Proper lung function relies on the precise balance of specialized epithelial cell types that coordinate to maintain homeostasis. The Hippo pathway has emerged as a critical regulator of cell fate both developmentally and in a regenerative setting. The work presented in this dissertation describes essential roles for the transcriptional effectors of Hippo pathway signaling, Yap and Taz, in maintaining lung epithelial homeostasis. The data presented here demonstrate that conditional deletion of Yap and Wwtr1/Taz in the lung epithelium of adult mice results in severe defects with consequent animal lethality. Phenotypes associated with Yap/Taz deletion include alveolar disorganization, a development of mucin hypersecretion throughout the airways, and ciliary disorganization. Through in vivo lineage tracing, analysis of mouse and human tissues, along with in vitro molecular experiments, these studies show that nuclear YAP/TAZ exert transcriptional control over club cell fate, while in multiciliated cells, they function within the cytoplasm to maintain ciliary structures. Within club cells, reduced YAP/TAZ activity promotes intrinsic goblet transdifferentiation of secretory airway epithelial cells. Global gene expression and ChIP-Seq analyses reveal that YAP/TAZ act through the TEAD family of transcription factors to suppress a goblet cell differentiation program in airway epithelial cells, including direct repression of the SPDEF gene, which encodes a transcription factor required for goblet cell identity. Further in vitro studies identify cooperation between YAP/TAZ-TEAD and the NuRD chromatin remodeling complex to inhibit SPDEF expression and that Hippo-regulated YAP/TAZ impinge on cytokine-induced goblet cell differentiation. Within multiciliated cells, we observe that phosphorylated Yap localizes in a planar polarized manner at the base of cilia and controls ciliary and basal body density. Lineage specific Yap/Taz deletion leads to reduced ciliary density and height due to a loss of apically basal bodies. Collectively, this work identifies YAP/TAZ as critical factors in lung epithelial homeostasis and offers new molecular insight into the mechanisms regulating the secretory and multiciliated cell lineages, which are frequently impaired in a broad range of lung diseases. / 2024-02-02T00:00:00Z

Goblet cells in the mucosal layer of the gastrointestinal tract are the primary source of gel-forming mucins, representing front-line defense. Sterile alpha motif-pointed domain ETS family transcription factor (SPDEF) has a crucial role in terminal differentiation, proliferation and maturation of goblet cells. Gut microbiota is an integral part of our internal environment. In a murine model of intestinal helminthic infection Trichuris muris, the interaction between host microbiota and parasite was seen to play critical roles in immune defense. This interaction is mediated through various mechanisms, including Toll-like receptor (TLR) and nucleotide-binding oligomerization domain (NOD)-like receptor signaling cascades. However, the precise role of intestinal microbiota and NOD/TLR signaling in regulating SPDEF is not yet understood. Hence, we investigated the role of SPDEF in intestinal goblet cell response, the role of helminth-microbiota axis and NOD/TLR signaling in modulating SPDEF during T. muris infection. Experiments were conducted in wild-type (SPDEF+/+) and SPDEF-deficient (SPDEF-/-) mice on BALB/c background at different timepoints of T. muris infection. We observed increased PAS+ goblet cells and higher expression of SPDEF and Muc2 in SPDEF+/+ mice following infection with elevated levels of IL-4 and IL-13. SPDEF+/+ mice showed decreased worm burden from day 14 to 21 post-infection. Microbial analysis revealed altered composition in SPDEF+/+ and SPDEF-/- after infection. Microbiota was transplanted from naïve and T. muris infected mice to separate groups of antibiotic-treated (ABX-treated) mice. Increased PAS+ goblet cells and higher expression of SPDEF and Muc2 were observed in ABX-treated mice after receiving naive and T. muris-altered