Browsing by Subject "Legehenne"

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Comprehensive characterization of microbiota in the gastrointestinal tract of quails and two high yielding laying hen breeds
(2023) Roth, Christoph Florian; Camarinha-Silva, Amélia
The microbiomes composition in the gastrointestinal tract (GIT) is subject to several changes and influences. In addition to breed, sex, or diet, age affects the GIT microbiome dynamics of laying hens and quails. From the first day, the microbiome develops and increases its bacterial load to thousands of species. Then, depending on the diet fed, the animals microbiome and associated active bacteria vary and directly influence the animals nutrient uptake and efficiency. Omics technologies give insights into changes in microbes in the GIT (crop, gizzard, duodenum, ileum, caeca). In addition, they can reveal how feed supplements such as calcium (Ca) or phosphorus (P) can affect host health and performance through alterations in the microbiome. The Japanese quail has been an established animal model for nutritional and biological studies in poultry for the last 60 years. In particular, its short development time makes it a convenient model for microbiome research. However, compared to broiler microbiome research, the quail microbiome is still poorly understood. Animals of the breed Coturnix japonica were housed under the same conditions, fed a diet with P below recommendation, and the ileum microbiota characterized. Microbiota relations with gender and higher or lower predisposition of the birds for PU, CaU, FI, BWG, and FC were described (Chapter II). In addition, these performance parameters influenced the relative average abundance of bacteria like Candidatus Arthromitus, Bacillus, and Leuconostoc. Gender affects specific bacterial groups of the GIT, such as Lactobacillus, Streptococcus, Escherichia, and Clostridium, which differ in average abundance between male and female quails. Despite the comprehensive microbiota analysis, the interplay between animal genetics, diet, sex, and microbiome functionality is not yet understood. The laying hen breeds Lohmann LSL-Classic and Lohmann Brown-Classic are used worldwide. Little is known about the interaction with microbiome composition, performance, dietary effects, and changes during the productive life that might help develop feeding strategies and microbiome responses on a large scale. Because of the importance of P and Ca in poultry diet, the research in Chapter III was conducted to challenge laying hens with reduced dietary P and Ca and describe the effect on GIT active microbiota. The breed was the primary driver of microbial differences. A core microbiome of active bacteria, present along the complete GIT, was revealed for the first time and consisted of five bacteria detected in 97% of all samples, including digesta and mucosa samples (uncl. Lactobacillus, Megamonas funiformis, Ligilactobacillus salivarius, Lactobacillus helveticus, uncl. Fuscatenibacter). Furthermore, significant microbial differences between the GIT sections and between the breeds were described. Minor dietary effects of the P and Ca reduction on the microbiota showed that a further decrease in Ca and P supplementation might be possible without affecting the gut microbial composition and bird performance. Furthermore, the microbiome of laying hens was characterized at five productive stages (weeks 10, 16, 24, 30, and 60) to analyze the age effect on the GIT microbiome (Chapter IV). Although the two breeds of laying hens were offered the same diet and housed under similar conditions, the active microbiota composition changed between the analyzed productive stages, the breed and the GIT sections. The major shift occurred between weeks 16 and 24 and supported the hypothesis of bacterial fluctuations due to the onset of the laying period. Those changes occurred mainly in the abundance of the genera Lactobacillus and Ligilactobacillus. However, it remains unclear whether the dietary changes, due to the development of the birds, influenced the microbiota shifts or if the anatomical and physiological modifications influenced the GIT microbiota. Furthermore, the shotgun metagenomic analysis revealed differences in regulatory functions and pathways between breeds, sections, and the two production stages. Different relative abundance levels of the microbial composition were observed between the RNA-based targeted sequencing and the DNA-based shotgun metagenomics. In conclusion, the comprehensive characterization of the microbiota in the GIT of quails and two high-yielding breeds of laying hens contributes to a broader knowledge of the microbiome dynamics within the fowl GIT. Age and breed play a more important role than diet in influencing the dynamics of microbial composition in laying hens, and individual performance and sex in quails. Research characterizing the microbiome in poultry and its effect on diet and host genetics will help improve feeding and breeding strategies in the future and reduce excretion of nutrients into the environment while ensuring overall animal health.
