Another year ends – although with journals, one is always ahead of the fact and it is only October as I write. For our northern hemisphere members, the cold of winter looms, whilst for us in the southern hemisphere we are hoping for good weather around the corner. This current issue covers topics including sustainability, stress in laying hens and quail, amino acids and protein sources, housing and management, omega 3 oils, reproduction in cockerels, breeds, comparisons of zinc sources, immunity, consumer preferences, disease and alternative feed ingredients – so quite a spread of topics. The recent Meat and Egg conference held in Scotland is hopefully going to provide a good source of invited papers which we are working on currently. Additionally, the Waterfowl meeting in Taiwan in October will hopefully be fertile ground for new topics for our members.

Looking forward to 2018, there are many events coming up for members to attend. These include trade shows such as the IPPE in Atlanta in January, VIV MEA in UAE in February and then the 11th Asia Pacific Poultry Conference in March, to be held in Bangkok. All WPSA related events can be found on the www.wpsa.com website under Calendar – please support the sponsors of these meetings as otherwise they wouldn’t be able to take place.

I am hoping to be able to announce some news regarding a new prize for best WPSJ review paper – to be awarded annually, although the details have yet to be decided with the Board or the Trust involved – so watch this space.

Poultry continues to be a major player in global meat production, although many new challenges are heading to various countries, most notably the removal of antibiotics from animal feed in the USA and Asia. As mentioned before, this hot topic means we have had a surge of papers regarding AGP alternatives, and the message regarding specificity requirements seems to have been taken on board. Thanks to all relevant authors in this regard.

It just remains for me to wish all our readers and members a Happy New Year from all of us in the Editorial Office and look forward to seeing you at a WPSA event in 2018!

Dr Lucy Waldron

Editor

This review examines the relative bioefficacy of 2-hydroxy-4-(methylthio) butanoic acid (HMTBA) and DL-methionine (DL-Met) which includes chemical, metabolic, nutritional, and statistical aspects of its bioefficacy. The chemical, enzymatic and biological differences and similarities between these two products are explained and the evidence and reasons for HMTBA relative bioefficacy to DL-Met in monogastric animals are discussed. In addition, appropriate statistical methods for comparing the bioefficacy of these two products for successful use of each product are provided. HMTBA is an organic acid precursor of L-Met. The chemical structure differences between HMTBA and DL-Met leads to differences in how and where the two materials are absorbed, enzymatically converted to L-Met and used by the animal. Because of these differences, when the two compounds are supplemented into animal feeds in graded doses, they do not produce dose response curves of the same form due in part to differences in intake and metabolism at the extremes of the dose response curves. At deficient levels of the response curve, HMTBA fed animals may exhibit lower feed consumption and growth than DL-Met while at requirement levels they may have greater feed consumption and growth. This review provides biological evidence for why these differences in growth response occur and demonstrates that lower growth, whether for DL-Met or HMTBA, does not mean that either product is being converted to methionine inefficiently. Since the two products have different dose response curves, statistically valid methods are provided for unbiased determination of relative bioefficacy across tested dose ranges. Field nutritionists typically feed commercial doses of HMTBA or DL-Met at a total sulphur amino acid dietary level capable of achieving maximum performance. At these commercial levels, and based on the evidence, the full relative bioefficacy of HMTBA relative to DL-Met is discussed.

Dendritic cells (DC) are central regulators of immune responses and professional antigen-presenting cells (APCs) with the unique ability to induce both innate immune responses and a highly specific acquired immunity. DC communicates through chemical and mechanical signals in the initiation and maintenance of immune responses. DC forms immunological synapses with T-cells thus pulling T-cells strings and leading to activation of T-cells. Owing to their properties, DC are often called ‘nature's adjuvants’ and thus have become an important component of any vaccination strategy. Coccidiosis is a major intestinal disease caused by Eimeria spp., affecting economically valuable livestock animals such as chickens and turkeys. Economic losses are associated with decreased productivity in afflicted poultry. Vaccination strategies involving DC have been developed owing to the special properties of these cells in coordinating innate and adaptive immune responses. Vaccination of chickens with exosomes isolated from DC containing parasite antigens (Ags) represents a promising alternative strategy to control avian coccidiosis. In recent years, emergence of new chicken DC has opened a new horizon for the development of new vaccines and DC derived vaccine could be a possible strategy to control coccidiosis in field. This review summarises the current state of knowledge of DC and their specific functions in immunity against avian coccidiosis.

