Institut für Nutztierwissenschaften

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Central carbon metabolism, sodium-motive electron ransfer, and ammonium formation by the vaginal pathogen Prevotella bivia
(2021) Schleicher, Lena; Herdan, Sebastian; Fritz, Günter; Trautmann, Andrej; Seifert, Jana; Steuber, Julia
Replacement of the Lactobacillus dominated vaginal microbiome by a mixed bacterial population including Prevotella bivia is associated with bacterial vaginosis (BV). To understand the impact of P. bivia on this microbiome, its growth requirements and mode of energy production were studied. Anoxic growth with glucose depended on CO2 and resulted in succinate formation, indicating phosphoenolpyruvate carboxylation and fumarate reduction as critical steps. The reductive branch of fermentation relied on two highly active, membrane-bound enzymes, namely the quinol:fumarate reductase (QFR) and Na+-translocating NADH:quinone oxidoreductase (NQR). Both enzymes were characterized by activity measurements, in-gel fluorography, and VIS difference spectroscopy, and the Na+-dependent build-up of a transmembrane voltage was demonstrated. NQR is a potential drug target for BV treatment since it is neither found in humans nor in Lactobacillus. In P. bivia, the highly active enzymes L-asparaginase and aspartate ammonia lyase catalyze the conversion of asparagine to the electron acceptor fumarate. However, the by-product ammonium is highly toxic. It has been proposed that P. bivia depends on ammonium-utilizing Gardnerella vaginalis, another typical pathogen associated with BV, and provides key nutrients to it. The product pattern of P. bivia growing on glucose in the presence of mixed amino acids substantiates this notion.
Feed clusters according to In Situ and In Vitro ruminal crude protein degradation
(2023) Okon, Paul; Bachmann, Martin; Wensch-Dorendorf, Monika; Titze, Natascha; Rodehutscord, Markus; Rupp, Christiane; Susenbeth, Andreas; Greef, Jörg Michael; Zeyner, Annette
Effective degradation (ED) of crude protein (CP) was estimated in vitro at 0.02, 0.05 and 0.08 h−1 assumed ruminal passage rates for a total of 40 feedstuffs, for which in situ ED was available and used as reference degradation values. For this, the Streptomyces griseus protease test was used. The differences between in vitro CP degradation and the in situ CP degradation values were lowest in legume grains and highest in cereal by-products and barley. The differences between in situ and in vitro ED were expressed using a degradation quotient (degQ), where degQ = (EDin vitro − EDin situ)/EDin situ. Among the tested feedstuffs, eight specific clusters were identified according to degQ for the assumed passage rates. The feedstuffs clustered in an unspecific way, i.e., feedstuffs of different nutrient composition, origin or treatment did not necessarily group together. Formaldehyde–treated rapeseed meal, soybean meal, wheat, a treated lupin, sunflower meal and barley could not be assigned to any of the clusters. Groupwise degradation (range of degQ for assumed passage rates are given in brackets) was detected in grass silages (−0.17, −0.11), cereal by-products together with sugar beet pulp (−0.47, −0.35) and partly in legume grains (−0.14, 0.14). The clustering probably based on different specific nutrient composition and matrix effects that influence the solubility of feed protein and limit the performance of the protease. The matrix can be affected by treatment (chemically, thermally or mechanically), changing the chemical and physical structure of the protein within the plant. The S. griseus protease test had reliable sensitivity to reflect differences between native feedstuffs and treatments (thermally or chemically) that were found in situ. The in situ results, however, are mostly underestimated. The clustering results do not allow a clear conclusion on the groupwise or feed-specific use of carbohydrate-degrading enzymes as pre- or co-inoculants as part of the S. griseus protease test and need to be tested for its potential to make this test more conform with in situ data.
Bi-objective optimization of nutrient intake and performance of broiler chickens using Gaussian process regression and genetic algorithm
(2023) Ahmadi, Hamed; Rodehutscord, Markus; Siegert, Wolfgang
This study investigated whether quantifying the trade-off between the maxima of two response traits increases the accuracy of diet formulation. To achieve this, average daily weight gain (ADG) and gain:feed ratio (G:F) responses of 7–21-day-old broiler chickens to the dietary supply of three nutrients (intake of digestible glycine equivalents, digestible threonine, and total choline) were modeled using a newly developed hybrid machine learning-based method of Gaussian process regression and genetic algorithm. The dataset comprised 90 data lines. Model-fit-criteria indicated a high model adjustment and no prediction bias of the models. The bi-objective optimization scenarios through Pareto front revealed the trade-off between maximized ADG and maximized G:F and provided information on the needed input of the three nutrients that interact with each other to achieve the trade-off scenarios. The trade-off scenarios followed a nonlinear pattern. This indicated that choosing target values intermediate to maximized ADG and G:F after single-objective optimization is less accurate than feed formulation after quantifying the trade-off. In conclusion, knowledge of the trade-off between maximized ADG and maximized G:F and the needed nutrient inputs will help feed formulators to optimize their feed with a more holistic approach.
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.
Dynamic development of viral and bacterial diversity during grass silage preservation
(2023) Sáenz, Johan S.; Rios-Galicia, Bibiana; Rehkugler, Bianca; Seifert, Jana
Ensilaging is one of the most common feed preservation processes using lactic acid bacteria to stabilize feed and save feed quality. The silage bacterial community is well known but the role of the virome and its relationship with the bacterial community is scarce. In the present study, metagenomics and amplicon sequencing were used to describe the composition of the bacterial and viral community during a 40-day grass silage preservation. During the first two days, we observed a rapid decrease in the pH and a shift in the bacterial and viral composition. The diversity of the dominant virus operational taxonomic units (vOTUs) decreased throughout the preservation. The changes in the bacterial community resembled the predicted putative host of the recovered vOTUs during each sampling time. Only 10% of the total recovered vOTUs clustered with a reference genome. Different antiviral defense mechanisms were found across the recovered metagenome-assembled genomes (MAGs); however, only a history of bacteriophage infection with Lentilactobacillus and Levilactobacillus was observed. In addition, vOTUs harbored potential auxiliary metabolic genes related to carbohydrate metabolism, organic nitrogen, stress tolerance, and transport. Our data suggest that vOTUs are enriched during grass silage preservation, and they could have a role in the establishment of the bacterial community.
