Inclusion body hepatitis (IBH) has been occurring as an economically important, emerging disease of broiler chickens in several countries. Historically, IBH has been identified as a secondary disease, often associated with common immunosuppressive diseases. However, few studies have identified IBH as a primary disease with no apparent association with immunosuppressive diseases. The objectives of this study were to develop an animal model of IBH in commercial broilers, to demonstrate vertical transmission of fowl adenoviruses (FAdVs) in broiler breeders and to control IBH in broilers by vaccinating their parents with an inactivated FAdV vaccine. In order to develop an animal model of IBH in commercial broilers, fourteen-day old broilers were inoculated intramuscularly with 1x104 1x107 CCID50 of either FAdV x11a-like virus, two strains of FAdV-8a (FAdV-8a strain TR-59 and FAdV-8a strain T8-A) or FAdV-11strain 1047. Four days following FAdV inoculation, 5% - 15% mortality was observed and dead birds showed histologic lesions of hemorrhagic necrotizing hepatitis. This animal model reproduced the clinical disease, and pathological lesions of IBH that have been described in commercial broilers. In order to demonstrate vertical transmission of the FAdV, 35-week-old broiler breeders were inoculated with 1x106 CCID50 of either FAdV x11a-like virus, FAdV-8a strain TR-59, FAdV-8a strain T8-A or FAdV-11 strain 1047. Eggs from infected breeders were collected and hatched seven days post-inoculation. Clinical signs or mortality were not observed in parents; however broiler progeny derived from broiler breeders inoculated with FAdV-8a strain T8-A had 30% IBH mortality by seven days of age. The hexon gene loop 1 sequence of the virus isolated from affected broiler progeny showed 100% identity to FAdV-8a strain T8-A. In order to demonstrate protection of broilers against IBH by vaccination of their parents, four groups of broiler breeders were vaccinated with either FAdV-8a strain T8-A (2x107 or 2x104 CCID50) formulated with 20% oil-in-water emulsion, or FAdV x11a-like virus (2x107 or 2x104 CCID50) formulated with 20% oil-in-water emulsion at the age of 12 and 15 weeks. The control group was inoculated with 20% oil-in-water emulsion. Broiler progeny were challenged with FAdV-8a strain T8-A to study the immunoprotective effect of the vaccine. Although, survival of broilers following FAdV-8a strain T8-A challenge was not significantly different among vaccinated and non-vaccinated groups (P>0.05), immunoprotective effect was enhanced by the increase dose of FAdV antigens (P>0.05). Further studies are necessary to improve the vaccine efficacy to protect broilers against IBH.<p> In conclusion, the results of this study support the hypothesis that IBH in broilers in Canada is a vertically-transmitted primary disease with no known immunosuppressive involvement. The results also demonstrated that inactivated antigens of FAdV are able to partially protect broilers against IBH by vaccinating their parents. Further studies with different formulations, and priming the immune system of broiler breeders with live FAdV prior to vaccination with inactivated FAdV vaccines are necessary to improve the efficacy of inactivated IBH vaccine.

Avian circadian clocks are composed of a distributed network of neural and peripheral oscillators. Three neural pacemakers, located in the pineal, the eyes, and the hypothalamus, control circadian rhythms of many biological processes through complex interactions with slave oscillators located throughout the body. This system, an astonishing reflection of the life history of this diverse class of vertebrates, allows birds to coordinate biochemical and physiological processes and harmonize them with a dynamic environment. Much work has been done to understand what roles these pacemakers have in avian biology, how they function, and how they interact to generate overt circadian rhythms. The experimental work presented in this dissertation uses the domestic chicken, Gallus domesticus, as a model to address these questions and carry forward current understanding about circadian biology in this species. To do so, we utilized a custom DNA microarray to investigate rhythmic transcription in cultured chick pineal cells. We then sought to identify genes which might be a component of the pineal clock by screening for rhythmic transcripts that are sensitive to a phase-shifting light stimulus. Finally, we surgically removed the eyes or pineal from chickens to examine the roles of these extra-SCN pacemakers in regulating central and peripheral rhythms in metabolism and clock gene expression. Using these methods, we show that the oscillating transcriptome is diminished in the chick pineal ex vivo, while the functional clustering of clock controlled genes is similar. This distribution reveals multiple conserved circadian regulated pathways, and supports an endogenous role for the pineal as an immune organ. Moreover, the robustness of rhythmic melatonin biosysnthesis is maintained in vitro, demonstrating that a functional circadian clock is preserved in the reduced subset of the rhythmic pineal transcriptome. In addition, our genomic screen has yielded a list of 28 genes that are candidates for functional screening. These should be evaluated to determine any potential role they may have as a component of the pineal circadian clock. Finally, we report that the eyes and pineal similarly function to reinforce rhythms in brain and peripheral tissue, but that metabolism and clock gene expression are differentially regulated in chick.

