Duration: 10/01/2007 to 09/30/2012

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Importance of research and potential consequences
Genetic selection for economically important traits has often been at the expense of others such as reproductive efficiency, metabolic disorders and immunological fitness. Limited information is available to describe the genetic inter-relationships or interaction of genes and their subsequent effects on traits. Therefore, it is the purpose of this project to develop co-operative research to define physiological, biochemical and gene expression consequences to genetic selection in poultry using both selected and commercial lines. Archaeological evidence for domestication of fowl dates to approximately 2000 BC in the Indus valley (India). Almost 4000 years later, the chicken accounts for nearly 75% of major domesticated animals in the world, with 2003 US population of over 300 billion. This increase is inextricably linked to the unprecedented increase in per capita consumption of poultry during the same time. By 2003, Americans consumed in excess of 110 lb. of poultry per capitaof which >90 lb. were chicken alone. The modern broiler-type chicken attains a 5.5 lb. body weight in 40-42 days of age with an overall feed efficiency of less than 1.9. Approximately 85-90% of this change in growth has been attributed to selection for growth, and has been achieved by reducing the market age to the same body weight by one day per year. With continued progress for further-processed products there has been a shift in market age to slaughter. This has resulted in the re-emergences of physiological and metabolic syndromes. The normal process of growth involves the simultaneous deposition of bone, muscles, and fat; each exhibiting an individual pattern of development. Selection for body weight has altered two phenomena that impact these processes. One is progenesis, which reflects the acceleration of development as defined by precocious sexual maturity. The other is neoteny, which is the retarded development of specific tissues and/or organs. Progenesis and neoteny have very different roles during selection for growth. Selection at the point of inflection leaves some characters in their juvenile state, while accelerating others. For example, there is a relatively larger increase in the proportion of muscle mass in chickens selected for high body weight as compared to late selection. Overall these alterations in developmental timing, called heterochrony, can occur via changes in gene expression and/or changes in the allometric relationships among physiological and metabolic sub-systems themselves. Difficulties in determining the underlying physiological and metabolic systems responsible for this distortion have been two fold. First, there has been an inability to define the non-linear dynamics of the growth process in relation to other physiological systems. In part, this has been due to the absence of animal model systems to compare and contrast the different developmental periods of growth. The second has been the limited application of appropriate molecular, physiological and/or biochemical tools to identify changes in genetic and physiological processes underlying growth. Domestication, genetic improvement and controlled reproduction have come with a cost. The broiler industry has seen increases in the incidence of obesity, skeletal problems, juvenile mortality, disease resistance, ascites, maladaptation to stress, metabolic disorders and inability to utilize phytate phosphorus. Reduced reproductive performance in the guise of erratic ovulation and defective egg syndrome has become common place among broiler-breeder hens. Recent reports suggest that the ability of the broiler-breeder male to fertilize eggs is declining at a rate of 0.5% per generation. Curiously, a major challenge to the poultry in and animal agriculture is the propagation of the idea that traditional selection parameters coupled with production practices are the direct cause of decrease animal fitness and welfare. The negative relationship between genetic selection and fitness has been surmised from the temporal congruence of the two events in both industrial and experimental settings. This conclusion is reinforced by current industry practices that recommend the restriction of early growth. However, data from the S289 Project have consistently distinguished between shared environmental and/or spurious correlations. The focus of this project is to investigate the underlying changes in physiological, cellular and biochemical mechanisms associated with genetic improvement of economically important traits in poultry.

Consequences if research is not done:
The lack of understanding of the underlying physiological, cellular and biochemical mechanisms associated with genetic improvement would mean that there would be no remedy or solutions for the current problems associated with poultry breeding as enumerated in the previous section.