Reduced parasite burden in feral honeybee colonies
(2023) Kohl, Patrick L.; D'Alvise, Paul; Rutschmann, Benjamin; Roth, Sebastian; Remter, Felix; Steffan‐Dewenter, Ingolf; Hasselmann, Martin
Bee parasites are the main threat to apiculture and since many parasite taxa can spill over from honeybees (Apis mellifera) to other bee species, honeybee disease management is important for pollinator conservation in general. It is unknown whether honeybees that escaped from apiaries (i.e. feral colonies) benefit from natural parasite‐reducing mechanisms like swarming or suffer from high parasite pressure due to the lack of medical treatment. In the latter case, they could function as parasite reservoirs and pose a risk to the health of managed honeybees (spillback) and wild bees (spillover). We compared the occurrence of 18 microparasites among managed (N = 74) and feral (N = 64) honeybee colony samples from four regions in Germany using qPCR. We distinguished five colony types representing differences in colony age and management histories, two variables potentially modulating parasite prevalence. Besides strong regional variation in parasite communities, parasite burden was consistently lower in feral than in managed colonies. The overall number of detected parasite taxa per colony was 15% lower and Trypanosomatidae, chronic bee paralysis virus, and deformed wing viruses A and B were less prevalent and abundant in feral colonies than in managed colonies. Parasite burden was lowest in newly founded feral colonies, intermediate in overwintered feral colonies and managed nucleus colonies, and highest in overwintered managed colonies and hived swarms. Our study confirms the hypothesis that the natural mode of colony reproduction and dispersal by swarming temporally reduces parasite pressure in honeybees. We conclude that feral colonies are unlikely to contribute significantly to the spread of bee diseases. There is no conflict between the conservation of wild‐living honeybees and the management of diseases in apiculture.
Detailed genomic analysis of correlation and causality between milk production and health traits in German Holstein cattle using high-dimensional genomic data and novel statistical methods
(2024) Schneider, Helen Hiam; Bennewitz, Jörn
Adverse side effects of high milk production on animal health have been mentioned frequently. They are compromising animal welfare, the farmers` economy, and the ecological footprint as well as the social acceptance of milk production. Consequently, many countries started to include functional traits into their breeding goal a few decades ago. The intention is thereby to avoid putative undesirable side effects of high production and to improve the cows` health in the long term through genetic gain. Indeed, positive genetic trends for various functional and health traits have been described in the literature. At the same time, the genetic trend of milk production traits remained positive. In general, sustainable genetic gain requires an appropriate weight of the individual traits in the selection index and a comprehensive understanding of the traits` genetic architecture and their interrelationship. This can be facilitated by recent innovations that enable the widespread availability of whole genome sequence (WGS) data. WGS data contains genomic information about millions of SNPs, derived either from sequencing or from imputing lower density SNP chip data to sequence level. Using external information about these sequence variants in genomic analyses, e.g., concerning their function during transcription and translation, has been shown to reveal additional knowledge about biological and molecular mechanisms shaping complex traits. Hence, applying external information to estimate genetic correlations might help to dissect the traits` interrelationship in more detail. Additionally, going beyond global genetic correlations, this is, reflecting the shared genetic effect throughout the genome, to the local scale, this is, the genetic sharing in specific genomic regions, would be an alternative to provide novel knowledge about the extent and direction of the shared genetic effect and its localization in the genome. The expected information is desired to understand and to avoid potential detrimental effects of selection decisions on animal health. Moreover, moving away from correlation towards causation would enable to predict the impact of management decisions and external interventions. The aim of this thesis was to scrutinize the genetic connection between health and milk production traits in dairy cattle using a large sample of 34,497 German Holstein cows with pedigree, 50K SNP chip, and imputed WGS data consisting of ~17 million variants. To this end, standard quantitative genetic analyses were augmented by a set of novel approaches to detect genomic regions with a substantial genetic effect on several traits and to investigate causal associations. Chapter one applied the 50K chip data to estimate additive genetic and dominance variance components for the milk production and health traits. This was done since substantial nonadditive genetic effects for functional traits have been mentioned in the literature, whereas little is known about these effects for the health traits examined in this thesis. It was demonstrated that the contribution of the dominance variance to the phenotypic variance was rather small for all traits. However, regarding the health traits, the contribution of the dominance variance to the genetic variance was almost as high as, and sometimes even higher than the contribution of the additive genetic variance. In addition, significant inbreeding depression was found for the milk production traits. Chapter two consisted of three steps. First, pedigree-based heritabilities of and global genetic correlations between milk production and health traits were estimated. Most heritabilities of the health traits and their genetic correlations with the milk production traits were low, whereby the genetic correlations were in an unfavorable direction. Next, genome-wide association studies (GWAS) were performed for each trait utilizing the 50K chip data to generate summary statistics. The summary statistics are required as input data for the last step that applied a tool to detect shared genomic regions. Genomic regions simultaneously affecting milk production and health traits were identified for each trait combination, of which some also had a sign in the favorable direction. This chapter confirmed the advantage of scrutinizing global genetic correlations down to the local scale. Chapter three utilized the 50K chip as well as the imputed WGS data. The latter was thereby divided into 27 subsets depending on the variants` functional and evolutionary annotation, e.g., as gene expression quantitative trait loci or selection signature. Heritabilities of and genetic correlations between milk yield and several health traits were estimated for the 50K chip and each of the 27 subsets. The results indicate that the 50K chip appears to be sufficient to explain the genetic variance of the investigated traits, whereas it seems to underestimate their genetic covariance. Furthermore, the importance of alternative splicing for the (co-)variation of quantitative traits and the important role of the negative energy balance causing the unfavorable side effects of high production on animal health has been confirmed. Chapter four was a Mendelian randomization (MR) analysis. Here, the causal effect of milk yield on a set of health traits was examined using a method that is based on summary statistics. In this chapter, the summary statistics were generated using the imputed WGS data. Unfavorable causal effects of milk yield on most health traits were identified that were strongest for mastitis and digital phlegmon. This indicates potential detrimental consequences for these traits with increasing milk yields, owed to selection decisions or inappropriately chosen weights in the selection index. The general discussion is addressing the negative side effects of high production on animal health with special focus on the negative energy balance. Moreover, including feed efficiency and resilience indicator traits into the breeding goal is discussed with respect to the results reported in the previous chapters. Besides, additional information about the methodology of MR analyses and the results of a MR analysis investigating the causal effect of protein and fat yield on the health traits are presented and debated. The general discussion ends with practical implications of the results regarding hologenomic selection strategies and strategies including functional information in genomic prediction.
Dietary L-carnitine supplementation modifies blood parameters of mid-lactating dairy cows during standardized lipopolysaccharide-induced inflammation
(2024) Seemann, Leonie; Frahm, Jana; Kersten, Susanne; Bühler, Susanne; Meyer, Ulrich; Visscher, Christian; Huber, Korinna; Dänicke, Sven
L-carnitine, available as feed additive, is essential for the beta-oxidation of free fatty acids in the mitochondrial matrix. It provides energy to immune cells and may positively impact the functionality of leukocytes during the acute phase response, a situation of high energy demand. To test this hypothesis, German Holstein cows were assigned to a control group (CON, n = 26) and an L-carnitine supplemented group (CAR, n = 27, rumen-protected L-carnitine product: 125 g/cow/d, corresponded to total L-carnitine intake: 25 g/cow/d, supplied with concentrate) and received an intravenous bolus injection of lipopolysaccharides (LPS, 0.5 µg/kg body weight, E. coli) on day 111 postpartum as a model of standardized systemic inflammation. Blood samples were collected from day 1 ante injectionem until day 14 post injectionem (pi), with frequent sampling through an indwelling venous catheter from 0.5 h pi to 12 h pi. All parameters of the white blood cell count responded significantly to LPS, while only a few parameters were affected by L-carnitine supplementation. The mean eosinophil count, as well as the percentage of basophils were significantly higher in CAR than in CON over time, which may be due to an increased membrane stability. However, phagocytosis and production of reactive oxygen species by leukocytes remained unchanged following L-carnitine supplementation. In conclusion, although supplementation with 25 g L-carnitine per cow and day resulted in increased proportions of specific leukocyte populations, it had only minor effects on the functional parameters studied in mid-lactating dairy cows during LPS-induced inflammation, and there was no evidence of direct improvement of immune functionality.
