The pathogenesis of <i>C. jejuni</i> in broiler chickens is still poorly understood despite the importance of poultry meat as a source of infection in humans. The overall objective of this project was to understand the role of flagella and Campylobacter invasion antigens in mucosal and systemic colonization, and to evaluate the vaccine potential of <i>C. jejuni</i> paralyzed flagella mutants. As a first step to track <i>C. jejuni in vivo</i>, a Green Fluorescent Protein (GFP) reporter system that is constitutively expressed was constructed. The system was transformed into different <i>C. jejuni</i> strains and isolates, and their mucosal and systemic spreading was studied over the period of 7 days. <i>C. jejuni</i> NCTC11168V1 and V26 share the same background but differ in their ability to colonize chickens. <i>C. jejuni</i> 81-176 and K2-55 share the same genetic background but K2-55 has an insertion mutation in <i>pflA</i> gene that produced paralyzed flagella. Although the K2-55 flagella remained intact structurally, it did not secret <i>Campylobacter</i> invasion antigens (Cia). The reporter system was stable in all of these strains both <i>in vitro</i> and <i>in vivo</i>. Fluorescent bacteria were visualized successfully using fluorescent and confocal microscopes. C. jejuni NCTC11168V1 and 81-176 were detected in the intestinal tract and in the liver and spleen of more than 30% of the challenged birds, while V26 and K2-55 were only detected in the intestinal tract. <i>C. jejuni</i> 81-176 and K2-55 did not spread systemically to the spleen and liver of BALB/c mice challenged using the same approach, although they colonized the ceca.<p> A live attenuated vaccine based on <i>C. jejuni</i> K2-55 protected broiler chickens from <i>C. jejuni</i> 81-176 challenge in chickens following streptomycin treatment of drinking water. The same vaccine had no significant protection against a heterolgous <i>C. jejuni</i> NCTC11168V1 strain challenge. The vaccine was a poor stimulator of secretory IgA.<p> Macrophage-like HD11 cells inflammatory response to the presence of <i>C. jejuni</i> K2-55 was not significantly different from their response to wild-type 81-176 when measured by qRT-PCR. The lack of Cia secretion and motility had no effect on expression of IL-1â, IL-2, IL-6, IL-8, IL, IL-10, IL-12â, or TLR5. A <i>flgK</i> mutant expressing the flagella up to the hook had a significantly lower expression of these genes.

The pathogenesis of <i>C. jejuni</i> in broiler chickens is still poorly understood despite the importance of poultry meat as a source of infection in humans. The overall objective of this project was to understand the role of flagella and Campylobacter invasion antigens in mucosal and systemic colonization, and to evaluate the vaccine potential of <i>C. jejuni</i> paralyzed flagella mutants. As a first step to track <i>C. jejuni in vivo</i>, a Green Fluorescent Protein (GFP) reporter system that is constitutively expressed was constructed. The system was transformed into different <i>C. jejuni</i> strains and isolates, and their mucosal and systemic spreading was studied over the period of 7 days. <i>C. jejuni</i> NCTC11168V1 and V26 share the same background but differ in their ability to colonize chickens. <i>C. jejuni</i> 81-176 and K2-55 share the same genetic background but K2-55 has an insertion mutation in <i>pflA</i> gene that produced paralyzed flagella. Although the K2-55 flagella remained intact structurally, it did not secret <i>Campylobacter</i> invasion antigens (Cia). The reporter system was stable in all of these strains both <i>in vitro</i> and <i>in vivo</i>. Fluorescent bacteria were visualized successfully using fluorescent and confocal microscopes. C. jejuni NCTC11168V1 and 81-176 were detected in the intestinal tract and in the liver and spleen of more than 30% of the challenged birds, while V26 and K2-55 were only detected in the intestinal tract. <i>C. jejuni</i> 81-176 and K2-55 did not spread systemically to the spleen and liver of BALB/c mice challenged using the same approach, although they colonized the ceca.<p> A live attenuated vaccine based on <i>C. jejuni</i> K2-55 protected broiler chickens from <i>C. jejuni</i> 81-176 challenge in chickens following streptomycin treatment of drinking water. The same vaccine had no significant protection against a heterolgous <i>C. jejuni</i> NCTC11168V1 strain challenge. The vaccine was a poor stimulator of secretory IgA.<p> Macrophage-like HD11 cells inflammatory response to the presence of <i>C. jejuni</i> K2-55 was not significantly different from their response to wild-type 81-176 when measured by qRT-PCR. The lack of Cia secretion and motility had no effect on expression of IL-1â, IL-2, IL-6, IL-8, IL, IL-10, IL-12â, or TLR5. A <i>flgK</i> mutant expressing the flagella up to the hook had a significantly lower expression of these genes.

