The importance of feed particle size, as a tool to optimise the utilisation of feed and improve production efficiency in broilers, has attracted increased attention in recent years. Particle size reduction is widely believed to enhance the access of digestive enzymes to substrates because of the increased surface area of feed particles. Fine particles can negatively affect the development of fore-gut (proventriculus and gizzard), which plays an important role in intestinal health and nutrient utilisation. A well-developed fore-gut can be achieved by feeding coarse particles which is associated with improvements in gut motility and health. However, the results of studies considering the effect of feed particle size on upper gastrointestinal tract development have been inconclusive, because of the confounding effects of feed form (mash vs. pellets). Feed particle size influences the development of gastrointestinal tract and bird performance to a greater extent when the broilers are fed mash than pelleted diets. Particle size-reducing properties of the pelleting process may result in suboptimal gizzard development and changes in the intestinal morphology and microbiota profile.

Inositol is a naturally occurring sugar-alcohol present in plants and animals, either in its free form, as a phospholipid component or as inositol phosphate (IP) esters. Dietary inositol is readily absorbed from the intestine via SMIT1 with levels being detectable in the blood as well as in various tissues. Recent studies have revealed a potential link between free inositol content and improved growth response in animals. There is limited data suggesting why an increase in inositol would result in improved growth; however, it would appear that inositol has numerous biological functions within the body. A number of tissues are capable of synthesising this polyol from glucose, although the kidney appears to be the primary site of catabolism. Studies investigating the effect of inositol deficiencies in various animal species have revealed a number of biological processes that are reliant on inositol to function. One of inositol's main functions appears to be its involvement as a phospholipid component of cell membranes and lipoproteins. Cell signalling pathways involving phosphoinositide phospholipids, such as the IP3/DAG and IGF/PIK/Akt pathways, lead to a number of cellular responses that are important for cell survival and growth. On a larger scale, inositol appears to be essential for both prenatal and postnatal development of peripheral nerves, CNS and bone. With regards to a potential growth response, upregulation of specific signalling pathways, such as the IGF/Akt/mTOR pathway, in the skeletal muscle has been shown in response to phytase supplementation and the consequential increase in free inositol. These signalling pathways are responsible for protein synthesis and increased glucose absorption in this tissue. Since inositol has also been shown to be an important regulator of the transport and deposition of fat, it may be possible to use inositol to support the growth of a lean animal.

The relationship between the use of antibiotics and the presence of antibiotic resistant strains of E. coli, as well as antibiotic residues in poultry litter, mainly due to irregular use of antibiotics is reviewed in the present paper. The aim of this review is to examine the existing problem of poultry waste management and how it can impact agricultural ecology and economy. Actions such as monitoring and reporting incidents of disease outbreaks in the future should provide an outline of how to improve and implement suitable regulations.

Due to exposure of animals to numerous stress-inducing factors and a high level of cellular metabolism resulting from the conditions and manner in which they are raised, destabilisation of the redox balance towards excessive activity of free radical species is a common phenomenon. Enhancing the antioxidant status of the animal organism by optimising the level and quality of feeding, and especially by supplementation with exogenous antioxidants, may be one essential and highly effective means of improving the health and thus the productivity of animals. Natural plant supplements in diets for poultry can be used to enhance antioxidant defence mechanisms and reduce the intensity of oxidation processes, which negatively affect the quality of poultry products, i.e. meat and eggs. Analysis of the available studies shows that antioxidant processes in the organism of birds can be stimulated via administration of extracted active compounds, among which the highest antioxidant activity is found in resveratrol, hesperidin, genistein, thymol and carvacrol, and herbs, for example from garlic, aloe vera, oregano and rosemary.