A shift towards succinate‐producing Prevotella in the ruminal microbiome challenged with monensin
(2022) Trautmann, Andrej; Schleicher, Lena; Koch, Ariane; Günther, Johannes; Steuber, Julia; Seifert, Jana
The time‐resolved impact of monensin on the active rumen microbiome was studied in a rumen‐simulating technique (Rusitec) with metaproteomic and metabolomic approaches. Monensin treatment caused a decreased fibre degradation potential that was observed by the reduced abundance of proteins assigned to fibrolytic bacteria and glycoside hydrolases, sugar transporters and carbohydrate metabolism. Decreased proteolytic activities resulted in reduced amounts of ammonium as well as branched‐chain fatty acids. The family Prevotellaceae exhibited increased resilience in the presence of monensin, with a switch of the metabolism from acetate to succinate production. Prevotella species harbour a membrane‐bound electron transfer complex, which drives the reduction of fumarate to succinate, which is the substrate for propionate production in the rumen habitat. Besides the increased succinate production, a concomitant depletion of methane concentration was observed upon monensin exposure. Our study demonstrates that Prevotella sp. shifts its metabolism successfully in response to monensin exposure and Prevotellaceae represents the key bacterial family stabilizing the rumen microbiota during exposure to monensin.
Squid meal and shrimp hydrolysate as novel protein sources for dog food
(2024) Guilherme-Fernandes, Joana; Aires, Tiago; Fonseca, António J. M.; Yergaliyev, Timur; Camarinha-Silva, Amélia; Lima, Sofia A. C.; Maia, Margarida R. G.; Cabrita, Ana R. J.
The world’s growing pet population is raising sustainability and environmental concerns for the petfood industry. Protein-rich marine by-products might contribute to mitigating negative environmental effects, decreasing waste, and improving economic efficiency. The present study evaluated two marine by-products, squid meal and shrimp hydrolysate, as novel protein sources for dog feeding. Along with the analysis of chemical composition and antioxidant activity, palatability was evaluated by comparing a commercial diet (basal diet) and diets with the inclusion of 150 g kg−1 of squid meal or shrimp hydrolysate using 12 Beagle dogs (2.2 ± 0.03 years). Two in vivo digestibility trials were conducted with six dogs, three experimental periods (10 days each) and three dietary inclusion levels (50, 100 and 150 g kg−1) of squid meal or shrimp hydrolysate in place of the basal diet to evaluate effects of inclusion level on apparent total tract digestibility (ATTD), metabolizable energy content, fecal characteristics, metabolites, and microbiota. Both protein sources presented higher protein and methionine contents than ingredients traditionally used in dog food formulation. Shrimp hydrolysate showed higher antioxidant activity than squid meal. First approach and taste were not affected by the inclusion of protein sources, but animals showed a preference for the basal diet. Effects on nutrient intake reflected the chemical composition of diets, and fecal output and characteristics were not affected by the increasing inclusion levels of both protein sources. The higher ATTD of dry matter, most nutrients and energy of diets with the inclusion of both by-products when compared to the basal diet, suggests their potential to be included in highly digestible diets for dogs. Although not affected by the inclusion level of protein sources, when compared to the basal diet, the inclusion of squid meal decreased butyrate concentration and shrimp hydrolysate increased all volatile fatty acids, except butyrate. Fecal microbiota was not affected by squid meal inclusion, whereas inclusion levels of shrimp hydrolysate significantly affected abundances of Oscillosperaceae (UCG-005), Firmicutes and Lactobacillus. Overall, results suggest that squid meal and shrimp hydrolysate constitute novel and promising protein sources for dog food, but further research is needed to fully evaluate their functional value.
High rates of honey bee colony losses and regional variability in Ethiopia based on the standardised COLOSS 2023 survey
(2024) Hailu, Teweldemedhn Gebretinsae; Atsbeha, Alem Tadesse; Wakjira, Kibebew; Gray, Alison
The COLOSS research association has been assessing honey bee colony losses, associated risk factors and management, focusing on Western countries but with a progressive international expansion. Here, we report the first survey on the loss rates of colonies in 2022/2023 in Ethiopia using COLOSS monitoring survey tools. A face-to-face interview questionnaire survey was conducted on 64 beekeepers selected from Oromia and Tigray regions. This covered 1713 honey bee colonies distributed in 68 apiaries. The percentages of colonies lost were significantly different between Oromia (24.1%) and Tigray (66.4%) regions. Colony losses were attributed as unsolvable queen problems (8% in Oromia; 10% in Tigray), natural disaster (32%; 82%), and empty hives or dead colonies (60%; 8%). The loss rate was significantly affected by queen replacement (p < 0.0001), use of natural comb (p < 0.0001), feed supplementation (p < 0.0001), region (p < 0.0001), varroa treatment (p < 0.0001), colony splitting (p < 0.01), and merging (p < 0.01). Beekeepers in Oromia managed more colonies and implemented improved practices compared to those in Tigray. However, all beekeepers in Oromia detected at least some bees with signs of deformed wing virus, compared to 76% of beekeepers in Tigray. In conclusion, the colony loss rate was significantly different between Oromia and Tigray regions due to differences in natural disasters, management, environment and health factors.
Influence of different plant extracts on CYP-mediated skatole and indole degradation in pigs
(2024) Marro, Philipp; Wesoly, Raffael; Stefanski, Volker
One of the primary substances responsible for the unpleasant odor in boar meat is skatole. Enzymes belonging to the cytochrome P450 (CYP) family play a pivotal role in the hepatic clearance of skatole. This study aimed to investigate the impact of oregano essential oil (OEO), Schisandra chinensis extract (SC), and garlic essential oil (GEO) on hepatic CYP2E1 and CYP2A activity in pigs. In three consecutive trials, cannulated castrated male pigs were provided with a diet containing 0.2–0.3% of one of these plant extracts. Following a 14-day feeding period, the animals were slaughtered, and liver and fat samples were collected. The findings indicate that the activities of CYP2E1 were unaffected by any treatment. However, GEO treatment demonstrated a significant reduction in CYP2A activity (p < 0.05). Pigs treated with GEO also exhibited a notable increase in skatole concentrations in both plasma and adipose tissue. In contrast, animals fed SC displayed elevated skatole concentrations in plasma but not in fat tissue. OEO did not influence skatole concentrations in either blood or fat. Furthermore, the study revealed that a supplementation of 6 g GEO per animal per day induced a significant increase in skatole concentrations in blood plasma within 24 h.
