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Fibre in the diet of the suckling pig : opportunities for the maturation of the gastrointestinal tract and post-weaning resilience
No full textResearch with weaned piglets has provided information that dietary fibre (DF) is implicated in gastrointestinal (GIT) maturation and health. Dietary fibre can mitigate the risk for intestinal infections and diarrhoea occurring in pigs that are weaned at 3 to 4 weeks of age, which is common practice on most farms. There is a paucity of scientific information, however, on the role of DF in the diet of suckling pigs.
A pig is born with a relatively immature gastrointestinal tract able to digest and absorb nutrients from sow milk. To attain capacity to digest diets containing high levels of vegetable feedstuffs the GIT needs to go through a process of maturation. In a natural setting, a large part of a pig’s diet consists of vegetable fibrous feedstuffs, such as leaves, roots, tubers, fruits, and seeds. Wild boar and feral piglets are anticipated to start consuming non-milk feed items already early in life, including vegetable material. This allows gradual adaptation of the GIT and its harbouring intestinal microbiota to the solid diet before weaning, which is completed in nature at 10-17 weeks of age. The diet of farmed pigs also contains a high proportion of vegetable material, with varying levels of DF. Commercial pre-weaning diets , on the other hand, are formulated to be highly digestible and nutrient-dense, using sow milk as the benchmark. In this regard, there seems to be a major difference in diet characteristics between the natural diet and a typical commercial low-fibre, nutrient dense piglet diet. The implications of this difference for the maturation of the GIT are not known. Chapter 1 provides a literature overview of the significant maturational changes in dentition and the GIT after birth. For this thesis, it was decided to focus on the stomach, small and large intestine, as these organs play a central role in feed digestion and absorption. The available information shows that early nutrition of piglets modulates many aspects of the maturational processes of the GIT and the residential microbiota. The microbiota, mostly bacteria, are starting to colonize the GIT of the piglet from the immediate prenatal period onwards, especially in the large intestine where they are most abundant. Its composition develops with age of the pig in a complex coexistence with the host and the diet. The microbiota thrive on undigested nutrients, sloughed off intestinal cells and secretions (e.g., mucus, enzymes) through a process called fermentation. From the fermentation of carbohydrates, mostly volatile fatty acids are produced, such as acetate, propionate and butyrate. Volatile fatty acids are an energy source for the intestinal mucosa and the host. Furthermore, they play a role in many body processes, such as immune modulation, mineral and water absorption in the hind gut among many others. The end- products from protein fermentation, such as ammonia and branched-chain fatty acids and biogenic amines are mostly regarded as a risk for intestinal health. It is generally accepted that the intestinal microbiota play a pivotal role in GIT maturation and general health of animals, but the underlying mechanisms are still largely unclear.
Dietary fibres are characterized by the fact that the pig’s own enzymes are unable to digest them. Consequently, they pass through the stomach and small intestine to subsequently arrive at the level of the large intestine as substrate for the microbiota. For the older pig, the large intestines are well developed, and the microbiome herein capable to digest and ferment DF to a large extent (up to 70%), provided it is well adapted (‘primed’) to the DF. A well-developed microbiome possesses a wide array of enzymes capable of digesting and fermenting DF. Dietary fibres consist of an array of chemical compounds, such as cellulose, hemicellulose, oligosaccharides, lignin, and pectin. Collectively, these compounds determine the physicochemical characteristics of DF and their effect in the GIT. Solubility, in this respect, is relevant as it is associated with the fermentability of the DF by the intestinal microbiota. On the other hand, an insoluble DF may exert maturational effects too, for instance through its bulking and abrasive effects in the GIT. However, a paucity of data exists on how, next to sow milk, DF in supplemental diet affects GIT maturation in suckling piglets. For this thesis we hypothesized that DF is important for early-life GIT maturation. Hence, the aim of this PhD was to evaluate the impact of DF enriched supplemental diets on GIT maturation in suckling pigs, including the capacity and functionality of stomach, small and large intestine, and the priming of GIT microbiota to ferment a typical post-weaning diet with plant-derived carbohydrates. The research questions deduced from this hypothesis were formulated in Chapter 2. A first study was performed to answer the question whether feral piglets start to ingest vegetable material from early life onwards and how this may be associated with GIT maturation (Chapter 3). To this aim, feral piglets were collected, and their age was estimated based on body size and their dentition. Stomachs were weighed and contents were examined to determine particle size distribution and to classify the diet items. Vegetable matter (mainly ‘leaves and stems’) was predominantly present in most piglets, representing a large part of their diet (on average 83% of total stomach contents by weight). This was reported earlier for older wild boars and feral pigs. Approximately 25% of the stomachs of piglets contained curd (clotted sow milk) representing on average 16 % by weight. Other diet items (e.g., insects, fruits, seeds, mammals), were less abundant or absent. The data also indicated that a large proportion of their diets consisted of larger feed particles. The stomach development of the feral pigs appeared to be advanced when compared to stomach of farmed piglets of similar age fed a nutrient-dense, finely ground diet. We inferred from these data that feral suckling piglets consume a variety of non-milk items, mainly consisting of vegetable material with a coarse particle size from their first week of life onwards. Moreover, their diet is associated with an enhanced stomach development compared to those of farmed piglets. In a next experiment (Chapter 4), the effect of DF on GIT maturation in suckling piglets was studied. From day two of life onwards, sow suckled piglets were fed either a nutrient dense, low fibre control diet or diets enriched with two types of DF: a diet with a soluble fermentable DF from wheat; a diet with a largely non-fermentable purified cellulose, or a diet containing both DF sources. Piglets consumed the fibre-containing milk supplements and creep diets well. Upon weaning at 25 days of age, their GIT and large intestinal microbiota composition were evaluated. Stomach size and small intestinal maturation were not affected by diet. Large intestinal fill was increased with the soluble DF only. Large intestinal weight and length was increased in piglets consuming the fibrous diet; length mainly by the insoluble cellulose. Cellulose also decreased ileal pH and tended to increase ileal DM content compared to the control diet. Moreover, the concentration of volatile fatty acids tended to increase in the caecum and especially in the large intestine by supplementation with cellulose. The soluble DF source stimulated caecal propionate only. The microbiota composition showed a high individual variation and only limited dietary impact. Nonetheless, cellulose induced minor shifts in specific genera, with notable reductions of putative pathogens. It was concluded that the DF altered large intestinal morphology with little effect on the small intestine and stomach. Moreover, changes in the large intestine were associated with greater fermentation and changes of the microbiota, with more prominent effects from the low-fermentable cellulose.