Effect of Omega-3 fatty acids and physical exercise on egg quality, bone characteristics and physiological parameters in laying hens
(2013) Jahja, Ardita; Grashorn, Michael
It is well proven that eggs enriched with omega-3 fatty (n-3) acids have additional health benefits in humans. Various feeding stuffs may be used for enriching eggs with n-3 PUFA. Besides nutrition physical exercise may play a role in this context. Physical exercise influences both the metabolism of fatty acids and the mechanisms of bone formation. Bone breakage is a serious welfare problem of laying hens. Broken bones were found in about 30% of hens before slaughter and the proportion reached 90% at the end of the processing line. Beneficial effects of n-3 fatty acids have been reported on bone strength in Japanese quail and growing chickens. Thus, the objectives of the present study were to elucidate the relationships between sources of dietary fatty acids and physical exercise in laying hens on performance, egg quality, bone characteristics and some physiological criteria of lipid metabolism. In total 36 brown laying hens were used and 12 hens each were fed with three experimental diets differing only in the fat source: Palm oil (PO), Soybean oil (SO), Linseed oil (LO), corresponding to a low content of poly unsaturated fatty acids (PUFA) ? PO, high content of omega-6 (n-6) fatty acids ? SO, and high content of n-3 fatty acids ? LO. Half of hens of each dietary group (6 birds) were exposed to exercise by walking on a treadmill (EG), whereas, the remaining 6 hens served as a control (CG). EG birds were exposed to a running treadmill every day for the whole experimental period (4 wk). On the first day the birds walked 5 min with the speed of 0.5 miles/h. Then duration of walking and speed was increased progressively until day eleven. Thereafter, until the end of the experiment hens walked 25 min/day. On the first day the distance walked was 67 m and increased to 469 m/day on day eleven. The experimental design was: 3 diets x 2 activities x 6 birds = 36 hens. At the end of the experiment eggs were collected to determine yolk fatty acids profiles and hens were slaughtered to collect blood indicators for lipid metabolism, tibia bones to determine bone characteristics and hearts and livers to calculate relative weights. Diets significantly influenced egg weight, yolk proportion and fatty acids profiles. The highest egg weight was observed for SO and the highest yolk proportion for LO. Contents of SAT and MUFA were significantly higher in eggs of group PO, whereas, LO and SO showed a higher content of PUFA. Eggs of treatments SO and LO had the highest proportions of linoleic acid and linolenic acid, respectively. N-6 and n-3 contents in PO and in SO eggs were eight times higher than for LO (P<0.05). Exercise of birds did not affect egg weight, yolk proportion or fatty acids profiles indicating a dominating effect of dietary fat source. The interaction exercise x diet was significant for yolk proportion only. There was no significant effect of diet or physical exercise on bone characteristics determined by computer tomography, but, there was a consistent trend of higher level of total area and corticalis area in the LO group as compared to PO and SO groups. Total density and cortical density showed the opposite tendency. Significant diet x exercise interactions were observed for total area, corticalis area and corticalis density. Running on the treadmill resulted in lower total area and corticalis area for diets LO and PO, whereas, higher values were observed for birds with exercise fed on diet SO. In contrast, for corticalis density lower values were observed for birds without exercise fed on diets LO and PO. Further characteristics of tibia were not significantly affected by main factors or their interaction, but tibia of birds fed on diet PO showed the highest ash, Ca and P contents (% dry matter). Diet PO resulted in lower body weight, increased relative liver weight and serum cholesterol level. Hens fed with diet SO showed the highest serum ALAT level indicating an accelerated lipid metabolism. There were no significant effects of exercise on other characteristics. Interactions between dietary fat and exercise revealed that exercise can compensate negative side-effects of an increased metabolic activity for diets SO and LO, whereas, the unfavourable effects of a diet with a low content of linoleic acid (PO) cannot be removed. In summary, fatty acids profile of egg yolk has been modified by diets as expected. Physical exercise, in contrast did not show any influence on yolk fatty acid profiles. Higher levels of n-3 fatty acids in free range eggs reported in earlier studies are obviously not caused by higher physical exercise. The effect of physical exercise and diet on bone stability is not caused by the individual factors but by their interactions. While physical exercise in the LO and PO diet reduced bone area and increased bone density, the opposite effect was observed for SO diet. Since lower bone density was compensated by larger bone area the treatments did not affect bone breaking strength.