Need as indicated by stakeholders (Poultry breeding Industry)
The prospect for genetic improvement continues to be encouraging. From poultry breeding industrys perspective, the limits of selection for growth rate and egg production may be on the horizon and industry will place increased emphasis on new sources of genetic variation, and appropriate biomarkers for the genetic improvement of fitness and welfare related traits. The upcoming transition period will be extremely important, and rate at which these changes can be adopted for commercial uses would influence the long-term economic sustainability of poultry as a viable source of food. A major effort to understand the physiological, cellular and biochemical mechanisms underlying genetic changes in poultry requires a wide range of expertise, which cannot be found in any single experimental station. Members of S289 group have primary expertise in genetics (quantitative, molecular/physiological), physiology, endocrinology and nutrition. While independent studies are conducted at the stations where primary genetic stocks are generated and maintained; it is the overall diversity of training and interest and consequential collaboration between stations that makes it possible to complete the objectives of this proposal. The chicken sequence is now available and this will change ways of conducting poultry research. Researchers can take advantages of the chicken genome and expressed sequences, microarrays and high-throughput genotyping that has been established (TX) and is available for all collaborators in the proposed projects. Interaction among project scientists would lead to the successful understanding of genetic mechanisms underlying growth, reproduction and fitness.

Multi-state Effort
The S289 and its predecessor S233 Projects have a strong history of interaction as evidenced by the many multi-authored publications, sharing of methods and genetic resources including semen, hatching eggs, DNA and/or RNA sequences. This project directly addresses a national initiative in the area of Genetic Resources, Development and Manipulation. Several disciplines and co-operative investigations are encompassed within the proposed research. However, the distinguishing feature of this project is its emphasis on a systems approach to the elucidation of molecular, biochemical and physiological changes as impacted by genetic selection. Only collaborative efforts between geneticists, physiologists, nutritionists, immunologists make this possible. No one experiment station possesses the expertise to maintain and select genetic lines while conducting the molecular, physiological and biochemical assays necessary to meet the objectives of this proposal.

Technical feasibility of research
Member stations have maintained models representing the major species of poultry (turkey, chicken, quail and guinea fowl) that will enable scientists to identify appropriate cellular, physiological and molecular mechanisms underlying genetic improvement in growth. Collaborative efforts are planned between stations housing and generating the primary genetic stocks and the remaining institutions. This multi-station effort is needed to better understand the consequences of direct selection for growth, immunological response and disease resistance on correlated traits such nutrient utilization, reproductive efficiency, metabolic and environmental stress. Genetically divergent poultry lines are an important resource for understanding the molecular basis of many economically important traits. Biochemical, physiological and molecular genetic tools will be used to determine the cellular effects of genetic selection.

Impact and benefit
Benefits of this research include a) basic information about selected lines for use by poultry breeders and b) elucidation of biochemical, physiological and cellular pathways affected by selection for economically important traits. This creates an opportunity to transfer scientific knowledge from specific studies involving the chicken to other less widely-studied poultry species including turkey, quail and guinea fowl.

