Review Article
Molecular genetics in a modern poultry breeding organization
- J.E. FULTON
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- Published online by Cambridge University Press:
- 13 June 2008, pp. 171-176
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Molecular genetics is providing the tool box of the 21st century for the modern poultry breeding company. These tools allow for rapid and accurate identification and selection at the gene level of those individuals with better performance traits. Genetic selection can be done before traits are expressed, molecular genetics testing can be applied to males for female limited traits, and it can be done on chicks shortly after hatch. They also allow for rapid diagnosis of genetic deficiencies and pathogen contamination, and allow excellent quality control and brand identification methods. This tool box will continue to improve as new methods and more rapid and less expensive methodologies are developed.
Long term selection for reduced or increased pecking behaviour in laying hens
- A.J. BUITENHUIS, J.B. KJAER
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- 12 November 2008, pp. 477-487
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Feather pecking in laying hens is an important issue in animal welfare. Four studies in laying hens were selected which investigated increased or reduced pecking behaviour using direct or indirect measures of feather pecking behaviour. Direct comparison of the selected experiments is difficult, as the selection criteria and even the selection procedures varied. Keeping these differences in mind, the results of the experiments showed that a) It is possible to change pecking behaviour in the desired direction using selection, b) Aggressive pecking is not related to feather pecking, c) There is no clear consensus as to the relation between selection on pecking behaviour and laying performance and egg quality, d) Plasma serotonin level in the blood was reduced in the lines selected against pecking behaviour in both the individual selected lines and the group selected lines and there were indications that dopamine also plays a role in the regulation of pecking behaviour, and finally e) There are differences between the selected lines and their control lines with regard to the immune parameters both in the individual selected lines as the group selected lines, indicating that direct as well as indirect selection for reduced pecking behaviour changes the immune response.
Involvement of the hypothalamic-pituitary-thyroid axis and its interaction with the hypothalamic-pituitary-adrenal axis in the ontogeny of avian thermoregulation: a review
- M. DEBONNE, P.J.J. BAARENDSE, H. VAN DEN BRAND, B. KEMP, V. BRUGGEMAN, E. DECUYPERE
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- 05 September 2008, pp. 309-321
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The emergence of thermoregulation in avian species is a complex matter in which neural as well as hormonal processes are involved. In a previous paper, the neural aspects of primary avian thermoregulation were discussed. In this paper the role of the hypothalamus-pituitary-thyroid axis (HPT-axis) and the hypothalamus-pituitary-adrenal axis (HPA-axis) in the ontogeny of avian thermoregulation is evaluated. The regulatory mechanisms and different important hormones of both axes, which have stimulatory or inhibitory effects, are discussed. Because the onset of functionality of the thermoregulatory system is of great interest, the ontogeny and functionality of the hormonal axes are clarified. There is a great difference between precocial and altricial birds in hormonal events as well as in neural processes which are involved in the emergence of thermoregulation. In precocial avian species the HPT-axis becomes functional during the mid- to late embryonic period while the same axis only becomes fully functional during the first week post-hatch in altricial avian species.
As early as the sixties, the emergence of homeothermy in chickens was investigated. It was concluded that the thyroid gland plays an important role in the thermoregulatory mechanisms of newly hatched chicks. More recent studies however were not able to show any direct effect of the thyroid hormones on the thermoregulation of day-old chicks, although blocking the conversion of T4 to T3 caused a decrease in body temperature in young chicks. Thyrotropin releasing hormone (TRH) is known to act in thermoregulation in mammals and several authors have found an effect of TRH on the metabolism of young and older chicks. However, the exact mechanism still remains unclear.
Because the HPT- and the HPA-axis show close relationships, the role of the HPA-axis in the ontogeny of thermoregulation is also taken into consideration in this review. In mammals as well as in birds, corticotropin releasing hormone (CRH) is involved in the primary thermoregulation.
We conclude that the HPT-axis has an important role in the ontogeny of avian thermoregulation. The exact role of the HPA-axis remains largely unclear although at least CRH is definitely of some importance.
