Well it’s been a busy time for us here recently at WPSJ, and the handover has now been made from Cambridge University Press (CUP) to Taylor and Francis (T&F). This is the last issue published by CUP, as the March issue will be assembled by T&F. I would like to thank all concerned, especially Dan Edwards and Richard Horley (CUP), Jennifer Stokes and her team (T&F) as well as Dr Shay Rutherford for keeping the papers moving whilst I was busy organising the handover, as well as Dorien Kleverwal in the Dutch office for helping organise the new workflows. Hence this is the last issue that will be produced by CUP. I would like to thank all their team, past and present, for their friendly, helpful work over the years, especially when we have needed fast responses to problems with publishing. The changeover has allowed new mechanisms regarding the journal to be put into place, including a new, and active section editor team in the form of the new Editorial Board, which will take a lot of workload off my shoulders. There will be more automation regarding submission of papers – so authors should expect emails regarding initial formatting and so on to come from T&F during pre-screening.

This issue contains the first retraction of a paper that I have presided over in my editorship. This is an important legal issue – and thanks to Rosemary Dickin for her expertise in publishing ethics (COPE) at CUP in ensuring the proper procedures were adhered to at all time. As editor, I had to ensure all the COPE guidelines were followed regarding checking reviewer’s comments and that all had been done properly at the editing end. Standard procedures had to be followed, regarding letters to and from authors and the complainant. However, as the author did not submit an official letter in response, in the required format, we have had to make a decision at the editorial level.

It may seem obvious to state, but as authors or reviewers, you must be aware that your comments and papers are open to public and commercial scrutiny. At WPSJ we have a system involving standard peer review, but we do rely on our reviewers to read papers fully and ensure there are no highly selective, conflicting or erroneous statements being made.

It only remains for me to send all our readers greeting for the holidays, and thanks to all our readers, reviewers, new editorial board members and authors for another year of support for the Journal.

Dr Lucy Waldron

Editor

Today's broiler is characterised by faster-, leaner-growth. A large part of this progress is attributed to the genetic selection that had, and continues to improve growth rate and composition of gain at steady pace. As an illustration of such increases in performance, 2.3 kg live gain (slaughter weight) has been reduced from requiring 52 days in 1995 to 36 days in 2017 - a reduction of 0.73 days per year. In addition, meat yield has increased as a proportion of the carcass, being 12% of body weight in the year 1957 and increasing to 20% in 2001 Recent work in 2017 using high density diets has shown to capacity of birds to attain an FCR of 1.19 at 2500 g live BW. Current research suggests that the optimum level of energy may be well below the recommendation by the primary breeders. For example, reducing energy from 100 to 92.5% (around -200 kcal/kg of diet) resulted in only 2 points loss in body weight corrected FCR. Indeed, very recent work showed that a similar reduction of -200 kcal/kg feed in finisher AME resulted in similar, or higher gains and breast yield while having no effect on FE. Published data regarding the balance between energy and protein in feed suggests an optimum AA density between 100 to 120% of breeder recommendations. It can be therefore suggested that today's broiler needs a higher ratio of essential amino acids to energy. In addition to a net increase in the absolute requirement of amino acids, there is an argument for higher dietary ratio of lysine: essential amino acids which will support increased meat production and may better fit modern broiler genetics.

The Turkish poultry industry has rapidly developed in the last decade. Viral pathogens continue to threaten the industry, causing economic losses worldwide, including Turkey. At present, infectious bronchitis and infectious laryngotracheitis are major challenges, as are, to a lesser extent, avian metapneumovirus, infectious bursal disease, Marek's disease and chicken infectious anaemia. The prevalence and severity of these diseases in Turkish chickens varies depending on environmental and management factors, vaccination strategies and biosecurity measures. In Turkey, infectious bronchitis virus, including vaccine and field strains, were detected in 83.6% (41/49) and 64.2% (9/14) vaccinated broiler and layer flocks, respectively. Virulent and vaccine strains of infectious bursal disease virus were found in 83.5% (1548/1855) of excised bursa Fabricius from vaccinated broilers. Virulent Marek's disease virus was found in 19.93% (120/620) of spleens from vaccinated chickens. Infectious laryngotracheitis virus in commercial poultry and Newcastle disease in backyard chickens have been detected. To date, Newcastle disease and avian influenza virus have not been reported in commercial poultry. Avian metapneumovirus was found in 7.2% (8/110) of the broiler samples. Antibodies to gyrovirus and avian leukosis virus have been detected. Commercial vaccines, such as attenuated, inactivated and vectored vaccines, are being used for prevention and control of viral poultry diseases in Turkey. This review summarises the available information on viral poultry diseases in Turkey. It highlights the need to strengthen surveillance and reporting for diseases and addresses the vaccination practices used in Turkish poultry industry. The future prospects of vaccination and need to empower diagnostic capacity in controlling viral poultry diseases are discussed. The information presented here is aimed at improving research, prevention, and control of poultry diseases for researchers, veterinarians, policy makers and other professions related to poultry industry.