No description available.

Antibiotics have been included in poultry feeds to improve growth performance. However, it is a concern that pathogens have become increasingly resistant to antibiotics. Lysozyme is a potential replacement for antibiotics. A trial with or without heat stress was conducted to investigate different inclusion levels (0, 50, 100 and 200ppm) of lysozyme on broiler chickens. Another two trials were conducted using clean or used litter to determine the effect of 100 ppm lysozyme on broiler chickens in each period of the growth cycle. Birds fed the 50 ppm treatment had heavier weight than birds fed the 200 ppm treatment on day 35 (P<0.05). When used litter was provided, feeding lysozyme to birds from days 5-14 and throughout the trial reduced the number of E. coli in the ileum compared with feeding antibiotic to birds (P<0.05). Dietary lysozyme positively influences bacterial numbers in the gastrointestinal tract of broiler chickens.

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Feed is the largest single cost factor (60%) in production of chicken meat with cost of energy being a major consideration given that birds eat to satisfy an energy requirement. The Australian chicken meat industry is highly dependent on supply of energy from cereals such as wheat and barley that are known to vary widely in apparent metabolisable energy (AME). In contrast, sorghum is a relatively consistent source of energy. Diets for broiler chickens are comprised mainly of cereal grains, legumes and protein-rich meals of plant and animal origin. The diets are formulated to provide essential nutrients for maintenance and rapid growth of the flock as a whole. However, some dietary ingredients may also have chemical and physical properties that can be detrimental to the processes of ingestion, digestion, absorption, transport and utilisation of nutrients. Soluble non-starch polysaccharides (NSP) in cereal grains such as wheat and barley can depress digestion of energy by broiler chickens. This thesis examined the general hypothesis that the effects of soluble NSP in cereal grains on gut structure and function, digesta transit time, and gut microflora differ substantially between individual chickens within a flock, thus contributing to variation in the digestion of energy by the flock as a whole. A major goal of the research was to determine what characteristics of the gastrointestinal tract of broiler chickens were the key determinants of digestion of energy. Twelve experiments were conducted during this study. Breath tests involving measurements of carbon dioxide, hydrogen and methane were developed as noninvasive indicators of digestive function, and were used in conjunction with conventional methods for measuring energy digestion in commercial strains of chickens. Sex of the chicken had a significant effect (P<0.05) on AME values obtained for a diet based on wheat with a high soluble NSP content. Females were superior to males (14.6 vs 14.0 MJ/kg DM), but strain of chicken had no effect on AME. Villus height and crypt depth in the intestinal epithelium were measured to determine if any relationships between gut morphology and AME could explain why males and females differed. Males had significantly greater ileal villus height than females (P<0.05). In one of the two strains of chickens studied, villus heights in the duodenum and jejunum tended to be greater in males than females (0.05<P<0.10). In the second strain of chicken, villus heights in the duodenum and ileum were lower (P<0.05) than those in the first strain, with little differences observed between males and females. Crypt depth was unaffected by strain or by sex of the chickens. Thus, individual measurements of gut morphology were poor indicators of AME. Furthermore, only 33% of the total variation in apparent metabolisable energy (AME) could be accounted for by combinations of measurements of villus height and crypt depth in the duodenal, jejunal and ileal sections of the small intestine. It was concluded that other determinants of digestive capacity were collectively more important than gut morphology. Energy excretion by male chickens was observed to rise in an exponential manner relative to energy intake, whereas the increase in females was linear. It was reasoned that increased energy excretion by males could be due to increased endogenous energy losses from the distal part of the intestinal tract, reduced production of volatile fatty acids (VF A) by microbial fermentation in the caeca, or reduced absorption of VFA by caeca. These possibilities pointed to the need for a closer examination of the role of gut microbiota on the digestive function of chickens. It was also clear that further studies should differentiate between digestion of energy in the small intestine (by measurement of ileal digestible energy) and whole of tract digestion (by measurement of AME). ileal digestible energy (DE) values for wheat and barley were unaffected by sex of chickens, whereas AME values were lower in male chickens compared with females. These results suggested that the sex-specific effects of microbiota occurred mainly in the hindgut. Furthermore, the influence of the gut microbiota on between-bird variation in AME was partially dependent on the type of cereal grain used in the diet, as indicated by the observation that the differential between males and females in expiration of hydrogen and methane in the breath changed according to the type of grain consumed. That is, the metabolic activity of the gut microbiota was influenced both by the sex of the chicken and by the properties of the diet. The results of these studies provided evidence that microbial colonisation of the gut is a key determinant of the digestive function of chickens. Further work is needed to determine why microbial colonisation of the gut is variable and why it differs substantially between male and female chickens. Then it may be possible to control the initial colonisation of newly hatched chicks and to maintain a health-promoting profile throughout the life of chickens in order to enhance efficient production, and product quality and safety. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1080042 / Thesis (Ph.D.) -- University of Adelaide, Dept. of Animal Science, 2003