Effects of strain, lifespan and dietary myo-inositol sources on poultry metabolism
(2020) Gonzalez Uarquin, Duvan Fernando; Huber, Korinna
Poultry production has shown a significant increase during the last decade. Meat and egg industry rapid growth implicates accelerating metabolic rate and general performance of birds. To maintain a high level of production, several strategies to achieve optimal raising and feeding have been implemented. Previous studies demonstrated the importance of MI metabolism on animal physiology; however, at present there is a substantial lack of information about the roles of MI and its metabolism in poultry. For instance, no information is available about MI concentration in organs of poultry. Moreover, it remains no elucidated, which are the effects of dietary sources of MI such as dietary phytase or pure MI supplementation. This thesis focused on gaining a comprehensive understanding of the potential roles of strain, productive period, and dietary sources of MI on poultry metabolism. To obtain the state of the art research on MI metabolism and its dietary sources in poultry, a comprehensive review of dietary MI was written (manuscript 1, chapter 3). This review revised information about MI in poultry such as feed sources, transport and cell metabolism, physiological meaning, and the influence of dietary MI in poultry. The revision indicated that MI appears to play critical roles in several different metabolic pathways so that understanding them could be an essential approach for future research in poultry. The second study was performed to study the effects of phytase and pure MI supplementation on the metabolite profile of broilers (manuscript 2, chapter 3). It was observed that phytase supplementation affected differently the metabolite profile than the supplementation of pure MI. Metabolites affected by phytase comprised several groups of metabolites such as acylcarnitines, phosphatidylcholines, sphingomyelins, lysophosphatidylcholines, and biogenic amines, whereas pure MI supplementation increased plasma concentrations of dopamine and serotonin. The third study was performed to get preliminary information about the effects caused by dietary phytase on systemic MI on the gastrointestinal tract, blood, and organs MI of broiler chickens (manuscript 3, chapter 3). Supplementation of 1500 FTU phytase/kg feed increased plasma and kidney MI concentrations. Plasma MI correlated negatively with InsP6 and positively with intestinal MI concentrations. A fourth study gave a general description of MI concentrations and general metabolite profile during the productive life of Lohmann Classic Brown and Lohmann LSL Classic laying hens. It was found that productive period affected MI and MI key enzymes expression. Moreover, the analyses showed differences in metabolite profiles being the onset of egg production, a determinant point. Differences were attributed to different groups of metabolites such as amino acids, biogenic amines, phosphatidylcholines, lysophosphatidylcholines, and sphingomyelins. The above mentioned, indicated each strain could express different MI concentrations and metabolite profiles during distinct productive periods what should be considered to future interventions. To conclude, findings from these investigations suggested intrinsic traits such as breed and stage of production and diet could affect MI and MI key enzymes expression as well as metabolite profiles. Future studies are needed to establish the roles of MI on poultry metabolism.
