No description available.

No description available.

Phosphorus in phytate is largely unavailable to chickens unless they are provided with dietary phytase. Phytase was shown to increase phytate degradation in the crop and proventriculus-gizzard and very little phytate degradation occurred in the duodenum-jejunum or ileum. These previous investigations were conducted on chickens fed corn based diets but not with wheat based diet. Increase in digesta passage or mean retention time (MRT) along the gastrointestinal tract could enhance phytase efficacy as the prolonged reaction time between substrates and phytase may further facilitate phytate dephosphorylation. Dietary fat and fibre supplementation have been shown to influence intestinal MRT in chickens therefore it is expected that inclusion of both dietary fat and fibre could be manipulated to further improve phytase efficacy in broiler chickens. Three experiments and preliminary studies were conducted: 1) to assess the effect of methodology on estimation of phytate hydrolysis and P digestibility in young broilers and 2) to investigate whether or not dietary fat and fibre could further improve phytase efficacy in broilers fed diets containing wheat by delaying digesta MRT. In the preliminary study, in order to facilitate analysis of limited digesta samples, a sample preparation protocol involving H2SO4 digestion for sequential analysis of titanium and other minerals in feed and digesta was established. It was also found that blood protein interfered with the colorimetric analysis of P and myo-inositol, thus deproteinization is required. Continuous feeding prior to sampling was recommended to obtain adequate amount of digesta for digestibility related analyses. In the first study, feeding duration (1 h or 5 h) and 1 h feeding followed by feed withdrawal and refeeding prior to sampling significantly affected the concentration of phytate, inositol phosphates and measured degradation and digestibility of phytate-P in different segments of gastrointestinal tract, which could lead to overestimation or underestimation of degradation and digestibility values. Therefore, it is also recommended to collect digesta samples at least 3 h after the start of photoperiod and avoid sampling 4 h prior to dark period when lighting program is applied. In the second study, 5% fat inclusion had no significant effect on growth performance, while phytase supplementation at 1500 FTU/kg improved feed intake (FI) and body weight gain (BWG). However, interactions between both factors additively increased FI from 804g to 1,221g, BWG from 630 g to 904 g, ileal phytate degradation by 44% and ileal P digestibility by 17%. Adding cellulose as filler in pellet-crumbled diet has diluted the nutrient concentration in 5% fat diet that eventually led to poorer FCR. However, phytase supplementation eliminated the negative effect of nutrient dilution by improving performance of chickens as good as those fed those fed 5% fat diet without cellulose addition. In the third study, a combination of 1500 FTU/kg phytase supplementation with 5% fat increased crop digesta MRT and improved phytate-P degradation compared to with 1% fat, providing evidence for the role of fat in improving phytase efficacy in broilers. This thesis has shown the importance of methodology standardization in estimating phytate hydrolysis and P digestibility and the role of dietary fat and fibre in improving phytase efficacy in broilers.

Traditional chicken breeds exhibit a range of phenotypic diversity, which in some cases is far removed from that of their jungle fowl ancestors. This diversity includes plumage pattern and colouration, feather stlUcture, comb morphology, egg colour, and numerous other behavioural and morphological characteristics. Extensive research over the last century has identified that a number of these phenotypic traits are inherited in a Mendelian fashion, enabling them to be studied at the genetic level with relative ease. Typically, the genetic mapping of these traits has required establishing resource mapping populations through inter-crossing or back-crossing to select for the trait(s) of interest. However, recent advances in technology have demonstrated that it is possible to fine-map phenotypic traits by comparing the DNA of different breeds. Through the contrasting of single-nucleotide polymorphisms (SNPs) in a range of breeds exhibiting the trait of interest, to breeds in which the trait is absent, it is possible to take advantage of countless recombination events that have taken place since the different breeds were established, enabling the trait to be mapped at higher resolution than might be achieved through a resource mapping population.