Since the removal of in feed antibiotics in the past few years commercial poultry production is especially sensitive to the health of the small intestine. Healthy small intestines balance nutrient absorption and defensive barrier functions to ensure the chicken is able to meet the whole-body nutritional needs and is able to help prevent internalization of pathogens or potentially toxic components. This balance can only be maintained under stable conditions. When a disturbance event occurs the intestine imbalances until a new, and less efficient, balance can be achieved. The objective of this dissertation is to propose a novel model to understanding intestinal homeostasis in the face of various disturbance events. Chapter 2 investigated the effects of Runting Stunting Syndrome on broiler chickens in four different groups of chicks displaying clinical symptoms. The major finding in this study was that in two of the four groups the expression of stem cell gene Olfactomedin 4 was absent from the crypt though other functional genes were found to still be expressed there. Chapter 3 characterized intestinal gene expression following a single challenge of Eimeria acervulina in broiler chickens. During Eimeria infection gene expression of multiple host defense peptide genes were decreased compared to uninfected chickens. Further, Eimeria infected chickens increased cell proliferation within the crypt and post-peak infection showed signs of intestinal recovery. Additionally, chapter 3 developed a novel method for visualizing Eimeria as it infects the intestine. In chapters 4 and 5 cell type population changes during the peri-hatch intestinal maturation process were evaluated. Peri-hatch intestinal maturation is critical for the successful transition from embryonic to post-hatch life. Chapter 4 profiled changes in proliferative cells and gene expression of various stem cell marker genes during the peri-hatch period: the last three days of embryogenesis and the first week post-hatch. The stem cell marker gene Leucine Rich Repeat Containing G Protein-Coupled Receptor 5 (Lgr5) decreased during the post-hatch period while Olfactomedin 4 increased post-hatch. Both stem cell genes were expressed within the intestinal crypt, though prior to hatch Lgr5 was expressed in the lamina propria and villi as well. Additionally, the marker of proliferation Ki67 gene was expressed in cells throughout the intestine prior to hatch but became restricted to the crypts and along the center of the villi. Chapter 5 assessed the effect of providing probiotics to late term embryos via in ovo feeding (IOF). The effects of IOF were primarily observed on embryonic day 20 (e20), roughly 48 hours after IOF. On e20 the embryos in ovo fed probiotics in saline had increased expression in the ileum of Peptide Transporter 1 (PepT1) a marker gene for enterocytes and Mucin-2 (Muc2) a marker gene for goblet cells compared to non-injected control embryos. Also, on e20 the embryos in ovo fed saline only had numerically increased PepT1 and Muc2 compared to non-injected control embryos. The difference in responses between the probiotic and saline fed embryos on e20 suggests different routes of stimulation. These investigations illustrate various possible scenarios and means of investigating intestinal homeostasis during disturbance events. / Doctor of Philosophy / In healthy birds, the small intestine absorbs nutrients while preventing the free passage of microbes or toxic chemicals into the body. The two functions: absorption and barrier exclusion seem contradictory, but a balance is struck to ensure both functions continue. This balance-point, homeostasis, persists until an event disturbs it. Once disturbed the balance-point is changed and the intestine is unable to maintain both functions, until a new balance is found following recovery. The objective of the dissertation is to better understand intestinal homeostasis, through four different research projects. Experiment 1 characterized the intestinal cell population changes in broiler chickens during Runting Stunting Syndrome, a viral infection. The major finding of this chapter was that a stem cell gene, that is normally robustly expressed was not expressed in some groups of infected chicks but not all. Experiment 2 investigated the intestinal response of broiler chickens to Eimeria acervulina, an intestinal parasitic infection. Eimeria, which infects intestinal enterocytes, caused a decrease in defensive genes during the peak of infection. Then after the peak the intestine began to recover, as indicated by increased cell proliferation. Experiment 3 profiled changes in the expression patterns of stem cell and proliferation genes in the small intestine during the last days before hatch and the first week post-hatch. Pre-hatch stem and proliferative gene expression occurred in the crypt and villus, but became restricted to the crypt early during the post-hatch period. Experiment 4 assessed the effect of feeding probiotics to embryos before hatching on intestinal gene expression. Embryos fed probiotics had increased Mucin-2 and Peptide Transporter 1 gene expression in the last segment of the intestine, the ileum compared to non-fed embryos 48 hours after feeding. Additionally, treatments fed saline also showed increased gene expression, though to a lesser extent. Together these projects illustrate various disturbances to intestinal homeostasis and how intestinal cells change and respond during the disturbance and recovery periods.