In Chapter 5, it was investigated whether piglets consuming fibrous supplemental diets prior to weaning were more resilient when exposed to an oral infection with enterotoxigenic E. coli (ETEC) one week after weaning. The suckling piglets were fed the same four supplemental diets as described for chapter 4. Upon weaning at approximately 25 days, piglets were fed the same low-fibre diet. Feed intake and body weight gain did not differ between treatments. Overall, indicators of GIT and general health of the piglets were similar between groups. Therefore, it was concluded that neither the supplementation of the soluble nor the insoluble DF source to the pre-weaning diet improved post-weaning growth or GIT health of piglets.
In Chapter 6, the effect of inclusion of fine and coarsely ground oat hulls on gastrointestinal development of suckling pigs was studied. Piglets were fed one of three experimental diets. A finely ground low-fibre, nutrient dense diet served as control diet. For the high-fibre diets, heat-treated starch in the control diet was exchanged with finely or coarsely ground oat hulls. Oat hulls are a source of insoluble, slowly fermentable DF. The suckling piglets were fed the diets for approximately 3.5 weeks with their individual feed intake being recorded two times per day when separated from their dam. Feeding oat hulls did not impede clinical health or production performance of the piglets. The full stomach weights tended to be greater for the coarsely ground oat hulls compared to the finely ground oat hulls, whereas CON was intermediate. The coarse oat hulls increased GIT full weight and the weight of the caecum contents compared to piglets fed the control diet and the diet with finely ground oat hulls. Supplementing oat hulls increased villus height in the small intestines and dry matter concentration of the caecal contents. For the colon, inclusion of oat hulls increased its length, contents weight, short-chain fatty acid concentration and reduced total bacterial count as well as γ-proteobacteria count and proportion. Furthermore, feeding the coarse oat hulls reduced colonic crypt depth when compared to the finely ground oat hulls. It was concluded that supplementing oat hulls to a diet for suckling piglets exerted subtle developmental effects on gastrointestinal morphology and colonic microbial community. These effects were largely independent from the particle size of the oat hulls. In the last experiment (Chapter 7), the growth performance and faecal consistency of piglets from birth to eight weeks of age was recorded with the objective to evaluate the inclusion of oat hulls in the diet during suckling and in the nursery period. From two weeks prior to weaning until two weeks after weaning (phase 1), the same diets were fed as described in chapter 6. For phase 2 of the study (day 14-28 after weaning), the inclusion level of oat hulls was decreased from 15% to 5%. The inclusion of oat hulls resulted in a reduction of the dietary net energy concentration by 12% and 4% for phase 1 and 2, respectively. The general health of all piglets remained good, based on the low morbidity and mortality rates. Pre-weaning feed intake and growth were not affected by diet. Overall, faeces score, body weight gain, feed intake and feed efficiency were similar across treatments. The overall net energy efficiency for weight gain was improved for pigs fed the oat hull diets. It was concluded that diluting pre- and post-weaning diets with oat hulls did not significantly influence performance in piglets.
In summary, with DF supplementation of diets for suckling piglets it was possible to alter the maturation of the gastrointestinal tract and large intestinal microbiota. This was associated with greater fermentation activity in the large intestine. The magnitude of the observed changes were, however, subtle. Early feeding of DF may represent a ‘window of opportunity’, but its relevance for post-weaning resilience of the piglet needs to be further elucidated. Still, the work described in this thesis shows that young pigs can adapt to fibrous diets, even before weaning, confirming data in grower-fattener pigs and sows. Further work is warranted to optimize DF nutrition in the youngest category of pigs, both with respect to inclusion level as well as for the period during which fibrous diets are fed. Increasing our understanding of the diet of pigs in nature may advance the development of healthy diets as part of a sustainable pig production system with high welfare standards
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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