Research Projects

Stress, immune function and health: Projects in farm animals

The findings in the field of psychoneuroimmunology have greatly expanded our knowledge of the diverse and close interactions between environmental factors and the immune system. Today it is clear: the immune system not only reacts to pathogens, but also to other environmental factors such as light, nutrition and especially stressors. In contrast to model organisms, the effects of stress on the immune system in farm animals are still inadequately investigated. In particular, there is a lack of comprehensive studies using the latest immunological methodology. This is astonishing, because diseases lead to severe performance losses in production and have a negative impact on animal welfare.

In our studies, we deal with the effects of social stressors such as social instability or high housing density on the immune system in domestic pigs and poultry, as well as in partner projects in other species such as horses (Konstanze Krüger, Nürtingen). Our work makes an important contribution to basic research in order to better understand changes in the immune competence of farm animals. At the same time, our research contributes to animal welfare and more sustainable animal husbandry.

Stress-induced immune modulations and interactions of immune cells with bacteria (interkingdom signaling)

Despite the importance of pigs in livestock production and their increasing role as a model organism for human physiology, knowledge about the porcine immune system under the influence of stress hormones is fragmentary. Our projects aim to systematically investigate specific glucocorticoid and catecholamine actions on the porcine immune system in in vitro and in vivo studies. Our results so far indicate a substantial immuno-modulatory effect of stress hormones with many similarities to humans, thus strengthening the pig as an excellent human model in psychoneuroimmunology.

Interkingdom cross-talk in times of stress: In stressful situations, catecholamines modulate mammalian immune function. Moreover, they can be sensed by many bacteria. Catecholamine sensing was also found in the zoonotic gut pathogen Salmonella typhimurium, probably contributing to the stress-induced increased risk of salmonellosis. Virulence traits such as proliferation and invasiveness are promoted upon bacterial catecholamine sensing, but it is unknown whether pathogens inhibit mammalian immune function in stressful situations. These questions are addressed in close collaboration with Julia Fritz-Steuber (University of Hohenheim, Cellular Microbiology). Our project was the first to demonstrate that bacteria grown in the presence of catecholamine stress hormones alter their growth environment, probably by producing immunomodulating substances, in a way that the host immune response is suppressed. These findings add a new dimension to interkingdom signaling and provide novel clues to explain the increased susceptibility of a stressed host to Salmonella infection.

Projects funded by the DFG (project number 272280174)

Biological rhythms and immune function in the pig

In order to secure a balanced timing of organ functions, physiology and behavior of many species are controlled by circadian and annual rhythms. Notably, rhythmic variations are also found within the immune system leading to diurnal as well as seasonal variations in the number and functionality of blood leukocytes. These variations are likely to alter the immune competence of an organism and thus its susceptibility for diseases and might also have immunological consequences if interrupted. Knowledge about rhythmic variations in immune parameters is also of clinical relevance for defining optimal time points for vaccinations, drug intake, or the assessment of immune function in patients. Diurnal and seasonal rhythms are largely controlled by photoperiodic information. Most studies investigating photoperiodic influences on immune cells were conducted using nocturnal rodents. However, the course of main mediators of photoperiodic information differ between nocturnal and diurnal species, for which results using nocturnal animals can hardly be transferred to diurnal species.

In various studies, we thus aim at the characterization of diurnal and seasonal variations in the distribution and function of peripheral immune cells as well as underlying mechanisms in the pig (Sus scrofa domestica). The knowledge of photoperiodic factors potentially influencing immunocompetence of pigs bears high potential for management in pig husbandry systems to prevent infectious diseases in pig stocks and to improve animal welfare. In addition, as the pig is regarded as well-suited model system, the results of these studies will further elucidate photoperiodic influences on immune competence and consequences for disease susceptibility of diurnal organisms in general.