Thesis (M.Sc) (Agriculture) --University of Limpopo,2009. / The study was conducted to determine the effect of dietary energy level and tanniniferous Acacia karroo leaf meal level of supplementation at finisher stage on performance and carcass characteristics of male and female Ross 308 broiler chickens. Three hundred and sixty, 21-day old male and female broiler chickens were assigned to twelve treatments with three replications of ten birds in a 2 (sex) x 3 (dietary energy level) x 3 (tanniniferous Acacia karroo leaf meal level) factorial, complete randomized design. Supplementation with Acacia karroo leaf meal had no effect on diet intake, digestibility and live weight of broiler chickens. However, supplementation with 9 and 12 g of Acacia karroo leaf meal per kg DM feed reduced fat pad weights in male broiler chickens by 26 and 29 percentage points, respectively. Similarly, supplementation with 9 and 12 g of Acacia karroo leaf meal per kg DM feed reduced fat pad weights in female chickens by 26 percentage points. These reductions were achieved without any significant reduction in feed intake and digestibility. However, the physiological explanation for this effect is not clear and it, thus, merits further investigation. / National Research Foundation.

A series of experiments were conducted to examine the effect of chemical composition of the diet on intestinal <i>Clostridium perfringens</i> populations and necrotic enteritis (NE) in broiler chickens. In the first experiment, birds were fed high concentrations of dietary protein (fish meal or soy protein concentrate) and soluble fiber (guar gum). Clinical NE was not observed, however, there was a high level of <i>C. perfringen</i> colonization especially in guar gum fed birds. The next set of experiments examined the effect of various levels of DL-Met or MHA-FA on <i>C. perfringen</i> and other intestinal microbes. These experiments demonstrated a significant reduction (P < 0.05) in <i>C. perfringen</i> growth with methionine supplementation in ileum and cecum. The results suggest that both DL-Met and MHA-FA may reduce intestinal populations of <i>C. perfringen</i> in broiler chickens when used in high concentrations. The next three experiments were conducted to examine the effect of dietary glycine levels on gut <i>C. perfringen</i> populations, α-toxin production and NE lesion scores. Majority of birds showed clinical signs of disease with 4.16-8.33% mortality. There was a direct correlation between intestinal <i>C. perfringen</i> populations, NE lesions scores and mortality with dietary glycine level. However, due to the use of gelatin as the dietary source of glycine in these experiments, the diets also contained high proline levels which confounded our results. The last study was conducted to establish a direct causative relationship between dietary glycine concentration and <i>C. perfringen</i> growth and/or NE in broiler chickens using encapsulated amino acids. Birds fed diets containing high levels of encapsulated glycine had higher NE lesion scores than those fed encapsulated proline or no encapsulated amino acids, thus demonstrating a direct effect of glycine on intestinal <i>C. perfringen</i> growth. It is concluded that amino acid composition of dietary protein is an important determinant of intestinal microbial growth, particularly <i>C. perfringen</i>, and could affect incidence of NE in broiler chickens.