Commercial poultry production is associated with various stresses affecting productive and reproductive performance of birds and their health status. Recently the vitagene concept has received substantial attention. In fact, the term vitagenes refers to a group of genes that are responsible for preserving cellular homeostasis in stress conditions. These genes play a crucial role in cell and whole organism adaptation to stress by regulating additional synthesis of stress resistance proteins, including heat shock proteins, thioredoxins, sirtuins and superoxide dismutase. Among four major types of stress, nutritional stresses have a special place, being detrimental for productive and reproductive performances of poultry. In particular, mycotoxins are unavoidable contaminants of poultry feed and at molecular level they cause oxidative stress in the body. Oxidised fat and nutrient imbalances are also detrimental for gut health, immunity, growth and development of chickens. Internal stresses, including peak of egg production and vaccinations are also of great importance for poultry production. Therefore, the development of the effective antioxidant solutions to decrease negative consequences of nutritional and internal stresses is an important task for poultry scientists. One of such approaches is based on the vitagene concept which will be considered in this review.

AA amyloidosis (AAA) is a disease known as amyloid arthropathy in chicken, which represents substantial economic losses, in addition to welfare concerns. Enterococcus faecalis (E. faecalis) is the major pathogen found in field outbreaks of amyloid arthropathy and its specific association with this disease has been extensively confirmed. The following review discusses the sequence types of E. faecalis associated with AAA that have been identified and characterised both poultry and humans and provide different hypotheses and theories about pathogenesis and transmission of this disease. This article covers the pathology both in field and induced cases of avian amyloidosis and concludes with approaches for a possible treatment, needs for further research and future perspectives. This paper is a consolidation of current knowledge on AAA in chickens which has been obtained over the last twenty years.

High ambient temperature is associated with decreasing growth rate, egg production, feed efficiency, nutrient utilisation, egg quality and is a major problem resulting in extensive economic losses in poultry. Poultry reared under heat stress may exhibit various metabolic disorders caused by a chronic state of oxidative stress and inflammation. Recently, nuclear factor-erythroid 2-related factor 2 (Nrf2) has emerged as an agent that plays a significant role in cellular protection against oxidative stress and inflammation. The nuclear factor kappa-B (NF-κB) signalling pathway has been associated with enhanced inflammatory response and its activation has been significantly correlated with heat stress. These transcription factors when activated can regulate antioxidant and anti-inflammatory cellular responses leading to the expression of detoxifying enzymes. Studies have shown that NF-κB and Nrf2 expression can be modulated by several factors, such as bioactive compounds. Green tea contains many polyphenolic antioxidants including the catechin, epigallocatechin-3-gallate (EGCG). As bioactive compounds, supplementing EGCG in poultry diets may improve antioxidant status in poultry. EGCG modulates signalling pathways including the NF-κB and Nrf2 that regulate antioxidant and anti-inflammatory responses. This review aims to discuss the evidence to justify a recommendation of EGCG in heat stressed poultry as a non-pharmacological option to activate the NF-κB and Nrf2 pathways.

First of all, happy 2016 to all, even through by the time this is published we will be three months into the New Year. The world of poultry science continues to be challenged with various issues, competition for feed raw materials with the human population, the changes in weather due to El Niňo, and so research has to continue into finding novel solutions to evolving problems. The current issue covers various topics including immunity, alternative raw materials for feed, welfare, behaviour, disease, genetics and breeding. 2015 saw a backlog of papers cleared where we were waiting for author revisions, allowing us to increase our turnaround time, although we still sometimes struggle to find suitable reviewers for more obscure topics – so please consider reviewer suggestions carefully if you’re submitting such as paper.

This year is a World Poultry Congress year - this time hosted by the Chinese Branch in Beijing. I am reliably informed that preparations are well under way – so I look forward to seeing a lot of new information and having the opportunity to get more review papers published from this event. Check out the WPSA.com website for details in submitting papers for this key event. I shall also be attending the WPSA UK event in Chester England in April, as part of my annual end of tax year meetings with publishers and hope to see various poultry scientists there.

So here’s to a productive and informative 2016, and do submit your reviews on any topic related to poultry. If you have any queries regarding publishing – do get in contact as we are happy to help!

