Nutrients such as minerals and vitamin D have clear roles in skeletal metabolism. Boron (B) has been examined as a possible essential nutrient in the metabolism and utilisation of several micro nutrients and hence could have an influence on bone mineral density and eggshell quality. However, there have been few direct studies to examine the dietary response to B in chicken and layer hen models, although there is evidence that both compositional and functional properties of bone are affected by dietary boron status in other model animals and humans. Bone integrity, skeletal problems in chickens and eggshell quality in laying hens are important economic, welfare and health issues for the poultry industry. Therefore, better understanding of certain role of B on mineral availability in chickens and layer hens is important to enhance productivity and improve animal welfare. The following review examines the published data relating to these aspects of B in poultry feed.

Postileal fermentation in the gastrointestinal tract of poultry takes place as a result of the interaction between two components of the intestinal ecosystem: rapidly changing microbiota and digesta with different physicochemical properties. Short chain fatty acids, the major products of fermentation, act to stabilise microbiota composition and maintain gut health, and constitute an additional source of energy. Due to different mechanisms of action of probiotics, phytobiotics and prebiotics in the intestinal ecosystem, the quantities and proportions of the major products of fermentation are affected by the type of feed additives. Some phytobiotics, including alkaloids, exert antimicrobial effects and reduce short chain fatty acids concentrations in the caecum. Mannan-oligosaccharides, regarded as prebiotics, may prevent the adhesion of pathogenic bacteria (mostly E. coli and Salmonella) to the gut wall. Prebiotic oligosaccharides, in particular fructo-oligosaccharides and inulin, are used by beneficial bacteria of the genera Bifidobacterium and Lactobacillus, thus enhancing the synthesis of short chain fatty acids in the lower gastro intestinal tract of poultry, while low intestinal pH inhibits the growth of pathogenic bacteria.

The restricted use of antibiotics in the poultry sector has greatly enhanced the search for environment-friendly alternatives and complementary therapeutic approaches to manage infectious diseases in poultry. Cytokines, as natural immune-modulators, offer alternatives to conventional chemical-based therapeutics. Cytokine usage is becoming more feasible in poultry due to recent advancements in the field of immunology and vaccination, leading to the identification and cloning of avian cytokine genes. Existing adjuvants for poultry vaccines can have deleterious side-effects on the health and products of poultry and a subsequent reduction in profits. Therefore, alternative adjuvants must be developed to enhance the impact of vaccination. The use of cloned cytokines as adjuvants in poultry is attracting attention after the identification of new cytokine genes in chicken. Hence, cytokines may be used as therapeutics and vaccine adjuvants for enhancing immune response during infection and vaccination. This review focuses on the recent advancements in the application of avian cytokines as therapeutics or vaccine adjuvants.

The onset of feeding broiler chicks after hatch is often delayed by 48-72 hours due to variations in hatching time and follow up hatchery practices, affecting their ultimate performance at marketable age. In the newly hatched chicks, residual yolk serves as a source of nutrients until access to exogenous sources of feed is established. However, despite the residual yolk being sufficient to maintain the chicks during the first three to four days of life, it does not provide the required level of nutrients to fully support the genetic expression of the bird's potential for growth, development of the gastro-intestinal tract or the immune system. Development of the avian immune system is triggered during embryogenesis, but is not evolved until a few weeks of age post hatch, and can be stunted due to the unavailability of nutrients if hatchlings are deprived of food immediately after hatch. Early feeding is not only associated with immune organ development, but also with the functioning of the immune system in broiler hatchlings. With the continued increase in the economic importance of broiler chickens, an understanding of the development and function of the immune system in these birds and their capacity to respond effectively to divergent antigens is necessary.

Postileal fermentation in the gastro intestinal tract of poultry is affected by the main raw materials used during feed formulation, for example cereal grains, rapeseed meal, soybean meal, lupin seeds. Since cereal grains are the main source of dietary non-starch polysaccharides, including the viscous water-soluble fraction, their quality determines the rate of postileal fermentation. The supplementation of poultry diets with selected enzymes, mostly xylanase andß-glucanase, suppresses fermentation in the upper gastro intestinal tract, and enhances the process in the caecum. Due to relatively high concentrations of raffinose family oligosaccharides in soybean meal, diets rich in that raw material may stimulate gut fermentation and decrease the growth performance of young birds. Rapeseed meal and lupin seeds, used as partial substitutes for soybean meal, affect fermentation processes in the gastrointestinal tract of poultry to a low degree, as compared with a soybean-based diet. Sunflower meal, even at low inclusion levels (14%), reduces the synthesis of caecal short chain fatty acids, probably due to an increase in lignified fibre in the diet.