microbiota. Goblet cell number, the expression of SPDEF and Muc2 were higher in ABX-treated mice who received T. muris-altered microbiota. Microbial analysis revealed differences in T. muris-altered microbiota compared to naïve microbiota. In vitro experiment was conducted in human colonic mucin secreting LS174T cells where we observed stimulated mRNA expression of SPDEF and MUC2 by T. muris excretory-secretory products. These findings reveal new information about major interactions among parasites, microbiota and SPDEF-mediated intestinal goblet cell response in the context of host defense. / Thesis / Master of Health Sciences (MSc)

O objetivo deste trabalho foi avaliar o efeito do colostro bovino liofilizado (CBL), utilizado como fonte parcial da dieta protéica, sobre as características histológicas do epitélio intestinal de juvenis de pacu (Piaractus mesopotamicus) e dourado (Salminus brasiliensis). Os juvenis foram distribuídos num delineamento experimental inteiramente casualizado em esquema fatorial 3x2. Foram utilizadas dietas com três níveis de inclusão de CBL (0%, 10% e 20%) e dois períodos experimentais (30 e 60 dias), oferecidas duas vezes ao dia até a saciedade aparente. Para o estudo histológico, o intestino foi dividido em três segmentos, S1, S2 e reto para pacu e S1, S2 e intestino posterior para dourado. Foram avaliadas a espessura da camada muscular; o volume parcial da mucosa absortiva (Vv); o número das células caliciformes contendo mucinas ácidas e neutras e totais, e os subtipos ácidas - sialomucinas e sufomucinas. Nos juvenis de pacu, a inclusão de 20% de CBL alterou a distribuição das células caliciformes contendo as mucinas ácidas, neutras e totais, os subtipos sialomucinas e sulfomucinas, e a espessura da camada muscular, enquanto o Vv foi afetado apenas pelo período experimental. Nos juvenis de dourados, efeito de período experimental foi observado para células caliciformes contendo mucinas ácidas, neutras e totais e os subtipos sialomucinas e sulfomucinas, espessura da camada muscular e Vv. A adição de 10% de CBL afetou apenas o Vv no segmento S1. Considerando os aspectos avaliados no presente estudo, a presença do colostro bovino liofilizado na dieta influenciou, no período estudado, as características histológicas entéricas de juvenis de pacu, enquanto que nos juvenis de dourado influencia desta secreção láctea não foi observada. / The aim of this study was to evaluate the effect of lyophilized bovine colostrum (LBC), used as partial source of protein in the diet, on the histological characteristics of the intestinal epithelium of juvenile pacu (Piaractus mesopotamicus) and juvenile dourado (Salminus brasiliensis). Juveniles were distributed in a completely randomized design in a factorial scheme 3x2. Three diets were used with different levels of LBC inclusion (0%, 10% and 20%) and two experimental periods (30 and 60 days) offered twice daily until apparent satiation. For the histological study, the intestine was divided into three segments, S1, S2 and rectum to the pacu and S1, S2 and posterior intestine to the dourado. The muscle layer thickness; the mucosal absorptive volume (Vv); the number of goblet cells containing acidic and neutral mucins and the acidic subtypes - sialomucin and sulphomucin were evaluated. In juvenile pacu, the inclusion of 20% of LBC changed the distribution of goblet cells containing acidic, neutral and total mucins, the subtypes sialomucins and sulphomucins, and the thickness of the muscle layer, while the Vv was affected only by the experimental period. In juvenile dourado, effect of experimental period was observed for goblet cells containing acidic, neutral and total mucins and subtypes sialomucins, sulphomucins, thickness of muscle layer and Vv. The addition of 10% of LBC affected only Vv in the segment S1. Considering the aspects studied, the presence of lyophilized bovine colostrum in the diet influenced, in the period studied, the enteric histological characteristics of juvenile pacu, while the juvenile dourado influence of this lacteal secretion was not observed.