Animals experiencing thermal stress tend to reduce heat production by limiting feed intake, with subsequent detrimental impacts on productive performance and health status. Heat stress as an environmental stressor has been an important concern among researchers, poultry producers and scientists for many decades, especially in tropical (wet and hot round the year) and arid (dry and hot round the year) regions of the world. It has been implicated in adverse marked impacts on productive and reproductive performance of quail. Several studies have investigated the negative impacts of heat stress on quail production and it has been shown that heat stress adversely affects both productivity and welfare of birds. The deleterious impacts of heat stress on different quail breeds such as Japanese quail (Coturnix coturnix japonica), bobwhite quail (Colinus virginianus), scaled quail (Callipepla californica) and Gambel's quail (Colinus gambelii) range from decreased body weight (7.7 to 13.2%), growth rate (11.0 to 14.5%), feed intake (6.1 to 21.6%), feed efficiency (4.3 to 8.6%), egg production (6.6 to 23.3%) and egg mass. Furthermore, the detrimental effects of heat stress on reproductive performance and welfare of quail have recently attracted awareness. However, further studies are required to increase the levels of information into basic mechanisms associated with the consequences of heat stress on quail. This review covers the published evidence available on the negative role of heat stress on growth performance, feed utilisation, egg production and mass, meat and egg quality and carcass traits as well as reproductive performance of quail.

The food processing industry is faced with complex challenges that are, among other things, associated with changes in the global environment. The goal of this paper is to gain knowledge about millennials (those born at the end of the 20th century) perceptions of locally sourced and produced fresh poultry in a developing economy, and to understand the influenced factors in the locally food market development. The research showed that this sector expresses a positive attitude towards locally sourced and produced fresh poultry. Additionally, there is a significant tendency towards purchasing fresh poultry of domestic origin because of its quality and safety. These results are particularly useful for product marketing and future product development in the locally sourced and produced poultry sector, as they provide an indication as how it can better reach and satisfy millennials. Our study shows significant opportunities, challenges and potentials in the development of the locally sourced and produced food market.

Historically, animal welfare has been defined by the absence of negative states such as disease, hunger and thirst. However, a shift in animal welfare science has led to the understanding that good animal welfare cannot be achieved without the experience of positive states. Unequivocally, the housing environment has significant impacts on animal welfare. This review summarises how cage and cage-free housing systems impact some of the key welfare issues for layer hens: musculoskeletal health, disease, severe feather pecking, and behavioural expression. Welfare in cage-free systems is currently highly variable, and needs to be addressed by management practices, genetic selection, further research, and appropriate design and maintenance of the housing environment. Conventional cages lack adequate space for movement, and do not include features to allow behavioural expression. Hens therefore experience extreme behavioural restriction, musculoskeletal weakness and an inability to experience positive affective states. Furnished cages retain the benefits of conventional cages in terms of production efficiency and hygiene, and offer some benefits of cage-free systems in terms of an increased behavioural repertoire, but do not allow full behavioural expression. In Australia, while the retail market share of free-range eggs has been increasing in recent years, the majority of hens (approximately 70%) remain housed in conventional cages, and furnished cages are not in use. Unlike many other countries including New Zealand, Canada, and all those within the European Union (where a legislated phase-out commenced in 1999 and was completed in 2012) a legislative phase-out of conventional cages has not been announced in Australia. This review came about in light of the current development of the Australian Animal Welfare Standards and Guidelines for Poultry in Australia. These standards are intended to provide nationally consistent legislation for the welfare of all poultry species in all Australian states and territories. While it is purported that the standards will reflect contemporary scientific knowledge, there is no scientific review, nor scientific committee to inform the development of these standards, and conventional cages are permitted in the standards with no phase-out proposed.