Bacterial contamination of table eggs and the influence of housing systems
- K. DE REU, W. MESSENS, M. HEYNDRICKX, T.B. RODENBURG, M. UYTTENDAELE, L. HERMAN
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- 07 May 2008, pp. 5-19
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With the introduction of alternative housing systems for laying hens in the EU, recent research has focussed on the bacterial contamination of table eggs, e.g. eggshell and egg content contamination. Contamination of eggshells with aerobic bacteria is generally higher for nest eggs from non-cage systems compared to nest eggs from furnished cages or eggs from conventional cages. Studies indicate limited or no systematic differences in eggshell contamination with aerobic bacteria between eggs laid in the nest boxes of furnished cages and eggs laid in conventional cages. The major differences found in experimental studies between cage- and non-cage systems are less pronounced under commercial conditions. The effect of housing system on eggshell contamination with specific groups of bacteria is variable. Limited information is available on the influence of housing system on egg content contamination. Recent research does not indicate large differences in egg content contamination between eggs from cage- and non-cage systems (ignoring outside nest and floor eggs). The microflora of the eggshell is dominated by Gram-positive bacteria, whereas Gram-negative bacteria are best equipped to overcome the antimicrobial defences of the egg content. Much of the research on eggshell and egg content contamination focuses on Salmonella, since infection with Salmonella enteritidis, resulting from the consumption of contaminated eggs or egg products, is still a major health problem. Observed Salmonella prevalence on the eggshell and in the egg content vary, depending on the fact whether investigations were based on randomly sampled table eggs or on eggs from naturally infected hens. The limited information available on other pathogens shows that they are exclusively isolated from the eggshell and not from the internal contents.
Review of poultry production and the physical and chemical characteristics of imported corn and soybean meal in major feed operations in Lebanon
- G.W. BARBOUR, M.T. FARRAN, N. USAYRAN, N.J. DAGHIR
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- 13 June 2008, pp. 177-186
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The poultry industry in Lebanon has developed since the 1950's and is expected to be worth $450 million by 2010. Annual egg production exceeds 600 million eggs whereas broiler meat production is over 130,000 t. Lebanese poultry producers are heavily reliant on imported feedstuffs. To evaluate the quality of feedstuffs used in poultry diets, the results of a recent survey are discussed. This was conducted to evaluate the grade, chemical composition, processing quality and aflatoxin concentration of imported corn and soybean meal in Lebanon. During a period of one year, samples of corn, 44% crude protein soybean meal (SBM 44), and 48% crude protein soybean meal (SBM 48) were collected from shipments delivered to four major feed mixing operations in Central Beqa'a, Lebanon. A sample of each of the feed ingredients was collected every week during a period of three months from each of the feedmills under investigation. Bushel weight, percent foreign seed or matter plus broken corn kernel, proximate analysis, and G1, G2, B1, and B2 aflatoxin concentration in the feed samples were measured. Urease activity in soybean meal was determined. Bushel weight and percentage foreign seed or matter plus broken kernels in imported corn grain were 25.9 kg and 22.1%, respectively. Moisture content in corn grain was 14.0% whereas crude protein, crude fat, crude fibre, and ash were 8.54, 3.52, 2.09, and 1.51% on dry matter basis, respectively. Moisture and crude protein levels in imported SBM 44 and SBM 48 were similar to that of their premium counterparts. Moreover, SBM 44 and SBM 48 had urease activity within the acceptable pH range and were free of G1, G2, B1, and B2. In contrast, 14% of commercial corn shipments were found to contain between 6 and 30 ppb B1 with no presence of G1, G2, and B2. It is recommended that poultry and animal feed importers in Lebanon re-evaluate their sources of corn grain and rehabilitate their feed storage facilities in order to preserve quality and reduce further contamination and/or mould growth.