Mucins, synthesised and secreted by goblet cells, possess potential binding sites for both commensal and pathogenic organisms, and may perform a defensive role during establishment of the intestinal barrier in newly hatched chickens. Increasing interest has been directed toward bacterial interactions within the mucus layer, and the mechanisms by which bacterial colonisation can influence mucus composition during early development. This is important, firstly, as a means to understand initiation of infection and secondly, to optimise the gut microflora for enhanced animal production. Currently, information on mucosal-bacterial interactions in poultry is limited. In order to observe the effects of bacterial exposure on intestinal goblet cell mucin production during early development, differences in the small intestine of conventionally-raised (CV) and low bacterial load (LBL) broiler chicks were examined during the first 7 days post-hatch. The initial aim of the study was to construct a small-scale, economical isolator system to hatch and raise chicks in a bacterial-free environment as a means to observe bacterial interactions with the intestinal mucosa in chickens exposed to normal environmental conditions. The design and construction of flexible plastic isolators for incubation and brooding are described, along with methodologies for preparation of eggs for entry into the isolators, incubation and hatching. Two trials were conducted, the first in August 2005 and the second in March 2006. It was found that the isolator system was successful in producing low bacterial load chicks for comparative studies with conventionally raised chicks, without compromising body weight. A histological study was then conducted whereby ileal and jejunal goblet cells were stained with either periodic acid-Schiff or high iron diamine/alcian blue pH 2.5 to discriminate between neutral, sulphated and sialyated acidic mucins. Total goblet cell numbers and goblet cell and villous/crypt morphology were also examined. Bacterial colonisation of CV animals induced an increase in sialic acid moieties in both ileal and jejunal goblet cell such that initiation of these changes occurred at day 3-4 post-hatch. Differences in intestinal morphology were also consistent with other germ-free animal studies. In order to further understand the extent to which bacteria affected mucin composition, purified, isolated oligosaccharide fractions from ileal mucin at d 4 and 7 post-hatch were collected and analysed using mass spectrometry techniques to determine any structural differences in chain length or chain number between LBL and CV animals. No differences in chain length or number were observed between CV and LBL animals at either d 4 or 7 post-hatch with both groups equally displaying chain lengths of both low and high molecular weights. Although structural differences in mucin oligosaccharides were not observed between LBL and CV animals, bacterial binding assays utilising whole ileal sections were employed to determine whether or not the differences in mucin composition between LBL and CV animals during early development may have deterred or enhanced binding of certain bacterial species. Escherichia coli and Lactobacillus salivarius were selected for the experiment. Binding of L. salivarius to ileal sections was very low whereas E. coli binding was greater, and more pronounced in LBL animals, especially at d 7 post-hatch. No statistically significant differences were observed in binding of E. coli to purified ileal mucin from LBL and CV animals at either d 4 or d 7 post-hatch. Correlations between E. coli and L. salivarius adherence to ileal tissue and mucin samples, and goblet cell parameters, were not statistically significant when fitted as co-variates. It was concluded that the changes in mucin composition played a minor role in bacterial adhesion of L. salivarius and this E. coli serotype. In summary, this thesis explores the physiological changes in goblet cell mucin production in response to bacterial exposure post-hatch. The thesis outlines the complexity of mucosal-bacterial interactions which would benefit from the employment of specialised techniques such as nuclear magnetic resonance spectroscopy and microarray technologies to examine a greater range of mucin structures and gene expression. This thesis provides support for future investigations into the influence of intestinal microflora on mucosal and mucin dynamics of poultry and the potential development of prebiotics for use in animal production. / http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1297640 / Thesis (Ph.D.) -- School of Agriculture, Food and Wine, 2007

This project has provided a better understanding of the human conjunctiva, the glistening tissue covering the white of the eye, at the cellular level. The observations of this study may serve as a useful marker against which changes in conjunctival tissue due to disease, surgery, drug therapy or contact lens wear can be assessed. Laser scanning confocal microscopy was used to observe and measure characteristics the conjunctiva of healthy human volunteer subjects. It was concluded that this technique is a powerful tool for studying the human conjunctiva and assessing key aspects of the structure of this tissue. The effects of contact lens wear on the conjunctiva can be investigated effectively at a cellular level using this technology.

Thesis (M.Sc.). / Written for the Dept. of Human Genetics. Title from title page of PDF (viewed 2009/07/02). Includes bibliographical references.

