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>Magister Scientiae - MSc / Campylobacter species are the most common bacteria associated with acute diarrhoea and is responsible for 400 to 500 million reported cases globally. It is not uncommon for 35% to 85% of chicken flocks to be infected with campylobacters and it is because of this high prevalence that chicken is considered to be the primary source of Campylobacter contamination in the domestic setting. Therefore, a very high risk of acquiring campylobacteriosis is associated with the mishandling and consumption of contaminated chicken. The present study had isolated a total number of 156 Campylobacter isolates, of which 102 isolates were C. jejuni and 51 were C. coli. The speciation of 3 Campylobacter isolates could not be determined. It had shown that there is a high prevalence of Campylobacter in South African chicken. Retail chicken (n = 84) has a lower prevalence of 27% whereas chicken sampled directly from the abattoir (n = 182), but also intended for human consumption, had an average prevalence of 73%. It also showed that free range chicken (n = 118) has a higher prevalence (average of 79%) of Campylobacter than commercial chicken (n = 64) (average of 56%). It is for this reason that free range chicken is not always the safer option considering that the purchasing of free range chicken is becoming more popular for health reasons. There is no standardized universal isolation protocol for Campylobacter species and the current isolation techniques creates a bias for the optimal growth of C. jejuni and C. coli, the two thermotolerant species most commonly associated with human illnesses. Recently, the non-selective Cape Town Protocol was designed for efficient isolation of campylobacters from clinical samples and proved to be superior to the former techniques in the isolation of the thermotolerant campylobacters as well as emerging campylobacters. However, the protocol is not suited to the isolation of Campylobacter from food samples. This study successfully optimized the Cape Town protocol by incorporating the use of the selective Bolton broth for the recovery and enrichment of injured cells from raw chicken samples. The technique proved to be equal in isolation efficiency to the ISO 1272-1:2006 method but loses its ability to recover all campylobacters that may be present in the food sample. It is for this reason that a non selective enrichment broth should be sought but the technique boasts superiority over the ISO 10272-1:2006 method in that it reduces the time in obtaining the results at least by 48 h and is more cost effective. / National Research Foundation (NRF)

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

Ultrastructural observations on the six-day chick embryo lens reveal that fibre cell differentiation, which involves extensive cell elongation, is characterized by the presence of numerous oriented microtubules and by marked changes in intercellular relationships which are felt to be important for cell extension. Increased Golgi activity in cells initiating elongation appears to be related to the formation of intercellular junctions and the elaboration of new surface membrane. Studies concerning the differentiation in vitro of anterior lens epithelia demonstrate that their cells elongate either to a great extent or to a limited extent, depending on factors deriving from the epithelial conformation.The conformation of an explanted anterior lens epithelium can be manipulated so that its cells elongate consistently to either a limited or a great extent. These cells, whether elongated to a limited or to a great extent, are ultrastructurally similar with respect to features reflecting cytoplasmic differentiation, including those important for morphogenesis. Their fine structure closely resembles that of fibre cells differentiating in vivo. The cells of anterior lens epithelia differentiating in vitro, whether elongating to a limited or to a great extent, are the same in terms of the nature and relative proportions of their soluble proteins as indicated by polyacrylamide gel electrophoresis. There is a change in the relative proportions of the soluble proteins accumulated by the anterior lens epithelia when they differentiate in vitro that is similar to that which occurs in cells undertaking fibre cell differentiation in vivo. It is concluded that those factors deriving from the conformation of the anterior lens epithelium that affect the degree of elongation of its cells differentiating in vitro are physical in nature. Since such physical factors are important with regard to restraining or encouraging the expression of morphogenetic potential in vitro, it is suggested that similar physical forces are important in lens morphogenesis in vivo. Observations concerning anterior lens epithelia elongating to a great extent in vitro demonstrate that their cells progressively elongate for only about three days. Well differentiated explants cultured for longer periods do not show greater elongation or further cytoplasmic differentiation. Their cells, at the ultrastructural level, resemble differentiating fibre cells in vivo rather than differentiated ones. It is concluded that the anterior lens epithelium has some capacity for differentiation independent of the ocular environment, but that the latter is essential for the expression of its full developmental potential. / Science, Faculty of / Zoology, Department of / Graduate