Divergence within the taxon ‘Candidatus Phytoplasma asteris’ confirmed by comparative genome analysis of carrot strains
(2024) Toth, Rafael; Ilic, Anna-Marie; Huettel, Bruno; Duduk, Bojan; Kube, Michael
Phytoplasmas are linked to diseases in hundreds of economically important crops, including carrots. In carrots, phytoplasmosis is associated with leaf chlorosis and necrosis, coupled with inhibited root system development, ultimately leading to significant economic losses. During a field study conducted in Baden-Württemberg (Germany), two strains of the provisional taxon ‘Candidatus Phytoplasma asteris’ were identified within a carrot plot. For further analysis, strains M8 and M33 underwent shotgun sequencing, utilising single-molecule-real-time (SMRT) long-read sequencing and sequencing-by-synthesis (SBS) paired-end short-read sequencing techniques. Hybrid assemblies resulted in complete de novo assemblies of two genomes harboring circular chromosomes and two plasmids. Analyses, including average nucleotide identity and sequence comparisons of established marker genes, confirmed the phylogenetic divergence of ‘Ca. P. asteris’ and a different assignment of strains to the 16S rRNA subgroup I-A for M33 and I-B for M8. These groups exhibited unique features, encompassing virulence factors and genes, associated with the mobilome. In contrast, pan-genome analysis revealed a highly conserved gene set related to metabolism across these strains. This analysis of the Aster Yellows (AY) group reaffirms the perception of phytoplasmas as bacteria that have undergone extensive genome reduction during their co-evolution with the host and an increase of genome size by mobilome.
Mothers’ parity and weaning age influence the transition from liquid to solid feed in female Holstein calves
(2023) Schwarzkopf, Sarah; Huber, Korinna
Milchbauern streben aus wirtschaftlichen Gründen ein junges Erstkalbealter an. Da diese jungen Färsen während der Trächtigkeit noch wachsen, könnten sie mit ihrem Kalb um Nährstoffe konkurrieren. Daher können die Parität der Mütter und die damit verbundene Nährstoffversorgung während der Trächtigkeit die frühe Entwicklung beeinflussen. Kälber werden als funktionell monogastrische Tiere geboren, die auf Milch oder Milchaustauscher zur Ernährung angewiesen sind. Um den Status eines Wiederkäuers zu erreichen und festes Futter als Nahrungsquelle zu verwenden, müssen sich viele digestive, endokrine und biochemische Funktionen ändern. Daher ist das Absetzen ein kritisches und potenziell stressiges Ereignis. Das durchschnittliche Absetzalter weiblicher Milchkälber beträgt 6 – 11 Wochen, was mit Stress einhergeht, der das Immunsystem, das Wachstum und die Magen-Darm-Entwicklung negativ beeinträchtigen kann. Daher kommt ein Aufschieben des Absetzens möglicherweise der Gesundheit und Entwicklung der Kälber zugute. Es verbessert das Wachstum, reduziert die mit dem Absetzen verbundene Belastung und erhöht möglicherweise das Alter bei der Entfernung aus der Herde. Die vorliegende Arbeit zielte darauf ab, die Auswirkungen von zwei Absetzaltersstufen und der Parität der Mütter auf die Entwicklung und Anpassung an die Entwöhnung zu identifizieren. Mittels eines Tierversuchs mit neunundfünfzig weiblichen Holstein-Kälbern wurden die Auswirkungen eines frühen (7 Wochen) und späten (17 Wochen) Absetzens auf Wachstum, Verhalten, Pansen- und Magen-Darm-Entwicklung und Anpassung des Leber- und Nierenstoffwechsels getestet. Darüber hinaus wurde der Einfluss unterschiedlicher Absetzalter auf Kälber von primiparen und multiparen Kühen berücksichtigt. Proben wurden kontinuierlich im Alter von 8 Tagen (Versuchstag 1) bis zum Alter von 21 Wochen (Versuchstag 140) genommen. Die Analysen und Ergebnisse werden in drei begutachteten wissenschaftlichen Arbeiten beschrieben und im Folgenden zusammengefasst. Die Wachstumsleistung wurde anhand von Lebendgewicht, Lebendgewichtszunahme, Widerrist- und Hüfthöhe, Brustumfang, Rücken- und Körperlänge bewertet. Der Energiestoffwechsel und die Leberfunktion wurden durch Messung der Serumkonzentrationen von Glukose, Insulin, Harnstoff, Cholesterin, Leptin, Beta-hydroxybutyrate und nicht-veresterten Fettsäuren quantifiziert (Manuskript 1). Das Verhalten der Tiere wurde beobachtet unterteilt in Ruhe-, Kau- und Aktivverhalten, um Rückschlüsse auf Anzeichen von Hunger und Stress sowie der Pansenentwicklung zu ziehen. Die Pansenentwicklung und entsprechende metabolische und adaptive Veränderungen im Säure-Basen-Stoffwechsel wurden durch Messung des pH-Wertes in Urin, Kot und Speichel sowie stickstoffhaltiger Metaboliten im Urin bewertet (Manuskript 2). Das Mikrobiom in Kotproben wurde analysiert, um die Reifung des Magen-Darm-Trakts zu beurteilen. Um Einblicke in metabolische Anpassungen zu erhalten, wurde eine umfassende Anzahl an Metaboliten gemessen. Dazu gehörten Aminosäuren, biogene Amine, Acylcarnitine und Sphingomyeline (Manuskript 3). Ein späteres Absetzen im Alter von 17 Lebenswochen wirkt sich positiv auf das Körperwachstum und die Anpassung des Energie- und Säure-Basen-Stoffwechsels aus (Manuskript 1; Manuskript 2). Der pH-Wert des Speichels stieg während des Experiments im Laufe der Zeit an, unabhängig vom Absetzalter oder der Parität der Mutter (Manuskript 2). Da ein alkalischer pH-Wert im Speichel für dessen Pufferkapazität wichtig ist, unterstreicht dies, wie wichtig es ist, das Absetzen zu verzögern. Die gastrointestinale Entwicklung war durch eine längere Milchaustauscheraufnahme nicht beeinträchtigt, sondern erreichte am Ende der Studie einen funktionellen Status. Faktoren der Pansenentwicklung (Manuskript 2) und die Mikrobiota im Kot (Manuskript 3) passten sich schnell an und deuteten auf eine altersabhängige Reifung hin. Die analysierten Metaboliten wiesen auf ausgeprägte Effekte eines frühen Absetzens auf verschiedene Stoffwechselwege hin (Manuskript 3). Insbesondere die Gluconeogenese in der Leber schienen bei früh abgesetzen Kälbern unzureichend zu sein. Die Leptinkonzentrationen und die Rückenlänge waren bei früh abgesetzten Kälbern primiparer Mütter reduziert, nicht jedoch bei spät abgesetzten Kälbern primiparer Mütter (Manuskript 1). Daher profitieren Kälber von primiparen Kühen besonders von einem späteren Absetzen. Die Ergebnisse zeigten, dass ein Absetzen im Alter von 7 Wochen nicht empfohlen werden kann, da es zu abrupten und möglicherweise belastenden Stoffwechselveränderungen und einer gestörten Reifung verschiedener Organe und deren Stoffwechselfunktionen führte. Die aktuelle Studie zeigte, dass die Verzögerung des Absetzens auf ein Alter von 17 Wochen einen gleichmäßigen Übergang verschiedener physiologischer Funktionen in den Wiederkäuerstatus ermöglicht. Deshalb schien es die mit dem Absetzen verbundenen Stoffwechselprobleme und den Stress zu reduzieren. Weitere Forschung über das Absetzen, unter Berücksichtigung der Aufzuchtkosten und späteren Milchleistung und Gesundheit, ist erforderlich.
