• Prof. Dr. Stefan Wittkopf

Professur für Holzenergie

Wir unterstützen die Lehre in den Studiengängen Management Erneuerbarer Energien und Forstingenieurwesen an der Hochschule Weihenstephan-Triesdorf und sind im dynamischen Sektor Holzenergie forschend tätig.

Mit dem Ziel der Weiterentwicklung von Lehre und Forschung arbeiten wir im Rahmen von Bachelorarbeiten, Forschungsprojekten und Lehrveranstaltungen mit verschiedenen Unternehmen und öffentlichen Einrichtungen zusammen. Hier eine Auswahl der bisherigen Kooperationspartner:

Leitung

Forschungsthemen

Forschungsprojekte

Publikationen

  • M.Sc. Andreas Niedermeier, Christian Mergel, Dr. Agnes Emberger-Klein, Prof. Dr. Klaus Menrad

    • Berechtigungen:  Open Access
    • Berechtigungen:  Peer Reviewed

    A predictive model approach to forecast consumers’ cluster membership in the green fast moving consumer goods sector (2024) DOI: 10.1016/j.bioeco.2024.100064

    Predictive models are increasingly crucial in navigating heterogeneous markets. This study develops a predictive model approach to forecast consumer cluster membership in the green fast-moving consumer goods sector, focusing on bio-based products like adhesives and plasters. Through two online surveys in Germany, we identified key factors acting as drivers and barriers, demonstrating their effectiveness in distinguishing similar consumer segments across both product categories. Utilizing multinomial logistic regression, we crafted a prediction model that accurately forecasts cluster membership, providing novel insights into consumer behavior towards non-food bio-based products. This facilitates the development of targeted business and marketing strategies, optimizing resource allocation in market research activities. Our findings offer significant contributions to understanding the dynamics influencing consumer choices in the bio-based product market.
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  • Prof. Dr. Jörg Ewald, Herbert Formayer, Josef Gadermaier, Tobias Huber, Klaus Katzensteiner, David Kessler, Michael Kessler, Ralf Klosterhuber, Roland Köck, F. Lehner, Manfred Lexer, Dr. Alois Simon, Gerfried Winkler, Markus Wilhelmy, Prof. Dr. Harald Vacik, Klaus Klebinder, Michael Englisch

    • Berechtigungen:  Peer Reviewed

    Supporting the management of protection forests in a changing climate (2024) 15th Congress INTERPRAEVENT 2024, June 10th - 13th .

  • Dr. Lea Lorenz, Prof. Dr. Armin Scholz, Dr. Christine Schmidt, Dipl.-Ing.(FH) Mirjam Lechner, Prof. Dr. Prisca Kremer-Rücker

    • Berechtigungen:  Peer Reviewed

    The potential of the tail tip as animal health indicator in dairy cows (2024) Proceedings of the 32nd World Buiatrics Congress 2024, Cancun, Mexico .