Important metabolic pathways in poultry embryos prior to hatch
- J.E. DE OLIVEIRA, Z. UNI, P.R. FERKET
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- 12 November 2008, pp. 488-499
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Growth performance and meat yield of commercial broilers and turkeys has improved linearly each year during the past four decades (Havenstein et al., 2003b; Havenstein et al., 2003a; Havenstein et al., 2007), and this trend is likely to continue in the future as new technologies in genetics, biotechnology and developmental biology are adopted by the poultry industry. As the time it takes meat birds to achieve market size decreases, the period of embryonic development becomes a greater proportion of a bird's productive life. Therefore, incubation and embryonic development towards hatch is of greater relative importance to the successful rearing of meat poultry than ever before (Hulet 2007; Foye et al., 2007b). Consequently, anything that supports or limits growth and development during the incubation period will have a marked effect on overall growth performance and health of modern strains of meat poultry. Many poultry researchers now realize that future gains in genetic and production potential of poultry will come from advancements made during the incubation period and embryogenesis (Elibol et al., 2002; Peebles et al., 2005; Christensen et al., 2007; Collin et al., 2007; Leksrisompong et al., 2007). The urgent need to explore and understand the biology of incubation has been emphasised by several symposia: two held at the annual conference of the U.S. Poultry Science Society (July 2006-Edmonton, Alberta, Canada “Managing the embryo for performance”, and July 2007-San Antonio, TX Informal Nutrition Meeting “The impact of imprinting on biological and economical performance in animals”), and one held by the European Federation of World Poultry Science Society (October 2007-Berlin, Germany “Fundamental physiology and perinatal development in poultry), which were specifically devoted to demonstrating the importance of the embryonic period on poultry performance. This review will summarise the metabolic events and pathways in four of the most active tissues of embryos during the period just prior to hatch, and the hormonal control that coordinates the marked changes as the embryo prepares for its post-hatch life.
Standard European footpad dermatitis scoring system for use in turkey processing plants
- P.M. HOCKING, R.K. MAYNE, R.W. ELSE, N.A. FRENCH, J. GATCLIFFE
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- 05 September 2008, pp. 323-328
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A standard scoring system for turkeys at slaughter that consists of 5 categories based on the size of the lesion was adopted as the recommended classification scheme for FPD in slaughter plants at a meeting of the WPSA European Poultry Federation Working Party Number 10: Turkeys. Each score of the classification scheme is defined and photographs of a minimal lesion in each category are presented. The numbers of turkeys required for scoring to determine the prevalence of FPD, if the target or expected frequency is 10, 20 or 40% respectively are 150, 250 and 400 birds. Assessment of the consecutive right foot for the required number of birds from the middle load of a specific flock with a minimum of 3 flocks from a given site is recommended. The classification scheme will facilitate comparisons across countries and systems of production and allow rational decisions to be made regarding management changes to decrease the prevalence of FPD in Europe.
Variability in wheat: factors affecting its nutritional value
- A. GUTIÉRREZ-ALAMO, P. PÉREZ DE AYALA, M.W.A. VERSTEGEN, L.A. DEN HARTOG, M.J. VILLAMIDE
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- 07 May 2008, pp. 20-39
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Wheat is a common raw material used to provide energy in broiler diets. Its apparent metabolisable energy and its influence on broiler performance varies between wheat samples. Reasons for that variability can be classified as intrinsic (variety, chemical composition) and extrinsic factors (growing conditions, storage, etc.), both of which affect nutrient digestibility and availability. However, these factors are not always considered when formulating the diets for broiler chickens. Moreover, research through the years has questioned the relation between wheat AME and animal performance. This review aims to describe factors that influence the observed variability in wheat nutritive value for broiler chickens by considering origin (variety, growing conditions and post-harvest storage), chemical composition of the grain (carbohydrates and protein) and the broiler chicken.