Genomic analyses of behavior traits in laying hen lines divergently selected for feather pecking
(2021) Iffland, Hanna; Bennewitz, Jörn
Feather pecking is a longstanding problem in commercial layer flocks. It often causes injured birds and even cannibalism. In the past, hens were beak trimmed to reduce feather pecking. Nevertheless, this procedure is already prohibited in some EU countries. Hence, a solution to this problem is urgently needed. The experimental populations analyzed in this thesis were formed by hens based on a White Leghorn layer strain which were divergently selected for high and low feather pecking since 1995. The first experimental population of this thesis was an F2 cross of about 900 hens which was established of the 10th generation of the pure selection lines. The second population consisted of about 500 hens of the 15th generation of these two lines. The aim of this thesis was to gain further knowledge of the genetic background of feather pecking and its relation to additional behavior traits and the gut microbiome. In chapter one, a novel model to detect extreme feather pecking hens was developed. Therefore, a mixture of two negative binomial distributions was fitted to feather pecking data of the F2 cross. With the estimated parameters, the trait posterior probability of a hen to belong to the extreme feather pecking subgroup (pEFP) was calculated. The fear tests tonic immobility and emerge box were conducted at juvenile and adult age of the hens to relate fearfulness to pEFP. After dichotomization, all traits were analyzed in a multivariate threshold model and subsequent genomewide association studies (GWAS) were performed. The fit revealed that extreme feather peckers made up a proportion of about one third of the hens. The new trait pEFP has a medium heritability of 0.35 and is positively correlated with the fear traits. Breeding for this new trait could be an option to reduce the proportion of extreme feather peckers. An index of fear related traits might serve as a proxy to breed indirectly against pEFP. In chapter two, the model to detect extreme feather pecking hens was applied to the pure selection lines. After calculation of the trait pEFP, GWAS with a subsequent post GWAS analysis were performed. Additionally, to find genomic regions influencing feather pecking, selection signatures were mapped by applying the intra-population iHS and the inter-population FST approach. Mapping of selection signatures revealed no clear regions under selection. GWAS revealed a region on chromosome one, where the existence of a quantitative trait locus (QTL) influencing feather pecking is likely. The candidate genes found in this region are a part of the GABAergic system. Despite the polygenic nature of feather pecking, selection on these candidate genes may reduce the extreme occurrence of it. In chapter three, the relation between agonistic behavior and feather pecking was analyzed. Therefore, the active parts of the traits (delivery of feather pecking, aggressive pecking or threatening) as well as the passive parts (reception of the traits) were considered. These groups of traits were additionally summarized by means of an index formation which led to the two additional traits Activity and Passivity, because all these behaviors are undesired in their excessive manifestations. Moreover, Indices were built by subtracting the passive traits from the respective active traits to obtain the feather pecking index, the aggression index and the threat index. Phenotypic correlations were estimated between all traits which were followed by heritability estimations and GWAS. Feather pecking is significantly positively correlated with the agonistic traits in both lines. The active traits and the feather pecking index show medium heritabilities. Hence, selection on high feather pecking leads to an increase of agonistic behavior whereas the correlation probably depends on the phase of establishing the social hierarchy and might disappear, after a stable ranking is established. GWAS revealed that the heritable traits in this study seem to be typical quantitative traits. Chapter four provides the analyses of the gut microbial composition of the two feather pecking lines, followed by the estimation of microbiabilities for feather pecking and the two agonistic behavior traits, to study the influence of the gut microbiome on behavior. Microbiota samples from digesta and mucosa were taken from ileum and caecum. The microbial communities were determined by using 16S RNA gene sequencing techniques. Although both lines differ significantly in some fractions of their gut microbial composition, the microbial animal effects were mostly negligibly small. Thus, the calculated microbiabilities were close to zero and not significant in both lines and for all traits investigated. Hence, trait variations were not affected by the gut microbial composition in both feather pecking lines. The thesis ends with a general discussion where additional results of a meta-analysis of pEFP and breeding strategies against feather pecking are considered.
Impact of housing environment and rearing condition on the immune system and welfare of laying hens
(2021) Hofmann, Tanja Melanie; Stefanski, Volker
