Browsing by Person "Sommerfeld, Vera"

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    Dietary phosphorus and calcium in feed affects miRNA profiles and their mRNA targets in jejunum of two strains of laying hens
    (2021) Iqbal, Muhammad Arsalan; Ali, Asghar; Hadlich, Frieder; Oster, Michael; Reyer, Henry; Trakooljul, Nares; Sommerfeld, Vera; Rodehutscord, Markus; Wimmers, Klaus; Ponsuksili, Siriluck
    Phosphorus (P) and calcium (Ca) are critical for egg production in laying hens. Most of P in plant-based poultry diet is bound as phytic acid and needs to be hydrolysed before absorption. To increase P bioavailability, exogenous phytases or bioavailable rock phosphate is added in feed. There is growing evidence of the importance of miRNAs as the epicentre of intestinal homeostasis and functional properties. Therefore, we demonstrated the expression of miRNA profiles and the corresponding target genes due to the different levels of P (recommended vs. 20% reduction) and/or Ca (recommended vs. 15% reduction) in feed. Jejunal miRNA profiles of Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) laying hens strains were used (n = 80). A total of 34 and 76 miRNAs were differentially expressed (DE) in the different diet groups within LSL and LB strains respectively. In LSL, the DE miRNAs and their targets were involved in calcium signaling pathway, inositol phosphate metabolism, and mitochondrial dysfunction. Similarly, in LB miRNAs targets were enriched in metabolic pathways such as glutathione metabolism, phosphonate metabolism and vitamin B6 metabolism. Our results suggest that both strains employ different intrinsic strategies to cope with modulated P and Ca supply and maintain mineral homeostasis.
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    In vivo and in vitro studies of degradation of inositol phosphates in the digestive tract of broiler chickens
    (2017) Sommerfeld, Vera; Rodehutscord, Markus
    Phosphorus (P) is an important element in poultry nutrition, which must be adequately supplied in the diet. However, for non-ruminant animals, it is only partially available from plant seeds—the major components of poultry diets—where P is predominantly bound as phytic acid (myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate); InsP6) and its salts, called phytate. InsP6-P can be utilized after the stepwise cleavage of the P from the phytate molecule by phytases and other phosphatases. After the theoretical complete dephosphorylation of InsP6, six phosphate groups and myo-inositol (MI) are potentially available for absorption. Recent studies assume an effect of MI on growth performance when it is added in its free form to the diet or released as a result of InsP6 breakdown. Because P is of specific economic and environmental relevance, the improvement of the digestibility of plant P in poultry is of great interest. The overarching aim of this thesis was therefore to gain a deeper insight into the degradation of InsPs in the digestive tract of broiler chickens, with a focus on the intermediate and end-products as influenced by the diet composition. An in vitro assay was established to study the disappearance of InsP6 and the formation of lower inositol phosphate (InsP) isomers in the poultry digestive tract. The assay simulates the conditions (pH, temperature, proteolytic enzymes, water content, and retention time) of the crop, stomach, and small intestine, using a poultry diet as matrix. The assay yielded highly reproducible results and was sensitive to the factors that varied in the three experiments. A diminishing effect on InsP degradation was found by the supplementation of P and Ca. The described assay is a suitable tool that can be used to screen feed enzymes and to investigate the effects of supplements in the absence of endogenous phytases. The first in vivo experiment aimed to distinguish between the single and interactive effects of P, calcium (Ca), and phytase. Effects on lower InsP esters and their isomers and MI in different segments of the digestive tract, and on the prececal digestibility of P, Ca, and amino acids (AAs) in broiler chickens were studied. Moreover, a complete picture was drawn of all dephosphorylation steps from InsP6 to MI in the digesta of the terminal ileum. The dietary treatments included diets without (P-) or with (P+) monosodium phosphate supplementation, without (Ca-) or with (Ca+) additional limestone supplementation, and without or with 1500 FTU phytase/kg feed. Up to the