Genetics and selection of mule ducks in France: a review
- C. MARIE-ETANCELIN, H. CHAPUIS, J.M. BRUN, C. LARZUL, M.M. MIALON-RICHARD, R. ROUVIER
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- 13 June 2008, pp. 187-208
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Duck breeding in France is directed mainly towards ‘foie gras’ (duck fatty liver) production. Nowadays the roasted duck, produced from the pure Muscovy, is economically a less important industry. About 95% of foie gras production comes from force-fed mule duck, the remaining 5% being from the Muscovy duck. After an overview of the French economical and technical context of this production, the paper will focus on the genetic aspects of the mule duck, at the level of theoretical knowledge and considering practical applications for selection. As the mule duck is an infertile hybrid between a female common duck (Anas Platyrhynchos) and a Muscovy drake (Cairina moschata), selection approaches are carried out on both parental strains. But to implement selection, genetic parameters (heritability and genetic correlations) and cross-breeding parameters (direct and maternal additive genetic effects, heterosis effect) need to be known. Our review covers both the reproductive mule parental traits, either in pure strain or in cross-breeding, with main results on the dam side for laying, fertility and hatchability and also considers the mule productive traits, such as growth, feather colour, behaviour, feed efficiency, body composition, force-feeding ability and products quality. Genetic variability of mule duck traits can be established from estimates on either the dam's side, on the sire's side, or on both sides simultaneously. This review represents a comparison of fatty duck selection, which is operated by three major private French companies, with outlines of the breeding scheme specificity.
Animal welfare in poultry production systems: impact of EU standards on world trade
- P.L.M. VAN HORNE, T.J. ACHTERBOSCH
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- 07 May 2008, pp. 40-52
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Animal welfare receives more legislative attention in the European Union (EU) than in many other regions of the world. Animal welfare standards for poultry are generally taken to be higher in the EU than in producing countries exporting to the EU, particularly developing countries. The recent action plan for animal welfare introduced by the European Commission aims to further expand the body of regulatory standards. In broiler production worldwide, birds are mainly kept on litter. Recently the EU agreed on a new Directive to set standards for maximum bird density. However, this is not considered likely to have a great impact on global trade. At present, the difference in animal conditions, including bird density, in Brazil and Thailand is limited compared to the EU. In egg production the majority of commercial layers are kept in laying cages. There is wide variation in space allowance per bird from 300 to 400 cm2 in Brazil, Ukraine and India towards the current minimum of 550 cm2 per hen in the EU. After 2012, hens in the EU will be kept in enriched cages with a minimum space allowance of 750 cm2 per hen. It is expected that this will have an impact on world trade in egg products and especially egg powder. Trade in table eggs will continue to be limited to the local region. The EU is considering the use of labelling to provide consumers with more information concerning the standard of production. Another option could be to use financial mechanisms such as taxes or tariffs to prevent imports from other countries with lower standards. The likelihood of a measure being challenged would depend on how difficult it was for exporters outside the EU to meet the requirements.
Qualitative attributes and consumer perception of organic and free-range poultry meat
- C. CASTELLINI, C. BERRI, E. LE BIHAN-DUVAL, G. MARTINO
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- 12 November 2008, pp. 500-512
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The effect of the organic production (OP) system on the qualitative characteristics and consumer perception of poultry meat is reviewed in the following paper. Age at slaughtering, genetic strains (fast- and slow-growing), physical activity, and pasture intake are key factors in determining meat quality. In conventional farming, fast-growing chicks are generally used, but these are not suitable for OP, since they may develop health and welfare problems, the most recurrent of which are leg disorders and lameness. Conversely, use of slow-growing strains in OP has positive repercussions on both animal welfare and product qualitative characteristics (eating quality and appearance) perceived by consumers. From the published data it can be concluded that organic poultry can be a viable production method, especially if suitable changes in EU Regulation. 1804/99 are made. The market opportunity for both organic and free range poultry products does not yet seem to be fully developed. We suggest that structured integration between production and consumption stages could resolve this problem.