In recent years, consumers’ interest in modern farm animal husbandry and, above all, criticism of intensive production systems that can impair animal welfare, have increased sharply. From hatch, chickens are confronted by a wide range of environmental and social stressors that may confound homeostasis and impair their health and welfare. Not being able to deal with the environment can lead to an activation of the stress system, resulting in a release of neuroendocrine signals like glucocorticoids. These have the potential to modify the immune system and alter species-specific behavior with possible detrimental impacts on animals’ health and welfare. In this context, early-life conditions play a special role as they were shown to have long-term consequences for physiology and behavior in the later life. High stocking densities which activate the hypothalamic-pituitary-adrenal-axis are said to be one of the largest welfare concerns in the poultry industry. Previous research has primarily focused on the effects of stocking density on broilers and adult laying hens, but few studies have focused explicitly on layer pullets, and none of them investigated long-term effects on the immune system. The understanding of short- and long-term consequences of environmental conditions during rearing on the immune system and behavior of layer pullets is essential for shaping an environment that avoids allostatic overload, thus promoting animal health and welfare. This doctoral thesis aimed to identify and evaluate potential immunomodulating factors in the housing environment of chickens. In order to achieve this, it summarizes and reviews important aspects of housing environments for the immune system in chickens. Furthermore, an existing flow cytometric method for the enumeration of leukocytes and discrimination of lymphocyte subsets in blood was adapted to lymphatic tissues. Moreover, short- and longterm consequences of stocking density during rearing on the immune system, stress hormone level and behavior in layer pullets were evaluated. The results are described in detail in three peer-reviewed manuscripts published in international journals. The literature analysis identified several housing conditions as immunomodulating factors. Light management was marked as an effective tool to modulate the immune response in chickens, as long light phases were demonstrated to lower adaptive cellular and humoral immune responses while certain light colors, especially of shorter wavelengths, promote some immune functions. Moreover, particularly high ammonia and hydrogen sulfide concentrations pose a threat to chickens’ health by dampening the adaptive immune response and promoting inflammation. However, the interaction between housing environment and management is complex. Depending on the type of housing form, chickens are confronted with different social and environmental challenges, which in turn can have an impact on the immune and stress system. An understanding of immunosuppressive risk factors is essential for successful poultry management aiming to optimize health, welfare and economic efficiency. To broaden the assessment of immune status for scientific purposes, new staining- and gating strategies for avian lymphatic tissues were adapted to an existing flow cytometric method for blood. The adaptation process showed that the application of already established protocols to other tissues is possible, but has to be examined carefully as tissue-specific effects or cell-preparative procedures might lead to differences in possible combinations of antibody-fluorochrome conjugates. The results of the experimental study within this doctoral thesis demonstrate for the first time that stocking density during rearing has not only short- but also long-term impacts on the immune system in laying hens. Pullets reared at high stocking densities showed stress-related alterations in immune cell numbers and higher incidences of feather pecking that manifest in the laying period. This highlights the significance of early-life conditions for immunocompetence throughout the whole production cycle. Of particular interest is that the number of gamma-delta T cells was lower in the high-density group, which has not been investigated in any stress-related studies with chickens before. The present doctoral thesis provides a significant contribution to the improvement of health and welfare in poultry farming and forms a basis for further research about long-lasting consequences of rearing conditions on the immune system, especially in laying hens.
Mitochondrial haplotypes, gene expression and nuclear diversity in two strains of laying hens
(2021) Dreyling, Clara; Hasselmann, Martin
The domesticated chicken (Gallus gallus domesticus) is the most popular and widely spread domestic fowl worldwide, providing human with a stable source of protein in form of meat and eggs for centuries. The ongoing growth of human population increases the need for food and made poultry production one of the fasted growing sectors in the past decades. This need for food has resulted in several different strains which outperform their wild ancestors in terms of meat and egg production. During the past decades not only animal welfare gained importance but also ecological aspects such as global warming and the shortage of resources are becoming more important to society. One important resource for mankind which is becoming shortened is phosphorus (P), whose deposits in form of rock phosphate could be exhausted within the next 50-100 years. 90% of P supply is used in agriculture as fertilizer, whose demand will increase as well with growing population. This thesis focuses on the mitochondrial genetic background and mitochondrial related gene expression in the context of the productive life span and different diets in two contrasting high-yielding strains of laying hens, Lohmann Brown-Classic (LB) and Lohmann LSL-Classic (LSL). Mitochondria, which are commonly known as the powerhouse of the cell due to their role as the main producer of energy, play roles in other processes from cellular homeostasis to the process of ageing. The process of oxidative phosphorylation depends on the availability of P and thus, they become an important part of the complex framework of P utilization. In addition, mitochondrial haplotypes are known to affect physiological traits such as body weight in laying hens or important traits such as e.g. the metabolic capacity in dairy cows. It is known, that single mutations in the mitochondrial