DFG funded project (project number 269213015)

Effects of dietary Ca/P supply on the immune system in two contrasting high-yielding laying hen strains

Phosphorus (P) and calcium (Ca) are essential nutrients for a functional and well-regulated immune system and are thus of utmost importance for animal health and welfare. The effects of dietary P and Ca supply on the immune system are poorly studied in poultry. Besides the pure availability, the form in which P is supplied also affects immune regulation. Recent evidence indicated a high potential of poultry to hydrolyze phytic acid with a large variation in phosphorus utilization. Laying hens differ from mammals, as their requirements of P and Ca drastically change during lifespan.

In our projects in collaboration with FOR2601, we investigate the effects of reduced dietary P and/or reduced dietary Ca on various immune traits in high-yielding and genetically diverse strains of laying hens. Present results show that dietary P and Ca supply, the onset of laying, and the genetic background affect the immune system in both strains. Diets with a reduced P content had an increasing effect on the number of innate and adaptive immune cells as well as on the antibody concentration in Brown (LB) and White (LSL) Leghorn hybrids, the effects being stronger in LB hens. Despite a similarly high laying performance, both lines differed significantly in their immunological properties. The LSL hybrids show a more pronounced adaptive phenotype, the LB hybrids a more pronounced innate immunological phenotype. Both hen lines maintain high egg productivity apparently by different physiological mechanisms.

Qualitative and quantitative aspects of male pig production with immunocastrates

Around 75% of male piglets in the EU are surgically castrated, although key stakeholders have committed to banning this practice by 2018. Castration is used to prevent the so-called boar taint in male pigs, which can develop after puberty. Piglet castration is painful and poses an animal welfare problem. The use of anesthesia during castration also has disadvantages and violates the principle of physical integrity. For a certain time, boar fattening was seen as the best alternative, but there are still problems with animal welfare (aggressive behavior, penis injuries of the boars) and meat quality (carcasses contaminated with odors) and a reduced processing quality (too little fat and too high a proportion of polyunsaturated fatty acids). Many of these problems can be avoided by immunocastration.

In an ERA-NET project (Sustainability in Pork Production with Immunocastration - SuSI) we aim to optimize immune castration as an alternative to surgical castration and boar fattening, with potential economic and ecological advantages. Seven international partners are involved in the project.

The current results from SuSI clearly show that immunocastration has considerable advantages in terms of animal welfare, but also ecological advantages compared to castrated animals. The meat quality of immunocastrates is good. Immune castration also has potential economic benefits if it gains market acceptance.

Overall, the current results from SuSI already offer optimized knowledge about immune castration to support the pork industry, farmers and government authorities in their decision-making processes for consumer-acceptable pork production across the EU and to improve sustainability in pork production

Animal welfare: Improving experimental approaches to assessing housing conditions and welfare in livestock

The question of how and to what extent social and non-social environmental factors can influence the behavior and physiology of animals is one of the central research questions in behavioral physiology. The design of the housing environment or the interactions of group members can affect animal welfare and ultimately also the health of farm animals significantly. However, there is still insufficient research into which elements of the husbandry environment are of particular importance for animal welfare.

In various projects, we are therefore investigating the influences of animal-welfare-relevant husbandry and management factors on behavior as well as on the hormonal and immune systems. The results of our research can also be used to make a substantial contribution to objectifying the discussion about animal welfare in farm animals.

Innovative approaches in pork production with entire males (COST)

(Funding Reference Number: CA15215)

Project Homepage

Project Duration: November 2016 to October 2020

Departments Involved: Fg. Verhaltensphysiologie von Nutztieren

Persons Involved: apl. Prof. Dr. Ulrike Weiler, Dr. Katharina Hölzle

Short Description: COST: European Cooperation in Science and Technology

Influence of stocking density on the immune system of laying hens with particular attention to the gut-associated immune system

(Funding Reference Number: HOH 44/17 TH)

Project Duration: 31.12.2019 - 31.1.2020

Departments Involved: Institute of Animal Science (460f), Department of of Livestock Population Genomics (460h), Department of Behavioral Physiology of Livestock (460f)

Researchers Involved: apl. Prof. Dr. sc. agr. habil. Michael A. Grashorn, Dr. rer. nat. Sonja Schmucker, M.Sc. Tanja Hofmann, Prof. Dr. Volker Stefanski