Mucociliary epithelia are found in the human airways and act as the first line of defence against inhaled foreign agents. Mucus traps potentially damaging particles and the cilia transport the mucus away from the airways to remove the threat. Modelling mucociliary epithelia for research purposes is challenging. This is because the airways are enclosed and are thus difficult to study directly. Instead, tissue is extracted or in vitro techniques are employed. Whilst these systems are useful, there is a need for accessible in vivo models to complement them. In this thesis I assess a new model system for studying mucociliary epithelia. This system is the larval epidermis of the amphibian, Xenopus tropicalis. Its epidermis comprises multi-ciliated cells that beat in a polarised direction reminiscent of those found in the human airways. It is also proposed to have a number of other cell types including mucus-secreting cells, but very little is known about them. The epidermis is open and accessible to manipulation meaning that it has great potential to be used in the study of mucociliary epithelia in live, native conditions. Such a system would be a valuable addition to the current models employed. However, the epidermis has not been thoroughly characterized before so its utility as a model system remains speculative.To develop and evaluate this new model, I fully characterize the epidermis, showing that it has five distinguishable cell types. This includes a population of cells called ionocytes that are shown to be essential for the health and function of the epidermis. I also test for the presence of mucins, the structural component of mucus, secreted from the epidermis in order to evaluate the proposal that mucus-secreting cells are present in the epidermis. A mucin-like protein called otogelin is identified. After characterizing the epidermal cell types, I compare them to the human mucociliary epithelium and consider potential applications and future perspectives for this model.

O objetivo deste trabalho foi avaliar o efeito do colostro bovino liofilizado (CBL), utilizado como fonte parcial da dieta protéica, sobre as características histológicas do epitélio intestinal de juvenis de pacu (Piaractus mesopotamicus) e dourado (Salminus brasiliensis). Os juvenis foram distribuídos num delineamento experimental inteiramente casualizado em esquema fatorial 3x2. Foram utilizadas dietas com três níveis de inclusão de CBL (0%, 10% e 20%) e dois períodos experimentais (30 e 60 dias), oferecidas duas vezes ao dia até a saciedade aparente. Para o estudo histológico, o intestino foi dividido em três segmentos, S1, S2 e reto para pacu e S1, S2 e intestino posterior para dourado. Foram avaliadas a espessura da camada muscular; o volume parcial da mucosa absortiva (Vv); o número das células caliciformes contendo mucinas ácidas e neutras e totais, e os subtipos ácidas - sialomucinas e sufomucinas. Nos juvenis de pacu, a inclusão de 20% de CBL alterou a distribuição das células caliciformes contendo as mucinas ácidas, neutras e totais, os subtipos sialomucinas e sulfomucinas, e a espessura da camada muscular, enquanto o Vv foi afetado apenas pelo período experimental. Nos juvenis de dourados, efeito de período experimental foi observado para células caliciformes contendo mucinas ácidas, neutras e totais e os subtipos sialomucinas e sulfomucinas, espessura da camada muscular e Vv. A adição de 10% de CBL afetou apenas o Vv no segmento S1. Considerando os aspectos avaliados no presente estudo, a presença do colostro bovino liofilizado na dieta influenciou, no período estudado, as características histológicas entéricas de juvenis de pacu, enquanto que nos juvenis de dourado influencia desta secreção láctea não foi observada. / The aim of this study was to evaluate the effect of lyophilized bovine colostrum (LBC), used as partial source of protein in the diet, on the histological characteristics of the intestinal epithelium of juvenile pacu (Piaractus mesopotamicus) and juvenile dourado (Salminus brasiliensis). Juveniles were distributed in a completely randomized design in a factorial scheme 3x2. Three diets were used with different levels of LBC inclusion (0%, 10% and 20%) and two experimental periods (30 and 60 days) offered twice daily until apparent satiation. For the histological study, the intestine was divided into three segments, S1, S2 and rectum to the pacu and S1, S2 and posterior intestine to the dourado. The muscle layer thickness; the mucosal absorptive volume (Vv); the number of goblet cells containing acidic and neutral mucins and the acidic subtypes - sialomucin and sulphomucin were evaluated. In juvenile pacu, the inclusion of 20% of LBC changed the distribution of goblet cells containing acidic, neutral and total mucins, the subtypes sialomucins and sulphomucins, and the thickness of the muscle layer, while the Vv was affected only by the experimental period. In juvenile dourado, effect of experimental period was observed for goblet cells containing acidic, neutral and total mucins and subtypes sialomucins, sulphomucins, thickness of muscle layer and Vv. The addition of 10% of LBC affected only Vv in the segment S1. Considering the aspects studied, the presence of lyophilized bovine colostrum in the diet influenced, in the period studied, the enteric histological characteristics of juvenile pacu, while the juvenile dourado influence of this lacteal secretion was not observed.