Poultry meat is considered to be the major vehicle of foodborne poisoning caused by the Gram-negative bacterium Salmonella. In the Kuwait State, the incidence of human salmonellosis has increased markedly over the last years. The adaptation responses of Salmonella enterica serovars to the current decontamination system used in poultry meat production in Kuwait enhanced their ability to colonise poultry meat and survive the system used in the Kuwait poultry processing plants. A commercial decontamination process is typically applied to remove bacteria from carcasses within a few minutes of chilling. This process usually involves washing the carcasses with a biocidal compound, such as chlorine in the form of sodium hypochlorite (NaOCl), and yet the washing process fails to remove all of the bacteria. This research was designed to investigate the increased colonisation abilities and adaptation responses of Salmonella in order to identify the main attributes of the pathogen in colonisation and survival in the poultry meat and to suggest interventions that could be used to control the organism during processing. This is particularly relevant to Salmonella enterica serovars Typhimurium and Enteritidis, which were found to be the most predominant strains from 2003-2011 among the human and food isolates in Kuwait (mainly raw chicken and cooked chicken products). The molecular typing technique of Pulsed Field Gel Electrophoresis (PFGE) was used in this research to determine the genetic diversity among the Kuwaiti culture collections of human and food isolates. A comparison between S. Typhimurium and S. Enteritidis isolates indicated a high level of genetic relatedness between the human and chicken isolates. The rate of attachment of the bacteria to chicken skin at chill temperature was measured that allowed detailed objective comparisons of the attachment processes under two different conditions, attachment of bacteria before and after exposure to chlorine. The rate of attachment was also compared with that of reference strains from international culture collections. A method to measure the probability of detachment was developed and was applied on the same bacterial strains. The outcome of measuring the attachment and detachment of bacteria to chicken skin showed adaptation responses of representative strains to chlorine, the adaptation that had led to enhanced ability of Salmonella to survive and colonise chicken carcasses. The origin of this adaptation was determined by the microarray technique at the Institute of Food Research, Norwich, UK. The data showed up-regulation of genes associated with oxidative stress response (mutT and icdA), iron stress (YbdZ), biofilm formation and cellulose biosynthesis (bcsG), transport (YgiK), and ribosomal proteins formation (RpsL, RpsQ, and RpsO). In contrast, genes predominantly associated with general cellular metabolism, ribosomal proteins, biofilm formation, flagella biosynthesis and virulence were down-regulated. Findings from this study suggest that the oxidative stress response and the formation of biofilm matrix may render Salmonella resistant to certain types of environmental stresses, which in turn contributes to its survival and persistence in the contaminated poultry meat products This research also includes a review of existing industry practices and control measures applied in the Kuwaiti slaughterhouses to control Salmonella in poultry meat against currently accepted standards such as those in the US, UK and recommended by international agencies. The information collected from selected slaughterhouses and the limited sampling at a number of arbitrarily chosen process steps indicated that there was little effective control and published good practice guidelines were not followed, which would explain the apparent high levels of Salmonella contamination. Given all the shortcomings and poor practices observed in some Kuwaiti slaughterhouses besides the inadequacy of NaOCl to affect a substantial enough reduction in Salmonella contamination in chicken skin, an alternative and more effective decontamination method was investigated. The preliminary study examined the efficacy of combining ultrasound with chlorine treatment on the inactivation of Salmonella inoculated onto the surface of chicken skin under laboratory conditions. Data from this study showed the effectiveness of this combined treatment in reducing the numbers of Salmonella to 2-2.5 log10 cycles with D-value of 30 min than those achieved by either chlorination or sonication alone, suggesting that there could be possible synergistic effects between chlorination and sonication. Findings of this research suggest that there was no major difference between the Salmonella strains isolated from the contaminated chicken meat in Kuwait and the international Salmonella strains in their colonisation, survival and attachment or detachment behaviour on chicken skin. Consequently, the development of HACCP-based food safety management systems, implementation of good hygiene practices and sustained food hygiene training of food handlers should prove to be effective measures to control the colonisation of poultry meat by and subsequent survival of Salmonella in Kuwait.