Infectious agents such as bacteria or viruses can grow rapidly. If a microorganism invades a host, it must be recognized rapidly and destroyed before it overwhelms the immune system. Limiting infection to a minimum in the early stage is critical for the outcome and the recovery from infection. The innate immune system has evolved to recognize a few highly conserved, constitutive structures present only in microorganisms, such as bacterial lipopolysaccharide (LPS), called pathogen-associated molecular patterns (PAMP). Toll-like receptors are the host receptors that recognize PAMP, ultimately activating a variety of transcription factors to induce expression of a wide spectrum of immune related genes, e.g. defensins. Defensins are antimicrobial peptides that play an important role in innate defense against microorganisms in plants and animals. Beta-defensins are the largest family of antimicrobial peptides, which can directly kill microorganisms and have regulatory effects on the immune system. Thirteen beta-defensins have been identified; however, the regulation of these genes has not been well-investigated in the chicken. The objective of this research was to understand constitutive and inducible gene expression of beta-defensins in chicken white blood cells. Real-time RT-PCR was used to quantify gene expression level before and after LPS stimulation. Transcription factor binding sites in the genes were identified to understand the gene expression regulation. From the expression profile results, most chicken beta-defensins had induced gene expression by LPS stimulation in the early phase (0- to 3-hour) and reduced gene expression in the late phase (3- to 8-hour). As for the level of gene expression, the results show that the induced gene expression in the early phase corresponded to the higher levels of expression at 3-hours after LPS stimulation, and the reduced gene expression in the late phase corresponded to the lower levels of gene expression at 8-hours after LPS stimulation.

Lesser prairie chicken (Tympanuchus pallidicinctus) numbers have declined considerably in Texas since the early 1900s. Conversion of native prairie to cropland has been the major cause of the decline. I trapped and monitored 115 (66 males, 49 females) lesser prairie chickens in the Rolling Plains of the Texas Panhandle from 2001 through 2003. I used an information-theoretic approach to model selection as implemented in program MARK to evaluate factors contributing to variation in survival and differences in nest success. I found breeding season survival of both males and females was lower compared to non-breeding season survival. Annual survival was 0.52 (95% CI: 0.32? 0.71). Model selection indicated higher nest success (70%) in the sand sagebrush (Artemisia filifolia) vegetation type as compared to the shinnery oak (Quercus harvardii) type (40%). I also evaluated post-burn habitat alterations and plant succession (1 year and 2 years after burning) as potential lesser prairie chicken habitat. After spring rainfalls stimulated re-growth of herbaceous plants, male lesser prairie chickens moved to the site, feeding on new-emerging forbs throughout the summer. A female lesser prairie chicken with a brood used the burned site during the first summer after the burn. A year later, males established a lek on the burned site. Two female lesser prairie chickens with broods used the burned site during the second summer. Burned sites had more forbs than nonburned sites and probably had more insects available which are an important food source for chicks during their first 4?5 weeks of age.

Avian influenza virus (AIV) is a type A virus of the family Orthomyxoviridae and its outbreaks not only cause economic losses in poultry, but also are worldwide threats to human health. The phenotypic changes in host cells induced by pathogens are always accompanied by remarkable changes in gene expression. Therefore understanding the gene expression profile of infected cells at the global level is important to get insights into interactions between hosts and viruses. Different genomic approaches have been utilized in the current study to investigate the host-AIV interactions in chickens. The Ser to Asn mutation on position 631 in the chicken Mx1 protein was reported to result in a positive antiviral function in vitro. With AIV infection, the Mx1 mRNA expression levels in heterozygous birds were significantly up-regulated. Additional mutations on the chicken Mx1 coding region were identified by sequencing. The results showed that most identified mutations were co-segregated with S631N mutation except one insertion in the position of 1544bp in the heterozygous birds. We speculate this insertion might be related to the up-regulation of mRNA expression of heterozygous birds with AIV infection. The miRNAs play critical roles in biological processes and are important effectors in host-pathogen interactions. The miRNA deep sequencing was used to profile miRNAs in AIV infected or non-infected chickens. Differentially expressed miRNAs identified have expanded our knowledge in the functions of these potential immune related chicken miRNAs regulating host response to AIV infection. Both microarray and transcriptome analysis by RNA-Seq were used in the current study to investigate the global gene expression of host response to AIV infection. Through the comprehensive analysis, a list of strong candidate miRNAs such as miR-32 and their host target genes including Mx1 were identified for further elucidating the regulatory mechanism of host-AIV interaction. In summary, we have identified many important candidate host genes and miRNAs which play important roles in the modulation of host response to AIV infection using genomic approaches. Further investigation of underline regulatory mechanisms of these genes, miRNAs or related pathways, followed by functional analysis, could lay solid foundation for understanding cellular and molecular mechanisms of the host-AIV interactions, thereby, pave a way for the development of novel protective strategies against AIV infection in chickens.