Dr Lucy Waldron

Editor

The relationships between metabolic pathways, nutrients and genes are the basis of the majority of current studies on poultry. The rapid advance of biochemical and molecular tools has now made it possible to understand the molecular base of important phenotypic characteristics. Fats are the main storage source of energy in animal body with important role in cell membrane structure, gene regulation and precursors of important regulatory metabolites. From a functional point of view, it has been suggested that dietary fats change liver fatty acid synthesis and other lipogenic enzymes by regulating mRNA synthesis. Nuclear hormone receptors are defined as ligand-activated transcription factors which directly and indirectly regulate a number of genes involved in lipid metabolism and inflammatory signalling. The peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of transcription factors. PPARs are involved in cellular differentiation, insulin sensitisation, cancer, atherosclerosis and several metabolic diseases. Three distinct PPAR genes have been recognised as α, δ and γ. The most important metabolic effect of PPARγ is its role in adipogenesis. PPARγ is a central gene regulator in adipose tissue and stimulate the expression of several genes involved in adipogenesis. Based upon examples taken from chicken lipid metabolism, it is possible to draw lessons from the study of PPARγ functions in order to approach the study of gene expression PPARγ functions regulatory pathways interactions.

Reduction of potential environmental pollutants is a major issue for the sustainable development of the poultry industry. Accumulation of excessive manure and nitrogen poses a risk to animal and human health and ground and surface water cleanliness. In conventional poultry, synthetic amino acids and enzyme supplementations are commonly used to balance the diet and improve digestibility of nutritive compounds. However, diet preparation with sufficient nutrients and minimum amount of excessive nitrogen which still provides optimal growth and health performance continues to be a challenge. This review focuses on various approaches leading to improvement of feed formulation in conventional poultry production systems. The use of crystalline amino acids and genetically engineered plant protein sources in the conventional poultry industry with regard to optimisation of nitrogen level in poultry diets are discussed, and the application of the ideal protein ratio concept in poultry feed preparation as a tool for nitrogen level optimisation is outlined.

Currently whole grain is incorporated into poultry diets to lower production costs, stimulate the development of the gizzard, prevent potentially pathogenic bacteria from entering the intestine and improve the growth rate and feed conversion of birds. The present review discusses the results of experiments performed on turkeys where whole grain (WG) or large-sized feed particles were incorporated into diets with the use of different processing methods (with pre- or post-pelleting inclusion) and in different quantities. The results of recent experiments indicated that, within the first month, gizzard weight increased significantly when the size of feed particles was increased from 380 to 806 mm, or when turkey diets were supplemented with 20% WG. In older birds, gizzard weight increased when the WG content of pelleted diets exceeded 20%. Dietary dilution with WG did not cause significant changes in the development or functionality of the small intestine, including mucosal enzyme activity. The presence of WG in the diet increased the amount of coarse particles in the digesta leaving the gizzard, which did not lower the apparent digestibility of dry matter and crude fibre or nitrogen retention. The inclusion of WG in turkey diets led to a decrease in the counts of Clostridium spp., Campylobacter and/or Escherichia coli, and an increase in the counts of Lactobacillus spp. and/or Bifidobacterium spp. in the caecal digesta. However the effect of WG inclusion in turkey diets on gut morphology has been investigated in only a few studies to date, and the results are inconclusive.

The roles of beneficial microorganisms as important inducers in the development and functions of the gastro-intestinal tract of chickens has aptly presented a need for understanding of how these microbes exert health and growth promoting effects on the host chickens. This review focuses on the microbes-host interactions mechanism leading to the proliferation of beneficial microbes and the colonisation of harmful microbes in the gut of chickens. Insight is provided on gut microflora development and control as it influences productivity of chickens. The future role of gut microorganisms and microbial dynamics in poultry nutrition as the basis for optimal utilisation of feed resources and hosts’ immune development is highlighted.