    Objectives Tail tip inflammation and necrosis is a well-recognised condition in several species that can have a significant impact on overall health. Fattening cattle, bulls and calves have often been prone to severe tail tip problems, often related to their housing conditions or environmental factors. In addition, a high frequency of tail tip lesions has recently been observed in dairy cattle. Tail tip changes have also been studied in pigs in relation to the newly defined Swine Inflammation and Necrosis Syndrome (SINS). Pathological changes including inflammation and necrosis of ears, teats, claws and tails have been observed in pigs as a result of systemic inflammation and reduced blood flow to the acra. This raised the question of whether changes in the tip of the tail were also associated with other health indicators in dairy cows. The aim of this study was therefore to investigate whether there is a correlation between changes in the tail tip, its temperature measured by thermography, and performance and health traits in Holstein Friesian dairy cows. Material and methods The study was conducted on a commercial dairy farm in Germany between May 2021 and June 2022. Every 14 days groups of 19-43 cows were examined. A total of n=530 observations from 351 different Holstein cows (lactation = 1 - 6) were analysed during the study period. Cows were examined at 150 days post partum and/or just before drying off. Data collection included examination of the tail tip for tail tip lesions (TT), annular lesions (AN), hyperkeratosis (HK), swelling (SW) and axis deviation (AD); pain sensation at the tail tips, body condition score (BCS) of the cow, the locomotion score (LMS) and the somatic cell count obtained from a current California Mastitis Test (CMT). Rectal temperature (BT) was measured and cows were clinically examined with particular attention to ruminal filling (Rumfill) and intensity of contractions (Rumint). In addition, a thermographic image of each tail tip was taken to record the maximum (TempMax), minimum (TempMin) and average temperature (TempAve) of the tail tip. The claws were trimmed and the diagnoses were converted to a claw score (SumClaw). Data from the milk performance testing as milk solids (MS), protein % (MP), fat % (MF) and somatic cell score (SCS) were also included in the statistical analysis. Cluster analysis using SAS version 9.4 was performed to identify possible patterns among the variables and resulted in 4 clusters. Results The highest coefficient of determination, i.e. the greatest effect on clustering, was SumClaw (R2=0.68), followed by TempAve (R2=0.63), TempMin (R2=0.60), TempMax (R2=0.55) and CMT values by quarter (R2=0.26-0.47). The first cluster stood out with the worst values for CMT and SCS. MP and MF were high due to low MS. Meanwhile, AN, HK and BCS were highest. Rumen values were above average, as were tail tip temperature and the LMS, but SumClaw was low. The cluster with the highest SumClaw also had the worst LMS, the lowest values for Rumfill and Rumint, and the highest values for TT, SW, AD and PS. Tail temperatures were well above average. Milk yield was low and udder health was the second worst of all groups. The cluster with the highest MS, and therefore lowest MF and MP, also showed lowest CMT and SCS. Tail alterations were below average, except for HK. In this group, tail tip temperatures were highest and so were Rumfill and Rumint. For the last cluster, the coldest tail tip temperatures were outstanding in contrast to the highest BT. TT, SW, AD were the second highest, while AN and HK were the lowest. In addition, Sumclaw, LMS and Rumfill and Rumint had low values. Conclusions An important finding was that SumClaw and tail tip temperatures strongly influenced cluster categorisation, both of which could have a significant impact on animal health. Furthermore, in cases of udder and claw issues, the tail tips presented the most severe alterations and the lowest temperatures. The tail tips of cows with good performance and minimal health issues remained warm and unaltered. Therefore, the results of this study indicate a correlation between the tail tip and different animal health traits that requires further investigation.FundingParts of this research were funded by the Tönnies Forschung, Rheda, Germany.
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  • Prof. Dr. Prisca Kremer-Rücker, Kim F. Schubert, Dr. Lea Lorenz, Dr. Saskia Meier, Dipl.-Ing.(FH) Mirjam Lechner

    • Berechtigungen:  Peer Reviewed

    First insights into possible risk factors for tail tip lesions in dairy cows (2024) Proceedings of the 32nd World Buiatrics Congress 2024, Cancun, Mexico .

    Objectives Although inflammation and necrosis of the tail tip has been a well-known problem in fattening cattle for several decades, the etiology of the disease is not fully understood, yet. While some authors hold husbandry conditions such as limited space allotment or slatted concrete floors responsible for the occurrence of tail lesions, other studies point towards a connection with rumen acidosis. Furthermore, tail necrosis has also been described in the context of mycotoxin intake, which leads to vasoconstriction, finally resulting in ischemia. In dairy cows, we observed lesions of the tail, which resemble those described in housed fattening cattle, although husbandry conditions of dairy cows differ from those of fattening cattle. In order to identify possible risk factors, the aim of this study was to investigate whether there are associations between the occurrence of tail tip lesions and selected health and performance parameters in dairy cows. Material and methods For this purpose, we monitored the course of the lesions over 10 months in a German dairy herd consistig of 1,300 cows. The cows were housed on slatted rubber floor in a loose housing system. The cubicles either contained straw manure bedding or were covered with waterbed mattresses. Manure was removed by an automatic scraper system. N = 213 cows that calved within a predetermined period of 2 months were selected for the study to ensure that all cows were at a similar stage of lactation. Number of lactation varied between cows, ranging from one to seven. The sample consisted of 89% Holstein Friesian cows, 10% crossbreds and 1% Brown Swiss cows. Examinations took place at every milk performance testing, starting after calving. One single person assessed tail tip lesions, locomotion score and body condition score of the cows. Number of lactation, days in milk, and data from milk performance testing including milk yield, milk fat:protein ratio and somatic cell count were used for further analysis. The frequencies of the individual tail lesions were calculated by dividing the number of each lesion by the number of all observed lesions. Data were processed using Rstudio version 2021.09.2. Chi2-test and a mixed model procedure were performed for statistical analysis of possible risk factors for the different lesions. Results Over the course of the examination period, every cow was affected by one or several lesions at least once. The examination of n = 213 cows resulted in 4,123 observations. We were able to observe all of the previously described lesions, with varying frequencies, namely: lesions at the very tip of the tail: 8.2 %, annular lesions: 8.5 %, hyperkeratosis: 52.0 %, swelling: 10.7 %, axis deviation: 9.2 %, thinning: 0.2 % and fibroma: 3.7 %. The frequency of tails without any visible lesion was 7.5 %. Regarding the results of the Chi2-test, with the exception of the somatic cell count, all parameters included in this study had a significant influence on at least one lesion. Days in milk significantly influenced all lesions (p < 0.01 or p < 0.001) except of thinnings of the tail. Lactation number had a significant impact on the occurrence of hyperkeratosis (p < 0.05), swellings (p < 0.001), axis deviations (p < 0.01) and fibromas (p < 0.001). Hyperkeratosis and axis deviations were furthermore influenced by milk yield (p < 0.05 and p < 0.001, respectively). Milk fat:protein ratio had a significant impact on hyperkeratosis (p < 0.05) and thinning (p < 0.001). Locomotion score significantly influenced annular lesions (p < 0.05) and axis deviations (p < 0.05), whereas body condition score had a significant impact on the occurrence of swellings (p < 0.001). Conclusions Our results demonstrate that there are multiple associations between tail tip lesions and different health- and performance parameters such as milk yield, locomotion score and body condition score. Based on our results, we conclude that the formation and development of tail tip lesions is a complex, presumably multi-factorial process. Further research is required to examine the individual risk factors in more detail.FundingParts of this research were funded by the Tönnies Forschung, Rheda, Germany.
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  • Dr. Lea Lorenz, Marielle Volkwein, Dr. Christine Schmidt, Dipl.-Ing.(FH) Mirjam Lechner, Prof. Dr. Prisca Kremer-Rücker

