 2 laying hen strains before and after the onset of egg laying using diets without or with a mineral phosphorus (P) supplement. One offspring of 10 roosters per strain (Lohmann Brown-classic [LB] and Lohmann LSL-classic [LSL]) was sacrificed before (wk 19) and after (wk 24) the onset of egg-laying activity and following 4 wk placement in a metabolic unit. Diets were corn-soybean meal-based and without supplemented P (P-) or with 1 g/kg supplemented P (P+) from monocalcium phosphate. In wk 19 and 24, the blood plasma and digesta of duodenum+jejunum and distal ileum were collected. The concentration of P in blood plasma was higher in hens fed P+ than P- (P < 0.001). In duodenum + jejunum and ileum content, the concentrations of InsP6, Ins(1,2,4,5,6)P5 and Ins(1,2,3,4,5)P5 were lower in P- than in P+ (P ≤ 0.009). In duodenum+jejunum, the concentrations of InsP6, Ins(1,2,4,5,6)P5 and Ins(1,2,3,4,5)P5 were lower in wk 24 than 19 and lower in LSL than LB hens (P < 0.001). The concentration of myo-inositol (MI) in duodenum + jejunum content was lower in wk 19 than 24 (P < 0.001). Following a 4-d total excreta collection, the retained amount of P was higher in P+ than P- (P < 0.001). Phosphorus retention was lower in LB hens fed P- than in other treatments (P × strain: P = 0.039). In the jejunal tissue, some genes related to intracellular InsP metabolism were higher expressed in LB than LSL hens. The renunciation of mineral P increased endogenous phytate degradation, but more P was retained with supplemented P. Differences in endogenous phytate degradation between the periods before and after the onset of egg laying might be attributed to different Ca concentrations in intestinal digesta caused by different Ca needs in both periods.
Effects of myo-inositol supplementation in the diet on myo-inositol concentrations in the intestine, blood, eggs, and excreta of laying hens
(2025) Sommerfeld, Vera; Hanauska, Anna; Huber, Korinna; Bennewitz, Jörn; Camarinha-Silva, Amélia; Feger, Martina; Föller, Michael; Oster, Michael; Ponsuksili, Siriluck; Schmucker, Sonja; Seifert, Jana; Stefanski, Volker; Wimmers, Klaus; Rodehutscord, Markus
The objectives of this study were to investigate whether an increased dietary myo-inositol (MI) supply translates into changes in MI concentrations and endogenous mucosal phosphatase activities in the intestine of laying hens and whether different laying hen strains respond differently to MI supplementation. The diets were corn–soybean meal-based and supplemented without (MI0) or with 1 (MI1), 2 (MI2), or 3 (MI3) g MI/kg feed. Ten hens per strain (Lohmann Brown-classic (LB) and Lohmann LSL-classic (LSL)) and diet were sacrificed at the age of 30 wk following a 4-wk stay in a metabolic unit. The blood plasma, digesta of the duodenum+jejunum and distal ileum, mucosa of the duodenum, and eggs were collected at wk 30. The concentration of MI in the blood plasma was increased by MI supplementation (P < 0.001); however, that of MI3 did not further increase compared with MI2. The concentration of MI in the duodenum+jejunum and ileum increased steadily (P < 0.001). The MI concentration in the duodenum+jejunum was higher in LB than in LSL hens (P = 0.017). The MI concentration in egg yolk was increased by MI supplementation (P < 0.001) and was higher in LB than in LSL hens (P = 0.015). Strain or diet did not affect mucosal phosphatase activity. Myo-inositol flow at the terminal ileum and postileal disappearance increased with each increment in MI supplementation (P < 0.001) and was higher in LB than in LSL hens (P ≤ 0.041). Regression analysis indicated that, on average, 84% of supplemented MI was retained in the body or metabolized and excreted in a different form. Based on the measured MI concentrations in the blood and eggs, dietary MI was not completely absorbed in the small intestine and, to a different extent, in the two laying hen strains. A higher dietary MI supply was followed by higher intestinal absorption or metabolism by microorganisms. The fate of supplemented MI and its relevance to birds warrant further research.