The incubation period is crucial for development and overall quality of a chick. The selection for fast growing broilers has allowed the birds to reach market weight at a faster rate making the incubation period a larger portion of a broiler's life. A faster growth rate can lead to the release of more metabolic heat inside of the egg toward the second half of incubation because the embryo shifts to a homeothermic state. More heat being released into the incubator can cause the incubation temperature to rise if the incubator is not electronically regulated or cannot be ventilated properly due to malfunction. A high incubation temperature can impact the hatchability, growth, and development of the chick. This thesis provides a more in-depth analysis of the effects of high incubation temperature (37.5°C versus 39.5°C) on the developing small intestine and yolk sac, which provide the chick with nutrients posthatch and during embryogenesis. Studying these organs and mechanisms occurring during this time could potentially indicate why chicks from eggs subjected to a higher incubation temperature are not developing and growing properly. Chicks from eggs incubated at a higher temperature had lower body weights, lower hatchability and lower villus height in the duodenum, jejunum, and ileum. There were also differences seen in the depth of the crypt, which is the site for stem cells. Chicks from eggs incubated at a higher temperature had a lower crypt depth in the duodenum and jejunum. There was no difference in the expression of the intestinal stem cell marker olfactomedin 4 (Olfm4) and mucin 2, which is secreted by goblet cells and forms mucus. In the yolk sac, heat shock proteins (HSP) 70 and 90 were elevated at embryonic day 15, and HSP90 still remained elevated at embryonic day 17. Chicks from eggs incubated at a higher temperature showed greater expression of peptide transporter 1 and avian beta-defensin 10 mRNA at embryonic day 13. Even though small intestinal morphology was impacted early posthatch and expression of genes in the yolk sac were elevated at embryonic day 13, there does not seem to be a long-lasting effect on the development of the small intestine or the yolk sac. It is still important to study the impact of the incubation environment to understand the development and growth of the chicks and how different incubation factors can impact the overall hatchability and health of the chick. / Master of Science / The incubation period is crucial for development and overall quality of a chick. The selection for fast growing broilers has allowed the birds to reach market weight at a faster rate making the incubation period a larger portion of a broiler’s life. A faster growth rate can lead to the release of more metabolic heat inside of the egg toward the second half of incubation because the embryo shifts to a homeothermic state. More heat being released into the incubator can cause the incubation temperature to rise if the incubator is not electronically regulated or cannot be ventilated properly due to malfunction. A high incubation temperature can impact the hatchability, growth, and development of the chick. This thesis provides a more in-depth analysis of the effects of high incubation temperature (37.5°C versus 39.5°C) on the developing small intestine and yolk sac, which provide the chick with nutrients posthatch and during embryogenesis. Studying these organs and mechanisms occurring during this time could potentially indicate why chicks from eggs subjected to a higher incubation temperature are not developing and growing properly. Chicks from eggs incubated at a higher temperature had lower body weights, lower hatchability and lower villus height in the duodenum, jejunum, and ileum. There were also differences seen in the depth of the crypt, which is the site for stem cells. Chicks from eggs incubated at a higher temperature had a lower crypt depth in the duodenum and jejunum. There was no difference in the expression of the intestinal stem cell marker olfactomedin 4 (Olfm4) and mucin 2, which is secreted by goblet cells and forms mucus. In the yolk sac, heat shock proteins (HSP) 70 and 90 were elevated at embryonic day 15, and HSP90 still remained elevated at embryonic day 17. Chicks from eggs incubated at a higher temperature showed greater expression of peptide transporter 1 and avian beta-defensin 10 mRNA at embryonic day 13. Even though small intestinal morphology was impacted early posthatch and expression of genes in the yolk sac were elevated at embryonic day 13, there does not seem to be a long-lasting effect on the development of the small intestine or the yolk sac. It is still important to study the impact of the incubation environment to understand the development and growth of the chicks and how different incubation factors can impact the overall hatchability and health of the chick.

