Reviews
Role of insoluble non-starch polysaccharides in poultry nutrition
- H. Hetland, M. Choct, B. Svihus
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 415-422
-
- Article
- Export citation
-
This paper reviews and presents new evidence for the role of insoluble fibre (nonstarch polysaccharides and lignin) in poultry nutrition. Insoluble fibre affects gut functions and modulates nutrient digestion. Thus, digestibility of starch is higher and digesta passage rate faster when a moderate level of insoluble fibre is present in the diet. The effect of insoluble fibre on gut functions stems from its ability to accumulate in the gizzard, which seems to regulate digesta passage rate and nutrient digestion in the intestine. Furthermore, there are indications that diets high in insoluble fibre are preventative of cannibalism outbreaks in laying hens. It is hypothesized that with nutrients disappearing from the lumen faster and digesta moving through the gut quicker, birds spend longer time eating and less time pecking each other. However, the ability of insoluble fibre to exert these effects appears to be related, in part, to particle size as fine grinding diminishes its stimulatory influence on the gizzard. More research is underway on the physical and chemical structure of fibre on gut functions, nutrient digestion and bird behaviour.
Ileal digestibility of amino acids in feed ingredients for broilers
- A. Lemme, V. Ravindran, W.L. Bryden
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 423-438
-
- Article
- Export citation
-
To more precisely formulate feed and predict animal performance, it is important to base both the recommendations and feed formulations on digestible rather than total amino acid contents. Most published data on the digestibility of amino acids in feed ingredients for poultry are based on excreta digestibility. Ileal digestibility is an alternative and preferred approach to estimate amino acid availability in feed ingredients. Both methodologies are described and assessed. In addition, the differences between apparent and standardised (in which corrections are made for basal endogenous losses) digestible amino acid systems are discussed. The concept of a standardised digestibility system as a mean of overcoming the limitations of apparent digestibility estimates is proposed. In this context, different methodologies for the determination of basal endogenous amino acid losses are discussed. Although each methodology suffers from some limitations and published data on endogenous losses at the ileal level in growing poultry are limited, averaged data from repeated experiments using the ‘enzymatically hydrolysed casein’ method are considered as the best measure of basal losses. Standardised ileal amino acid digestibility values of 17 feed ingredients commonly used in broiler nutrition are presented including grains (barley, corn, sorghum, triticale, wheat), grain by-products (wheat middlings, rice pollard), plant protein sources (soybean meal, canola meal, corn gluten meal, cottonseed meal, lupins, peas/beans, sunflower meal), and animal by-products (feather meal, fish meal, meat and bone meal). This comprehensive set of the ileal amino acid digestibility of feed ingredients in broiler nutrition may serve as a basis for the establishment of the system in broiler feeding and for further research.
Natural mating in broiler breeders: present and future concerns
- J.P. Brillard
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 439-445
-
- Article
- Export citation
-
Intensive selection based on growth traits in meat-type breeder flocks has resulted in new breeds expressing early sexual precocity but limited persistence of gonad development. This can be in part circumvented by adequate use of specific light regimes. However, these breeds require environmentally controlled housing in which light, temperature and ventilation can be properly balanced, a situation which to date is technically feasible only under relatively mild climatic conditions. In recent years there has been a progressive shift in chicken production to warm geographic regions. As a consequence, increasing numbers of breeder flocks are now raised in open houses in which light regimes are only partly controlled. In most instances, reproductive performance in standard meat-type breeds remains satisfactory if sexual precocity can be delayed until 23–25wks of age. However, the early maturation of flocks stimulated by external photoperiods may result in small eggs during the early parts of the season. Early sexual precocity in breeder males is generally followed by a rapid decline in reproductive performance, resulting in their partial or even total replacement to maintain acceptable fertility rates throughout the season. Such changes, which are currently performed on a large scale, are costly, pose health risks and are only partly effective in maintaining adequate fertility rates. In addition to photoperiod, another common practice to for controlling sexual precocity and reproductive performance in meat-type chickens is based on strict control of feed allowance for each sex. In countries where housing and feed equipment are accessible, techniques such as sex-separate feeding combined with quantitative feed restriction have been of practical value to limit body growth. However, such equipment is costly and requires strict management practices. Severe feed restriction in maturing breeder flocks may be stressful and, which induces heterogeneity in body growth. Another concern is the moderate but constant decline in fertilising potential. A Furthermore a negative correlation between reproductive and growth traits may be responsible for such the decline in fertilising potential of birds selected for rapid growth. This may ultimately favour the emergence of breeds with less intensive growth rates and/or the extension of artificial insemination.
