Review Article
Changes in poultry production and trade worldwide
- H.-W. WINDHORST
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- Published online by Cambridge University Press:
- 02 February 2007, pp. 585-602
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Global poultry meat and egg production as well as trade with poultry products have shown a remarkable dynamic during the last 35 years. Between 1970 and 2005 poultry meat and egg production increased faster than that of beef and veal or pigmeat. The trade volume of poultry meat increased even faster than production. In 2004, 12% of the poultry meat produced reached the world market but only 1.8% of the eggs. The rapid increase in poultry meat production has been very imbalanced.
Whereas North and Central America as well as Europe lost market shares, China and Brazil became new centres of production in Asia and South America. In hen egg production Asia was the only winner in the analysed time period, all other continents lost market shares. The increase in regional concentration is mainly due to the dominating role of China. Developing countries surpassed developed countries in their production volume between 1990 and 2000. At the present time, they contribute about 55% to global poultry meat and 68% to egg production.
The trade volume of poultry products increased parallel to the rapid growth of global poultry meat and egg production. The regional concentration of poultry meat as well as egg exports and imports is very high. In contrast to production, the contribution of developing countries to the export volume of poultry products is still much lower than that of developed countries. Even though developing countries were able to gain higher market shares during the past 35 years, the regional shift from developed to developing countries has been less dramatic than that in poultry meat and hen egg production. Especially hen eggs are still mainly traded between European as well as Asian countries.
Outbreaks of Avian Influenza will have impacts on production and consumption, resulting in serious financial problems of major producers and new spatial patterns of production and trade flows. The full implementation of directive 1999/74/EU for laying hens will also have impacts on egg production and egg trade, as the EU will probably no longer be an egg surplus region but be forced to import.
Study on molecular genetic diversity of native duck breeds in China
- H. LI, N. YANG, K. CHEN, G. CHEN, Q. TANG, Y. TU, Y. YU, Y. MA
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- 02 February 2007, pp. 603-611
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Twenty four Chinese native duck breeds were studied to estimate genetic diversity and genetic structure using microsatellite markers. The genetic relationships between breeds were analyzed in combination with their geographic distribution. A total of 28 microsatellite markers were amplified. All the breeds exhibited genetic diversity, through the estimation of polymorphic information content (PIC) and mean heterozygosity (H) index. The mean genetic diversity of the populations was 0.569, while the PIC values for Chinese native duck breeds was relatively high. Neighbour-joining was used to calculate genetic distances. Cluster analysis divided the twenty-four populations into five groups, and the genetic relationships among the populations had obvious association with their phylogenetic relationship with historical relations and geographical distribution. The developmental history of native duck breeds in China appears to have had an effect on their genetic structure.
Growth performance and metabolic response of the gastrointestinal tract of turkeys to diets with different levels of mannan-oligosaccharide
- J. JUŚKIEWICZ, Z. ZDUÑCZYK, J. JANKOWSKI
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- 02 February 2007, pp. 612-625
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In four studies, we evaluated the influence of dietary MOS on the performance of turkeys and their intestinal health status at various stages of the production. Turkey growth, feed efficiency and large intestine parameters were examined after 4-, 8- and 16-week administration of diets with different levels (0.1 to 1.0%) of a MOS. The experimental 4- and 8-week feeding with various levels of MOS (up to 0.5%) did not affect the productivity of the birds, yet medium (0.4 and 0.2% in the first and second 8-wk periods, respectively) and high (1.0 and 0.4% in the first and second 8-wk periods, respectively) levels of dietary MOS were found to significantly increase live body weight after feeding for 16 weeks. At the age of 8 weeks, we observed a similar effect of MOS and inulin on the productivity parameters. The caecal metabolism was affected by dietary mannan variously depending on the dose of MOS and the age of birds. Generally, the dietary mannan-oligosaccharides more considerably changed caecal metabolism at early ages. At 4 weeks of age, we found some positive effects of adding MOS to the diet, such as lowering ammonia concentration and decreasing β-glucuronidase activity in the caeca, as well as some negative effects, including decreased bacterial glycolytic activity and raised pH of digesta. In our 8-week experiment, non-linear changes were observed in the parameters of caecal digesta at different doses of MOS. It seems that dietary supplementation with 0.25% MOS, compared to other doses, exerted a specific effect on gut-colonizing microflora enhancing its proliferation and activity, which has been reflected in a higher concentration of Lowry's protein and an increased glycolytic activity. After feeding the turkeys for 16 weeks, their caecal metabolism was affected by dietary MOS to some extent. Although MOS did not change the caecal pH or the bacterial enzyme activity, when applied at medium and higher doses it decreased ammonia as well as SCFA concentration (mainly acetate) in the caecal digesta. Dietary MOS had no significant effect on the caecal populations of Bifidobacterium and Lactobacillus, whereas the populations of caecal E. coli were observed to decrease, especially upon medium and high experimental concentrations.