<p>Препарати ћелијског зида квасца користе се у исхрани домаћих животиња са<br />циљем побољшања њихових производних резултата и здравља. Ћелијски зид<br />квасца садржи две врсте бета глукана и алфа манан чијим разлагањем настају<br />мананолигосахариди. Овим једињењима се приписују бројна корисна дејства<br />као што су везивање непожељних бактерија и микотоксина, имуномодулаторно<br />дејство итд. Огледи обухваћени овом дисертацијом испитивали су утицај једног<br />новог препарата ћелијског зида квасца на бројлерске пилиће. У првом огледу,<br />два нивоа препарата су поређена са стандардном смешом и праћен је утицај на<br />телесне масе пилића, конверзију хране, морталитет пилића, дужине и масе<br />црева, масе различитих органа, бактеријске популације црева, морфометрију<br />црева, пехарасте ћелије у епителу црева и стање простирке. У наредном огледу<br />три концентрације препарата су поређене са контролном групом и праћени су<br />исти параметри као у првом огледу, осим бактеријских популација, дужина и<br />маса црева и стања простирке. У трећем и четвртом огледу, испитивања<br />препарата су вршена на пилићима који су са 13 дана старости раздвојени у<br />тежинске групе. Трећи оглед је, уз праћење производних параметара, обухватио<br />испитивања цревних ресица и пехарастих ћелија епитела црева, док су се у<br />четвртом огледу испитивали само производни резултати. Добијени резултати,<br />тумачени у контексту бројних других истраживања на ову тему, указују да<br />додатак препарата ћелијског зида квасца може довести до побољшања<br />производних параметара бројлерских пилића. Просечно побољшање које се<br />добија употребом новог препарата слично је или благо боље од просечних<br />побољшања до којих доводе ранији слични препарати. Завршна телесна маса је<br />просечно већа за око 40 g, утрошак хране по тони произведене живе масе<br />смањен је за око 34 kg хране, а преживљавање пилића је веће за око 1,5%. Од<br />испитиваних концентрација препарата, најефикаснијом се показала 0,04%,<br />односно 400 g препарата по тони хране. Ова концентрација је неколико пута<br />нижа од уобичајено коришћених концентрација претходних сличних препарата,<br />што потврђује да је нови препарат концентрисанији од претходних. Утврђена је<br />велика варијабилност дејства препарата ћелијског зида квасца која се кретала од<br />потпуног изостанка утицаја до веома снажних ефеката. Део ове варијабилности<br />се може објаснити различитим условима узгајања пилића. У четири огледа<br />обухваћена дисертацијом потврђена је хипотеза да се дејство препарата јаче<br />испољава када су пилићи у неповољнијој ситуацији. Најјаче дејство је<br />забележено у огледу у коме су постигнути најслабији производни резултати, а<br />најслабије у огледу са најбољим производним резултатима. Трећи и четврти<br />оглед су показали да се пилићи чија телесна маса одступа од просека суочавају<br />са различитим проблемима. Додатак препарата је делимично успео да ублажи<br />уочене проблеме код пилића малих и великих телесних маса, не мењајући при<br />томе битно резултате просечних пилића. Ово указује да препарат испољава<br />своје дејство првенствено на пилићима угроженим одређеним проблемима, што<br />је веома важно за његову практичну примену. Додатак препарата није изазвао<br />промене у броју укупних аеробних и анаеробних бактерија, лактобактерија,<br />бифидобактерија, ентерокока и Е. coli у садржају слепих црева бројлерских<br />пилића. Утицаји додатка препарата на дужину танког црева и његових поједних<br />делова, масе црева, масе органа, висину и ширину цревних ресица, дубину<br />цревних крипти и остале везане параметре били су варијабилни. Није утврђено<br />да постоји директна повезаност ових промена са производним резултатима, па<br />се може претпоставити да се ради о ефектима који се јављају паралелно се<br />побољшањем производних резултата, а не као узрок тог побољшања. Најјачи<br />утицај препарата утврђен је на пехарасте ћелије црева бројлерских пилића.