Genomic research and applications in the duck (Anas platyrhynchos)
- Y.H. HUANG, N. LI, D.W. BURT, F. WU
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- 05 September 2008, pp. 329-341
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As a major natural reservoir of influenza virus and an important food source, the duck is of great biological interest, e.g. in the area of host-pathogen interactions. Recently, preliminary genetic and cytogenetic maps of the duck have become available, providing for the first time a glimpse at a comparative map between the duck and chicken. These genetic tools have been used to detect QTLs related to duck growth, carcass and meat quality traits. However, molecular genetic research in the duck is only in its infancy. In the future we can expect the development of new duck resources, including a high-density genetic map, detailed comparative maps with the chicken and other vertebrates - and given the pace of genomics, possibly a genome sequence. These new resources will be used to evaluate the genetic diversity of global duck breeds, to define genetic markers to increase the quantity and quality of egg and meat products, and to aid in the battle against infectious diseases, such as avian influenza.
Poultry meat consumption trends in Europe
- P. MAGDELAINE, M.P. SPIESS, E. VALCESCHINI
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- 07 May 2008, pp. 53-64
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What are the main factors affecting consumption of poultry meat? Can buying behaviour and consumption attitudes be altered by a context that seems to be lastingly affected by the presence of avian influenza? This paper proposes some answers to these questions by taking into account the geographical diversity of consumption and its recent evolution in Europe. Relatively low and competitive pricing of poultry compared to other meat, the absence of cultural or religious obstacles, and dietary and nutritional (protein) qualities are the main factors explaining its attractiveness. Others factors underly consumers' attraction to poultry. Firstly, during the various health crises consumers' attention has been focused on production methods (feed, animals' well-being, etc.) and on reliability of information. Interest in 'approved local' products, whose appeal is based on the credibility-taste combination, has consequently spread in Europe. Secondly, consumption has developed around more elaborate products incorporating two types of service: a saving of preparation time ('ready-to-eat' food) and a diversification of places of consumption (catering outside the home).The main trends within poultry's consumption have not been changed by the avian influenza episode. Tendencies noted during the last decade and described in the article are anticipated to remain the same.
Avian influenza in poultry
- D.J. ALEXANDER, I. CAPUA
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- 12 November 2008, pp. 513-532
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Influenza A viruses that infect poultry can be divided into two groups. Very virulent viruses cause highly pathogenic avian influenza (HPAI), with flock mortality as high as 100%. These viruses have been restricted to subtypes H5 and H7, although not all H5 and H7 viruses cause HPAI. All other viruses cause a milder, primarily respiratory, disease (LPAI), unless exacerbated. Until recently, HPAI viruses were rarely isolated from wild birds, but for LPAI viruses extremely high isolation rates have been recorded in surveillance studies. Influenza viruses may infect all types of domestic or captive birds in all areas of the world. The frequency with which primary infections occur in any type of bird usually depends on the degree of contact there is with feral birds. Secondary spread is typically associated with human involvement, either by birds or bird product movement or by transferring infective faeces from infected to susceptible birds, but potentially wild birds can be involved. In recent years the frequency of HPAI outbreaks appears to have increased and there have been particularly costly outbreaks of HPAI in densely populated poultry areas in Italy, The Netherlands and Canada. In each outbreak millions of birds were slaughtered to bring the outbreaks under control. Since the 1990s, AI infections due to two subtypes have been widespread in poultry across a large area of the World. LPAI H9N2 appears to have spread across the whole of Asia in that time and has become endemic in poultry in many of the affected countries. However, these outbreaks have been overshadowed by the H5N1 HPAI virus, initially isolated in China that has now spread in poultry and/or wild birds throughout Asia and into Europe and Africa, resulting in the death or culling of hundreds of millions of poultry and posing a significant zoonosis threat. To date control methods seem to have been unsuccessful on the larger scale and HPAI H5N1 outbreaks continue to be reported.