genome lead to a better adaptation to height in the Tibetan chicken or play a role in diseases from Alzheimer to obesity or lead to resistance to disease such as Marek’s disease in birds. This work provides insight into the whole mitochondrial genome of 180 laying hens of two commercial strains and links this information to physiological traits and genetic diversity. In addition, the first large-scaled gene expression analyses in the context of the productive life span and different P and Ca contents in laying hens is implemented. The analysis of mitochondrial haplotypes revealed a low level of genetic diversity with only three haplotypes within the LB strain while all LSL hens shared the same mitochondrial genome. Following from this observation, the nuclear genome was analysed based on genotyping data to reveal the whole genetic diversity of both strains. On the nuclear genetic level, both strains appeared as clearly distinct and equally diverse, while some individuals appear as strikingly close related. These individuals are mostly half-siblings sharing the same mitochondrial haplotype, underlining the need for more analyses about the genetic structure about the parental generation, especially the maternal background. Although there were no strong associations were found between the mitochondrial haplotypes and the analysed phenotypic traits (feed intake, body weight, P and Ca utilization), the differences between the strains indicate a potential involvement of the mitochondrial genetic background. The gene expression analyses revealed tissue type and point of the productive life span as the main influencers on gene expression while the influence of the strain is secondary. In addition, the expression of the gene GAPDH, which is frequently used as a reference gene for normalization in gene expression studies, was influenced by tissue and strain, leading to the decision to exclude it as a reference, that should be considered for in further studies. Further, no influence of the changes in dietary P and Ca on gene expression could be observed, suggesting that a reduction of 20% of both minerals is possible without the need to adapt gene expression. However, the results show, that a reduction of both minerals has less effect than a reduction of P alone, leading to an imbalance. In the context of the productive live span, mitochondrial and mitochondrial regulatory genes react contrary, illustrating the complexity of mitochondrial gene expression and regulation. In addition to the higher variance in the analysed phenotypic traits and mitochondrial genome in LB hens, they showed signs of increased oxidative stress compared to LSL hens. In the context of the productive life span, a potential higher demand for energy is suggested, since OXPHOS related gene expression is increasing. As a conclusion this work provides an insight into the mitochondrial genome and provides the first large scaled analysis of mitochondrial linked gene expression in two contrasting laying hen strains.
Untersuchungen zu den Beziehungen von Federpicken, Exploration und Nahrungsaufnahme bei Legehennen
(2008) Benda, Isabel; Bessei, Werner
First documented in 1873 by Oettel (1873), the problem of feather pecking and feather eating remains a major issue in modern laying hen husbandry. Various motivational models developed in the past years interpret feather pecking as redirected foraging behaviour, pecking while sand bathing or as misdirected exploratory behaviour. The laying hens, however, only show exploratory curiosity in these diverse materials for a short time. It has been shown that diet-related deficiencies elicit increased exploratory behaviour and feather pecking. In the first section of this experiment, we attempted to redirect the exploratory pecking activity of the laying hens to an alternative object (pecking block) for a sustained period of time through offering the animals food and calcium separately. Less feather pecking behaviour was expected to result. Investigations carried out in recent years indicate an association between feather pecking and feather eating. Although almost indigestible, both wood shavings (cellulose) and feathers are eaten by laying hens. Hence, the influence of feathers and cellulose in food on the behaviour of laying hens was tested in the second section of this experiment. The inclusion of feathers or cellulose in food was expected to reduce feather pecking behaviour, since the animals? requirement for these substrates was adequately covered in the food. The goal of the third section of the experiment was to determine if the ingestion of feathers or wood shavings has an underlying physiological background, which consequently initiates a need for these substrates. The effect of substrate ingestion was tested in two different lines. The first experiment comprised three feeding treatments. Group 1 received a calcium-poor ration (0.67% Ca) whereas groups 2 and 3 received a calcium-balanced ration (3.45% Ca). An additional pecking block containing molasses and bran was available to birds in groups 1 and 2. The pecking block available to birds in group 1 had a calcium content of 31%. Each of the 3 treatments was repeated 10 times with 8 laying hens per treatment. Half of the animals were brown, the other half white laying hybrids. The three groups did not differ in their propensity to feather peck. However, animals in group 1 showed a better feather condition than those in groups 2 and 3. Breed origin had a significant effect on pecking activity, whereby brown laying hybrids displayed aggressive and vigorous feather pecking more frequently than their white counterparts. The second section of the investigation likewise comprised three feeding treatments. The first group received pellets with 10% feather grit, the second group pellets with 10% cellulose and the third group received additive-free pellets. Each