</p> / <p>Preparati ćelijskog zida kvasca koriste se u ishrani domaćih životinja sa<br />ciljem poboljšanja njihovih proizvodnih rezultata i zdravlja. Ćelijski zid<br />kvasca sadrži dve vrste beta glukana i alfa manan čijim razlaganjem nastaju<br />mananoligosaharidi. Ovim jedinjenjima se pripisuju brojna korisna dejstva<br />kao što su vezivanje nepoželjnih bakterija i mikotoksina, imunomodulatorno<br />dejstvo itd. Ogledi obuhvaćeni ovom disertacijom ispitivali su uticaj jednog<br />novog preparata ćelijskog zida kvasca na brojlerske piliće. U prvom ogledu,<br />dva nivoa preparata su poređena sa standardnom smešom i praćen je uticaj na<br />telesne mase pilića, konverziju hrane, mortalitet pilića, dužine i mase<br />creva, mase različitih organa, bakterijske populacije creva, morfometriju<br />creva, peharaste ćelije u epitelu creva i stanje prostirke. U narednom ogledu<br />tri koncentracije preparata su poređene sa kontrolnom grupom i praćeni su<br />isti parametri kao u prvom ogledu, osim bakterijskih populacija, dužina i<br />masa creva i stanja prostirke. U trećem i četvrtom ogledu, ispitivanja<br />preparata su vršena na pilićima koji su sa 13 dana starosti razdvojeni u<br />težinske grupe. Treći ogled je, uz praćenje proizvodnih parametara, obuhvatio<br />ispitivanja crevnih resica i peharastih ćelija epitela creva, dok su se u<br />četvrtom ogledu ispitivali samo proizvodni rezultati. Dobijeni rezultati,<br />tumačeni u kontekstu brojnih drugih istraživanja na ovu temu, ukazuju da<br />dodatak preparata ćelijskog zida kvasca može dovesti do poboljšanja<br />proizvodnih parametara brojlerskih pilića. Prosečno poboljšanje koje se<br />dobija upotrebom novog preparata slično je ili blago bolje od prosečnih<br />poboljšanja do kojih dovode raniji slični preparati. Završna telesna masa je<br />prosečno veća za oko 40 g, utrošak hrane po toni proizvedene žive mase<br />smanjen je za oko 34 kg hrane, a preživljavanje pilića je veće za oko 1,5%. Od<br />ispitivanih koncentracija preparata, najefikasnijom se pokazala 0,04%,<br />odnosno 400 g preparata po toni hrane. Ova koncentracija je nekoliko puta<br />niža od uobičajeno korišćenih koncentracija prethodnih sličnih preparata,<br />što potvrđuje da je novi preparat koncentrisaniji od prethodnih. Utvrđena je<br />velika varijabilnost dejstva preparata ćelijskog zida kvasca koja se kretala od<br />potpunog izostanka uticaja do veoma snažnih efekata. Deo ove varijabilnosti<br />se može objasniti različitim uslovima uzgajanja pilića. U četiri ogleda<br />obuhvaćena disertacijom potvrđena je hipoteza da se dejstvo preparata jače<br />ispoljava kada su pilići u nepovoljnijoj situaciji. Najjače dejstvo je<br />zabeleženo u ogledu u kome su postignuti najslabiji proizvodni rezultati, a<br />najslabije u ogledu sa najboljim proizvodnim rezultatima. Treći i četvrti<br />ogled su pokazali da se pilići čija telesna masa odstupa od proseka suočavaju<br />sa različitim problemima. Dodatak preparata je delimično uspeo da ublaži<br />uočene probleme kod pilića malih i velikih telesnih masa, ne menjajući pri<br />tome bitno rezultate prosečnih pilića. Ovo ukazuje da preparat ispoljava<br />svoje dejstvo prvenstveno na pilićima ugroženim određenim problemima, što<br />je veoma važno za njegovu praktičnu primenu. Dodatak preparata nije izazvao<br />promene u broju ukupnih aerobnih i anaerobnih bakterija, laktobakterija,<br />bifidobakterija, enterokoka i E. coli u sadržaju slepih creva brojlerskih<br />pilića. Uticaji dodatka preparata na dužinu tankog creva i njegovih pojednih<br />delova, mase creva, mase organa, visinu i širinu crevnih resica, dubinu<br />crevnih kripti i ostale vezane parametre bili su varijabilni. Nije utvrđeno<br />da postoji direktna povezanost ovih promena sa proizvodnim rezultatima, pa<br />se može pretpostaviti da se radi o efektima koji se javljaju paralelno se<br />poboljšanjem proizvodnih rezultata, a ne kao uzrok tog poboljšanja. Najjači<br />uticaj preparata utvrđen je na peharaste ćelije creva brojlerskih pilića.