Related, Current and Previous Work

A major part of S-289 projects have been on the polygenic basis to phenotypic expression of traits of economic importance. Chicken, turkey and quail lines have been developed by the S-289 group that are divergently selected for wide variations in growth rate (Liu et al., 1995; Marks, 1993; Barbato, 1996; Nestor et al., 1996), ascites (Balog et al., 2003), phytate phosphorus bioavailability (Aggrey et al., 2002; Zhang et al., 2003). These lines have been used and still being used to identify genes and metabolic pathways affecting growth, ascites, tibia dyschondroplasia, phytate phosphorus utilization in commercial poultry. The genetic basis for ascites and its concomitant relationship with other traits have been identified (Anthony and Balog, 2003). Relationships between growth and reproductive capacity have been cited in Poultry Genetics, Breeding and Biotechnology (W.H. Muir and S.E. Aggrey, eds., 2003; Decuypere et al., 2003). The growth related lines established by VA has been used in quantitative trait loci studies, and through that study, some candidate genes associated with growth have been cited in the proceedings of the XII World Poultry Congress. A sperm binding assay associated with reproductive capacity in male chickens has been identified by scientist from the S-289 group (Barbato et al., 1998). The molecular basis for changes in muscle and other traits from divergently selected lines for growth (Smith, et al. 2000; Kerr et al., 2001, Sizemore and Barbato, 2001; Kuhnlein et al., 2003a) have produced candidate genes (Smith et al., 2000; Kuhlein et al., 2003a). The tibial dyschondroplasia (TD) lines are being used in to identify the specific genes involved the TD syndrome in broiler chickens. Work to date definitively demonstrates that the tissue specific expression of the deiodinase II enzyme gene is deficient in the high TD lines. Calbindin is also differentially expressed in the TD lines (Shirley et al., 2003). Regulation of immune response and disease resistance or susceptibility is a major function of the proteins encoded by the major histocompatibility complex (MHC). Major histocompatibility complex alleles have been changed by selection for egg production and disease resistance. The B21 locus as described in the high and low antibody lines at Virginia show that genes at this locus with the MHC confer resistance to Mareks disease. Molecular markers associated with the B21 locus has been identified and the biochemical pathways influenced by selection and expression of major genes of the MHC are direct focus of this group. Members of the regional project S-289 have identified and studied genes and gene products known be to associated with a particular trait; dissection of commercial traits into its physiological components, so that genes can be identified through their actions (Aggrey et al., 2004; Pinard-van der Laan et al., 2003; Kuhnlein et al., 2003a, b). Under Objective 2 of the S-289 regional project, research was conducted on the effects of immune modulators on reproductive performance in laying hens and bobwhite quail. Mouse, tumor necrosis factor alpha (TNF±), attenuated ovine luteninzing hormone (oLH) and increased progesterone secretion by White Leghorn preovulatory follicle granulosa cells. Similar results in mice have been reported indicating that there may be differential occupation of type I vs. type II TNF cell surface receptors. Results from these studies indicate that TNFa may play a role in the ovulatory response of avian granulosa cells to LH, and that immune status of the hen may alter this response through differential occupation of cell surface receptors responsive to the cytokine TNF a. (Grizzle et al, 1999). The acute 50% lethal dose (LD50) trichothecene mycotoxin, T-2 toxin, hepatacide, biological warfare agent, and strong immunosupressant in bobwhite quail is 14.7 mg/kg body weight (BW) which is approximately 3 times greater than for the domestic chicken (Grizzle et al., 2004; Kersten, 1998). Reasons for the resistance of the bobwhite quail to T-2 toxin is unknown, but if discovered may lead to therapies for individuals exposed to this mycotoxin. Reproductive effects of T-2 toxin on the bobwhite hen were studied. In hens, delayed puberty, reduced fertility and total hatchability of eggs for the first 2 weeks following exposure were observed (Kersten, 1998). In males body weight change, testicular weight, length and diameter were all significantly less (P < 0.05) among males fed 16 mg/kg T-2 toxin as compared to untreated controls. Mouth lesion scores were higher (P < 0.01) among birds fed 8 or 16 mg/kg T-2 toxin. Similarly morphological evaluation of testis tissue showed a dose dependent decrease in spermatogenesis, particularly the elongation of spermatids to mature spermatocytes. Analysis of blood samples taken from these males showed that plasma luteinizing hormone (LH) was unaffected by any level dietary T-2 toxin, while testosterone levels were significantly (P < .01) less among birds fed any level T-2 toxin (5.75 ng/ml testosterone vs. 0.65 ng/ml for 0 and 16 mg/kg feed T-2 toxin respectively). Analysis of fixed testis tissue using the terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick-end labeling (Tunnel) assay showed that T-2 toxin was acting at least partially through the mechanism of apoptosis. Thus T-2 toxin may act as an endocrine regulator in birds. Additional evidence has been found to show that T-2 toxin may act as an endocrine modulator in birds, but most importantly at levels far below that which will impact on the mortality of flocks. Production and accumulation of egg yolk phosphoproteins are dependent on interactions between nutrition, endocrinology and age of the hen. Studies using phytase to improve phosphorus digestibility indicate that it may be possible to manipulate egg size, and hence chick size, through changes in phosphorus nutrition (Berry et al., 2003). The rate of reproductive maturation in breeder hens is constrained by the minimum egg size to produce a viable embryo. This should not be a constraint for males. Studies from this group have found that it is feasible to rear roosters using a faster growth program than is customary. And some of the advantages to early maturation of breeder males include improved reproductive fitness and health of the males with reduced cost of feed, labor, and facilities (Hess et al., 2003).