treatment was repeated 4 times on 15 hens (white laying hybrid). Feed preference with respect to the different pellet variations available was examined and feather eating behaviour was tested after the test rations were discontinued. Birds in both the feather grit and cellulose groups showed less feather pecking behaviour than control animals throughout the entire experiment. Likewise, birds in the feather grit group had a significantly better plumage condition than those in the control group. Animals in the feather grit group also ate more pellets and ingested significantly more feathers than those in both the control and cellulose groups. The third section of the experiment was conducted with animal selected on high (HFP) and low (LFP) feather pecking activity (KJAER et al., 2001); three different feeding treatments were tested. Birds in the first group were offered 70 feathers per week (HF and LF), birds in the second group had access to wood shavings ad libitum (HSp and LSp), and birds in the third group were not offered any additional substrates (H0 and L0). The intestinal passage rate of each group was investigated, whereby animals receiving additional substrates were selected for comparison when the amount of substrate (feathers or wood shavings) ingested was comparable. Animals in the HF group showed the fastest intestinal passage rate, followed by LF and H0 birds. The L0 animals had the slowest marker excretion. Although feather intake in HF and LF groups was similar, only the HF birds had a significantly faster passage rate. HFP birds which had access to wood shavings showed faster marker excretion as LFP birds in comparison. This experiment demonstrates that misdirected exploratory behaviour does not seem to be the primary cause of feather pecking. Rather the ingestion of feathers or wood shavings / cellulose plays a meaningful role in this behaviour. The results of this study show that feather pecking can be classified as feeding behaviour. This is in accordance with previous literature in which feather pecking is identified as feather eating. Furthermore, genetic discrepancies between HFP and LFP animals seem to exist, since the ingestion of a similar amount of feathers or wood shavings had different effects on the intestinal tracts of the animals in the two lines. Further research is necessary to validate the results of this study.
Untersuchungen zur Motivation zum Federfressen bei Legehennen
(2007) Häusler, Kirsten; Bessei, Werner
The focus of this thesis is to unveil the dependency of feather pecking as an expression of explorative behaviour (foraging and activity) and the actual ingestion of feathers. The survey of motivation ratio was realized through conduction a preference test. This was performed by two substrate variations (feathers and feed) at three different grades of accessibility within the trial location. In addition the strength of motivation was measured by force records of pecking impacts vial corresponding gratification in a facility for operant conditioning (Skinner Box). The trials have been conducted with White Leghorn hens, which were selected over six generations on performing high (HFP) and low (LFP) feather pecking activity. At first 20 HFP and 20 LFP individuals were tested in the preference test. The choice presented was displayed as loose feathers (for ingestion), affixed feathers (activity), feed and an empty alternative. Each substrate was provided in equal quantity and frequency at all three grades of accessibility. The findings confirm the HFP type to peck a distinct higher degree of feathers than the LFP. Even affixed feathers were found to be atorn for ingestion mainly by the HFP. The highest grade of substrates displayed by transparent plastic foil remained untouched. 28 individual hens (14 HFP and14 LFP) were selected from the group of hens which were tested in the preference test. The strength of motivation was revealed by the operant conditioning method. The hens were taught tit peck at a pecking device for food and mealworms. They were tested with a fixed (FR)-reinforcement schedule. By using the FR the hens had to peck in the pecking device for a determinate number (1, 5, 10, ...). The number of pecks with had to be fulfilled by the hens where increased after each testing period until twenty by the increments of five. The described experiments were succeeded by a progressive ratio (PR = reinforcement schedule, which includes a successive increase of pecking impacts within a testing period (3x1, 3x3, 3x5, etc.) Mealworms were used to validate the system. Pecking without a reward was checked to pose as reward itself for the conditioned hens. In contrast to the LFP, the HFP (positive and negative evidence) performed a higher motivation expressed by the pecking frequency for feathers. This meets the results of the first preference test. For the second preference test 23 remaining hens (12 HFP and 11 LFP) were tested. Since affixed festhers were ingested and substrate underneath the transparent foil remained unattended in the first preference test, the dispositions of the choises were modified. Affixed feathers were removed and transparent foil was changed into non transparent plastic foil. Visual examination of the covered substrate was disqualified. Furthermore the social partner was moved from the nearby compartment to a place where contact was reduced to an audio exposure. The results of the second preference test provided no further evidence of feather pecking motivation of the conditioned individuals. HFP and LFP results showed no further discrepancy. The results of the present experiments are in contrast to the exisiting hypothesis that describes the motivation of feather pecking mainly as driven by foraging and exploration behaviour, as well as boredom. It is assumed that ingestion of feathers is a relevant issue of the motivation for feather pecking.