The effect of intensive selection for egg production on foraging related behavior and performance related hormones in laying hens
(2023) Höhne, Anja; Bessei, Werner
The production performance of livestock has increased massively in recent decades. Changing performance levels through intensive selection has played a major role in this. Over the years, a limited number of high-performing lines have emerged. The high performance level of chicken laying lines can only be achieved with optimal feeding and intensive conditions. However, these laying hens are increasingly exposed to changing housing and husbandry systems including changing environmental conditions. Therefore, the aim of the present work was to investigate possible side effects of intensive selection on egg production, such as behavioral and physiological changes leading to a reduced adaptability to alternative environmental conditions. We used four different chicken laying lines: pairs of brown and white layers each with a high (BLA, WLA) and a low (L68, R11) laying performance. All experiments were done before and during the laying period. Foraging strategies and behavior related to foraging were analyzed in groups of 12 hens per pen. The foraging strategy was tested using a contrafreeloading (CFL) paradigm. CFL describes a behavior in which animals prefer food that is laborious to obtain, although it is freely available at the same time. Foraging behavior (number of hens scratching or pecking in the litter area) and the litter area parameter (number of hens in the litter area) were also observed. In addition, hens’ activity in the feeding area was measured using an antenna-transponder system, recording activity around the feeder and time in the feeding area. Because these behaviors lose importance when food is offered ad libitum, we hypothesized that high-performing lines will prefer freely available feed in the CFL and will exhibit less foraging behavior. The peptide hormone ghrelin is related to the regulation of feed intake and feeding behavior. Based on previous studies in chickens and the expected difference in nutrient requirements depending on performance level, we expected lower plasma ghrelin concentration in the high-performing lines compared to the low-performing lines. To investigate the effects of controlled environmental conditions during the intensive selection, plasma ghrelin was recorded both in cages, i.e., in a controlled and barren environment, and in a structured floor housing with 30 hens per compartment. Due to its function in growth and its relationship to ghrelin, the plasma concentration of growth hormone was also analyzed. One of the most important gonadal steroid hormones with various functions in regulating reproduction and, thus, also laying performance is the sexual hormone estradiol-17ß. Egg formation is closely related to its concentration. It was expected that lines with a high ovulation rate would have higher estradiol-17ß concentrations than lines with low performance. Estradiol-17ß was also measured in individual cages and in floor housing systems with 30 hens per compartment. A side effect of the selection on foraging-related behavior was confirmed by the results. High-performing selected hens showed less CFL and foraging behavior, were observed less often in the litter area, and showed less activity in the feeding area compared with non-selected hens. In addition, white hens exhibited more foraging behavior and were observed less frequently in the litter area compared to brown hens. Contrary to our expectations, ghrelin concentration did not differ between the four lines before and during laying period. In adult laying hens, ghrelin does not appear to be involved in the regulation of energy intake associated with laying performance. An influence of selection on plasma estradiol-17ß concentrations during the laying period was confirmed. Hens with high performance showed higher estradiol-17ß concentrations than hens with low performance. The phylogenetic origin showed no effect on the plasma concentration of estradiol-17ß. The increased concentration of estradiol-17ß may affect its further functions. The highest concentration after the laying peak indicates its involvement in calcium and bone metabolism. Especially in high-performing lines, high concentrations of estradiol-17ß have been associated with a reduction in bone strength and an increased risk of bone fractures. Hens in floor housing with more movement opportunities showed lower estradiol-17ß concentrations and, in the growth phase before the start of laying, higher ghrelin concentrations than hens in individual cages. Since this was the same in all lines, it was not an effect of intensive selection, but rather seems to be related to more movement opportunities. Foraging behavior and estradiol-17ß concentration are not used as selection traits, but both traits are associated with performance levels of laying hens. The high level of egg production and controlled environmental conditions during performance testing are associated with behaviors that allow hens to meet their higher energy requirements more efficiently. Energy conservation through reduced activity likely allows them to divert energy to reproduction, i.e., laying performance. Adaptability to husbandry systems including changing environmental conditions is lower in high-yielding selected hens than in non-selected hens. Therefore, adaptation of housing systems should be considered in intensive selection.
Untersuchung der Populationsstrukturen und genomische Analysen für relevante Merkmale in der Weidehaltung bei F1-Merinolandkreuzungen
(2023) Gürtler, Johannes; Bennewitz, Jörn
Die Schafhaltung in Deutschland hat eine reiche Tradition, die über Generationen hinweg die Landschaft geprägt hat. Die Beweidung mit Schafen hat die Entstehung von ökologisch wertvollen Gebieten wie Wacholderheiden und Trockenrasen ermöglicht, die heute als wichtige Hotspots der Artenvielfalt gelten. Vielen Schafbetrieben in Deutschland verschafft die Landschaftspflege von extensiven Grünlandflächen einen Großteil ihres Einkommens. Vor allem in Baden-Württemberg sind das Merinolandschaf und dessen Anpassungsfähigkeit an die Landschaftspflege bevorzugt. Auf den Weiden sind Schafe und Lämmer jedoch Magen-Darm-Würmern ausgesetzt, was nicht nur gesundheitliche Folgen, sondern auch wirtschaftliche Auswirkungen hat. Aufgrund von Resistenzen gegen Anthelminthika sind herkömmliche Bekämpfungsstrategien nur noch eingeschränkt wirksam. Insbesondere junge Lämmer sind gefährdet, da ihr Immunsystem noch nicht vollständig entwickelt ist. Daher wächst das Interesse an alternativen Bekämpfungsstrategien, wie dem Zuchteinsatz von Schafen mit natürlicher Resistenz gegenüber Magen-Darm-Parasiten. Zusätzlich zur Landschaftspflege sind Schafbetriebe auch im Verkauf von Schlachtlämmern tätig. In der extensiven Weidemast gestaltet sich die Erzielung hochwertiger Schlachtkörper aufgrund schwankender Futterqualitäten als Herausforderung, insbesondere angesichts des Wettbewerbes mit Importware aus anderen Ländern. Aus diesem Grund werden Merinolandschafe gezielt mit Fleischrassen gekreuzt, um die Schlachtkörperqualität zu verbessern. In Kapitel 1 ist eine ausführliche Literaturübersicht zu den Themen dieser Arbeit zu finden. In Kapitel 2 wurde ein Datensatz von F1-Merinokreuzungslämmern aus den Vaterrassen Charollais, Ile de France, Schwarzköpfiges Fleischschaf, Suffolk, Texel und Merinolandschaf untersucht. Es wurden Populationsstrukturen analysiert, um ein besseres Verständnis der Strukturen und deren