Preadipocytes are distinct precursor cells with the ability to generate and differentiate into adipocytes - a process that is regulated by a variety of genes. Adipocyte differentiation has been extensively studied in mammals; however, little is known about adipocyte differentiation in poultry. This review summarises the isolation, in vitro culture and characterisation of poultry preadipocytes. The most commonly used method for isolating primary preadipocytes is collagenase digestion and the cells are cultured in an incubator with 5% CO2 at 37°C. Preadipocytes of most species can differentiate into mature adipocytes using a combination of growth factors (a so-called ‘hormone cocktail’), which include 3-isobutyl-1-methylxanthine (IBMX), dexamethasone (DEX) and insulin. Only the addition of a fatty acid mixture, transferrin, insulin and albumin induced primary preadipocyte differentiation, indicating that exogenous fatty acids are key factors that influence this process in chickens. As for the molecular regulation of poultry preadipocytes, studies have found several transcription factors that regulate adipose differentiation, which included peroxisome proliferator-activated receptors (PPARs), CCAAT/enhancer binding proteins (C/EBPs) and sterol response element-binding proteins (SREBPs). These transcription factors have been shown to regulate adipocyte differentiation by affecting the expression levels or activity of target genes.

Around 10% of all table eggs number in the world come from quail and their meat represents about 0.2% of the global poultry production. The domestic quail population involved in production of meat and eggs represents around 11.8% of all productive birds, placing them second after laying hens. China, Spain, France, Italy, Brazil, the USA and Japan are global leading countries in quail farming. Contemporary domesticated Japanese quail, widely used in agricultural practice, originate from wild Japanese breeds (C. japonica). The wild Asian quail is similar to common quail (Coturnix coturnix) and until recently, was accepted as its subspecies (Coturnix coturnix japonica). In the scientific literature, several names for domestic quail are available, so readers can easily become confused as to which species is really meant - wild, domesticated or common quail. In order to avoid confusion of names and to emphasise changes resulting from domestication, the term ‘domestic quail’ and its corresponding Latin name Coturnix japonica domestica is more appropriate. Within the EU legal framework, domestic quail should be included in parallel to other domestic fowl species.

Incidences of myopathies such as white striping (WS), woody breast (WB) and spaghetti meat (SP) in breast meat from young broilers have been observed globally over the past decade. Some industry reports suggest up to 20% WB occurrence in fast growing heavy broilers (~4.0 kg) with an estimated cost of more than US$500 million/year to the US industry alone, but may actually be far higher. The proportions and severity of the anomaly appear to be flock-dependent and are related to factors such as genetics, nutrition (e.g. protein level during the fast-growing phase), growth rate, activity of the birds at young age, sudden bursts of activity, number of embryonic stem cells and litter management. These three myopathies can appear together or individually, but it appears that they are all related. When meat is processed, these myopathies represent quality issues (firmer meat and/or lower water binding, aesthetics) but do not present a food safety issue. The poultry industry is now focusing on ways to reduce or eliminate the occurrence of these myopathies. Recently some improvements have been made as more is learned about the interactions between environmental and management (e.g., nutrition) factors, and some producers are already implementing new procedures. Breeding programmes are starting to show some promise and are expected to help reduce WB (estimated at 10% of birds per year) and deliver more solutions in the future.

Decreasing heat increment through lowering crude protein (CP) level via supplemental amino acids (AA) have long been suggested as a nutritional practice to alleviate negative heat stress effects on broiler performance. However, there is a considerable body of inconclusive reports on optimisation of such practices, whereby bird performance remains unchanged. The exact mechanism underlying the impaired growth performance in birds fed with reduced-CP diets is not clear yet. Furthermore, adding the environmental temperature factor to the situation may complicate the solution. To date, there is no agreement on the extent of reducing CP level via AA supplementation so that growth performance remains unaffected. Evidence suggests that dietary CP could be reduced safely by 2.3% via essential AA supplementation during later ages, when birds are exposed to an average daily ambient temperature of ≤27.3°C. When Gly was added (a non-essential AA source), the margin of CP reduction could be increased to 5.1% without compromising the growth of broilers subjected to cyclic heat stress. Nonetheless, feeding broilers with a similar Gly-fortified, reduced protein diet failed to support optimal performance under hot and humid tropical climates in 1-21-d-old broilers and had a major impact on growth in broilers reared at 34°C. Regardless of supplemental AA composition or the level of CP reduction, the performance of broilers was negatively affected when birds were subjected to chronic heat stress conditions (≥30°C). These discrepancies can be attributed to a wide range of confounding factors, such as the extent of lowering CP level, types of AA used, age and environmental conditions. Accordingly, the addition of Gly may represent a good approach for reducing dietary CP levels for broilers raised under elevated ambient temperature. Reducing dietary CP is recommended when birds are exposed to moderate but not chronic heat stress conditions.