Soybean meal (SBM) remains the most important and preferred protein feed source for poultry. However, the supply and quality of SBM fluctuates, and the meal is expensive due to processing and transportation costs. Although there is a growing interest in the use of raw SBM for birds, its nutritive value is negatively affected by the presence of anti-nutritive factors (ANF). Heat treatment is applied to alleviate some ANF, such as trypsin inhibitors and lectins, but both under- and over-processing of soybeans can reduce the digestibility of key components in the meal. Feed supplementation with exogenous enzymes, such as phytase and protease enzymes, is a biotechnological option for improving the nutritional values of SBM and other protein-rich ingredients. Proteases break down both stored proteins and proteinaceous anti-nutrients in feeds. Various studies have shown that the performance of birds can be improved through dietary supplementation with new-generation protease enzymes. Phytase is also effective in breaking down phytate (phytic acid), which chelates with mineral cations and other nutrients in soybeans. Recent in vitro and in vivo studies have shown that an enzyme cocktail (combined use of protease and phytase) is more effective in reducing ANF in soybean meal for birds than the use of single enzyme products. This review provides information on how microbial enzymes, particularly protease and phytase, contribute to the improvement of the nutritional values of different types of SBM for poultry.

Commercial poultry production is associated with four major types of stresses, including environmental, technological, nutritional and internal stresses, affecting productive and reproductive performance of birds and their health status. It has been suggested that at the molecular level most stresses are associated with overproduction of free radicals and oxidative stress. Therefore, the development of the effective antioxidant solutions to decrease negative consequences of commercially-relevant stresses is an important task for poultry scientists. One approach is based on possibilities of modulation of vitagenes, a family of genes responsible for animal/poultry adaptation to stress. In fact, the vitagene network includes heat shock proteins (HSPs), thioredoxin system, sirtuins and superoxide dismutases (SOD) and plays a regulatory role in most important cellular processes in stress conditions. Indeed, HSPs, including haem oxygenase-1 (HO-1) and HSP70, are responsible for protein homeostasis in stress conditions, while the thioredoxin system is the major player in maintaining redox status of the cell involved in protein and DNA synthesis and repair as well as in regulation of expression of many important genes. Furthermore, sirtuins regulate the biological functions of various molecules post-translationally by removing acetyl groups from protein substrates ranging from histones to transcription factors and orchestrate cellular stress response by maintenance of genome integrity and protein stability. Finally, SOD belong to the first level of antioxidant defence preventing lipid and protein oxidation at the very early stages. All vitagenes operate in concert building a reliable system of stress detection and adequate response and are considered to be key elements in stress adaptation. Indeed, further work is required to understand molecular mechanisms of the interactions of vitagenes with various signalling pathways and transcription factors in the cell to build an effective adaptive response to minimise the detrimental consequences of commercially-relevant stresses in poultry production.

The consumption of n-3 PUFAs is low, particularly the long chain (>18 carbon atoms) fatty acids that are most commonly found in fish oils. These dietary fatty acids have been shown to have a great effect on the health and immune status of different species including humans, rats and poultry. The current paper reviews studies on the effect of dietary polyunsaturated fatty acids on B- and T-cell subpopulations in peripheral blood, spleen, and thymus of poultry.

The shell colour of the eggs laid by pheasants is determined genetically and can vary from very light to dark brown. In general, four basic colours may be distinguished: dark brown, light brown, olive, and blue. A number of studies indicate that there is a relationship between the colour of pheasant eggshells and their quality. Pheasant eggs with different shell colours differ in terms of morphological (shape) and physical features (weight, egg specific gravity, yolk and albumen share and indices) as well as eggshell quality (thickness, strength, ultrastructure). Studies conducted by previous authors demonstrated a range of structural and physical properties of pheasant eggs. The microscopic structure of the blue-coloured shells demonstrates some abnormalities in the structure and thickness of the shell layers and the shells of these eggs are the thinnest. This may be the cause of poorer hatchability in blue-coloured shell eggs.