Salmonella enterica serovar Enteritidis (SE) is one of the most common food-borne pathogens that cause human salmonellosis. Contamination of consumed poultry products continues to be a global threat to public health. Genetic resistance using genomic approach provides a promising solution to controlling SE infection in poultry. The mechanism of SE resistance in chickens remains elusive. Three different approaches, microarray techology, gene silencing, and computational gene analysis, have been utilized to study SE-induced transcriptional changes of host immune response in the chicken. A whole genome chicken 44K microarray was used to analyze the transcriptome of heterophils from SE-resistant (line A) and SE-susceptible chickens (line B) with/without in vitro SE stimulation. Many differentially expressed immune-related genes were found in the SE-infected to non-infected comparison, where more immune-related genes were down-regulated in line B than line A. These results suggested a similar Toll-like receptor (TLR) regulatory network might exist in heterophils of both lines, and provided strong candidates for further investigating SE resistance and susceptibility in chickens. In the gene silencing study, small interfering RNAs (siRNA) were used to specifically inhibit the expression of NFkB1 in the chicken HD11 macrophage cell line with SE challenge. Genes related to the NF-kB signaling pathway were selected to examine the effect of NFkB1 inhibition on TLR pathway. With 36% inhibition of NFkB1 expression, the results showed an increased expression of TLR4 and interleukin (IL)-6 following SE challenge and suggested a likely inhibitory regulation of NFkB1 on TLR signal pathway. Finally, two novel chicken C-type lectin-like receptors were identified and annotated to chicken CD69 and CD94/NKG2-like with multiple evidences generated by computational (in-silico) sequence analysis. Both genes located in a region on chicken chromosome 1 that is syntenic to mammalian Nature Killer Receptor Complex (NKC) region, which may have existed before the divergence between mammals and aves. While siRNA lays the foundation of using loss-of-function approach on testifying gene-gene interactions, in-silico analysis aids in gathering information of unknown genes of great interest. Both approaches provide great potential to use for down-stream analysis following microarray study.