Experiments were conducted to determine dietary and non-dietary factors that influence ascorbic acid (AsA), a major antioxidant and regulator of cell function, biosynthesis in poultry. Time-course changes in L-gulonolactone oxidase activity (GLO), the final step in biosynthesis, in immature broilers was best characterized by a segmented response function with the maximum value at 13 days and declined linearly from day 16. Strain by age and diet by age interactions were detected for GLO and estimated synthetic capacity with significantly greater decline in commercial broiler strains fed supplemental AsA and dietary AsA markedly depressed biosynthesis (Hooper et al. 2002). Cadmium and vanadium influenced growth with 50 mg/kg Cd causing a significant depression in GLO (Maurice et al. 2004a). Hyperthyroidism, induced by feeding triiodothyronine, depressed AsA biosynthesis and this was associated with ascites whose incidence was reduced by supplemental AsA. Brown and white egg strains of layers differed in GLO but within each strain differences were not detected when birds producing strong and weak eggshells were compared (Maurice et al. 2004b).

There are other regional projects that are interested in the expression of economically important genes in the avian genome. Regional project NC-1008 seeks to develop high resolution integrated maps and develop new genetic variation by gene transfer and chromosome alteration. This project does not seek to duplicate efforts of regional projects through gene transfer, high resolution maps, transgenesis or manipulation, or to solely identify genes involved with disease resistance. The primary goal of this proposal is to use an integrative systems approach to determine cellular, physiological and biochemical mechanisms as impacted by traditional methods of selection. For the most part, S-289 and its predecessor S-233 project members have taken a polygenic approach to the phenotypic expression of economically important traits. Substantial contributions have been made by members of S289 and S233 as evidenced by citations in two leading comprehensive texts in Poultry Genetics. Poultry Breeding and Genetics, R.D. Crawford, ed., and Poultry Genetics, Breeding and Biotechnology, W. H. Muir and S. E. Aggrey, eds. Members from stations VA, OH, GA, TX, PA contributed 5 chapters and editorial assistances to these books. In addition 150 refereed journal articles, 8 conference proceedings, 3 web reprints, 3 popular articles and 15 thesis/dissertation were published by S-289 members during the last 5 years. The accomplishments of this group are evident. However, current advances in science, especially molecular biology and proteomics have provided unique opportunities for further elucidation of biochemical, physiological and molecular genetic mechanisms as impacted by selection.

Objectives

1. To determine the functional mechanisms of genetic changes as a result of selection and gene introgression.
   
2. To determine the effect of genotype by environmental interaction on the biochemical and physiological mechanisms involved in the expression of productive phenotypes.
   