In 1957, strains 3 and 4, two highly selected but unrelated strains of Single Comb White Leghorn chickens from Agriculture Canada's Animal Research Station at Ottawa were crossed to establish the Agassiz strain (strain 6). Further selection was imposed on strain 6 for improvements in hen-housed egg production (HHEP) based on part-records to 273 days and maintenance of egg weight, fertility, hatchability and viability. Data from 1957 to 1963 were analysed utilizing the SAS programs. There were no significant improvements in performance for HHEP, but egg weight, fertility, hatchability and viability were maintained. The lack of response to selection for HHEP was probably due to the following reasons: 1) too many traits were considered in the selection program at the same time, 2) negative genetic correlations existed among the selected traits, 3) strict adherence to a selection scheme was not practiced, 4) most of the traits under selection had low heritabilities, 5) the duration of the study was not long enough, and 6) the population size of strain 6 may not have been large enough. There was a significant decrease in body weight at 365 days (-4.33 ± 0.48, p < 0.0009). This decrease may be because of selection within full-sibs for more refined birds with better conformation as parents of the next generation. There were significant decreases in egg specific gravity at 225 and 450 days, and in Haugh units at 225 days, although Haugh units were increasing when measured at 450 days. The mean h²s for HHEP was 0.45, and the mean h²s for egg production to 273 days was 0.20 and the mean h²d for the same trait was 0.33. The mean h²s and h²d estimates for egg weight at 225 days were 0.60 and 0.50, respectively. The mean h²s and h²d for age at sexual maturity were 0.22 and 0.33, respectively, and those for body weight at 365 days were 0.53 and 0.62, respectively. The mean h²s and h²d for egg specific gravity at 225 were 0.64 and 0.33, respectively while those for Haugh units at 225 days were 0.57 and 0.68, respectively. These estimates were consistent with those found in the literature. The sctual selection differentials showed that selection was positive for egg production, while those for egg weight at 225 days were zero, and those for body weight at 365 days showed that selection was in the downward direction on the sires. / Land and Food Systems, Faculty of / Graduate

The H9N2 low pathogenic avian influenza virus (LPAIV) is considered a prime candidate for evolving into a highly pathogenic AIV (HPAIV) following circulation in domestic poultry, due to its widespread endemism in Eurasia and the donation of internal genes to H5 and H7 HPAIV. In this study, we investigated if a LP H9N2 virus could acquire increased pathogenicity following nineteen serial passages in week-old chickens. We show that the H9N2 virus remained low pathogenic in chickens after nineteen serial passages, evidenced by a lack of mortality in chickens despite efficient viral replication in chicken organs. An overregulation of cytokine response to infection, typical of highly pathogenic viruses, was not observed in tissue organs analyzed by quantitative PCR. The serial passaging of the H9N2 virus led to reduced virulence in chicken embryos and reduction in Hemagglutinin heat stability after passaging. The positive selection of Leucine at amino acid position 226 (L226) after 19 passages suggests the H9N2 can gain mammalian adaptation markers following circulation in domestic poultry. In addition, we carried out four experiments to determine the effectiveness of aerosol exposure of H6N1, H10N7, H10N8 and H13N6 LPAIV’s in causing infection, immune dysregulation and mortality in chickens compared to intranasal and oral inoculation routes. From our study, we observed mortality of chickens exposed to H6N1 and H10N8 viruses via aerosols. Aerosol exposure also resulted in more efficient replication in the respiratory tracts of chickens than intranasal or oral inoculated chickens. In addition, overexpression of pro-inflammatory (IL-6, IL-1ß) and antiviral (INF- γ) cytokines was observed in chickens exposed to aerosols compared to intranasal and oral inoculation. Our results show that the aerosol route of exposure is efficient at causing infection in chickens and should be factored into control and prevention strategies against AIV.

Chickens and eggs rank fourth among the farm enterprises in Utah as a source of farm cach receipts. In 1948 about 21 million dollars of cash receipts were received from sales of chickens and eggs which represent 13.2 percent of total receipts from farm marketings (table 1). In the same year 17.7 of the total receipts were derived from cattle and calves, the largest enterprise. Receipts from dairy products represented 15 percent and sheep, lambs, and wool 13.8 percent.