The broiler chick's gastrointestinal tract undergoes significant morphological and physiological changes during the first days after hatch. These changes occur mostly because birds switch from a diet based on fatty acids from the yolk sac to a diet based on carbohydrates, provided by commercial feeds, often formulated with corn and soya bean meal. In ovo feeding techniques enable the study of the early adaptation of the avian gastrointestinal tract, such as supplementation with carbohydrates during embryonic development. This procedure consists of inoculation into the amniotic fluid through a hole in the egg shell near the air-chamber during late embryonic growth. The hatching process requires large supply of energy to the muscles, and in ovo feeding has the objective of providing extra energy in order to avoid glycogen store reductions, which are needed during the first days after hatch. However, published reports have shown that in ovo manipulation can reduce incubation yield, mostly when applied during the beginning of embryonic development. The best results of in ovo feeding were found when supplementation was with carbohydrates.

The hypothesis that glucose and amino acids should be made available in appropriately balanced quantities at the sites of protein synthesis for efficient protein deposition and growth performance is not new in animal nutrition. The objective of this review is to consider starch and protein digestive dynamics in light of recent developments and research outcomes in relation to chicken-meat production. This will concentrate on the concept that catabolism of amino acids in enterocytes provides energy for the gut and slowly digestible starch benefits performance. These are supported by relatively recent developments and studies with reducing agents. Practices such as whole grain feeding, hydrothermally processing diets, addition of exogenous enzymes and synthetic amino acids to broiler diets modify starch and protein digestive dynamics. It may be possible to enhance feed conversion efficiency of broiler chickens by manipulating starch and protein digestive dynamics and likelihood of using these methods is considered in this review.

Synthetic methionine use is currently limited to 1 kg and 1.5 kg per metric tonne (2, 2, and 3 lbs per short ton) of feed for organic laying hens, broilers, and turkeys and other poultry, respectively, in the United States of America. All other synthetic amino acids (AA) have been banned from use in organic poultry diets in this country. It is challenging to provide sufficient methionine (Met) to maintain bird growth and productive performance up to current industry standards given the recent restrictions that have been placed on synthetic Met. Without synthetic AA, Met requirements can alternatively be obtained for organic poultry by dramatically increasing dietary crude protein (CP) e.g. via additional inclusion of expeller-pressed soybean meal to the diets. However, this strategy leads to both major increases in feed costs and environmental concerns due to increasing nitrogen excretion, with concurrent rises in ammonia emissions, and corresponding welfare issues due to ammonia and litter quality. This review aims to examine feed ingredients that may contribute to a solution to this issue. Otherwise, further negative impacts may soon be felt from the current limitation on synthetic Met or a potential ban on its entire use in the future.

Over the past half century the turkey industry has seen significant changes in the methods used to harvest meat. Some of the major changes include an increase of over three fold in line speed (new plants are designed to process up to 3,600 bph) and processing larger birds; both resulted in a six fold rise in kg processed per hour. The industry has also seen a large increase in the proportion of cut up and deboned meat (i.e. helped year round sales), as well as substantial improvements in sanitation. These advancements have been possible due to knowledge gained in areas such as genetics, muscle biology (post mortem processes), live bird handling (transportation, unloading, stunning), heat and mass transfer (scalding, chilling) and computer science (e.g. image analysis, in-line weighing and tracking). This review includes a general summary of the steps involved in primary turkey processing and focuses on several principles that have been used to achieve greater efficiencies in mechanising the process. The main focus areas include automating unloading, stunning, chilling and mechanical filleting. These topics are also used to demonstrate the importance of moving from a batch operation to a continuous line where speed, efficiency and traceability could be improved by mechanisation. Overall, integrating and automating the whole process is a challenge that must be met by both the processing plant personnel and equipment manufacturer who should understand the whole farm to fork approach.

Smallholder farmers in Africa and other developing countries raise village chickens under low input production systems characterised by minimal management and veterinary interventions. However, village chickens have a major contribution to village communities as a source of protein, income and cultural needs. The village chickens are described as nondescript birds that have not been developed as a breed and with uncharacterised genetic attributes. Local chickens are found in the most marginalised farming systems, to which they have adapted and survived the harsh production and environmental conditions. Such survival and adaptive attributes need to be characterised, conserved, and utilised. Several studies on Southern African local chickens have revealed high genetic variation within and among the village chicken populations and indicated that village chickens contribute diversity that is unique and different from that of commercial and specialised chicken populations. The availability of whole genome single nucleotide polymorphism (SNP) data facilitates the use of powerful statistical methods for in depth investigations into the evolutionary history and population demographics of village chickens. Linkage disequilibrium (LD), as a function of effective population size, has been used to estimate rate and level of inbreeding as well as selection pressures in the absence of pedigree information. The extent and distribution of LD in the genome has been exploited to shed light on the origin and domestication of animals and facilitate an understanding of breeds’ relatedness. The Illumina iSelect chicken 60K SNP chip has over 54 000 SNPs that have found application in population and quantitative genetics studies and has revealed demographic history, effective population size and level of genetic erosion in commercial and traditional/village chicken populations. The recent launching of the 600 K Affymetrix® Axiom® HD genotyping array for chickens and the ever decreasing cost of sequencing will see improved estimation of LD and the associated population parameters.