Incidence, sources, and control of food-borne Salmonella spp. in poultry feeds
- K.G. Maciorowski, F.T. Jones, S.D. Pillai, S.C. Ricke
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 446-457
-
- Article
- Export citation
-
Transmission of food-poisoning salmonellae in the poultry industry is often associated with a contaminated feed supply. Occurrence of food-borne Salmonella spp. continues to be documented on poultry feeds and feed ingredients. This is in part due to the wide variety of environmental origins for Salmonella spp. and its ability to easily cross-contaminate during feed processing and storage. Since Salmonella spp. have been shown to survive for several months under feed storage conditions, they can remain a persistent problem for poultry production. Limiting Salmonella spp. contamination of poultry feeds requires application of surveillance approaches during feed manufacturing and distribution along with the introduction of effective intervention and hurdle technologies. Representative sampling approaches may be needed to achieve consistent contamination reduction.
Breeding strategies to improve the egg's natural defence
- I.C. Dunn
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 458-468
-
- Article
- Export citation
-
The risk posed by food borne pathogens in eggs has taken on a high priority for government and consumer. In Europe there has been concern that plans to move from battery cages may increase the risk from eggs. For this reason there is some pressure to demonstrate progress in reducing risk from eggs. At the level of the egg the approach has been to improve resistance of the eggshell to breakage using selection for quasi-static compression or specific gravity. The review will consider phenotypic measurement and developments in genetics and genomics that can place new tools in the hands of poultry breeders, should they want to use them.
New phenotypic measurements that better describe the physical and antibacterial properties of the egg and eggshell need to be developed which accurately measure the egg's natural defence characteristics to complement the developments in chicken genomics. Acoustic resonance analysis to measure the stiffness of the eggshell and ultra-structural measurements using electron microscopy in pedigree populations are methods which have been examined. Also organic matrix measurements, antimicrobial properties and bacterial penetration measurements that have only been of academic interest may be used in test populations. Genetics and genomics can be used with these phenotypic measurements to identify genetic markers that can be used in selection programmes, rather than the measurements themselves, using whole genome scans for quantitative trait loci and association analysis with candidate genes. The availability of the chicken genome sequence and EST resources has made carrying out these analyses easier in pedigree breeding flocks.
Recent developments in European and international welfare regulations
- H.J. Blokhuis
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 469-477
-
- Article
- Export citation
-
The Protocol on Animal Welfare annexed to the EC Treaty in 1999 obliges the European Institutions to fully consider animal welfare in the drafting and implementation of Community legislation. The reform of the common agricultural policies (CAP) foreseen by Agenda 2000 follows the trend of more market oriented measures decoupling subsidies from production. Farming is seen as fundamental to other key societal goals such as food safety and quality, animal welfare, rural development, sustainability etc.
Over the years, recommendations of the Council of Europe and EU Directives specifically concerning farm animal welfare were developed and these are becoming increasingly stringent. European regulations relevant for poultry include Directives on the housing of laying hens, transport and slaughter.
Recently, the World Organisation for Animal Health (OIE) identified animal welfare as a high priority for the coming years. Actions include the development of internationally applicable guiding principles and standards for good animal welfare practice.
Animal welfare is an issue of increasing significance for European consumers and citizens. Since the consumer is the end-user, his or her requirements form the bottom-line for any effort intended to achieve the ultimate fine-tuning necessary to assure societal and economic sustainability of agri- and food-chains (‘from farn to fork’). This means that efforts to inform the consumers and to address their concerns about animal welfare need to be at the forefront of policy and industry agendas.
Embryonic cardiovascular variables during incubation
- H. Tazawa
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 478-488
-
- Article
- Export citation
-
Avian embryos develop within the confines of an eggshell independent of maternal physiological functions. The eggshell provides not only an airway for diffusive gas exchange of the embryo, but also a wide space available for measurements of physiological functions and makes it possible to regulate directly external nvironments for physiological study. Firstly, in materials and methods section are shown measurements of various cardiogenic and electrical signals while maintaining dequate gas exchange through the eggshell. Secondly, the report summarizes mainly our studies on embryonic gas exchange and measurements of circulatory variables with an emphasis on the embryonic heart rate which we measured taking advantage of the hard eggshell. Lastly, development of thermoregulatory competence in avian embryos is briefly summarized.
