Review Article
The changing role of agriculture in Europe and how it affects poultry education and technology transfer
- F. WERRIJ
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- 25 June 2007, pp. 205-211
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European agriculture – its economic significance, its social status, its political weight, its technological level – has undergone considerable changes over the past decades. Indeed, these changes will also continue in the coming years. Accordingly, the knowledge, expertise and education base underpinning agriculture as an industrial and societal activity has to follow these changes by adapting its science base, its priorities, its organization and its way of operation. This paper seeks to present a bird's eye view of the developments in European agricultural research and education structure and will try to formulate the paradigms of a new concept of the notion ‘agricultural knowledge and expertise base’: As from the end of World War II the European industry and society developed gradually from a more or less regulated situation into a virtually completely open industrial market and civil society. And within that context, the agri-food industry developed from a mainstay of European economy into just one stakeholder in a whole complex of rural economy. Accordingly the agricultural research and education and knowledge system is developing from a homogeneous, oligo-disciplinary, institutional and monopolistic system into a heterogeneous, poly-disciplinary and virtual system.
Current status in avian semen cryopreservation
- E. BLESBOIS
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- 25 June 2007, pp. 213-222
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Semen cryopreservation in domestic birds has been studied extensively in the past fifty years. However, efficient methods to freeze semen of chicken of different breeds have emerged only in the last decade of the 20th century. Methods using the cryoprotectants glycerol, dimethyl acetamide and dimethyl sulfoxide, slow or rapid freezing-thawing procedures, pellets or vials or straws packaging have been developed. Other methods have been studied in turkeys, guinea fowl, ducks, ganders and some wild species. They are often less successful than chicken freezing methods with wide intra-species variability.
Reliable predictors of suitability of semen for cryopreservation are also needed to improve freezing methods and to optimize the management of frozen semen. The quality of whole fresh semen measured by classical morphologic, metabolic and mobility tests is an indicator. More specialized tests such as membrane fluidity of fresh spermatozoa are indicative of the freezing ability of the gametes.
The main use of semen cryopreservation in birds is the ex situ management of genetic resources in the context of dramatic decrease in avian genetic biodiversity. This is achieved through germplasm cryobanks. There are three main national avian germplasm cryobank programmes in 2006, operating in North America, The Netherlands and France. They mainly include semen and blood samples issued from Public Research Lines, indigenous breeds and individual specific genotypes.
The future need for semen cryopreservation programmes will focus mainly on three objectives 1) improvement of predictors of male suitability for semen freezing, 2) emergence of standardized methods of semen freezing in species other than chicken and 3) increasing development of avian cryobanks.
Recent advances in Australian broiler litter utilisation
- J.R. TURNELL, R.D. FAULKNER, G.N. HINCH
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- 25 June 2007, pp. 223-231
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The global poultry industry is undergoing many changes, one being the need for efficient disposal of its broiler litter (BL) due to a reduction in the land available for cost effective disposal. To date, Australian BL disposal has been achieved by selling the litter as a fertiliser to agricultural sectors. Research indicates BL and other poultry industry waste streams could be used as a food source for vermiculture systems, allowing the sale of vermi-cast as a biologically enhanced fertiliser and worms for protein. If this approach is economically viable then the poultry industry could reduce its environmental impact and operate more like a closed loop system. Integrated bio-systems using vermiculture, composting and waste-to-energy technologies have developed significantly overseas and have shown potential to solve many of the issues associated with poultry waste disposal.
Mechanisms of aggression and production in chickens: genetic variations in the functions of serotonin, catecholamine, and corticosterone
- H.W. CHENG, W.M. MUIR
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- 25 June 2007, pp. 233-254
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The neuroendocrine systems, such as dopamine (DA) and serotonin (5-HT) as well as corticosterone (CORT), are involved in regulating behavioural patterns and reproduction in humans and other mammals. Similar functions of neuroendocrine system may present in laying hens. To test the hypothesis, two divergent chicken lines were used in the study. Each line has distinct levels of aggressiveness and productivity at a group setting and exhibits differen susceptibility to various environmental stressors. We found that, at 21 wks of age, LGPS (Low Group Productivity and Survivability) birds had significantly higher blood concentrations of DA and epinephrine than the KGB birds (Kind Gentle Birds, also previously termed HGPS, birds with a High Group Productivity and Survivability) (P<0.01, respectively). The blood concentration of norepinephrine was not significantly different between the lines but the ratio of epinephrine to norepinephrine was higher in LGPS birds (P<0.01). The blood concentration of 5-HT was also significantly higher in LGPS birds compared to KGB birds (P<0.01). In contrast, KGB birds tended to have a higher level of blood CORT (P=0.1). The results suggest that genetic selection for productivity and survivability with domestic behaviours alters the birds' neuroendocrine homeostasis. The selection-associated plasticity of the neuroendocrine system in controlling animal aggression and productivity were discussed in the article.