Mitochondrial DNA (mtDNA) is has recently lost relevance especially when utilised to study species that are characterised with a history of several migrations. Nonetheless, mtDNA can still represents a useful additional tool in the study of molecular genetic diversity. The reason for the adoption of mtDNA is that it is easy to amplify because it appears in multiple copies in the cells and the mitochondrial gene content is strongly conserved across generations. Thousands of published studies have reached conclusions about population history, patterns of gene flow, genetic structure, and species limits, on the basis of mtDNA sequence variation. MtDNA has been used to study phylo-geographic structure of avian species, and to identify the number of maternal lineages and their geographic origins. Most studies of chicken mtDNA rely on sequences of partial control region but recent researches used the complete mtDNA genome to reconstruct the history of animal domestication. The first genetic study on mtDNA suggests that the Indochinese Red Junglefowl subspecies Gallus gallus gallus is the primary ancestor of the domestic chicken (Gallus gallus domesticus). Other studies showed that at least three subspecies of Gallus gallus were enrolled in the origin of domestic chicken breeds, and that there may be at least two domestication centres: one in Southeast Asia and one in the Indian subcontinent. The authors suggested nine highly divergent clades (named clade A-I) related to geographical distribution in a wide range of domestic chickens and Red Junglefowls across Eurasian regions. Understanding when chickens were transported out of domestication centres and the directions in which they were moved provides information about prehistoric human migration, trade routes and cultural diffusion. MtDNA has been used to infer regions of domestication and to identify the number of maternal lineages and their geographic origins in macroevolution studies.

The aim of this review is to discuss the use of microalgae as a feed ingredient in poultry nutrition. Microalgae are unicellular, photosynthetic aquatic plants. They are introduced to poultry diets mainly as a rich source of n-3 long chain polyunsaturated fatty acids, including docohexaenoic and eicosapentaenoic acid, but they can also serve as a protein, microelement, vitamin and antioxidants source, as well as a pigmentation agent for skin and egg yolks. The majority of experiments have shown that microalgae, mainly Spirulina and Chlorella sourced as a defatted biomass from biofuel production, can be successfully used as a feed ingredient in poultry nutrition. They can have beneficial effects on meat and egg quality, i.e. via an increased concentration of n-3 polyunsaturated fatty acids and carotenoids, and in regards to performance indices and immune function. Positive results were obtained when fresh microalgae biomass was used to replace antibiotic growth promoters in poultry diets. In conclusion, because of their chemical composition, microalgae can be efficiently used in poultry nutrition to enhance the pigmentation and nutritional value of meat and eggs, as well as partial replacement of conventional dietary protein sources.

Although fertility rates are dependent on both sexes, this characteristic is most often associated with males. For example, the practice of spiking, in which males with undesirable characteristics are replaced with younger males, is often used to improve fertility rates. Dietary restrictions may offset genetic shortcomings to some extent, but nutritional deficiencies due to dietary restrictions may themselves reduce the efficiency of breeding systems. Thus, the challenge is to maintain rooster fertility even when they are receiving diets that meet the nutritional requirements for females. Subjective visual selection is often used for diagnosis of roosters as being unfit for reproduction, with those deemed as overweight or underweight, or those with too small a comb and/or too slightly pigmented, among other phenotypic parameters, being removed. Diagnosis of infertility may only be confirmed after sperm quality evaluation, with reliance on visual diagnosis often resulting in discarding of roosters suitable for reproduction but with unfavourable visual characters. This review aims to characterise reproductive management of roosters in Brazil, highlight aspects of their physiological and sperm quality parameters, and explore nutritional strategies that might contribute to extending their reproductive life.

The aim of this review is to discuss aspects of poultry meat quality which are influenced by supplementing the bird's diets with plant extracts. Nutritional approaches are often more effective than direct addition of the additive to meat since the compound is preferably deposited where it is most needed. Physical qualities of broiler meat, including pH and colour, is of major importance, since broiler chicken meat is nowadays usually consumed as cut up pieces or processed products. Sensory and proximate meat quality should be taken into consideration because this allows manufacturers to identify, understand and respond to consumer preferences more effectively. Lipids including cholesterol are an important component of meat and contribute to several desirable sensory characteristics of meat and meat products. Amongst meat products, poultry meat is considered to be more prone to the development of oxidative rancidity compared to red meat. This is explained by the higher content of phospholipids in poultry meat. The available literature is limited regarding changes in meat quality due to the effect of medicinal plants, especially in poultry, however this review will summarise the results of the investigations that have been published to date.