Identification of new chicken egg proteins by mass spectrometry-based proteomic analysis
- K. MANN, J.V. OLSEN, B. MAČEK, F. GNAD, M. MANN
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- 13 June 2008, pp. 209-218
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The chicken egg and foods containing egg components are an important part of human nutrition. Furthermore, eggs are a potential source of bioactive molecules and a potential delivery system for therapeutic proteins, explaining the continuing scientific interest in eggs and their components. Using mass spectrometry-based high-throughput proteomic techniques, 119 proteins in egg yolk, 78 proteins in egg white, and 528 proteins in the decalcified eggshell organic matrix have recently been identified. Most of these proteins were identified in their respective egg compartment for the first time. Some of these proteins were already known from chicken tissues or other egg compartments, but many were novel. In the eggshell soluble matrix 39 phosphoproteins containing more than 150 different phosphorylation sites were identified. Twenty-two of the identified phosphoproteins had not been recognized as phosphoproteins previously.
Controlling reproductive seasonality in the geese: a review
- Z.D. SHI, Y.B. TIAN, W. WU, Z.Y. WANG
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- 05 September 2008, pp. 343-355
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The following paper reviews the breeding seasonality and its control in the domestic geese. Geese breeds can be classified into 3 types according to their breeding season: Type 1 inhabits higher latitude (40 to 45º N) temperate zones, and breeds during the longer days in spring and early summer. Types 2 inhabits mid-latitude (30 to 40º N) temperate regions, and start their breeding season in autumn and end in the following spring - early summer. Type 3 are the short-day breeding geese, located in subtropical areas (22 to 25º N), which breed from late summer to the following spring. Differences in breeding seasonalities are attributed to adaptations to environment conditions, enabling geese to fully utilize these conditions to achieve maximal reproductive performance and survival. Divergent breeding seasons are caused by the different pituitary secretions of gonadotrophins and prolactin in response to annual changes in photoperiod. In practical goose production, laying seasons can be controlled by imposing artificial photoperiods, with almost opposite photo-programmes for long or short day breeding geese, respectively. In addition, genetic selection and other animal husbandry measures such as timing of gosling stocking and nutritional intake levels can modify, to various degrees, the goose breeding seasonality.
Review of the initial validation and characterization of a 3K chicken SNP array
- W.M. MUIR, G.K. WONG, Y. ZHANG, J. WANG, M.A.M. GROENEN, R.P.M.A. CROOIJMANS, H.-J. MEGENS, H.M. ZHANG, J.C. MCKAY, S. MCLEOD, R. OKIMOTO, J.E. FULTON, P. SETTAR, N.P. O'SULLIVAN, A. VEREIJKEN, A. JUNGERIUS-RATTINK, G.A.A. ALBERS, C. TAYLOR LAWLEY, M.E. DELANY, H.H. CHENG
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- 13 June 2008, pp. 219-226
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In 2004 the chicken genome sequence and more than 2.8 million single nucleotide polymorphisms (SNPs) were reported. This information greatly enhanced the ability of poultry scientists to understand chicken biology, especially with respect to identification of quantitative trait loci (QTL) and genes that control simple and complex traits. To validate and address the quality of the reported SNPs, assays for 3072 SNPS were developed and used to genotype 2576 DNAs isolated from commercial and experimental birds. Over 90% of the SNPs were valid based on the criterion used for segregating, and over 88% had a minor allele frequency of 2% or greater. As the East Lansing (EL) and Wageningen University (WAU) reference panels were genotyped, 1933 SNPs were added to the chicken genetic map, which was used in the second chicken genome sequence assembly. It was also discovered that linkage disequilibrium varied considerably between commercial layers and broilers; with the latter having haplotype blocks averaging 10 to 50 kb in size. Finally, it was estimated that commercial lines have lost 70% or more of their genetic diversity, with the majority of allele loss attributable to the limited number of chicken breeds used.