Variability of amino acid digestibility of cereal grains in laying hens
(2017) Zuber, Tobias; Rodehutscord, Markus
It was the objective of this doctoral thesis to generate a comprehensive data set of AA digestibility values of cereal grains in laying hens by using a strictly standardized assay procedure. Additionally, the suitability of two approaches to predict AA digestibility was examined. For this purpose, 80 genotypes of triticale, rye, corn, and wheat grains (n = 20 each) were grown as part of the “GrainUp” project. Apart from corn, the cereal species were grown under identical environmental conditions. The grain samples were comprehensively analyzed according to their physical properties, chemical composition, and gross energy concentration. The concentration of crude protein in the grain samples of triticale, rye, corn, and wheat was in the range of 113-138, 108-127, 78-112, and 125-162 g/kg dry matter, respectively. Additionally, the in vitro solubility of nitrogen (N) was determined in the grains after pretreatment with porcine pepsin and pancreatin. The animal trial comprised 16 Latin Squares (6x6), distributed among six subsequent runs. Thus, each run contained two to three Latin Squares. Cecectomized laying hens were individually housed in metabolism cages and fed either on a basal diet containing 500 g/kg cornstarch or one of the 80 cereal diets, with the cornstarch being replaced with a grain sample, for eight days. During the last four days, feed intake was recorded and excreta were collected quantitatively twice daily. After each collection period, the hens were group-housed in a floor pen for two days and offered a conventional layer diet. Amino acid digestibility of the grain samples was calculated using a linear regression approach. Relationships between AA digestibility and single analyzed fractions or the in vitro solubility of N of the cereal grains were examined by calculating Pearson product-moment correlation coefficients. Prediction equations to estimate AA digestibility were calculated by multiple regression analysis using a stepwise selection approach. Therefore, the variables were pooled according to their characteristics, and the prediction equations were calculated for the digestibility of each AA using each pool. The variables were offered in a linear or linear plus quadratic fashion and classified as significant predictors at P<0.10. The equations were assessed based on the adjusted R² and the root-mean-square error. The AA digestibility varied widely within and among the cereal species. The mean digestibility of lysine was 74% (digestibility range: 68-80%), 49% (35-59%), 79% (64-85%), and 80% (69-87%) for triticale, rye, corn, and wheat grains, respectively. A similar ranking was observed for methionine with a mean digestibility of 83% (digestibility range: 77-86%), 67% (57-75%), 91% (86-94%) and 84% (70-93%) for triticale, rye, corn, and wheat grains, respectively. Correlation analysis showed inconsistent results within and across the cereal species. Among the physical characteristics, significant correlations were detected for the thousand seed weight and the digestibility of a few AA in wheat, and for the test weight and the digestibility of a few AA in rye and corn. Significant correlations between NSP fractions and the digestibility of essential AA were detected only for rye grains. In this crop, the concentration of arabinoxylans and total NSP in the grains was negatively correlated with the digestibility of arginine, leucine, phenylalanine, and threonine. The concentration of crude protein in corn grains was positively correlated with the digestibility of essential AA, except isoleucine, tryptophan, and valine. In contrast, only a few significant positive correlations between crude protein concentration and essential AA digestibility were found for triticale and rye grains. No significant correlations were found for wheat grains in this regard. The in vitro solubility of N was negatively and positively correlated with the digestibility of a few AA in triticale and rye grains, respectively. The accuracy of the predictive equations was generally low (adjusted R² below 0.7 in most cases), and varied considerably between both pools of variables for the same AA and the same pool of variables for different AA. Thus, single or several physical or chemical characteristics could not explain the variation in AA digestibility in laying hens and the development of prediction equations sufficiently precise for the practical application was not possible.