The overall aim of this thesis was to determine if day old turkey gonads could be cryopreserved and transplanted into recipient poults. This would allow for grafts to develop and mature normally and potentially produce donor-derived offspring. In addition, the monitoring of folliculogenesis in chickens was studied to determine if ultrasonography would be a useful technique to study this biological process, with the intention of using this method in future studies on ovarian graft development. Three studies were conducted: cell and tissue viability of vitrified day old turkey gonads, transplantation of day old turkey gonads into recipient poults, and monitoring of follicle growth in chickens using ultrasonography. The objective of the first study was to determine if day old turkey gonads were viable after vitrification using a standard protocol or with variation in equilibrium solution (ES) and/or vitrification solution (VS) absorption times. Three different ES time points were tested 10, 15 and 20 min (10ES, 15ES and 20ES) and two different VS time points 2 and 3 min (2VS and 3 VS). The cell and tissue viability was determined by Trypan Blue Assay and light microscopy, respectively. Testicular cell viability was conducted using three vitrification protocols and fresh tissue. All vitrification protocols along with fresh tissue were assessed by light microscopy, to evaluate histological alterations, in ovarian and testicular tissue. Protocols with the highest cell viability and best morphological scores were selected as being the most suitable for cryopreservation. Testicular tissue vitrified using 15ES or 20ES with 3VS had the highest cell viability. Ovarian and testicular tissue vitrified using 15ES with (3VS or 2VS), showed the best morphological scores, out of all the protocols. The second study was broken down into two parts: Part A (Trial 1 & 2) was to determine the most suitable age group for poults pre-surgery to give the highest survivability; Part B (Trial 3) was to determine if previously vitrified day old turkey gonads could develop and mature normally, by retrieving grafts post-surgery, at- different time points. In Trial 1, large white turkeys (LWT) 1, 3, 4 and 7 days of age were used and for Trial 2, LWT’s aged 1, 3, 4, and 5 days of age were used. In Trial 3, bronze turkeys at 1 day of age were used, and graft tissue was used from day old LWT’s previously vitrified (10ES/2VS) or fresh. For all Trials, the survivability at each time point was analyzed, and for the third Trial, the grafts recovered were histologically analysed. From Trials 1 and 2, seven and three day old poults had the highest survivability ratios (3/5 and 6/8) respectively. For Trial 3, day old male poults (96%) had a higher survivability than the females (68%). From Trial 3, transplants were only recovered in females and males up until 4 days and 4 weeks post-surgery respectively, with no fresh tissue grafts recovered. The histological analysis of testicular transplants showed deteriorating structure, with a steady progression away from normal morphology, post-surgery. The third study’s objective was to determine the growth rates and patterns of folliculogenesis in Barred Plymouth Rock (BPR) hens by using ultrasonography. Two ultrasound Trials were performed: the first to determine the optimum time interval between serial ultrasound scans to accurately map follicles, and the second to tackle the main objective of the third part of this thesis. For the first Trial, BPR hens were scanned periodically over 24 hours, follicle diameter and position were recorded and mapped with respect to the ovary and neighbouring follicles. Proportional follicle growth, compared to the first scanning session showed that the 24hr time point had the only significant (P<0.001) proportional follicle growth. It is recommended here that scans occur twice a day (morning and afternoon) to capture a more precise growth rate of follicles. In the second Trial, BPR hens were scanned twice a day, over an 11-day period. Follicle diameters (height and width) were recorded to calculate follicle area. The growth of each follicle’s area was compared to the time before ovulation to determine the overall follicle growth rate. Additionally, it was determined if time (night, day) and type of preovulatory follicle (F1-F5) played a significant role in follicle growth rates. The overall follicle growth rate was best described by a cubic equation (R2=0.907, P<0.001). Follicle growth rates were influenced by both time (P=0.009) and type (P<0.001). With F2 and F3 follicles (P<0.05) having a higher growth rate than F1 and F5 types. In conclusion, modifications to the standard vitrification protocol used on quail gonads were necessary to increase cell viability and lower morphological alterations for turkey gonads left whole. For future work it has been shown that day old turkey poults can survive gonad transplantation. The lack of development of grafts is most likely due to a combination of tissue damage after vitrification-warming procedures and insufficient immunosuppression of the host. This work has paved the way for the poultry industry to be able to cryogenically store turkey gonads and revive lines when required. Additionally it was shown that serial ultrasound scans twice a day provided accurate monitoring of follicle growth in Barred Plymouth Rock hens. For BPR hen’s follicle growth rates and patterns were successfully measured. This gives the industry another tool to better select superior laying hens and to create a more homogeneous laying flock. Future application of ultrasonography on gonad monitoring has the potential to show growth and maturation of grafted tissue before the production of donor-derived offspring, enabling earlier detection of successful transplantation.

The effects of deep fat frying and oven baking on mass transfer (moisture loss and oil uptake), color and textural characteristics of chicken nuggets were studied. Deep fat frying was performed at three oil temperatures, namely 150, 170 and 190°C. The frying times were 1, 2, 3 and 4 min. Oven baking was accomplished at three temperature levels: 200, 220, and 240°C, and the baking times were 10, 15, 20 and 25 min. / Moisture content of the breading portion of the fried chicken nuggets decreased following a typical drying curve and ranged from 0.90 to 0.22 g/g (db), while the moisture content of the core portion of the chicken nuggets decreased almost linearly and ranged from 1.96 to 1.4 g/g (db). Fat contents of the breading and core portions increased linearly with time. Generally, frying temperature significantly affected the moisture contents of the breading and core. It also affected the fat content of the core but not that of the breading. (Abstract shortened by UMI.)