terminal ileum, InsP6 disappearance was found to decrease in P+Ca-, and even more so in P+Ca+, when no phytase was added. Adding phytase removed all effects of P and Ca. However, P+Ca+ increased the concentrations of lower InsP esters and reduced free MI in the ileum, even in the presence of phytase. Supplementation with phytase increased the concentration of MI in all segments of the digestive tract and in blood plasma, demonstrating the ability of broilers to fully degrade phytate and absorb the released MI. While the prececal AA digestibility was not affected by P and Ca or an interaction between P, Ca, and phytase, it increased with the addition of phytase. The objective of the second in vivo experiment was to investigate the effects of supplementation with free MI or graded levels of phytase on InsP degradation, concentrations of MI in the digestive tract and blood, bone mineralization, and prececal digestibility of AA. Birds were fed a control diet with adequate levels of all nutrients without or with MI supplementation, or one of three experimental diets that differed in phytase level, with reduced P and Ca levels. These outcomes indicate that MI might have been a relevant cause for the increase in gain:feed. Therefore, it is likely that the release of MI after complete dephosphorylation of phytate is one of the beneficial effects of phytase, along with the release of P and improvement in digestibility of other nutrients. It can be concluded that the established in vitro assay is a suitable tool to investigate effects on feed enzymes or differences between different feed enzymes in a feed matrix under standardized conditions without the interference of endogenous phytases, or depending on animal-specific variations. Based on the outcome of the in vitro and in vivo experiments of the present project, the combined supplementation of P and Ca—rather than supplementation of P or Ca solely—seems to be crucial for InsP degradation. There is now some evidence that MI can affect the growth and feed efficiency of broiler chickens without affecting the metabolism of InsPs or AAs. As the results regarding the effects of P and Ca on InsP6 degradation or phytase effects on AA digestibility are not consistent across studies, and studies investigating the effects of MI are scarce and not consistent, further systematic research is needed.
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    Multi-omics reveals different strategies in the immune and metabolic systems of high-yielding strains of laying hens
    (2022) Iqbal, Muhammad Arsalan; Reyer, Henry; Oster, Michael; Hadlich, Frieder; Trakooljul, Nares; Perdomo-Sabogal, Alvaro; Schmucker, Sonja; Stefanski, Volker; Roth, Christoph; Camarinha Silva, Amélia; Huber, Korinna; Sommerfeld, Vera; Rodehutscord, Markus; Wimmers, Klaus; Ponsuksili, Siriluck
    Lohmann Brown (LB) and Lohmann Selected Leghorn (LSL) are two commercially important laying hen strains due to their high egg production and excellent commercial suitability. The present study integrated multiple data sets along the genotype-phenotype map to better understand how the genetic background of the two strains influences their molecular pathways. In total, 71 individuals were analyzed (LB, n = 36; LSL, n = 35). Data sets include gut miRNA and mRNA transcriptome data, microbiota composition, immune cells, inositol phosphate metabolites, minerals, and hormones from different organs of the two hen strains. All complex data sets were pre-processed, normalized, and compatible with the mixOmics platform. The most discriminant features between two laying strains included 20 miRNAs, 20 mRNAs, 16 immune cells, 10 microbes, 11 phenotypic traits, and 16 metabolites. The expression of specific miRNAs and the abundance of immune cell types were related to the enrichment of immune pathways in the LSL strain. In contrast, more microbial taxa specific to the LB strain were identified, and the abundance of certain microbes strongly correlated with host gut transcripts enriched in immunological and metabolic pathways. Our findings indicate that both strains employ distinct inherent strategies to acquire and maintain their immune and metabolic systems under high-performance conditions. In addition, the study provides a new perspective on a view of the functional biodiversity that emerges during strain selection and contributes to the understanding of the role of host–gut interaction, including immune phenotype, microbiota, gut transcriptome, and metabolome.