Auswirkungen auf genomweite Assoziationskartierungen zu bekommen. Des Weiteren wurden genetische Parameter für ausgewählte Mast- und Schlachtleistungsmerkmale, wie die täglichen Zunahmen, das Schlachtkörpergewicht und die Rückenlänge ermittelt. Die Kreuzungslämmer wurden auf sieben Betrieben aufgezogen und anschließend zentral in einem Stall gemästet und geschlachtet. Für die Populationsstrukturen wurden das Kopplungsungleichgewicht (linkage disequilibrium, LD) berechnet sowie ein multidimensionaler Skalierungsansatz analysiert. Unter Zuhilfenahme von gemischt linearen Modellen wurden für die erhobenen Merkmale Heritabilitäten geschätzt. Mit Hilfe von genomweiten Assoziationsanalysen wurde versucht, einen Zusammenhang zwischen den Phänotypen und Markern zu identifizieren. Für die Auswertung standen 50k SNP-Chip Genotypen von 1.470 Lämmern zur Verfügung. Die Daten wurden zu einem Datensatz über alle Kreuzungen hinweg gepoolt (Multi-Cross-Datensatz). Im Multi-Cross-Datensatz war das Kopplungsungleichgewicht gering und nahm mit zunehmendem Markerabstand rapide ab. Bei den einzelnen Kreuzungen war das LD etwa doppelt so groß, nahm aber mit zunehmendem Markerabstand auch rapide ab. Insgesamt konnten im Multi-Cross-Datensatz 21 nominal-signifikante SNPs identifiziert werden, sowie ein genomweiter SNP auf Chromosom 1 für das Merkmal Schulterbreite. Die berechneten Heritabilitäten der Mast- und Schlachtleistungsmerkmale lagen im moderaten bis hohen Bereich zwischen 0,20 für das Schlachtkörpergewicht und 0,41 für das Merkmal Rückenlänge. In Kapitel 3 wurde ein weiterer Datensatz von F1-Merinokreuzungslämmern ausgewertet. Die eingesetzten Vaterrassen waren Ile de France, Schwarzköpfiges Fleischschaf, Suffolk, Texel und Merinolandschaf. Neben der Analyse der Populationsstrukturen wurden genomweite Assoziationskartierungen durchgeführt und genetische Parameter für Schlacht- und Weidemerkmale ermittelt. Die untersuchten Lämmer wurden auf drei Betrieben erzeugt und in zwei verschiedenen Weidesystemen (extensive und intensive Weide) gehalten und bei Schlachtreife zentral geschlachtet. Für die Populationsstrukturen wurden das LD berechnet sowie eine Hauptkomponentenanalyse durchgeführt. Unter Verwendung von gemischt linearen Modellen wurden für die erhobenen Merkmale Heritabilitäten geschätzt. Mit Hilfe von genomweiten Assoziationsanalysen wurde versucht, einen Zusammenhang zwischen den Phänotypen und Markern zu identifizieren. Ausgewertet wurden 1.060 bis1.167 Lämmer, von denen sowohl Phänotypen als auch 50k SNP-Chip Genotypen zur Verfügung standen. Über alle Kreuzungen hinweg fiel das LD mit steigendem Markerabstand schnell ab. Heritabilitäten für die Weidemerkmale waren im geringen Bereich zwischen 0,01 und 0,13. Bei den Schlachtmerkmalen waren die geschätzten Heritabilitäten im Bereich zwischen 0,08 für die Klassifizierung und 0,25 für den Keulenumfang. Bei der genomweiten Assoziationskartierung war die Power allgemein gering. Für die Weidemerkmale konnten neun nominal signifikante SNPs und bei den Schlachtmerkmalen 16 SNPs identifiziert werden. Abschließend wurden die Unterschiede und Gemeinsamkeiten der beiden betrachteten Kapitel diskutiert.
Investigations on phytate degradation of rapeseed meal and soybean meal in ruminants
(2023) Chi, Yung-Ping; Rodehutscord, Markus
Oilseed meals are widely used protein feeds in ruminant nutrition. However, aside from the high crude protein (CP) content, oilseed meals also contain high amounts of phosphorus (P), which is predominantly present in organic form as different salts of myo-inositol 1,2,3,4,5,6 hexakis dihydrogen phosphate (InsP6). To become available for intestinal absorption and further utilisation by animals, P must be cleaved from the InsP6 molecule by a specific group of phosphatases, which is known as phytase. Over the decades, ruminants were considered to be capable of utilising nearly all P bound in InsP6 because of the substantial phytase activity exhibited by rumen microbiota. Nevertheless, recent studies have reported variable extents of ruminal InsP6 degradation which seems to be influenced by different factors. In case of an incomplete ruminal InsP6 degradation, post-ruminal InsP6 degradation may be of higher relevance. However, post-ruminal InsP6 degradation has been rarely studied to date. The aim of this thesis was to systematically investigate InsP6 degradation of rapeseed meal (RSM) and soybean meal (SBM) in ruminants, including the possible influencing factors and their combinations. Different study methods (in vivo, in situ, and in vitro) were applied to evaluate the effects of RSM and SBM. The first study (Manuscript 1) was conducted to investigate ruminal and post-ruminal InsP6 degradation in wethers fed a diet containing RSM or SBM, and to link the ruminal disappearance determined in slaughtered wethers with in situ calculated rumen effective degradation of InsP6 (InsP6ED) from cows. Firstly, RSM and SBM was incubated according to a standard in situ procedure in three lactating Jersey cows for 2, 4, 6, 8, 16, 24, 48, and 72 h to obtain InsP6ED for the oilseed meals at rumen passage rates of 0.02 (InsP6ED2) and 0.05 h-1 (InsP6ED5). Secondly, eight wethers were randomly assigned to two treatment groups that were fed a diet containing equal amount of RSM (Diet RSM) or SBM (Diet SBM) for 8 weeks of adaptation. Then, digesta from the reticulo-rumen, omasum, abomasum, jejunum, colon, and rectum were sampled. In consistence with in situ calculated InsP6ED2 (83 and 93% for RSM and SBM, respectively), ruminal InsP6 disappearance was lower in wethers fed Diet RSM (76%) compared to those fed Diet SBM (89%). Post-ruminal InsP6 disappearance did not differ between dietary treatments (6% for Diet RSM vs. 4% for Diet SBM). A higher amount of ruminally degraded InsP6 was observed upon feeding RSM (4.5 g/d for Diet RSM and 3.4 g/d for Diet SBM). Due to the low rumen passage rate in this study, it was suggested that P from InsP6 being available to ruminants is almost entirely from InsP6 degradation in the rumen. As InsP6 is located in a protein-rich structure in seeds and InsP6 degradation has been recently reported to vary in a pattern similar to CP degradation for RSM, the second study (Manuscript 2) was carried out to investigate the variation of in situ ruminal InsP6 degradation of SBM and its relation to CP degradation. In this study, nine commercial solvent-extracted SBM from Europe and South America were incubated in three rumen-fistulated lactating Jersey cows with the same procedure performed in the first study. Rumen effective degradation of CP and InsP6 were calculated for a rumen passage rate of 0.06 h-1 (CPED6 and InsP6ED6). Chemical protein fractions of SBM variants were determined according to Cornell Net Carbohydrate and Protein System (CNCPS). The SBM variants exhibited a considerable variation in CP and InsP6 degradation. Significant correlations were found between InsP6ED6 and CPED6 and between InsP6ED6 and all CNCPS protein fractions, which confirmed the close relationship between CP and InsP6 degradation for SBM. The results suggested that using a general value of InsP6 degradation for diet formulation may not be precise enough, and InsP6ED may be predicted based on CPED or CNCPS protein fractions by using linear regression equations. The third study (Chapter 4.3) aimed to achieve a better understanding of how in vitro InsP6 degradation of RSM and SBM is influenced by different amounts of InsP6 in feed. The same batches of RSM and SBM as used in Manuscript 1 were incubated in a modified rumen simulation