    • Berechtigungen:  Peer Reviewed

    Tail tip lesions in dairy cows – a look on the inside (2024) Proceedings of the 32nd World Buiatrics Congress 2024, Cancun, Mexico .

    Objectives In our previous work, we observed a variety of tail tip lesions in dairy cows, which we classified into 7 different clusters. Prevalences of severe lesions such as bleeding or necrotic tail tips reached up to 26 %. These results might indicate that we are dealing with an animal health and welfare issue that has gone unnoticed by now. In fattening cattle, histopathological examination of affected tails led to the presumption that the observed lesions might be caused by cutaneous ischemia. The objective of this study was therefore to find out which histopathological changes underlie the different tail tip lesions in dairy cows in order to contribute to a better understanding of this malady. Material and methods We collected 16 tails of dairy cows of different breeds (Holstein Friesian, Simmental, Brown Swiss and crossbreeds between beef- and dairy breeds) at a slaughterhouse in South Germany after slaughtering. The tail tips were selected to cover all types of macroscopically visible lesions that we have observed in previous studies. Selected samples originated from cows aged two to ten years. After collecting, the tails were packed on ice during the one hour transport. Immediately after arrival, tail tips were shorn, washed, photo documented and examined macroscopically. For histopathological examination, observed lesions were fixed in 10 % buffered formalin for at least four days. Subsequently, all samples were embedded in paraffin, processed routinely for histologic examination, and stained with hematoxylin and eosin (H&E). Selected sections were also stained with periodic acid Schiff reaction (PAS) or Masson-Goldner trichrome for examination of connective tissue. The slides were examined using light microscopy. Results In all cases of macroscopically visible constrictions as well as in hairless areas of the tail tips we found dermal granulation tissue of different age stages that extended to the central longitudinally arranged connective tissue of the tail. In six out of ten tail tips with macroscopically visible annular constrictions, the epidermis was without any particular finding. In the other four cases, we found inflammation of the epidermis with underlying cell-rich granulation tissue. The epidermis of samples showing alopecic tail tips was either free from pathological findings or showed signs of orthokeratotic hyperkeratosis. In tail tips macroscpically exhibiting hyperkeratosis, we observed predominantly orthokeratotic and partly also parakeratotic hyperkeratosis. In one macroscopically unremarkable tail, histological examination also revealed hyperkeratosis. Tail tips with macroscopically visible swelling of the central longitudinal connective tissue were histologically characterized by extracellular and low protein edema. Intracellular edema could be observed in the marginal areas of constrictions with bloody encrustations and in hairless areas. In tail tips which showed macroscopically visible thinning, all layers of the tail were reduced in thickness. Only in one tail tip, we found a concrete thinning of the dermis on only one side of the tail distal to a constriction. Another frequent histopathological finding was the partly focal, partly diffuse hyperemia of the papillary bodies in the dermis, which was found in ten samples. We observed hyperemia in areas affected by hyperkeratosis and in annular constrictions, but also in macroscopically unconspicuous tail tips, in hairless areas and in tail tips showing hyperkeratosis or necrosis. In some cases, the hyperemia was accompanied by free erythrocytes, whereas no accumulation of inflammatory cells could be detected in these areas. Conclusions Our histopathological examination of tail tip lesions in dairy cows revealed amongst others granulation tissue formation, ortho- and parakeratotic hyperkeratosis and hyperemia of the papillary bodies with free erythrocytes. These results resemble those found in fattening cattle. Based on the macroscopical and histological appearance of the lesions, trauma as the sole cause seems unlikely. Future research is required to clarify the underlying etiology and to determine risk factors associated with the observed lesions.FundingParts of this research were funded by the Tönnies Forschung, Rheda, Germany.
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