Vitamin requirements: is there basis for re-evaluating dietary specifications?
- S. LEESON
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- 25 June 2007, pp. 255-266
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There has been little work conducted over the last 40 years on estimating vitamin requirements of poultry, and so consequently NRC (1994) values are still often quoted as standards. A review of this information indicates many values are estimates, or extrapolated from comparable species, or as with broiler breeders, simply not given. The current concern related to formulating vitamin levels in poultry diets is the assumption that change in genetic potential of layers and meat birds necessitates re-evaluation, and that parameters for assessing needs are now more complex than simple production metrics as used previously. Unfortunately information on maintenance needs for vitamins is lacking, and while there is now information available on vitamin content of eggs, comprehensive details of the vitamin level in poultry meat products is surprising lacking. With unprecedented egg output of modern layer strains, and ever improving feed efficiency in meat birds, vitamin intake per unit of output is continually declining. For layers the estimate is around a 1% yearly decline in vitamin intake per egg produced, while for meat birds there has been a 0.6-0.8% yearly decline per kg body gain. This reduced intake of vitamins is the basis for improved performance in layers and meat birds fed a higher than normal level of vitamins. However, an even more important basis for reevaluating vitamin needs is change in measurement criteria. Many vitamins and especially the fat soluble vitamins accumulate in eggs and meat in proportion to diet inclusion. Development of vitamin enriched designer poultry products therefore dictates elevated feeding levels of vitamins. Co-incidentally, increased levels of vitamin E in poultry products has led to the realization that increased antioxidant capacity of these tissues enhances shelf life and appearance. Of greatest impact in reevaluating diet vitamin specifications has been the effect of these nutrients on bird health and in particular immune response. For example dietary levels of vitamin E far in excess of NRC (1994) requirements have been shown to positively impact immune response in all ages of bird and also the performance of heat-stressed birds. Expectations of ever increasing performance dictate the need for continual reevaluation in determining vitamin levels within diet formulations as detailed in recent publications on optimum vitamin nutrition of poultry to improve health, welfare, performance and the quality of poultry products.
Ontogeny of avian thermoregulation from a neural point of view
- P.J.J. BAARENDSE, M. DEBONNE, E. DECUYPERE, B. KEMP, H. VAN DEN BRAND
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- 25 June 2007, pp. 267-276
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The ontogeny of thermoregulation differs among (avian) species, but in all species both neural and endocrinological processes are involved. In this review the neural processes in ontogeny of thermoregulation during the prenatal and early postnatal phase are discussed. Only in a few avian species (chicken, ducklings) the ontogeny of some important neural structures are described. In the early post hatching phase, peripheral and deep-body thermoreceptors are present and functional, even in altricial species, in which the thermoregulation is still immature at hatch. It is suggested that the development of peripheral and deep-body thermoreceptors is not responsible for the inability to maintain a stable body temperature at cold ambient temperatures during early postnatal phase, although studies examined the ontogeny of thermoreception only in an indirect manner. Thus, other factors, such as volume to surface ratio and rate of insulation are important. Studies regarding the ontogeny of hypothalamic cold- and warm-sensitivity neurons in precocial species demonstrate that maturation of the hypothalamic temperature sensitivity takes place during the late prenatal and early postnatal period, with a relatively high cold sensitivity of the hypothalamus during the transition from poikilotherm to homeotherm. In addition, incubation temperatures are demonstrated to influence postnatal hypothalamic thermosensitivity. Brain temperature regulation is found to maturate during avian ontogeny as well and is demonstrated to coincide with the ontogenic pattern of general thermoregulation in several avian species. Relevant information of the ontogeny of the spinal cord and effector pathways related to the development of avian thermoregulation is lacking. We concluded that both prenatal and early postnatal temperature affects hypothalamic thermosensitivity and consequently condition thermoregulation in later life.
Nutritive value of poultry meat: relationship between vitamin E and PUFA
- A. C. BARROETA
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- 25 June 2007, pp. 277-284
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Fat content in poultry meat is relatively low (2.8 g/100 g breast and 13 g/100 g thigh) and with a positive unsaturated/saturated fatty acid ratio, from a human health point of view. It is well established that we can modify lipid fraction through dietary strategies in order to improve nutritive value. When the dietary polyunsaturated fatty acid (PUFA) level increases, the PUFA content in the chicken tissues also increases. But this enrichment in PUFA, especially in omega-3, leads to a higher number of double bonds in the meat and this provokes different consequences. The use of dietary PUFA fat causes a decrease in the body fat deposition in broilers. Furthermore, an increase in the degree of PUFA in meat enhances the development of organoleptic problems and increases the susceptibility to oxidation. Since antioxidants, especially vitamin E, protect PUFA from oxidation damage, its inclusion in chicken diets must be assured. Alpha-Tocopherol (alpha-Toc) content in poultry meat increases linearly as the dietary alpha-Toc supplementation increases, but it is affected by the PUFA content. As the dietary PUFA level increases, the alpha-Toc content of chicken meat decreases. To achieve the same tissue alpha-Toc concentration, the vitamin E requirements increase by 2.5 and 3.7 mg per each g of dietary PUFA. The potential healthy beneficial effect of PUFA enriched meat will be limited if the antioxidant content, such as vitamin E, which prevents oxidation, is not assured. The dietary supplementation with alpha-Toc and PUFA should be adjusted depending on our aims: nutrient enrichment and/or lipid oxidation minimization.