</p> / <p>Yeast cell wall products are used in animal nutrition to improve their performance and<br />health. The yeast cell wall contains two beta glucans and alpha mannan that can be<br />degraded into mannan-oligosaccharides. Numerous positive effects are attributed to<br />these compounds, like binding unwanted bacteria and mycotoxins, modulating<br />immune response etc. Trials within this PhD thesis focused on testing effect of a new<br />yeast cell wall product on broiler chickens. In first trial, diets containing two levels of<br />product were compared to a standard diet, and following parameters were recorder:<br />body weight, feed conversion ratio, chicken mortality, lengths and weights of<br />intestine, organ weights, bacterial populations of digesta, small intestine<br />morphometrics, goblet cells of intestinal epithelium and litter quality. Next trial<br />compared three concentrations of the product with a control group. Same parameters<br />to that in first trial were recorded, except lengths and weights of intestine, bacterial<br />populations of digesta and litter quality. In the third and the fourth trial, the yeast cell<br />wall product&rsquo;s effect was tested on broiler chickens grouped according to their 13th<br />day body weight. Performance, intestinal villi and goblet cells were monitored in the<br />third trial, and only performance data in the fourth trial. Results, interpreted in the<br />context of numerous other studies on this subject, indicate that feeding the yeast cell<br />wall product can improve performance of broiler chickens. Average improvement<br />observed using the new product is similar to, or slightly better than, average<br />improvements observed using earlier similar products. Final body weight was<br />increased by 40 g, feed consumption per tonne of live weight was reduced by 34 kg of<br />feed, and survival rate of chicks was 1.5% higher. The most effective concentration<br />was 0.04% (400 g/t). This concentration is several times lower than usual<br />concentrations of previous similar products, confirming that the new product is more<br />concentrated than the previous ones. Effects were very variable, ranging from the<br />complete absence of influence to very strong effects. Part of this variability can be<br />explained by the different conditions of broiler growing. In four experiments covered<br />by the thesis, the hypothesis that the effects are stronger when chickens are facing<br />certain challenges was confirmed. The strongest effect was observed in the<br />experiment when the worst performance was achieved, and the weakest effect was<br />observed in the trial with the best production results. The third and fourth trial showed<br />that the broilers with low or high body weight face different problems. Feeding the<br />yeast cell wall product partially alleviated problems identified in chickens with low<br />and high body weight, without changing results of average chicks. These results<br />suggest that this product exerts its effect mainly on chickens challenged with certain<br />problems. This conclusion is very important for product&rsquo;s practical application. The<br />yeast cell wall product did not cause changes in the number of total aerobic and<br />anaerobic bacteria, lactobacteria, bifidobacteria, enterococci and E. coli in the digesta<br />of broiler chickens. Effects on the length of the small intestine and certain parts of it,<br />the weight of the intestine, organs weight, height and width of the intestinal villi,<br />depth of intestinal crypts and other related parameters were variable. It seems that<br />there is not a direct correlation of these parameters with the performance results. It<br />can be assumed that these effects are not the cause of observed performance<br />improvements. The strongest effect of yeast cell wall product was observed on the<br />goblet cells in the intestine of broiler chickens.</p>