The nutritive quality of wheat as a main source of the energy in poultry diets is variable, particularly with respect to the low-apparent metabolisable energy (AME) values of some varieties. It has been speculated that the higher protein content and the stronger bonds between proteins and starch in hard wheat may be involved in a negative relationship between hardness and energy availability. The objective of the current study was to examine whether there was a difference in starch and nitrogen digestibility in broiler chickens when given wheat varieties with different hardness values. Each wheat sample was included at a fixed rate of 750 g/kg in a semi-synthetic diet. Each diet was offered ad libitum to 6 cages (2 birds / cage) from 20 to 23 days of age. Three experiments were conducted. In the first trial, twelve cultivars from the 2007 growing season with different hardness values from 34 to 86 and twelve cultivars were used in the second trial from the 2008 season with different hardness values from 10 to 68. In both trials samples were used in a broiler feeding experiment and laboratory analysis for ileal and total tract starch and nitrogen digestibility evaluation. In the third trial ten cultivars were used from the 2009 harvest season, four samples had different 'hard' mutations in Pinb-DI (2 lines with Pinb-DIb and 2 with Pin-DIe). The hardness values were from 10 to 73. This trial was focussed only on the ileal and total tract nitrogen retention and digestibility evaluation, to examine whether the genetic differences have any effect. Although there was a variation in starch digestibility for each diet in both trials 1 and 2, the effects of wheat hardness were not significant for either ileal or total coefficient of apparent starch digestibility of diets (P> 0.05). Similarly, there were no significant effects on the coefficient of apparent nitrogen digestibility (P< 0.05) in both experiments. Neither nitrogen nor starch content had a significant effect on starch digestibility. This gives an indicator that the difference between hard and soft endosperm not only depends on nitrogen and starch content but may also be based on the adhesive strength between the starch granules and surrounding protein matrix. It was concluded 11 that the variation in starch digestibility with wheats could not be attributed only to hardness of wheat and that other factors appear to be implicated in the low digestibility observed with some wheat samples tested in the current experiment. The digestible starch content increased from the ileum (digesta) and total tract (excreta) with 0.826 and 0.907, and the digestible starch content increased from the ileum (digesta) and total tract (excreta) with 0.889 and 0.922 in 2008 diets. The effect of region is to be expected, since starch is increasingly well digested as it passes through the gut. The results of trial 1 also showed that there were no significant differences in coefficient of apparent nitrogen retention or digestibility of diets based on wheat cultivars. The second trial results showed there were no significant differences in coefficient of apparent nitrogen retention or digestibility of diets based on wheat cultivars. Total nitrogen digestibility tended to show an increase with increased endosperm hardness (P= 0.082) The third trial results showed that there were no significant differences in ileal and total tract nitrogen retention. On the other hand there was highly significant effect of wheat hardness on total tract nitrogen digestibility (P<0.001), but there was no evidence of a linear effect. This is probably because the 10 samples used in this trial include 4 samples characterised by different genotype. These different genotypes showed a highly significant effect on nitrogen digestibility. In general, nitrogen digestibility coefficients based on excreta (total nitrogen digestibility) were numerically lower than those determined at the terminal ileum. This is probably due to the nitrogen synthesis of microbial nitrogenous compounds in the hindgut. When the end result of microbial activity is synthesis, the reverse situation will occur resulting in under estimates of digestibility. Evaluating the effects of wheat hardness on feed intake, nitrogen retention and digestibility of diets across the three trials, showed that the effect of endosperm hardness was highly significant and positively correlated with feed intake (r2 = 0.8157, P = 0.003). The year of harvest also has an effect on feed intake (P < 0.001) and there was a positive tendency that this effect was related to the endosperm hardness (P= 0.078). Statistical analysis indicated a 111 z highly significant effect of wheat hardness on ileal, total tract nitrogen retention and total tract nitrogen digestibility (P<O.OOl). This may result from the effect of the large range between the wheat hardness values between the wheat varieties. The effect of genetic differences Pinb-DI band Pinb-DI c in the third trial showed significant differences between the diets in nitrogen retention and digestibility (P < 0.05). That means the genetic differences were important in terms of nutritional value. However nitrogen retention and digestibility were also significantly affected by wheat hardness in these samples (P < 0.05). This may explain partially the highly significant effect of wheat hardness on total tract nitrogen digestibility in the third trial. Moreover, these samples showed that the nitrogen content was strongly cOlTelated with endosperm hardness (1)= - 0.959) that had a highly significant effect on nitrogen digestibility; P values were identical to those resulting from the effect of endospenn hardness. These results draw attention to the fact that differences can be influenced by genetic factors. This factor will play an important role in the future particularly with the emergence of new wheat cultivars. In general the effect of wheat hardness in this study was unclear and, even if it was significant, it was associated with positive or negative cOlTelation with nitrogen or starch content. 1

No description available.