Imprinting and critical periods in early development
- B. TZSCHENTKE, A. PLAGEMANN
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- 02 February 2007, pp. 626-637
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The review addresses the fundamental process of ‘imprinting’. In his classical studies on newly hatched goslings Konrad Lorenz analysed the development of social binding and established the term ‘imprinting’ to describe this process. One of his major ideas was that imprinting occurs in ‘critical periods’, which are limited and severely restricted to the animal's very early life. For some time past, the term ‘imprinting’ is also used for an epigenetic mechanism, the ‘genomic imprinting’, which can be simply defined as gamete-of-origin dependent modification of genotype. Furthermore, in the course of the perinatal period ‘imprinting’ of physiological control systems occurs. Functional systems of the organism develop from open loop systems without feedback control into closed systems controlled by feedback mechanism. During ‘critical periods’, the actual environment influences the development of the respective physiological control systems for the entire life period, especially by changes in neuroorganization and expression of related effector genes. On the one hand, these mechanisms may cause perinatal malprogramming, which has been related to, e.g., metabolic disorders and cardiovascular diseases during later life in humans as well as in animals. On the other hand, knowledge on these mechanisms might be specifically used to induce long-term adaptation of the organism, for instance, to the postnatal climatic conditions (epigenetic temperature adaptation). Furthermore, the question if ‘critical period’ and ‘sensitive period’ are synonymous or different, and problems of identifying these developmental windows are discussed. Environmental manipulation of immature physiological mechanisms may be a physiological tool for characterization of ‘critical periods’.
Dietary electrolyte balance: implications in heat stressed broilers
- T. AHMAD, M. SARWAR
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- Published online by Cambridge University Press:
- 02 February 2007, pp. 638-653
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Modern fast-growing meat-type broiler chickens are facing difficulties in coping with heat stress. The increase in broiler growth rate increases their body heat production. The global environmental temperature is also showing an upward trend. This situation demands an efficient means to economically improve the thermotolerance of broiler chickens in hot climates without affecting their productivity. Different managemental techniques and dietary modifications have been employed to overcome the adverse effects of heat stress. These strategies may often have proved beneficial but not all the time. Some of them even increased the cost of production. Many of these techniques did not show promising results, especially at higher ambient temperatures. This is probably due to not considering the loss of electrolytes during the periods of heat stress when panting birds are experiencing respiratory alkalosis. During heat stress, the loss of carbon dioxide (CO2) through respiration and bicarbonate ions coupled with monovalent cations (particularly sodium and potassium) through urine, disturbed the acid-base balance (respiratory alkalosis). The corrections in blood acid-base balance have been achieved by electrolyte supplementation, either through drinking water or feed. These electrolytes, in different amounts and proportions, proved beneficial for broilers under different heat stress regimens. The proportions of sodium, potassium and chloride in diets determine the dietary electrolyte balance (DEB=sodium plus potassium minus chloride, milliequivalents per kg). The discrepancies exist among different research workers about an appropriate DEB for heat-stressed broilers. Different environmental conditions in which broilers are reared; heat stress regimens (cyclic, acute, chronic), feeding regimens, source of electrolyte salts, combination of different electrolyte sources and the bird's genotype itself are factors that influence the requirements of a particular electrolyte as well as their balance in the diet. This review considers the usefulness and limitations of DEB equation, and the impact of different DEB on live performance, carcass characteristics, mortality and blood parameters in broilers reared under heat stress environments.
Rearing factors that influence the propensity for injurious feather pecking in laying hens
- H.A. VAN DE WEERD, A. ELSON
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- 02 February 2007, pp. 654-664
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Feather pecking during rearing is difficult to identify and therefore often underestimated. However, as rearing conditions will affect the behaviour of adult hens, it is important or prevent feather pecking during rearing. This paper reviews the knowledge in the scientific literature on the effect of rearing conditions on injurious pecking. Factors such as stocking density and feeding strategies during rearing are known to influence feather pecking. Minimising the differences between the rearing and laying environment via a seamless transition is likely to make a flock less prone to injurious feather pecking. This can be achieved by providing perches and substrate for foraging and dust bathing during rearing, by providing facilities (e.g. litter trays) on perforated platforms during early lay and by focussing on early access to the range.
Reducing shell egg cholesterol content. I. Overview, genetic approaches, and nutritional strategies
- R.G. ELKIN
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- 02 February 2007, pp. 665-687
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In laying hens, cholesterol is primarily biosynthesized in the liver and incorporated into vitellogenin (VTG) and triglyceride-rich very low density lipoprotein (VLDL) particles, which are secreted into the bloodstream and subsequently taken up by growing oocytes via receptor-mediated endocytosis. VLDL and VTG are then intracellularly transformed into yolk, constituting ∼60% and 24% of yolk dry matter and ∼95% and 5% of yolk cholesterol, respectively. During the past four decades, research efforts directed toward reducing shell egg cholesterol content have centred on genetic selection or alteration of the laying hens’ diet with various nutrients, natural products, non-nutritive factors, or pharmacological agents. The present paper will provide a justification for low-cholesterol egg production, primarily in the context of the heterogeneity of response to dietary cholesterol in humans, and will review cholesterol metabolism in the laying hen, avian embryonic cholesterol needs, and genetic and nutritional approaches to chicken egg cholesterol reduction. A subsequent paper will provide a comprehensive overview of the use of non-nutritive dietary factors and select pharmaceuticals as egg cholesterol-lowering agents, and will discuss emerging strategies for lowering the cholesterol content of shell eggs.