A projection of the regional development of egg production until 2015
- H.-W. WINDHORST
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- 05 September 2008, pp. 356-376
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In contrast to detailed projections for the development of plant and animal production, as published by the United States Department of Agriculture (USDA) or the Food and Agricultural Policy Research Institute (FAPRI), for a great number of commodities, there are hardly any projections for the development of hen egg production. The OECD publishes projections for the coming decade annually, but the data cover all poultry eggs, the EU Commission gives data only for EU member states. In this paper, a projection for the development of hen egg consumption and hen egg production between 2005 and 2015 is presented. It is based on an analysis of the development between 1995 and 2005 as well as on basic population and socio-economic data, such as population development, age structure of the population, urbanisation of a society, development of the gross national product and the per capita national income. Based on these data, the development of the per capita consumption of shell eggs was calculated for the decade until 2015. These data were then used in combination with the predicted development of the population to calculate the additional egg demand in 2015. It is estimated that the additional egg demand will be as high as 12 million metric tonnes. This will result in a total production volume of 70.9 million tonnes. About 67% of this demand will arise in Asia, 12% in Africa, and 11% in Latin America. These continents will gain shares in global egg production, North America and Europe will lose shares. Whether the required volume of 70.9 million tonnes can be reached, will depend on several factors, e.g. outbreaks of Avian Influenza, higher feed costs because of the booming bio-energy production, and political decisions (e.g. banning of conventional cages in the EU).
Asia's changing role in the global egg industry – an analysis of past, present and foreseeable future dynamics
- H.-W. WINDHORST
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- 12 November 2008, pp. 533-552
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Between 1970 and 2006, regional patterns of egg production and egg trade changed considerably. Until 1980, European countries dominated global egg production. In the following decade, less developed countries surpassed the more developed countries in their production volume. This shift was caused by the rapid increase of egg production in Asia. In 2006, Asian countries contributed more than 60% to the global production volume. In particular, the dramatic growth in China has been responsible for the spatial shift of production centres. In several other countries, such as India, Indonesia, Malaysia, egg production increased also considerably. The expansion of egg production had impacts on the patterns of egg exports and imports. European countries still dominate the trade in shell eggs, but Asian countries could gain market shares, in particular since the 1990s when several newcomers entered the global egg market. Malaysia and India became important egg exporting countries and changed the traditional market patterns in the Near East and in Southeast Asia. In 2005, 25% of all shell eggs that were traded worldwide had an Asian country as their destination. Besides importing countries with a long tradition, such as Singapore, Saudi Arabia or the United Arab Emirates, new importing countries entered the market, such as Japan. Asia will also play an outstanding role in the projected additional egg demand of 12 million t until 2015 and will also strengthen its position as the leading continent in egg production. About 75% of the expected additional demand will occur in Asia, more than 50% in China alone. In 2015, Asia will contribute over 62% to global egg production in 2015. These future dynamics will open new markets in several Asian countries for breeding companies as well as developers and producers of equipment for laying hens. In these countries, the feed industry will expand, which again will impact on the trade patterns of raw materials for compound feed. The growth of egg trade and the new patterns of trade flows will increase the risk of the introduction and dissemination of highly infectious poultry diseases. This and the foreseeable increase of feed prices may result in slower growth rates and even massive disturbances of the present and projected pattern of egg production in Asia.
History, changing scenarios and future strategies to induce moulting in laying hens
- M. YOUSAF, A.S. CHAUDHRY
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- 07 May 2008, pp. 65-75
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Moulting is a natural phenomenon in birds during which they replace old plumage with new feathers, reduce feed intake, lose body weight and suspend reproduction. Moulting in laying hens can be induced by using photoperiods, feed deprivation or restriction or diets containing minerals or variable amounts of other ingredients. Induced moulting can result in higher egg production and improved quality. It reduces mortality, production costs and investments in new farms and hatcheries. While feed withdrawal has been a most effective way to induce moult in poultry birds, it is illegal on welfare grounds in the UK and Europe. This may have implications for the global poultry industry. Therefore, efforts to find a non feed removal method as a desirable alternative to induce moulting in poultry birds are underway in different countries. This paper reviews the history of induced moulting and its future implications by examining different methods that have been tested in the past and their potential to become a more acceptable alternative to feed removal method of inducing moulting in laying hens.