The application of novel feedstuffs in poultry diets, especially in developing countries, has received attention in recent years. Jatropha (Jatropha curcas) is a non-edible oil seed, and its meal is a rich in protein. Jatropha meal (JM) has been characterised as a potentially useful animal feedstuff due to its high content of crude protein level (35-50%), essential amino acid and mineral content. However, jatropha kernel contains high amounts of phytate, ranging from 7 to 10%, which would require phytase supplementation for it to be used in feeds. Jatropha contains toxic compounds and anti-nutritional factors, including lectin, tannin, saponin, phorbol esters and trypsin inhibitors, which require different treatments (physical, chemical or biological) to make it suitable for poultry diets. As a result of the presence of detrimental compounds, only low levels of jatropha in feed are recommended from animal trials. It may be used to partially substitute soybean meal, but not maize. It has been suggested in the literature that, after physical or chemical treatment of jatropha seed meal, it may have other benefits, including as an immunomodulant and antioxidant, as well as hypocholestermic, antihypertensive, hepatoprotectant, antiretroviral, anti-inflammatory, analgesic and antibacterial properties. It appears that heat and enzyme treated jatropha could be used in poultry diets without detrimental effects on productive and reproductive performance and may promote health status in poultry.

Avian influenza virus (AIV) type A subtype H9N2 usually causes mild asymptomatic infections, and is mostly undetected and is, therefore, under-reported. This has allowed the virus to rapidly evolve via mutations and reassortments in its genome with other avian influenza subtypes especially H1N1, H5N1 and H7N3 thereby introducing new variant strains and producing severe disease. It has been reported that the AIV H9N2 donated its internal genes for the devastating 1997 Hong Kong outbreak and furthermore, it may be the cause of the next influenza pandemic. There are many factors such as its wide host range, ability to cross the species barrier, ecological diversity, antiviral resistance and zoonotic importance that make it an excellent candidate for the next influenza pandemic. These and other factors like ineffective vaccination, negative immunological pressures, lack of surveillance, which contribute to its continuous persistence and evolutionary dynamics are discussed in this paper. It is important to take the necessary measures to control and prevent its unchecked circulation to prevent the future outbreaks.

Health benefits of fatty acids (FA) of the n-3 family have been well documented. The current consumption of n-3 FA by humans is below the recommended intake in Western countries. There are two sources of n-3 FA: α-linolenic acid (18-3 n-3, ALA) from terrestrial sources and long chain 20 and 22 carbon n-3 FA from marine oils. There is an increased interest in developing food products such as eggs and meat enriched with n-3 FA to meet the human requirement. In this context, poultry food lipids are a highly targeted and well-researched food item. Among the different feed sources, flaxseed, owing to its high fat (~40-42%) and ALA (>50%) contents along with other nutritional properties (e.g., metabolisable energy, protein content), is the most common feed ingredient explored for n-3 FA enrichment. This review attempts to bring together the use of flaxseeds in poultry feeds and its role in meeting the human requirements of n-3 FA through n-3 FA enriched foods. The antinutritional factors (ANF) present in flaxseeds and ways to mitigate the negative effects of ANF in poultry feeding are also included.

Cholesterol plays an essential role in the synthesis of cell membrane, bile acids, and steroid hormones as well as vitamin D. Dietary cholesterol comes from only animal sources, such as meat, butter, cheese and eggs, and contributes about 20% per day to the body pool in humans. Chicken egg, which is a good source of essential amino acids, fatty acids, vitamins and minerals, contains approximately 213 mg cholesterol. Data available related to egg intake and the risk of cardiovascular disease (CVD) is inconsistent. Early research suggested that egg intake elevated plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) identified as a major risk factor for CVD in humans. Recent studies show that dietary cholesterol may not be the actual factor in an individual's plasma TC, LDL-C and CVD. According to the latest nutrition recommendations, one egg may be eaten as long as one's total daily dietary cholesterol is limited to ≤300 mg per day. Health professionals suggest restricting dietary cholesterol to avoid elevating blood LDL-C and risk of CVD. This suggestion influences per capita consumption of the egg playing an important role in the nutrition of children and elderly people. This review focuses on egg intake, LDL-C and TC levels in the blood and the regulatory mechanism maintaining the homeostasis of serum cholesterol in the human body.