Methods and technologies for handling mortality losses
- J.P. Blake
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 489-499
-
- Article
- Export citation
-
Poultry carcasses resulting from death by natural occurrences at high levels of production represents a tremendous amount of organic matter that requires environmentally and biologically safe disposal or utilization. Methods for disposal of poultry carcasses include burial, incineration, composting, and rendering. Burial pits used for carcass disposal pose concerns that include the decline in ground water quality where pits are located and residue remaining in pits after years of use. Burial is no longer permitted in some poultry producing areas of the United States except in he case of catastrophic loss. Incineration is a biologically safe method of disposal; however, it tends to be slow and expensive even when highly efficient incinerators are used. Burial and incineration impose environmental concerns that are becoming less acceptable. Research has been conducted during the past decade in support of composting for carcass disposal. When poultry carcass composting is properly conducted, disease-causing microorganisms do not survive the process and the composted material can be used as a soil amendment. Composting is environmentally sound, relatively inexpensive, and has gained widespread acceptance. Rendering carcasses into a protein by-product meal is an alternative in the United States, but is not permitted in the European Union. Poultry carcasses can be removed from the farm, but the spread of pathogenic microorganisms during routine pickup and transportation to a rendering facility may present a substantial threat. Refrigeration, principally freezing, has potential for short-term storage prior to rendering, but costs of operation and transportation need careful consideration. Lactic acid fermentation of poultry carcasses prior to transportation stabilizes carcass deterioration and minimizes pathogen threat. Fermentation allows for longterm on-farm storage of poultry carcasses, reduced transportation costs and results in a usable feed ingredient. When coupled with rendering, fermentation is an excellent alternative for storing and transporting pathogen-free poultry carcasses. All methods that allow for the environmentally safe and bio-secure disposal of poultry carcasses should be considered. No single method will completely solve the problem.
The future of Japanese quail for research and production
- F. Minvielle
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 500-507
-
- Article
- Export citation
-
Japanese quail research measured by the number of published papers has gradually diminished over the past 10 years, and the trend appears to be due to the decrease of works using Japanese quail as an animal model or for biological studies. The flow of avian science-related papers on quail published in international journals remains about co nstant and low over the same period as the number of teams or laboratories with a quail research programme are few. On the other hand, commercial production of Japanese quail for eggs and meat is difficult to track precisely, and it is quite unequal across countries and continents, with increasing production in a few places, like Brazil. The futures of quail research and of quail production are not independent, however, and better links between both activities are needed to promote relevant research, explore new avenues of quail production, and help maintain this bird as an essential animal model.
Defining normal: comparison of feed restriction and full feeding of female broiler breeders
- R.A. Renema, F.E. Robinson
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 508-522
-
- Article
- Export citation
-
Genetic selection for growth parameters in broiler stocks has created parent stocks that are unable to self-regulate feed intake to a level that permits reproductive function. Modern broiler breeders are feed restricted to limit the incidence of reproductive disorders and excessive body weight gain. A high degree of feed restriction is common during the pullet phase, which has been identified as a welfare issue. This paper examines the productive and welfare implications of feed restriction in modern breeders and the implications of returning to ad libitum (AL) feeding conditions. Feed restricted hens are compared to ALfed hens to demonstrate the full range in potential results from eliminating or reducing the degree of feed restriction in broiler breeder management. Both full feeding and restricted feeding programmes impact bird welfare. The contrast of these methods is intended to provide background information for the development of a definition of what a normal or appropriate growth profile is for broiler breeders. The implications of overfeeding on the well-being of the birds make current feed restriction programmes the more welfare-friendly alternative, despite apparent drawbacks.
Regional Report
Direct assessment of nutrient resources in free-range and scavenging systems
- E.B. Sonaiya
-
- Published online by Cambridge University Press:
- 18 September 2007, pp. 523-535
-
- Article
- Export citation
-
The low-input:low-output scavenging systems in Africa, Asia and Latin America and the pastured and organic farming systems in Europe and North America depend on the free-range. Nutrient resources available in free-range and scavenging systems can be assessed by three parameters: Scavengeable Feed Resource Inventory (SFRI); Range Coverage (RC); and Scavengeable Feed Resource Harvest (SFRH). SFRI is estimated by 4 procedures: determination of the quantity of Household Leftovers (HHL) added to the range and determination of the quantity of scavengeable flora and fauna using Pitfall Traps; Transect Mappings; and Quadrants. RC is assessed by 3 procedures: visual inspection; physical space measurement; and automatic monitoring of birds by telemetry. SFRH, or the intake of scavengeable materials (HHL, plants, insects and metazoans) from the range, is estimated by applying 3 procedures to the content of the crops of scavenging birds: visual identification; physical separation and weighing; and chemical analysis. The assessment methods and parameters are still rudimentary and require a lot of improvement in accuracy and repeatability.