technique (RUSITEC) system with different amounts for 3, 6, 12, 24, and 48 h. Degradation of InsP6 from bag residues was calculated and expressed as amount and in percentage using the same equation as applied for in situ calculations. In vitro degradation of InsP6 in response to InsP6 amount differed between RSM and SBM, which may be attributed to the different internal structure and nutrient composition of the oilseed meals. Only when expressing in amounts, the calculated InsP6ED was observed to increase linearly with increasing InsP6 amount in feed. Accordingly, it was recommended to compare InsP6 degradation based on InsP6 amount in the feed and to express degradation as amount instead of using relative value which might not reflect the real degradation kinetics. In conclusion, the results of this thesis showed that the extent of ruminal InsP6 degradation differs when the diet contains either RSM or SBM, while post-ruminal InsP6 degradation is negligibly low given a long rumen retention time. By using linear regression equations, ruminal InsP6 degradation may be predicted from CP degradation due to the close relationship therebetween. Effects of InsP6 amount on InsP6 degradation is dependent on InsP6 source. Based on the high similarity among ruminal InsP6 degradation determined by different methods in this thesis, ruminal InsP6 degradation of oilseed meals measured by in situ or in vitro study may be applicable for in vivo conditions.
Zinc supplementation effects on phytate degradation, mineral digestibility, and bone characteristics in broiler chickens
(2024) Philippi, Hanna; Rodehutscord, Markus
An adequate supply of phosphorus (P) is important in poultry nutrition, as P is essential for numerous metabolic processes. However, oversupply should be avoided to reduce the environmental impact of poultry production. The main source of P in plant feedstuffs commonly used in poultry nutrition is phytate, the salt form of phytic acid (InsP6). For P from InsP6 to be utilized by animals, it needs to be cleaved by phytases or other phosphatases. However, the capacity of endogenous phosphatases of non-ruminant animals does not suffice to release sufficient P to fulfill the animal’s P requirement. Therefore, commercial poultry diets usually are supplemented with P from mineral sources. By using exogenous phytases, the supplementation of mineral P can be reduced, and finite P reserves can be conserved. To feed poultry without mineral P in the future, phytase efficacy must be improved further. Thus, it is important to know and understand all factors influencing phytase efficacy. The results of in vitro studies have indicated that zinc (Zn) may be an influencing factor. The supplementation of Zn could inhibit phytase activity, with the degree of inhibition depending on the exogenous Zn source used. A literature review on the interactions of Zn with phytate and phytase (Manuscript A of this thesis) has identified a lack of in vivo studies investigating the effects of Zn supplementation on phytase with direct measurements, such as intestinal phytate degradation and prececal P digestibility. Therefore, three in vivo studies were conducted as part of this thesis with the main objective to investigate the effect of Zn supplementation and exogenous Zn source on intestinal phytate degradation in broiler chickens. It was hypothesized that due to the formation of insoluble complexes of Zn and phytate, the supplementation of Zn could reduce phytase efficacy with the extent of reduction depending on the exogenous Zn source. Further, other traits that are affected by Zn supply, such as bone mineralization and gene expression, were also investigated in these in vivo studies. The first experiment (Manuscript B) aimed to determine the effect of dietary Zn level and source on intestinal phytate breakdown, mineral digestibility, bone mineralization, and Zn status without and with exogenous phytase in the feed. Ross 308 broiler chickens were fed experimental diets from day 7 to 28. The basal diet contained 33 mg/kg dry matter native Zn and a high phytate-P concentration to challenge interactions in the digestive tract. The experimental diets differed in the level of exogenous phytase (0 or 750 FTU/kg) and in the Zn source (none, 30 mg/kg of Zn-sulfate, or 30 mg/kg of Zn-oxide). Additionally, two experimental diets with a high Zn supplementation level (90 mg/kg) in the form of Zn-sulfate or Zn-oxide, both containing exogenous phytase, were tested. Intestinal phytate breakdown, P digestibility, and bone mineralization were not affected by Zn source or Zn level but only by phytase supplementation. The concentration of ileal myo-inositol was influenced by phytase × Zn source interaction. Birds fed without phytase supplementation had similarly low myo-inositol concentrations whether they received Zn supplementation or not, whereas birds receiving phytase supplementation and Zn supplementation had significantly higher ileal myo-inositol concentrations than birds fed without Zn supplementation but with phytase supplementation. The missing effect of Zn level or Zn source on phytate degradation indicates that no interactions of Zn and phytate relevant for phytase efficacy occurred in the digestive tract of broilers when Zn was supplemented at levels up to 90 mg/kg in the form of Zn-sulfate or Zn-oxide. Based on the results of the first experiment, where Zn alone did not show relevant interactions with phytate, the second experiment (Manuscript C) aimed to investigate whether the combined supplementation of Zn, copper (Cu), and manganese (Mn) from different sources without and with exogenous phytase in the feed affects intestinal phytate breakdown, prececal mineral digestibility, bone mineralization, and mRNA expression of mineral transporters. Cobb 500 broiler chickens received experimental diets from day 0 to 28. Experimental diets differed in the level of phytase supplementation (0 or 750 FTU/kg) and in the trace mineral source (TMS: 100 mg/kg Zn, 100 mg/kg Mn, and 125 mg/kg Cu as sulfates, oxides, or chelates). Prececal InsP6 disappearance and P digestibility were significantly affected by phytase × TMS interaction. Whereas birds receiving exogenous phytase had similar InsP6 disappearance and P digestibility irrespective of TMS, birds fed without exogenous phytase and with chelated trace minerals had a higher InsP6 disappearance and P digestibility than birds receiving no exogenous phytase and oxides or sulfates. These results indicate that the combined supplementation of Zn, Mn, and Cu at high levels may challenge interactions with phytate in non-phytase-supplemented diets with the extent of interaction depending on the TMS. In phytase-supplemented diets however, the choice of TMS was irrelevant for phytate degradation under the conditions of this study. The third experiment (Manuscript D) aimed to determine the impact of Zn level and Zn source on prececal phytate degradation, mineral digestibility, bone mineralization, and mRNA expression of intestinal (trace) mineral transporters. In contrast to the first experiment, an inorganic Zn source and a chelated Zn source were tested. Cobb 500 broiler chickens received experimental diets from day 0 to 21. The experimental diets differed in Zn supplementation level (10, 30, 50 mg/kg Zn) and exogenous Zn source (Zn-oxide or Zn-glycinate). A cornsoybean meal-based diet without Zn supplementation containing 35 mg/kg native Zn was used as a control. All experimental diets were supplemented with 750 FTU/kg phytase. Prececal InsP6 disappearance, P digestibility, and