Low protein diets for broilers
- U. AFTAB, M. ASHRAF, Z. JIANG
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- 02 February 2007, pp. 688-701
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A review of the literature regarding Low Protein diets (LCP) for broilers reveals that by using crystalline amino acids, dietary CP could be reduced in each phase safely by a factor of 10% (a figure fairly consistent with turkeys but quite low with that found for ducks and swine) from the respective NRC (1994) levels; the calculated minimum dietary CP levels thus appeared to be 20.7, 18.0, and 16.2% respectively for 0-21, 21-42 and 42-56 days of age. It is, however, noted that the magnitude of protein reduction, without affecting the growth performance of broilers, could have been increased depending upon the EAA concentration and balance of LCP vs. control-CP diets as well as the response criteria used (gain vs. composition of gain). Further reduction in dietary protein results in depressed live/carcass yield in almost all cases. Depressed feed intake appears partially to explain the negative effect of LCP diets in some cases. Addition of NEAA-like glycine above the current NRC recommendations has shown partially to alleviate the negative effect of LCP diets indicating imprecision of our knowledge about NEAA (like glycine, serine and proline etc) requirements of broilers under these conditions. The dietary NEAA/EAA ratio seems to be an important, though poorly understood, factor in defining the performance of broilers fed on LCP diets. It seems that regardless of the absolute amounts of dietary amino acids, performance tend to be depressed when NEAA/EAA ratio is decreased from 50/50; thus the NEAA level of about 50% of protein seems “minimum” state of adequacy. More work is needed before a precise role of the ratio of nitrogen coming from NEAA vs. EAA is proposed. A wider NE:ME in LCP diets seems to explain the higher body fat accretion on these diets; more work on how dietary NE:ME ratio modulates the growth performance of broilers, and how it interacts with different genetic stocks (lean vs. fat lines) is warranted.
Regional Report
Poultry industry in Kuwait
- A. AL-NASSER
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- Published online by Cambridge University Press:
- 02 February 2007, pp. 702-708
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The poultry industry in Kuwait is one of the leading food industries in the country. It consists of several poultry companies that vary between large, medium and small size poultry producers. The majority of poultry production concentrates on chicken meat and eggs, due to consumers' demand. An estimated 60% of the local broiler production is marketed live, 5% chilled and the rest as frozen. The poultry industry in Kuwait is moving towards production of specialty food such as eggs enriched with omega-3-fatty acids which, it seems, will take part of the market share in the future. Per capita consumption of poultry meat in Kuwait reached 63.3, 61.2, and 60.8 Kg in the years 2004, 2005, and 2006 respectively. Average per capita consumption of poultry meat before the invasion by Iraq was 22 Kg and after liberation per capita consumption increased. Before the invasion, chicken meat was considered as the second most popular meat consumed after lamb and mutton. However, after liberation, red meat consumption was reduced in the years 1996 to 2002. This could be due to concern about the so-called ‘Mad Cow’ disease that shifted consumer preferences from red meat to poultry. In addition, increased consumers' health awareness and presence of the coalition troops in Kuwait and near Iraq increased the demand for poultry meat. Since local producers supplied only 47% of the poultry meat and 55% of table eggs consumed and the remainder of the local poultry consumption imported from other countries, more development and improvement in production is needed in the industry in order to gain confidence of their consumers and increase their share in the market.
Review Article
Linkages between socio-economic variables and the efficient marketing of poultry feeds in Delta State, Nigeria: implication for extension services
- F.O. ACHOJA, A.U. OFUOKU, R.N. OKOH
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- Published online by Cambridge University Press:
- 02 February 2007, pp. 709-715
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This study investigated the linkages between socio-economic variables and the efficient marketing of poultry feeds in Delta State. Primary data collected from 100 randomly selected respondent poultry feed marketers, using structured questionnaire/interview schedule, were analysed using descriptive statistics and pairwise correlation model. The study revealed that marketers' years of experience (0.89) and improved packaging (0.62) have positive and significant relationship (linkages) with efficient marketing of poultry feeds; while distance between source of procurement and selling centre (−0.74) and associated cost of transportation (−0.98) have negative relationship (linkages) with the efficient marketing of poultry feeds. Price per bag and poor road network (market access condition) were the major problems affecting efficient marketing of poultry feeds in the study area. Implication for extension officers participation in poultry feeds marketing was emphasized.