In recent years, polyunsaturated fatty acids (PUFA) have received considerable attention in both human and animal nutrition, particularly those of the n-3 family (omega-3 fatty acids). These are PUFA in which the first double bond is situated on the third carbon atom from the methyl end of the fatty acid molecule. Consumption of n-3 PUFA are low, particularly the long chain (>18 carbon atoms) ones that are most commonly found in fish oils. As a means of increasing the low consumption of the long chain n-3 PUFA in humans, there is interest in the enrichment of poultry meat with these fatty acids for people seeking healthy lifestyles.

In view of the increasing public awareness of the relationship between healthy diet and prevention of many diseases, particularly civilisation-related diseases, producers are trying to focus consumers’ attention on the health-promoting components found in poultry meat or introduced to final products. The health-promoting quality of poultry meat may be improved by undertaking certain animal management measures (genetic and nutritional factors), reducing undesirable components, adding individual biocomponents and applying appropriate technological measures. These include changing fatty acid profiles, increased content of bioactive protein and reduced content of sodium chloride, nitrates and nitrites. At present research is being conducted on methods to enrich the composition of meat and its processed products with bioactive substances such as vitamins, polyunsaturated fatty acids and other beneficial components, e.g. fibre.

The objective of this review is to update and discuss the current findings from studies with laying hens on dietary factors that can beneficially affect eggshell quality, with special emphasis on microelements and feed additives. The crucial importance of dietary calcium, phosphorus and vitamin D3 levels and sources for eggshell quality has been well documented in scientific literature. Many recent studies regarding the effect of nutrition on eggshell parameters have focussed on dietary micromineral levels and sources. There has been also growing interest in the influence of feed additives on the improvement of intestinal health and mineral availability. The results of the experiments presented here demonstrate that efficacy of layer diet supplementation with microelements and feed additives is not consistent, however findings of several trials indicate, that eggshell quality may be positively affected in certain conditions by optimal dietary level and form of manganese, as well as by the addition of pre- and probiotics, organic acids, and herb extracts.

Boron (B) is a trace element that plays an important role in mineral and hormonal metabolism, cell membrane function, and enzymatic reactions. The current evidence supports the hypothesis that boron has an important biological role that affects the mineral metabolism of both humans and animals by interacting with Ca, Mg, P and cholecalciferol (vitamin D), all of which are important in bone metabolism. This implies that B can play a vital role in bone development and normal growth. However, the use of B occasionally results in apparently inconsistent responses in terms of performance in broiler chickens and layer hens. Although some studies have reported the effectiveness of B, no clear mode of action has been proposed. There are many potential reasons for the inconsistent results of B in eliciting beneficial responses. Available data obtained from relevant studies suggest that there are several concurrent factors involved. Of these, nutritional variables predominate. The purpose of this paper is to review the available studies examining the nutritional role of B on the production performance in broiler chickens and laying hens.

The poultry industry is affected by economically important problems such as Newcastle disease (ND). Newcastle disease virus (NDV) belongs to the Paramyxoviridae family and manifests as different strains; lentogenic, mesogenic and velogenic. ND affects the quality of eggs and impairs growth performance of birds. Various efforts have been made to control economic losses due to this disease, including using live and killed vaccines, which do not confer 100% immunity in all cases. Due to mutations within viral strains, NDV can become resistant and difficult to control, and there is a need to search for alternative measures. Medicinal plants are considered as a complementary means to control this virus, especially in developing countries, because they have been implicated in treatments for a variety of infectious and non-infectious diseases. Alkaloids, flavonoids, saponins and tannins found in plants have been regarded as novel antiviral agents. The following paper encompasses the studies related to plants having in vitro antiviral activity against ND such as Momordica balamina, Adansonia digitata, Artemisia annua, Azadirachta indica, Psidium guajava, Moringa oleifera and plants having good in vivo antiviral activity such as Aloe secundiflora, Cucumis metuliferus and Anthocleista nobilis as well. It discusses plants with the potential to improve the immunity of infected birds, such as Mangrove halophytes, Nigella sativa, Polysavone, Melissa officinalis, Momordica cochinchinensis, Echinacea purpurea, Withania somnifera and Aspargus Racemosus.

Spices, herbs and medicinal plants as a feed supplements present promising alternatives to antibiotic growth promoters due to their high content of bioactive substances. A large number of experiments have confirmed a wide range of activities of spices in poultry nutrition such as stimulation of feed intake, antimicrobial, antioxidative and coccidiostat stimulation, increase of body weight gain, lowering the mortality rate and improvement of the blood and tissue lipid profile. The present paper gives a review on the characteristics of hot red pepper and its mode of action in broilers nutrition.