<p>  </p> <p>This thesis aimed to evaluate the effect of heat treatment of different ingredients on their respective phosphorus digestibility and assess the impact of protein source in the basal diet on the regression-derived phosphorus digestibility methodology. Two studies were carried out to evaluate the objectives.</p> <p>In study 1, regression-derived ileal digestibility and utilization coefficients of phosphorus (P) responses to autoclaving soybean meal (SBM) or poultry meal (PM) were investigated in two experiments. On day 19 post hatching male Cobb 500 broiler chickens were individually weighed and allotted into 6 or 5 treatments in experiment (Exp.) 1 or 2, respectively, in a randomized complete block design, with 8 replicate cages and 8 birds per cage in both experiments. In Exp. 1, diets were formulated with either non-autoclaved or autoclaved soybean meal at 380, 480, or 580 g/kg in a 2 file:///C:/Users/vshae/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png 3 factorial arrangement. Experiment 2 consisted of a basal diet and other four diets, with 40 or 80 g/kg of non-autoclaved PM or autoclaved PM arranged as a 2 file:///C:/Users/vshae/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png 2 + 1 factorial. Chromic oxide was added as an indigestible index marker to determine nutrient ileal digestibility and retention. Birds received the experimental diets for 3 days, and excreta collection was conducted during the last two days. All birds were euthanized by CO2 asphyxiation, and ileal digesta samples were collected. Data were analyzed using the GLM procedure. In both studies autoclaving decreased (<em>P</em> < 0.05) DM digestibility and retention. Increasing the inclusion level of test ingredients linearly increased (<em>P</em> < 0.05) intake of digestible and utilizable P in both studies and linearly reduced the digestibility and retention of DM and P in the soybean meal study. Autoclaving SBM resulted in higher (<em>P</em> < 0.01) ileal digestibility of P and retention of P and Ca. The estimated ileal digestibility of P in SBM, autoclaved SBM, PM, and autoclaved PM were 45, 53.6, 61.2 and 61.2%, respectively, and the corresponding retention were 40.6, 45, 51.7, and 59.2%. Autoclaved SBM tended (<em>P</em> = 0.058) to have higher P digestibility than non-autoclaved, but no effect was noted with PM. These results indicated that autoclaving feed ingredients reduced the digestibility and retention of dry matter, and the digestibility of phosphorus of soybean meal may be improved by heat treatment but not that of poultry meal, which may be due to phytate P degradation.</p> <p>The second study was conducted to evaluate the effect of varying protein sources in the basal diet on the regression-derived P digestibility in soybean meal. This experiment was organized in a 4 × 3 factorial arrangement, consisting of 4 diet types that differed in their protein sources; with the test ingredient as the only source of protein, or with one of 3 protein supplements (casein, potato protein isolate (PPI) or dried egg albumen (DEA)) added at 60 g/kg, and 3 levels of test ingredient (SBM) inclusion at 290, 370 or 450 g/kg. Male Cobb 500 broiler chickens were individually weighed and distributed in the 12 treatments in a randomized complete block design, with 8 replicate cages and 6 birds per cage on day 19 post hatching. Birds were fed the experimental diets for 3 days, and ileal digesta and excreta samples were collected similarly to the first study. Diet type affected (<em>P</em> < 0.01) the digestibility and total tract retention of DM, P, N, and Ca. Diets with added casein presented the highest (<em>P</em> < 0.05) digestibility of P, Ca, and N, retention of P and Ca, and intake of digestible and utilizable P. The digestibility and retention of DM linearly decreased (<em>P</em> < 0.001) with increasing inclusion levels of SBM in all diet types. The estimated ileal digestibility of P in SBM was 56.9, 62.6, 59.1, and 36.4% for diets without protein supplements, with casein, PPI, or DEA, respectively; the corresponding retention of P were 51.7, 82.6, 42.7, and 52.2%. Diet type affected (<em>P</em> < 0.05) the slope and intercept of P digestibility in SBM. A comparison of the coefficients using confidence intervals demonstrated that the ileal digestibility of P in SBM determined in diets with DEA was lower (<em>P</em> < 0.05) than in the other diet types, which were not different from one another. These results indicate that the selection of dietary protein supplements may affect P digestibility essays using the regression method. </p> <p>In summary, the digestibility of P in soybean meal may be improved by heat treatment while not that of poultry meal, which may be ascribed to the higher phytate P content of SBM, and phytate degradation from heat treatment. Results from the second study demonstrated that the protein source, but not level in the basal diet affects the P digestibility of the essay ingredient determined using the regression method. These findings can contribute to reducing P excretion by enhancing the formulation of broiler diets on a digestible P basis, providing information on the effect of heat treatment on dietary P availability, and refining the methodology used to determine P digestibility.</p>

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