A series of experiments were conducted to examine the effect of chemical composition of the diet on intestinal <i>Clostridium perfringens</i> populations and necrotic enteritis (NE) in broiler chickens. In the first experiment, birds were fed high concentrations of dietary protein (fish meal or soy protein concentrate) and soluble fiber (guar gum). Clinical NE was not observed, however, there was a high level of <i>C. perfringen</i> colonization especially in guar gum fed birds. The next set of experiments examined the effect of various levels of DL-Met or MHA-FA on <i>C. perfringen</i> and other intestinal microbes. These experiments demonstrated a significant reduction (P < 0.05) in <i>C. perfringen</i> growth with methionine supplementation in ileum and cecum. The results suggest that both DL-Met and MHA-FA may reduce intestinal populations of <i>C. perfringen</i> in broiler chickens when used in high concentrations. The next three experiments were conducted to examine the effect of dietary glycine levels on gut <i>C. perfringen</i> populations, α-toxin production and NE lesion scores. Majority of birds showed clinical signs of disease with 4.16-8.33% mortality. There was a direct correlation between intestinal <i>C. perfringen</i> populations, NE lesions scores and mortality with dietary glycine level. However, due to the use of gelatin as the dietary source of glycine in these experiments, the diets also contained high proline levels which confounded our results. The last study was conducted to establish a direct causative relationship between dietary glycine concentration and <i>C. perfringen</i> growth and/or NE in broiler chickens using encapsulated amino acids. Birds fed diets containing high levels of encapsulated glycine had higher NE lesion scores than those fed encapsulated proline or no encapsulated amino acids, thus demonstrating a direct effect of glycine on intestinal <i>C. perfringen</i> growth. It is concluded that amino acid composition of dietary protein is an important determinant of intestinal microbial growth, particularly <i>C. perfringen</i>, and could affect incidence of NE in broiler chickens.

The main aim of the studies was to evaluate the modes of actions of Bio-Mos and the effect that it has on intestinal health as well as performance in broiler chickens. For the purpose of this study there were 2 main objectives. The first was to determine the effect of Bio-Mos as well as soluble mannan on salmonella colonization and to do this it was necessary to develop an in vivo pathogen challenge model, specifically designed for salmonella, using the chicken as animal model. The aim with this salmonella assay was to design a model that could accurately determine the efficacy of different components of the yeast cell wall at reducing or eliminating salmonella colonisation in chickens. The second objective was to evaluate the effect of Bio-Mos with or without the addition of a soluble mannan, fed at different inclusion levels, on chicken health. Specific parameters measured included feed conversion ratios (FCR), volatile fatty acid (VFA) analysis, antibiotic resistance amongst coliform populations, immunoglobulin quantification and gut morphology. Gut morphology measurements included villi height and width, crypt depth, muscularis thickness, goblet cell size and goblet cell density. The salmonella assay trial was not able to yield positive results for either the cell wall preparations or the positive control, indicating that there are some external factors that have to be addressed before this assay can be used to draw any accurate conclusions from. The second section of this study did show FCR differences between some of the treatments, but did not show numerically large differences for VFA production or antibiotic resistance, however the histological evaluation did yield interesting results. Measurements based on the villi height and width, crypt depth and muscularis thickness showed no significant differences between treatments but there was a treatment effect on the goblet cells. The goblet cells of chickens receiving cell wall preparations were statistically significantly larger and present at a higher density than those of the control treatment birds. In an attempt to develop the salmonella assay several aspects of the existing assay model were altered or eliminated. It is possible that the assay can work with some more adjustments, but due to time constrictions it was not possible to further explore alternative approaches. Little research has been done on the effect of nutrition on the goblet cells in chicken intestines. The results noted in this report warrant a more in-depth investigation into the exact modes of action resulting in the differences in goblet cells observed. The use of cell wall preparations on a commercial level holds many advantages, as cell wall preparations appear to affect animal health in a positive way. / Dissertation (MSc (Agric) : Animal Nutrition)--University of Pretoria, 2008. / Animal and Wildlife Sciences / MSc (Agric) / unrestricted