3. Evaluate individual loci and resultant protein expression on performance phenotypes and genetic background.
   

Methods

OBJECTIVE 1: To determine genetic changes as impacted by selection and gene introgression. Genetic Selection: Genetic lines will continue to be selected for growth rate, antibody response, susceptibility to ascites, TD, phyate phosphorus utilization (PPU), and Rous sarcoma regression. Published research shows that there is a long history of sharing genetic lines among cooperators. In addition, previous members of this group freely make their lines available for use. The dwarf line (GA) was developed by introgression. Other single gene traits lines will be developed and studied by gene introgression. The development and maintenance of these lines are part of the primary focus of this aspect of Objective 1, and is primarily accomplished at individual stations as this is where the lines are generated and the scientific expertise in genetics is located. (see attachment 2). Growth-Body Weight: The Arkansas (AR) and Georgia (GA) stations have established programs to determine the effect of selection for body weight (BW) or BW gain (BWG) on patterns of growth in quail. The AR station currently maintain Japanese quail lines H10, H17, H28, and H40 which have been selected for high rate of growth at 10, 17, 28, or 40 days of age respectively. Line HL has been selected for high growth rate between days 10-17 of age, and low BWG between 17 and 28 d of age. Line LH has been selected for a low rate of growth between 10 to 17 d of age, and a high rate of growth between 17 to 28 d of age. All lines have been selected for 35 generations and distinct patterns of growth. Similar to the lines developed at AR, the GA station has Japanese quail lines divergently selected for high and low 4-week BW. The Ohio station has Japanese quail lines divergently selected for high and low 4-wk BW (HW and LW). The HW and LW lines are in their 45th generation of selection. These quail lines from these institutions will be maintained and routine measurements of selected and correlated traits will be made. The lines are available for use in collaborative studies. Pennsylvania currently maintains 4 unique chicken lines selected for exponential growth rate (EGR). Similar to the AR quail lines, these birds have been selected for high or low EGR from hatch to 14 days of age (14H:14), and high or low growth rate from hatch to 42 days of age (42L: 42H). These lines have undergone over 15 generations of selections. AR, PA and GA plan to consolidate the growth curve response observed for these lines in an effort to characterize growth dynamics of the fowl. Virginia (VA) has established lines of chickens selected for growth rate. Virginia maintains several lines of White Plymouth Rock chickens selected for high or low growth response. Lines HW and LW have been selected for high or low juvenile, 8-week body weight respectively. The VA lines have been the bases of QTL mapping studies, and microarray and proteomic studies will subsequently follow. Antibody Response The VA station continues to be one of the major reservoirs of genetic lines and selection trails for the group. In addition to the high and low juvenile body weight lines, VA maintains genetic lines of White Leghorn chickens selected 24 generations for high or low antibody titers (HA, LA) in response to sheep red blood cell challenge (Siegel and Gross, 1980). The HA line is known to he haplotype B21/B21, and the low line B13/B13 at the MHC. The lines are under study in search of genetic markers associated with high or low antibody titers. Susceptibility and resistance to rous sarcoma: The Arkansas station maintains two Leghorn type populations that have exhibited resistance and susceptibility to Rous sarcoma tumor virus. Gyles et al. (1967) first reported on the development of these two lines (Arkansas Progressor and Arkansas Regressor). The Regressor line typically regressed induced. Rous sarcomas but the Progressor develop a fatal tumor. Since the two lines have been developed various aspects of their immune system have been investigated. The lines have been characterized and fixed for various blood groups. Ascites: The Arkansas station has developed divergent lines for susceptibility to ascites as induced by hypobaric hypoxia (Anthony and Balog, 2003). The base population for these lines was a commercial elite line that had experienced one generation of relaxed selection. This line is currently maintained with the ascites selected lines. Line selection was accomplished through family selection where sibs were selected based on performance at 9000 feet altitude. Lines are in their 10th generation of selection and progeny are available for use at other stations. Current ascites incidence is 25 and 95% for the resistant and susceptible line respectively when reared in high altitude conditions. Arkansas and Ohio State stations would collaborate on studies involved muscle morphology as evaluated by fiber degradation by creatine kinase concentration. Phosphorus Utilization:The GA station has developed divergent lines for high and low phytate phosphorus utilization (PPU). The divergent lines were developed from the Athens-Canadian Random bred population (ACRB). The selection was accomplished through individual performance (PPU) at 4 wk of age. Lines are in their 5th generation and progeny are available for use at other stations. The correlation between PPU and BW, feed efficiency and reproductive capacity will be done in subsequent studies. If successful, strains able to utilize organic or phytate phosphorus would be more cost efficient to produce. However, more importantly phosphorus content of house litter will be less, and result in reduced environmental pollution. Tibial Dyschondroplasia (TD): Tibial dyschondroplasia is a genetic leg defect with a lesion of avascular, non-mineralized cartilage below the growth plate of the proximal tibiatarsus