L-carnitine (B-hydroxy-Y-N-trimethyl aminobutyrate) is a water-soluble product, found in animals, plants and microorganisms. Its synthesis takes place from two important amino acids, lysine and methionine. Essentially, L-carnitine has an intermediary role in metabolism. It promotes energy metabolism for cell and regulates co-enzyme A concentration in cystosol and mitochondria, which are important in glucose and lipid metabolism. L-carnitine was first isolated from the chicken embryo in a significant amount, but is absent in the egg. Under normal physiological conditions, the endogenously synthesised levels are sufficient for normal growth and functions. Its requirements are increased in stressful conditions and during metabolic and physiological higher demands, such as growth and laying periods. L-carnitine increases energy production, fat metabolism and improves immune status in birds, which is energy demanding. In this review, several aspects of the beneficial effects of dietary supplementation of L-carnitine on poultry health and production are briefly summarised.

Antibiotic resistance has led poultry nutritionists to find alternatives for antibacterial growth promoters in broilers. Among these substitutes, one is mannan oligosaccharides (MOS), a yeast cell wall derived prebiotic. MOS decreases the load of pathogenic bacteria through 1) binding bacterial type-1 fimbriae 2) increasing goblet cells which produce bactericidal mucin and 3) providing favourable environment for the growth of beneficial bacteria leading to competitive exclusion. Balance between pathogenic and beneficial bacteria causes increase in villus length and decrease in crypt depth which are biomarkers for gut morphological improvement. As structure is equal to function, improvement in intestinal morphology increases activity of digestive enzymes and ultimately improves digestion. Besides these, immunomodulatory effect of MOS activates macrophages of gut associated lymphoid tissues resulting in improvement in cellular, humoral and cutaneous immunity. MOS also increases production of butyric acid and decrease pH of intestine in broilers. Though these combined mechanisms, MOS improves growth rate and performance of broilers.

The reduction of reproductive performance associated with stress is a known phenomenon in domestic birds. This review demonstrates the involvement of glucocorticoids, a stress hormone, in the decision-making process regarding energy ingestion and distribution in laying hens. During the energetic challenge induced by a stressful environment, corticosterone stimulates energy intake and a preference for a high-fat diet by up-regulating neuropeptide Y (NPY) expression via the AMP-activated protein kinase (AMPK) pathway. The elevated corticosterone levels in response to stressors may be associated with suppressed reproduction in laying hens via a possible perturbation of the hypothalamic-pituitary-gonadal (HPG) axis. Corticosterone suppresses follicular development and is energy dependent by decreasing the availability of the circulating yolk precursor and the prevention of yolk deposition in follicles. Energy status is also involved in rejuvenation in moult hens.

Avian tuberculosis is a chronic infectious disease caused by M. avium including four subspecies Mycobacterium avium subspecies avium; M. avium hominissuis; M. avium paratuberculosis; M. avium silvaticum. This disease is characterised by the formation of granulomatous lesions in viscera, a progressive weight loss and death. It can be transmitted to healthy birds in the flock, and occasionally to human beings. It is important to diagnose avian tuberculosis in order to prevent the spread of infection and epidemiology. This paper reviews the available techniques for the diagnosis of avian tuberculosis along with their pros and cons. The main problem in diagnosis is poor availability of samples due to infrequent shedding in faeces, pattern and colour of feathers, wattle and comb and lack of specific signs and symptoms. Any single technique is not effective in diagnosing the disease due to the lack of required sensitivity and specificity. Application of two or more techniques is not a feasible option in developing countries due to financial constraints. In the short term, more research is needed to develop multidisciplinary approaches which can help fully understand the aetiology and epidemiology of disease.

Nigella sativa L. (black cumin), an aromatic plant, is used as a natural remedy due to the presence of antimicrobial, antioxidant and other pharmacological properties. The presence of large number of essential nutrients and a variety of pharmacologically active compounds make black cumin seeds (BCS) potentially suitable for the use in poultry diets as a feed ingredient. Many studies have been conducted to investigate the possibility of introducing BCS as a natural feed additive for better productive performance under normal or stress conditions in birds. Supplementation of BCS in poultry diets increased growth performance, daily feed intake and feed efficiency in several studies. Nutrient utilisation also increased as a result of BCS inclusion in the diets. The population of some pathogenic bacteria were decreased by BCS. Antibody titres against viral diseases after vaccination increased owing to supplementation of BCS in the diets. The inclusion of BCS in poultry diets showed pronounced cholesterol lowering effect in blood. There is limited information on the chemical composition and antioxidant properties in meat and eggs from chickens fed with BCS diet. However, few studies reported that BCS may increase polyunsaturated fatty acid content and antioxidant properties in meat. The present paper reviews the effect of BCS as an alternative to growth promoters in poultry nutrition.