tibia ash quantity and concentration, and Zn concentration in tibia ash were not affected by diet. Bone breaking strength and tibia width did not differ between treatments. Tibia thickness was lower in the treatments with 30 mg Zn as Zn-oxide and 50 mg Zn as Zn-glycinate than in the treatment with 10 mg Zn as Zn-oxide. The expression of intestinal (trace) mineral transporters was not affected by treatment. These results indicate that in phytase-supplemented diets the native Zn concentration of cornsoybean meal-based diets is satisfactory to achieve maximal Zn concentration in tibia ash during the first 3 weeks of age. The missing effect of Zn level or Zn source on phytate degradation confirms the results from Manuscript B, that Zn and phytate do not interact to a level relevant for phytate degradation by exogenous phytase. It is concluded that contrary to the hypothesis that Zn inhibits phytate degradation by complex formation with phytate, the Zn supplementation up to 100 mg/kg does not appear to influence exogenous phytase efficacy. Minor effects were found on the endogenous phytate degradation if Zn, Cu, and Mn were supplemented combined at high levels, where the extent of reduction in endogenous phytate degradation was dependent on the TMS. It remains unclear whether the inhibiting effect on endogenous phytate degradation occurs only due to the combined supplementation or whether an individual high supplementation of a single trace mineral caused the effect. Further experiments are needed to investigate the effect of Zn on endogenous phosphatases, where the activity of endogenous mucosal activity should be determined in broilers fed diets differing in the Zn supplementation level. Moreover, further experiments are needed to test what level of Zn supplementation is needed in phytase-supplemented diets to ensure the birds sufficient supply in all areas. Besides bone development and growth, effects on the immune system, microbiota composition, and the antioxidative system should be considered.
Novel bacterial species from the chicken gastrointestinal tract and their functional diversity
(2023) Rios Galicia, Bibiana; Seifert, Jana
The digestive system of chicken presents different physicochemical conditions along the gastrointestinal tract (GIT), shaping an individual microbial profile along sections with different metabolic capacities and divergence on the adaptations to the environment. Efforts to obtain cultivable bacteria originating from the upper region of chicken GIT enrich the reference genome database and provide information about the site- specific adaptations of bacteria colonizing such GIT sections allowing to understand the metabolic profile and adaptive strategies to the environment. However, the lack of sufficient reference genomes limits the interpretation of sequencing data and restrain the study of complex functions. In this study, 43 strains obtained from crop, jejunum and ileum of chicken were isolated, characterised and genome analysed to observe their metabolic profiles, adaptive strategies and to serve as future references. Eight isolates represent new species that colonise the upper gut intestinal tract and present consistent adaptations that enable us to predict their ecological role, expanding our knowledge on the adaptative functions. Strains of Limosilactobacillus were found to be more abundant in the crop, while Ligilactobacillus dominated the ileal digesta. Isolates from crop encode a high number of glycosidases specialised in complex polysaccharides compared to strains isolated from jejunum and ileum. While isolates from jejunum and ileum encode a higher number of genes that interact with the host such as collagenases and hyaluronidases, indicating preferential persistence and adaptations along the GIT. These results represent the first repository of bacteria obtained from the crop and small intestine of chicken using culturomics, improving the potential handling of chicken microbiome with biotechnological applications
Epidemiological and clinical description of Candidatus Mycoplasma haemosuis, an emerging pathogen in pigs
(2023) Ade, Julia; Hölzle, Ludwig
Candidatus Mycoplasma haemosuis is an emerging pathogen infecting pigs. It belongs to the group of uncultivable hemotrophic mycoplasmas. This group includes other long-known porcine representatives, i. e. Mycoplasma parvum und Mycoplasma suis. M. suis is the causative agent of infectious porcine anemia (IAP), a disease of great economic importance to the pig industry. Previously, Ca. M. haemosuis was only described in China, South Korea and Thailand, with no knowledge of its occurrence outside Asia or of its general clinical and economic importance in general. The present work investigates the occurrence of the novel hemotrophic bacterium and its clinical importance in Germany for the first time. For this, a quantitative real-time PCR was first successfully developed for the detection of Ca. M. haemosuis in pigs. The SYBR® Green-based PCR amplifies a 177-bp fragment of the Ca. M. haemosuis gap, which encodes the NAD-dependent glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Using this PCR, Ca. M. haemosuis was detected in a total of seven pigs during an acute clinical disease in May 2017. This represents the first detailed description of a disease induced by Ca. M. haemosuis and the first detection of this novel HM species outside of Asia. In a further study, the newly established PCR was used to comprehensively investigate the occurrence of Ca. M. haemosuis in clinically healthy animals of different age groups in Southern Germany. Ca. M. haemosuis was prevalent in 6.25% of the sows (n=208), in 4.50% of the piglets (n=622), in 17.50% of the pigs (n=200), and in 0.00% of the breeding boars (n=183). By sampling the piglets immediately after birth and prior to the first colostrum uptake, the possibility of a vertical transmission of Ca. M. haemosuis was also determined within this thesis. Since 76.92% of the Ca. M. haemosuis positive sows gave birth to at least one Ca. M. haemosuis positive piglet, a vertical transmission is regarded as very likely. HMs are known to be transmitted blood-dependent and thus, transmitted iatrogenic or via wounds from animal to animal. The detection of M. suis in blood-free excretions such as saliva, urine, nasal, and vaginal secretions from experimentally infected animals has initiated the discussion of additional, blood-independent transmission routes. Saliva (n=148) and urine samples (n=47) were also collected from the sows examined by blood sampling, semen samples (n=183) were also obtained from the examined boars and applied to Ca. M. haemosuis qPCR. The pathogen was not detected in any of the saliva, urine, or semen samples. On the one hand, this demonstrates the lack of suitability of blood-free sample materials for diagnostics; on the other hand, it highlights the blood-dependent transmission pathways known to date and thus strengthens the potential to limit infections through strict hygiene measures during veterinary procedures and through the control of bloodsucking arthropods. In conclusion, based on the newly established qPCR assay for the sensitive and specific detection of Ca. M. haemosuis, the present work provides the first clinical and epidemiological description of the emerging hemotrophic pathogen in pigs. Further, the qPCR assay will be the basis for future studies regarding the epidemiology as well as the clinical relevance and pathogenesis of Ca. M. haemosuis -infections in pigs.

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