in commercial broilers and turkeys. It is a common cause of bone deformity and lameness in fast growing birds. Although economic losses directly due to TD are unknown, the US broiler industry loses $120 million annually due to leg problems. Leg problems increase mortality, the number of culls, and downgrades of chicken meats. The etiologies remain unclear though the trait is highly heritable. TD resistant and susceptible lines are currently maintained in AU. These lines will be used to produce a resource population to map the loci underlying the disease. The success of the project will provide a genetic marker for broiler breeding company to eliminate the susceptible alleles. It may also have similar implementation in the turkey industry. Studies will be initiated between AU and Texas A & M stations in identifying genes involved in TD syndrome. Poultry as a biomedical model: (Atherosclerosis and Cardiomyopathy): Heart disease is considered the number one killer of individuals in the United States of America. According to the American Heart Association (AHA) in 2001, 60,800,000 Americans have one or more type of cardiovascular disease. Data from molecular analysis of poultry genes implicated in cardiovascular disease could be used to model human disease. Poultry as a model for human health has been used in a variety of biological studies. Poultry Chickens have been used to study atherosclerosis (Armstrong and Heistad, 1990), hypertension, and cholesterol metabolism (Bogin, 1989). The drug (furazolidone) induced model of turkey cardimyopathy has been evaluated as a model for human dilated cardiomyopathy (Jankus et al., 1972) of which the etiology is unknown. Infection of chickens with Mareks disease Herpesvirus causes lesions of atherosclerosis, that are similar to those of human atherosclerosis, rendering the chicken a suitable model to study atherosclerosis in humans (Fabricant and Fabricant, 1999). The Major Histocompatibility Complex (MHC), among many functions, encodes proteins that are involved in the immune response and resistance to disease (Sacco et al., 2001, Yonash et al., 1999, Lamont, 1998). The MHC is involved in presentation of antigens to T cells). The link between the MHC and resistance to MDV in chickens has been established (Kariuki and Dangler, 1995). Tuskegee University will initiate various projects to screen turkey and chicken genomes for genes associated with cardiovascular disease (atherosclerosis and cardiomyopathy) and the link if any, between the MHC and their expression will be investigated. In vivo studies will use the MDV-induced atherosclerotic model in chickens to determine the link between the expression of MHC and genes implicated in atherosclerosis. INTROGRESSION: The era of molecular genetics and transgenic animals have made it possible to map genes that control traits and also study possible interactions between major genes and the background genome. Divergent chicken and quail lines developed by stations from this group (AK, PA, GA, VA) have been mapped for traits of economic importance. Genes of commercial interests identified in experimental populations maintained at member stations could be introgressed into commercial lines. A common approach has been to first cross the donor and recipient strains to produce an F1, which will be heterozygous for all loci that differ between the two strains. A series of backcrosses to the domestic strain is then performed, but only individuals carrying the donor allele for that gene being introgressed are selected as parent for the next backcross generation. After the final backcross generation the backcross progeny are mated among themselves, and individuals homozygous for the donor allele of the introgressed gene is selected. It is known that the genetic background of a population and/or the environment under which a population is raised can influence the expression of a defined phenotype. It is imperative not only to study introgressed genes in different populations, but also under different environmental conditions. There is ample evidence to demonstrate the different effect of gene introgression. For example the VA station introgessed the dwarfing allele into the high and low BW selected lines and found differences in performance. The GA station observed performance differences when the naked neck gene was introgressed on ACRB and raised under different ambient temperatures. Introgression of genes of interests may result in favorable or adverse effects on the background genome, particularly if the interaction results in compromised growth and fitness. As a result part of objective 1 would have to address the potential issues of introgression. Objective 2: To determine the effect of genotype by environment interaction on biochemical and physiological mechanisms involved in the expression of production phenotypes. What are the impacts of dietary and environmental factors on nutrient utilization, requirements, oxidative stress, reproductive and immunological responses among commercial and selected strains of poultry? What is the impact of genetic selection for economic traits on health, efficiency of nutrient utilization and reproductive performance of domestic poultry? What are the physiological responses to diverse environmental stressors among lines of selected birds? Nutrient Utilization: Cooperative studies between GA, SC and TN stations will be conducted to determine intestinal phytase activity in strains of chickens divergently selected for phosphorus utilization. Chickens and guinea fowl will be fed diets with varying concentrations of phosphorus and calcium and samples of intestines will be obtained. The mucosa from the small intestine will be collected and processed to obtain a supernatant that will be assayed for phytase activity as measured by the release of phosphorus from an appropriate substrate. The strains of chickens divergently selected for phosphorus utilization will also