Thailand and Germany's poultry industries face different agro-ecological and socio-economic circumstances, as well as a variety of public policies on sustainability in poultry production. Based on literature, 26 sustainability issues were identified and categorised into the five dimensions of sustainability, including environmental, economic, social, political and animal welfare aspects. Through a two-round Delphi methodology with an expert panel, additional concerning issues were proposed and all the sustainability issues were weighted by level of concern, from level 1 (not at all concerned) to level 5 (very concerned). Results showed that social, animal welfare and economic issues dominate the current discussion of sustainable poultry production. The use of antibiotics in poultry production, killing of male layer chicks and the role of food retailers were rated ‘very concerning’ by the German experts, whereas the Thai experts considered the outbreak of avian influenza and other highly infectious diseases, disease control in neighbouring countries, use of antibiotics in poultry production, contamination of meat and eggs with zoonotic microorganisms, and standards for poultry products required by importing countries as the most concerning issues.

Zinc (Zn) is an essential component in animal and poultry metabolism of various biochemical pathways. It serves as a nutrient and also as a feed additive for improving reproductive functions, productive indices, cellular immunity, normal growth and the maintenance of feathers, bone tissues as well as appetite. Furthermore, Zn has many roles as an antioxidant agent. This mineral is essential for hormone function, including pancreatic (insulin and glucagon), sex and growth hormones. It is a part of more than 300 enzymes that are involved in the metabolism of protein, energy, carbohydrates and nucleic acids. Previous studies demonstrated many beneficial impacts of supplemental Zn on different physiological and immunological functions above the established concentration in diets, including alleviating heat stress. Zinc supplementation in layer diets increases albumen weight, and may alter egg shell thickness and total egg weight. Zinc deficiency can cause a fraying of the feathers and retardation in growth of broilers. Different Zn sources (organic or inorganic) positively impact health and performance in poultry including meat or egg production, feed intake and conversion efficiency, carcass traits, blood parameters and apparent nutrient digestibility. This review compares and provides a review of the nutritional and physiological aspects of different Zn sources.

Native or local chicken breeds play an important role in the rural sector and small households in developing countries, as well as provide a reservoir of potentially useful genetics for commercial strains. Standardisation and classification of the available native chicken populations based on morphological appearance, coupled with genetic diversity are necessary to conserve them for genetic improvement strategies. Most of the studies conducted on Saudi native chickens to evaluate their productive performance usually ignore the genetic origin and purity of the breed. Despite most native chickens having poor productivity, people in Saudi Arabia traditionally raise these chickens for their preferred eggs and ornamented appearance. The majority of such native chickens are maintained in rural communities and household poultry farms however, some native chickens with genes such as naked neck (Na), frizzle (F) and crest (Cr) are kept by poultry fanciers in small populations. These genotypes exhibit better performance under hot environmental conditions, a trait that may be useful in commercial strains. Six Saudi native chicken populations have been recognised and characterised. Their morphological characteristics, plumage appearance and productive performance have extensively been studied and documented in the current review.

The growing global demand for soybeans due to its different uses and by-products, as well as its use in the diet of several livestock species, is forcing the industry to seek alternative protein sources. Environmental concerns related to huge volumes of poultry manure serve as a warning for the choice of more sustainable production systems. Thus, the current review investigates the processing of an insect meal as an alternative protein source to feed broilers. The five desirable features in the selection of insect species proposed by the Food and Agriculture Organization (FAO) show that the high productivity of biomass, feed conversion efficiency and the organic waste conversion capacity from poultry farms is aided by the use of larvae from housefly and black soldier fly species. Brazilian production of such insects is possible due to climatic and environmental conditions and has the potential to supply part of the protein demands of the Brazilian poultry industry when raised in controlled environments. The prevalence of tropical climatic conditions and the possible use of organic waste from poultry farms as substrate can mitigate some environmental issues as well as generate income to smallholder farms prevailing in this activity.