The effects of plant density and duration of vegetative growth phase on agronomic traits of medicinal cannabis (Cannabis sativa L.): a regression analysis
(2024) Schober, Torsten; Präger, Achim; Hartung, Jens; Graeff-Hönninger, Simone
Empirical data on the effect of plant density (PD) and length of the vegetative phase (DVP) on plant growth, yield, and cannabinoid concentration of medicinal cannabis (Cannabis sativa L.) are still scarce, leading to a lack of specific cultivation recommendations. We conducted two greenhouse experiments to investigate the effect of PD in the range of 12–36 plants m-2 (D-trial) and DVP in the range of 1–4 weeks (V-trial) on plant morphology, biomass growth of individual plant organs, and CBD concentration of individual inflorescence fractions. Empirical models for the relationships between the investigated plant traits and PD/DVP were created using linear regression analysis preceded by a lack-of-fit test. An increase in PD led to a linear decrease in inflorescence yield per plant (p = 0.02), whereas a positive linear relationship was found for inflorescence yield (p = 0.0001) and CBD yield (p = 0.0002) per m2. Total area yields in the D-trial ranged from 119 to 247 g m-2 from lowest to highest PD. DVP showed a positive linear relationship with inflorescence yield on an individual plant (p = 0.0001) and area basis (p < 0.0001) along with most other relevant agronomic traits such as CBD production, plant size and lateral shoot length. Total area yields in the V-trial ranged from 295 to 571 g m-2 from lowest to highest DVP. The yield increase could be linked to the increased inflorescence number per plant rather than inflorescence size. In contrast to expectations, neither PD nor DVP had significant effects on the cannabinoid concentration gradient from upper to lower canopy layers. CBD concentrations in inflorescences from lower canopy layers were reduced by 23% in the V-trial and 46% in the D-trial. However, with increasing PD, the proportion of higher-concentrated inflorescence fractions from upper canopy layers increased from 46% to 68%, while an extension of DVP shifted this proportion only marginally from 45% to 50%. In the context of standardized production, we therefore advocate high-density production systems that increase the proportion of desired inflorescence fractions from upper canopy layers.
Effects of Prosopis juliflora pods on sheep performance and carcass traits, and their methane mitigation potential as assessed in vitro
(2025) Tadesse, Assefa; Titze, Natascha; Rodehutscord, Markus; Melesse, Aberra
This study aimed to assess the effect of partial substitution of concentrate mix (CM) with Prosopis juliflora pod (PJP) on growth performance and carcass traits in sheep, and its potential to reduce methane (CH4) production in vitro. A total of 25 yearling rams with an initial body weight of 15.8±1.53 kg was randomly assigned to five treatment diets. The diets were a control diet (JP0) and JP0 replaced with PJP at the level of 5% (JP5), 10% (JP10), 15% (JP15), and 20% (JP20). Data were collected on feed intake, body weight, and carcass characteristics. Methane production was determined from 24 h in vitro gas production. The substitution of CM with PJP did not affect feed intake, body weight, weight gain, feed efficiency, and carcass traits (p>0.05). The in vitro CH4 production was reduced (p<0.001) in diets containing increased levels of PJP. The metabolizable energy for JP10, JP15 and JP20 diets was 11.9, 11.6 and 11.5 MJ/kg DM, respectively (p>0.05). In conclusion, replacing CM with PJP did not negatively affect growth performance and carcass characteristics and could be used as potential supplement to mitigate methane emissions. Further in vivo studies involving respiration chambers are recommended to investigate the CH4 reduction potential of PJP.