be used to determine expression of genes that are associated with phytase. The GA station plans a series integrative research on the genetics of feed utilization efficiency using the ARB from the AR station. Pedigreed mating would be done in Arkansas and eggs shipped to GA for incubation and hatching. Individual feed utilization efficiency will be determined. The physiological mechanisms underlying feed utilization efficiency will be studied jointly by GA and PA. Nutrient Requirement : Interest in raising guinea fowl as a meat bird has increased in the US in the last few decades. Although the guinea fowl does not comprise a very large portion of poultry meat market in the United States, it is sold all year round in supermarkets and served as a delicacy in restaurants. Also with the decline in game bird production there is increasing tendency in many restaurants and hotels in the US to use guinea as a substitute for game birds in their menus. There is however limited information on the nutrient requirements of the different strain of the guinea fowl. Cooperative studies between TN, GA and SC will evaluate major mineral and vitamin needs of these different strains of guinea fowl. AU and TU experimental stations would collaborate on the inclusion of phytase in broiler breeder hens in order to reduce phosphorus waste in excreta. Oxidative Stress Responsiveness: Reactive oxygen and nitrogen species are generated during normal metabolism. Various species, breeds, and strains of poultry differ in rates of oxygen utilization and generation of free radicals that induce oxidative stress. Strains of chickens also vary in their ability to quench free radicals produced. Oxidative stress is responsible for reduced feed efficiency, compromised welfare, susceptibility to diseases, losses during handling and transport, and a growing list of metabolic disorders. There is limited information on genotypic variation in the capacity of poultry to accommodate oxidative stress. This negatively impacts production efficiency, and selection for enhanced antioxidant capacity. Cooperative studies between SC, AR, VA and TN will examine antioxidants, total antioxidant capacity, and expression of the gene for L-gulonolactone oxidase. Reproductive and Immunological Responses: Phytoestrogens are plant compounds capable of producing estrogenic effects on animals. Negative reproductive effects of dietary phytoestrogens exposure in sheep fed clover are well recognized. However, there is limited information on the effects of phytoestrogens in poultry. Domestic poultry receive considerable dietary exposure to some of the most potent phytoestrogens. Cooperative studies between AU and Texas A&M will evaluate the effects of phytoestrogens on reproductive and immunological responses of poultry. Mycotoxin contaminants may be encountered by poultry in feeds or material obtained by foraging. In the US, mycotoxin contamination of feed grains is not unique. While primarily aflatoxin, reported contamination due to trichothecene mycotoxins DON and T-2 are noted. It is estimated that the annual cost to the US for lost revenues from mycotoxins is $1.5 billion (CAST, 1989). The real threat from mycotoxins comes from disease states, immune suppression, and synergistic effects from mixtures of mycotoxins (Cardwell et al., 2001). While strict FDA guidelines monitor individual levels of mycotoxins (Meronuck and Concibido, 1998), little research is present on the additive effects of multiple mycotoxins consumed at low levels. Experiments will be conducted at the UT to determine the singular and additives effects of T-2 toxin, aflatoxin, Deoxynivalenol (DON) and other mycotoxins on male fertility and reproductive performance in quail and chickens. Birds will be fed mycotoxin contaminated diets and bred to non mycotoxin fed females. Puberty, plasma testosterone and LH will be determined, as well as fertility and hatchability of eggs fertilized by test males. Chicks sired by mycotoxin fed males will be raised on uncontaminated and contaminated diets. At various time points during the rearing period, males will be sacrificed and testis morphology determined. OBJECTIVE 3: Evaluate individual loci and resultant protein expression on performance phenotypes. The evaluation of individual genes that affect performance phenotypes is the third objective of this regional project. The goal of quantitative trait loci (QTL) and microarray studies are to identify genes that affect traits of economic importance. The ultimate goal is to evaluate identified genes for their contribution towards a phenotype. The quintessential pre-requisite for evaluation of genes is the establishment of randomly mating unselected populations with well defined phenotypes. Randombred lines established by member stations of this group are: Arkansas randombred: This population represent a composite of 6 female and 7 male commercial parent stock available at 1996. They have been random-mated for 9 generations using 24 sire families with 3 dams per sire. The growth and reproductive performance of this random bred line is consistent with industry standards. Athens-Canadian randombred: The ACRB was established in the 1950s (Hess, 1962) from a composite of commercial lines. Evaluation of loci requires (1) Identification of sequence variation in genes that might either cause a change in the protein, or be in linkage disequilibrium with functional changes, (2) Establishment of genotyping assays and subsequently genotyping the variants in the randombred populations and (3) Using statistical methods to determine whether there is a correlation between those variants and the phenotype. It is not currently feasible to test all polymorphisms for association with phenotypes. On average, markers that are in close physical proximity are more highly correlated than those that are spaced far apart. Therefore new innovative statistical tools have to be developed to meet the new challenges.