Despite their beneficial effects, concerns have been raised about the role of antimicrobial growth promoters (AGP) in the emergence of antibiotic resistant bacteria. This study evaluated the effects of approved AGP on the emergence of antibiotic resistance in commensal E. coli and foodborne pathogen Salmonella. A survey of antibiotic resistance levels in commercial broiler chicken farms in the Fraser Valley (B.C.) and an experimental feeding trial were conducted from May 2004 to February 2005 and May to November 2005, respectively. The latter examined the effects of ten AGP formulations (bambermycin, penicillin, salinomycin, bacitracin, combination of salinomycin and bacitracin, chlortetracycline, virginiamycin 11ppm, virginiamycin 22ppm, monensin and narasin) on bird performance as well. Multiple antibiotic resistant commensal E. coli and Salmonella carrying virulence genes were found at commercial broiler chicken farms and therefore may serve as reservoirs for these genes. There was no significant difference between feed formulations on the phenotypic or genotypic characteristics of the isolates, except for tetracycline resistance gene tet(B). In the experimental feeding trial, broiler chickens were fed a diet including or excluding AGP. Birds were sampled prior to and weekly during feeding of the control and the AGPP containing diets. Although not detected on day 0, E. coli increased after day 7 to more than 9.9 log10 CFU/g in ceca. Multi-drug resistant E. coli were isolated from birds fed the ten AGP containing diets as well as the control diet. Except for penicillin, none of the AGP containing diets significantly improved bird performance compared to the control diet (P>0.05). Good management practices can significantly improve broiler chickens performance and decrease the mortality rate.

Per pastaruosius 20 metų daug pasiekta auginant viščiukus broilerius – ženkliai padidėjo viščiukų augimo greitis ir maisto pasisavinimo efektyvumas. Šiuolaikiniai komerciniai hibridai greitai vystosi ir jiems reikia daug energijos turinčių lesalų, kurie leidžia maksimaliai išnaudoti jų genetines galimybes. Daugiau pasiekta ir vištų dedeklių lesinime balansuojant lesalus skirtingais dėslumo etapais, ypač ankstyvojo dėjimo periodu. Pastaruoju metu paukščių lesinime didelis dėmesys skiriamas optimaliam kalcio, fosforo, natrio, kalio ir chloro subalansavimui. Parinkus netinkamas kalcį ir fosforą nešančias medžiagas, taip pat nesubalansavus natrio, kalio ir chloro tarpusavio santykio, t.y. anijonų katijonų balanso, padidėja vandens suvartojimas, sutrinka virškinimo trakto mikrobiologinė pusiausvyra, blogėja kraiko kokybė ir mikroklimato parametrai, susidaro sąlygos paukščiams susirgti ascitais, padaugėja paukščių staigių gaišimo atvejų. Vitaminai ir mineralai yra svarbi sudedamoji paukščių raciono dalis. Šios medžiagos įtraukiamos į racioną kaip priedai atitinkamais kiekiais, kad būtų patenkintas jų poreikis sveikiems produkciją duodantiems paukščiams. Mineralų ir vitaminų trūkumas gali būti kritiškas tam tikrais organizmo vystymosi etapais, todėl kai kurie autoriai teigia, kad net ir trumpas vitaminų bei mineralų apribojimas augimo fazės metu gali turėti neigiamų pasekmių. Magistrinio darbo tikslas – nustatyti mineralinių medžiagų įtaką dėsliųjų vištų ir viščiukų broilerių... [toliau žr. visą tekstą] / Minerals play a very important role in digestion and metabolism of poultry. They are necessary, for the maintenance, growth, production and health of birds. Laying hens also require minerals, primarily calcium, for eggshell formation. Minerals is divided into the macrominerals (those needed in relatively large amounts) and the micro- or trace minerals. Although microminerals are required only in small amounts, the lack of an adequate dietary supply can be just as detrimental to poultry as a lack of one of the macrominerals. Grains are low in minerals, so all poultry feeds contain supplemental sources. Calcium, phosphorus and salt are needed in the greatest amounts. Microminerals such as iron, copper, zinc, manganese and iodine are normally supplied through a trace mineral mix. The minerals influence by the bird‘s physiological status, requirement of minerals and its source is describe in the theory part. Two experiment were performed with broiler chickens and laying hens. The feed intake, feed conversion ratio, birds mortality, the degree of mineralization in the bone tibia, pH, macroelements Ca, P, Mg, Na, K, Cl and alkaline phosphatase in the blood serm were researched in experiment of broiler chickens. Number and weight of eggs, body weight, laying intensity, leftover and utilization of feed to get 1 kg eggs mass, quality parameters of eggshells, the physiological conditions and mortality reasons were researched in test of laying hens. Conclusions. Sodium bicarbonate was... [to full text]