Overview of chicken taxonomy and domestication
- A. AL-NASSER, H. Al-KHALAIFA, A. AL-SAFFAR, F. KHALIL, M. ALBAHOUH, G. RAGHEB, A. AL-HADDAD, M. MASHALY
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- 25 June 2007, pp. 285-300
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Chickens are the most popular poultry worldwide and are now used for both meat and egg production. There is only a sporadic information in the literature on chicken taxonomy; and there is a lack of a single concise document that deals with different issues related to this important topic. The present document contains detailed information on the tree taxonomy of chickens. In addition, process of domestication and its effect on chicken genetic diversity, physiology and behaviour are also discussed. The major conclusions are as follows: 1) Chickens are classified as: order: Galliformes, family: Phasianidae, genus: Gallus (junglefowl). Four species of junglefowl are recognized. These are: a) Gallus gallus (red junglefowl), b) Gallus varius (green junglefowl), c) Gallus sonneratii (grey junglefowl) and d) Gallus lafayetii (Ceylon junglefowl). The current chickens that are used for both meat and egg production commercially are domesticated fowl and are the descendants of the red junglefowl species. 2) Domestication process is a complicated one and involves intensive breeding and selection programmes. During this process, genetic diversity is still maintained, yet reduced, so careful attention is needed in the future to maintain the diversity of specialized chicken species. 3) Domestication resulted in basic changes in the behaviour, physiology and production of the bird, but still there are some similarities between the ancestor and the current chickens.
Microbiological challenges of poultry egg production in the US
- P. CURTIS
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- 25 June 2007, pp. 301-307
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Over the past 40 years there have been many changes in egg production and processing, as well as, the egg itself. Many of these changes have contributed to the microbial challenges of the egg that we face today. Salmonella enterica serovar Enteritidis (SE) and more recently Salmonella enterica serovar Heidelberg (SH) are the two organisms of most concern associated with eggs. Most U. S. egg producers utilize some type of control programme to ensure egg safety. Many use the United Egg Producers' “5-Start” Food Safety Programme. Commercial egg washing significantly reduced concentrations of aerobic bacteria, yeasts and moulds, Enterobacteriaceae, and E. coli on shell egg surfaces. However, refrigeration of eggs is often identified as one the most critical issues in minimizing the risks associated with Salmonella contamination in eggs. The condensation question always arises any time egg refrigeration is discussed. Moisture often condenses on the shell surface when cold eggs are moved from the cool storage into hot and/or humid conditions. Research has shown that the ability of any microbes present on the shell to penetrate the shell was not increased with egg sweating. Also, heat sensitivity of SE can be induced by exposure to low temperatures. Although low numbers of SE and SH can contaminate eggs via the transovarian or shell penetration route, these small numbers cannot be ignored. Storage at temperatures as low 4°C combined with natural defences does not completely prevent growth. Furthermore, rapid growth occurs at 25°C, so minimal temperature abuse could result in high levels of contamination within eggs. The need for proper management during production, properly controlled storage, cooking and serving is critical.
Regional Report
Village chicken production in Myanmar – purpose, magnitude and major constraints
- J. HENNING, R. PYM, T. HLA, N. KYAW, J. MEERS
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- 25 June 2007, pp. 308-322
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The main objective of this work was to describe the characteristics of and major constraints to village chicken production in Myanmar. Data on village chicken production, health, husbandry and marketing were collected in 296 households in 10 villages in the Yangon division of Myanmar in November 2003. The average flock size in the study area was about 30 birds, comprising 12 chicks, 12 growers, 4 hens and 2 cocks. Disease as a cause of mortality was more prominent in growers and adults, while predation and exposure to unfavourable environmental conditions were major causes of mortality in chicks. The main predators identified were: birds, rats, snakes, dogs and cats in 32, 31, 17, 15 and 3% of households respectively. Two main strategies were identified to improve village chicken production: vaccination as a means of protecting birds against Newcastle disease and confinement rearing and supplementary feeding of chicks, as a means of reducing the attrition rate of young chicks. This is the first survey conducted describing village chicken population structure and productivity in Myanmar.