MicroRNAs (miRNAs), short non-coding RNAs, which act post-transcriptionally to regulate gene expression, are of widespread significance and have been implicated in many biological processes during development and disease, including muscle disease. In addition to the myomiRs, which are miRNAs highly enriched in striated muscles, recent advances in sequencing technology and bioinformatics led to the identification of a large number of miRNAs in vertebrates and other species. However, for many of these miRNAs specific roles, in particular during myogenesis, have not yet been determined. Here, I investigated the potential functions of miR-128, confirmed an interaction with one of its candidate targets, Eya4, and looked at the impact of its knock-down on skeletal myogenesis in the chicken embryo. The expression pattern of miR-128, as well as 22 other somitic miRNAs, were characterised by LNA in situ hybridisation (LNA ISH). Eya4 was identified as a candidate ‘muscle’ target of miR-128 by computational analysis. Its expression pattern was characterised; miR-128 and Gga-Eya4 displayed similar profiles in developing somites. Using the miRanda algorithm potential miRNA binding sites were identified in the 3’ untranslated region (UTR) of other transcription factors, which along with Eya4 are members of the PAX-SIX-EYA-DACH (PSED) network (Six1/4, Eya1/2/3, and Dach1). These miRNA/target interactions were examined in vitro and in vivo. Gga-Eya4 was confirmed as a target of miR-128 as well as miR-206 by luciferase reporter assays. MiR-128/Gga-Eya4 interaction was validated by RNA ISH and RT-qPCR after antagomiR (AM)-128 injection in chicken embryos. Knock-down of miR-128 resulted in a significant de-repression of Gga-Eya4 expression; an increase in Gga-Six4 and Gga-Pax3 expression was also observed, whereas Gga-MyoD1 expression was decreased. With this project, using a combination of cell-based experiments and animal studies, I showed that miR-128 could play an important role in the regulation of skeletal myogenesis in the chicken embryo by targeting Gga-Eya4, a member of the PSED network.

No description available.

Various criteria that could he used for the measurement of local immunity to Newcastle disease virus (NDV) and avian infectious bronchitis virus (IBV) were examined. Virus isolation and the measurement of antibody concentration in the serum and secretions were selected for use in the subsequent studies. Both resistance of the respiratory tract to infection and specific antibody in the upper respiratory tract secretions; could be induced by the administration of live or inactivated lentogenic NDV directly into the respiratory tract. Virus-neutralising antibody appeared in tracheal secretions as early as 6 days after inflection and, after an early peak, declined in titre, whereas antibody did not appear in the nasal secretions until 8 days after infection, but then proved to be more persistent. Antibody was also detected in lung secretions following the intramuscular inoculation of live virus. The direct or indirect exposure of the respiratory tract tissues to antigen was necessary for the development of resistance and the production of local antibody because inactivated virus administered parenterally failed to stimulate either, despite the high concentrations of serum antibody that were usually induced. In passively immunised chicks the circulating; antibody response to NDV was markedly suppressed, but no concomitant suppression. of local immunity could be demonstrated, indicating that the latter was independent of the former. Further evidence in support of a role for local immunity in NDV and IBV infections came from studies on tracheal explants derived from variously immunised or untreated chickens. Such explants were found to differ in their ability to support virus growth. Respiratory tract secretions contained IgA and IgG and variable amounts of IgM, as well as an additional antigenic component that was present in all secretions examined but was absent from the serum. Antibody activity in tracheal secretions appeared to be associated with the IgA fraction.