Measurement of Progress and Results

Outputs

• The results of research activity will be information about selected lines for use by poultry breeders and data on biochemical, physiological and cellular pathways affected by selection for economically important traits. This creates an opportunity to transfer scientific knowledge from specific studies involving the chicken to other less widely-studied poultry species including turkey, quail and guinea fowl.

Outcomes or Projected Impacts

• Increased understanding of gene organization, function and identification of candidate genes involved in economically important traits in poultry.
• Enhanced understanding of cellular and physiological mechanisms underlying genes associated with trait changes.
• Increased scientific knowledge about the inter-relationship between production, nutrient utilization, reproduction, disease resistance and fitness.
• Elucidation of genotype-nutrition-immunological interactions on the biochemical and physiological mechanisms associated with the expression of phenotypes.
• Technology transfer to the appropriate clientele in the poultry industry.

Milestones

Projected Participation

View Appendix E: Participation

Outreach Plan

New technology or information generated by this group will be disseminated to relevant clientele through public-access databases, websites, scientific meetings, workshops, symposia, conferences, scientific journal publications, popular articles and industry technical committee meetings.

Organization/Governance

The Technical Committee is composed of a representative from each contributing experimental station or agency, and a Representative of the USDA Cooperative State Research, Education and Extension Service (CSREES). This committee shall have the responsibility for overseeing the duties associated with the execution of the regional project. These duties shall include the review and acceptance of contributing projects, review and modification of the project outline, review of data generated under declared objectives, and preparation of an annual report to be forwarded to CSREES by the administrative advisor upon approval. Committee business shall be conducted by an elected executive committee, and shall consist of an elected Chair and Vice-Chairpersons. The immediate past Chairperson, a Secretary, and the Administrative Advisor shall also be members of the executive committee. Term for elected officers shall be two years. Every two years a new Vice Chairperson shall be elected, and will advance to Chairperson after completion of his or her term. The Chairperson shall oversee the annual meeting of the Technical meeting, collate and distribute annual station reports to all committee members, and forward minutes and annual report to the administrative advisor for submission to CSREES. The chairperson may also name subcommittees to prepare proposals or publications, develop manuals, or other tasks needed in execution of committee business. The Vice-Chairperson shall serve on the executive committee and aid in conducting committee business. The Secretary will prepare minutes of the annual meeting, and an annual report which is to be a condensed version of all research results from the past year, and will forward these documents to the Committee Chairman for distribution. The Chairperson shall act as liaison between this regional project and other related projects for the purpose of information sharing and to prevent duplication of effort between this project and others which may be similar. It shall be the responsibility of individual committee members to prepare an annual report for their station. These reports are to be distributed to all committee members at the yearly meeting of the Technical committee. Members not in attendance shall forward the annual report to the local host in the time of distribution of the annual meeting.

Literature Cited

Aggrey, S. E., G. M. Pesti, R. I. Bakalli, and H. M. Edwards, Jr., 2004. Molecular factors affecting phytate phosphorus utilization in growing birds. In, Proc 22nd World Poultry Congress, 4 pp. Istanbul, Turkey.

Aggrey, S. E., W. Zhang, R. I. Bakalli, G.M. Pesti and H.M. Edwards, Jr., 2002. Genetics of phytate phosphorus bio-availability in poultry. In, Proc 7th World Congress on Genetics Applied to Livestock Production, 31:277-279. Montpellier, France.

Anthony, N.B., J.M. Balog, 2003. Divergent selection for ascites: Development of susceptible and resistant lines. Proceedings 52 National Breeders Roundtable.

Armstrong, M. L., and D. D. Heistad, 1990. Animal models of Atherosclerosis. Atherosclerosis 85:15-24.

Balog, J. M., B. D. Kidd, W. E. Huff, G. R. Huff, N.C. Rath, and N.B. Anthony, 2003. Effect of cold stress on broilers selected for resistance or susceptibility to ascites syndrome. Poultry Sci. 82: 1383-1387.

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