Endogenous mucosal phosphatases characterization in duodenum brush border membrane of laying hens
(2025) Hanauska, Anna; Sommerfeld, Vera; Schollenberger, Margit; Huber, Korinna; Rodehutscord, Markus
Chicken mucosal phosphatases can partially degrade phytate contained in the feed. Little is known about the characteristics and degradation products of such mucosal phosphatases and the effects of age and genetic strain of the chicken. The objective of this study was to characterize endogenous mucosal phosphatases of two laying hen strains fed diets with or without mineral phosphorus (P) before and after the onset of egg laying. Hens of the strains Lohmann Brown-classic (LB) and Lohmann LSL-classic (LSL) were sacrificed in weeks 19 and 24 of age after 4 weeks of feeding one of two diets with (P+) or without (P-) mineral P supplement. Mucosa of the duodenum was collected, and the brush border membrane (BBM) of enterocytes was enriched and used for phosphatase activity determination. Additionally, the BBM was used in a modified three-step in vitro assay to study the InsP6 degradation products. The results of both in vitro assays were not significantly affected by hen strain and diet. The activity of mucosal phosphatase in 19-week-old hens was, on average, 0.8 µmol Pi/g BBM protein/min lower than in 24-week-old hens (P < 0.002). Consistently, the InsP6 concentration in the incubation residue was significantly higher in 19-week-old hens than in 24-week-old hens (P < 0.001). In the incubation residue, the concentrations of Ins(1,2,3,4,5)P5, Ins(1,2,3,4,6)P5, and Ins(1,2,3,4)P4 were significantly lower (P ≤ 0.002), and those of InsP3 and InsP2 were significantly higher (P ≤ 0.027) when BBM of 24-week-old hens was used compared to 19-week-old hens. The InsP6 degradation products suggest the activity primarily of a 6- and secondarily of a 5-phytase in the duodenal mucosa. The consistent results from both in vitro assays provide a comprehensive characterization of these enzymes. Under the conditions of this study, small intestine calcium concentration appeared to influence mucosal enzyme activity more than dietary mineral P supplementation.
Expression of fibroblast growth factor 23 (FGF23) and αKlotho in two commercial laying hen strains fed with and without dietary mineral P supplements before and after the onset of the laying phase
(2025) Meier, Leonie; Wallauch, Nadine; Feger, Martina; Oster, Michael; Sommerfeld, Vera; Schmucker, Sonja; Wimmers, Klaus; Huber, Korinna; Stefanski, Volker; Rodehutscord, Markus; Föller, Michael
Maintenance of phosphate homeostasis is particularly critical in laying hens for bone formation and calcium mobilization. The supplementation of their feed with mineral phosphate is common although recent research questions the usual levels of supplementation. Phosphate homeostasis is classically regulated by active vitamin D (calcitriol) and parathyroid hormone, whereas fibroblast growth factor 23 (FGF23) and its co-receptor αKlotho are novel factors. FGF23 has emerged as an important disease biomarker and αKlotho as an anti-aging factor in mammals, however, little is known about their role in poultry. Here, we studied FGF23 and αKlotho expression in two commercial laying hen strains under conditions of dietary mineral phosphorus renunciation and sufficient phosphorus supply. Fifteen- and 20-week-old Lohmann Brown-Classic (LB) or LSL-Classic (LSL) hens were fed a standard maize-soybean-based diet containing 0 or 1 g/kg additional mineral phosphorus for 4 weeks. The animals were sacrificed, and gene expression studied in different organs by quantitative real-time PCR and protein expression by western blotting. Statistical correlation with further parameters of mineral metabolism was analyzed by Pearson’s correlation coefficient or Spearman’s Rho. As a result, FGF23 bone expression was significantly lower and hepatic FGF23 expression higher in 24-week-old than in 19-week-old hens. Bone, hepatic, and renal αKlotho expression was significantly higher in older than younger animals. Compared to LB hens, LSL hens exhibited higher hepatic αKlotho irrespective of diet and age. Dietary phosphorus content did not significantly affect FGF23 and αKlotho expression. Bone FGF23 expression was positively and hepatic FGF23 negatively associated with plasma phosphate concentration whereas bone FGF23 expression was negatively and hepatic FGF23 positively associated with plasma calcitriol concentration. To conclude, we uncovered a strong impact of age and strain on FGF23 and αKlotho expression in two high performance laying hen strains, effects possibly associated with initiation of the egg-laying phase. Moreover, the regulation of hepatic FGF23 expression differed from the regulation of bone FGF23 expression. Further studies are needed to elucidate the physiological relevance.

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