Ducks are waterfowl belonging to the Anatidae family of cosmopolitan distribution. In duck production systems, obtaining ducklings at one-day-old is determinant for the productive chain. The egg production in some species of ducks reaches about 250 to 300 eggs per year. Obtaining one-day-old ducklings can be done by natural incubation with a broody female duck or artificially in an incubator. During artificial incubation, fertility and hatchability are the most important indicators that must be controlled, because they influence the supply of ducklings to the farm. Many factors are related to fertility and hatching, such as environmental conditions, production system, season, nutrition, management of broodstock, storage time of egg and cleaning of eggs before the incubation. According to some reports, Pekin eggs have greater hatchability than Muscovy eggs. The eggs of Muscovy have presented values lower than 22.7% of hatchability. The hatchability of Pekin duck eggs was 78.0% in the spring, while in summer it was around 46.5%. The best hatchability is observed during the winter (57.68%), as in the summer it decreases to 54.14%. The reproductive characteristics of flocks, age, external and internal quality of the egg, male female relation, and presence of lethal genes are factors that directly involve breeders. Larger sexual ratios between males and females of 1:4.3 to 1: 10 cause reduced egg fertility from 75.9% down to 49.6%. Successful production of day-old ducklings starts with the proper selection and management of breeding stock, proper post-lay handling of fertile eggs and the correct incubation process. There are different methods used to improve the hatchability such as dipping eggs in nutrients during the incubation period.

Duck production has the potential to play a major role in agricultural economy. Asian countries alone contribute 84.2% of total duck meat produced in the world. Driven by the demand of processed foods among consumers, the global duck meat market is expected to grow at a steady pace, reaching a value of about $11.23 billion in the coming years. Duck meat has higher muscle fibre content in breast meat compared to chicken, and is considered as red meat. Moreover, due to a higher fat content (13.8%) than chicken and a stronger gamey flavour, duck meat can be less appreciated by the consumer. Development and diversification of ready-to-eat duck meat products is expected to increase consumption levels. Hence, the status of duck meat production, physicochemical properties, processing, including traditional products, and development of novel value-added ready-to-eat products from spent duck meat is discussed in detail to explore its importance as an alternative to chicken.

Global poultry production has increased rapidly over the last 50 years and is now the most-consumed meat species in the world. The consumption of poultry in Poland accounts for almost 40% of the total meat consumption and averages 30 kg per person. Being the most flourishing sector of agriculture, poultry production faces many challenges from increasing competition (high quality products and lower prices for consumers). The profitability of poultry breeding and rearing is determined by the production of healthy and well-developed chicks, and the value of hatching eggs is closely linked to genetic line, flock age, layer housing conditions and parent flock nutrition, as well as incubation and pre- and post-hatching management. The qualitative assessment of newly hatched chicks must be based on clear and objective methods regarding health status of the flock and performance of the birds. It is essential that modern poultry production pays particular attention to these factors to achieve a high percentage of hatchability and the production of chicks which fully express their genetic potential under intensive production systems.

Dietary lutein has received considerable attention in relation to human health because of its preventative effects on various eye diseases. Eggs are considered a good source due to good accumulation and relatively high concentrations of lutein. Therefore, many studies have been conducted to produce lutein-enriched eggs by various dietary regimens. Previous studies reported that purified lutein supplements, at the inclusion levels of up to 1,000 mg/kg, increased concentrations by up to10-fold in eggs. However, a linear increase in lutein concentrations in eggs failed to show further increases at very high inclusion of lutein supplements. The use of feed ingredients high in lutein such as corn co-products, alfalfa meal, marigold flower extracts, algae-derived products, and even food ingredients have successfully increased lutein concentrations in eggs. For instance, inclusion of 20% corn distillers dried grains with solubles (DDGS), 7% corn gluten meal, 2% marigold flower extracts, or 2% chlorella products in layer diets showed more than two-fold increase in lutein concentrations in eggs. However, the efficacy of those ingredients for lutein retention in eggs was highly variable and depended on inclusion levels in diets and feeding periods. Finally, non-dietary factors such as management systems, environmental stress, disease, age, and breed may affect the lutein concentrations in eggs; however, limited information is available in this regard.

The World’s Poultry Science Journal is indebted to Prof J.A. Castello, Prof D.K. Flock, Dr M. Tixier-Boichard, Dr S. Cherepanov and Dr Jiangxia Zheng for the translations of these summaries.

Methionine: comparing methionine hydroxyl analogues for broilers, with focus on different thermal environments RETRACTION

F.S. DALÓLIO, V.R.S.M. BARROS, L.F.T. ALBINO, P.H.R.F. CAMPOS, J.N. SILVA and S.R.F. PINHEIRO

DOI: https://doi.org/10.1017/S0043933919000230

Published online by Cambridge University Press: 05 April 2019

After publication of the paper entitled ‘Methionine: comparing methionine hydroxyl analogues for broilers, with focus on different thermal environments’ (Dalólio et al., 2019), the journal received a complaint alleging wrong citations and statements, and misleading conclusions. Specifically, the bioequivalence between methionine sources was deemed erroneous. Following COPE (Committee on Publication Ethics) guidelines and due diligence, the editor and publisher investigated this claim with the reviewers, the Board and the authors in detail. The corresponding author acknowledged and accepted the errors, and all authors have been informed of the retraction of the paper. Broadly, the problems with the paper are mainly concerned with misrepresentation of the technical information from the papers they used in their review of commercial methionine products.