The second issue of the 2019 volume has already come around, and it has been a busy year to date, with many publishing changes occurring with the move of the WPSJ from Cambridge University Press to Taylor and Francis, our new publishing house. Thanks to all staff and to the WPSJ Editorial Committee, Drs. Bob Buresh, Werner Bessei and Zehava Uni, as well as other WPSA and publisher staff for their help with these changes. An official announcement for members is now being prepared.

The conference season is already upon us, with meetings being reported from Asia as well as Europe in this issues Association News. I have recently attended the UK WPSA meetings, held jointly with the British Society of Animal Science in Edinburgh in April. At the WPSA meeting, Dr. Emily Burton announced the new Gordon Rosen Award which is aimed at providing grant money for people either in or recently completed their PhD programme who wish to travel to work for short periods in other institutes away from their home country. This can be to increase knowledge of certain techniques or increase their understanding of what they can do within the world of poultry science. Sadly, Gordon died a couple of years ago, and is fondly remembered not only for his wit and intelligence, but also his generosity to the WPSA over many years where he supported membership for students. Many thanks must go to the generosity of Mrs. Vanda Rosen for making this award, as well as to Dr. Mike Bedford, who has been on the trustees board with myself to get this off the ground, and Dr. Dawn Scholey for her input during the meeting.

In this current issue, readers can find reviews on microalgae, nutraceuticals, yeast, fertility, genetics and nutrition, as well as welfare in terms of injuries caused by housing systems. We are experiencing a good number of submissions on antibiotic alternatives – and authors need to note that these must be very specific and focussed tightly on certain aspects in detail, rather than general reviews, as this topic is very popular around the world currently, and requires in-depth reviewing. This is due to the increasing limitations on AGP use in feed in various countries, such as China and the USA. So, we in the editorial office expect more on alternatives to keep coming in. As a result, we are always encouraging reviews in other topics to keep the WPSJ as balanced as we are able for our readership.

Dr Lucy Waldron

Editor

Supplementation of methionine (Met) in broiler chicken diets is essential to support productive performance and optimise carcass yield. Met is the first limiting amino acid in corn and soybean-meal based diets for poultry. The DL-Met form is the main source used in broiler diets, but other sources such as acid free hydroxy-analogous methionine (HMA-FA) are available. Studies have indicated that the molar bioequivalence of HMA-FA is approximately 88% compared with DL-Met at 99% for growth traits. However, differences in absorption and metabolism between Met sources can influence their efficacy, especially when broilers are exposed to high temperatures. The substitution of DL-Met by HMA-FA is a potential strategy to mitigate the negative effects of heat stress because it is passively absorbed in the upper portion of the gastrointestinal tract. This review highlights the effects of substituting HMA-FA for DL-Met in diets for broiler chickens reared in different thermal environments.

The importance of ascites in the poultry industry warrants a comprehensive systematic review and in-silico modelling to explain responses seen in previous studies in this field. By identifying the genes which are effective and relevant to different indicator traits of ascites in poultry, genes were separated base on chromosomes to determine the most effective chromosome in ascites. Consequently, 12 chromosomes have been discovered as containing effective regions on ascites incidence. Meanwhile, 24 genes including MPPK2, AT1, RhoGTPase, MC4R, CDH6, NOS3, HIF-1A, OSBL6, CCDC141, BMPR2, LEPR, AGTR1, UTS2D, 5HT2B, SST, CHRD, TFRC, CDH13, ACVRL1, ARNT, ACE, ACVRL1, MEF2C, and HTR1A affect ascites according to published studies. The results show that chromosome 9, with the presence of six related genes, chromosomes 1, 2 and 7 with three related genes and Z containing two genes have the most influence on the sensitivity to the ascites syndrome, respectively.

Heracleum persicum (golpar) is an endemic medicinal plant that is commonly known as hogweed or Persian hogweed. It contains flavonoids and furanocoumarins that probably could stimulate both cell- and antibody-mediated immune responses. Besides, golpar has a substantial immunostimulatory effect on beta-lymphocytes and macrophages that played important role in antibody synthesis. Its extract at a supplementation level of 1-2.5 ml/l in drinking water showed a remarkable increase in the total immunoglobulins (Ig) (70%), immunoglobulin G (IgG) (100%) and immunoglobulin M (IgM) (94%) titres and an increase in antibody titre against Newcastle disease virus (96%) in broilers. In addition, supplementation positively affected the feed intake (9.4%), weight gain (14.7%) and food conversion ratio (FCR) (8.7%) in broilers. Moreover, in several studies, it has potential as an antifungal, antidiabetic, hypocholesterolaemic and growth enhancer agent; which endorsed its extensive contents of phytochemicals (terpenoids, triterpenes, furanocoumarins, volatile substances, flavonoids and alkaloids). It has a positive effect on the levels of glutathione (GSH), peroxidation lipids (MDA), the total antioxidant capacity of plasma or ferric reducing ability of plasma (FRAP) and glutathione s-transferase (GST), in addition to modulatory effects on liver enzymes including alanine transferase (ALT) and aspartate transferase (AST). After reviewing the published literature, it was apparent that golpar has multidimensional biological effects. Nevertheless, little research is available on the effects of golpar on productive performance and other health-related parameters in avian species. Hence, this review encourages veterinarians and poultry researcher to undertake further work to demonstrate the promising beneficial effects of golpar at effective levels to potentially replace the synthetic antibiotic growth promoters in commercial poultry diets.

Feed cost is a major impediment to commercial poultry production in the South Pacific region because traditional feed ingredients (grains and oilseeds) are not grown in the region and imported at high price. As a result, meat has to be imported, which in Fiji increased by 69% between 2010 and 2011 (Diarra, 2017). Samoa was valued at about US$ 17 million or 87% of total cost of meat import in the country in 2012 and 2013. Several ingredients, which are available locally, could be included to reduce feed cost in the region. By-products of root/tuber harvest (peels and leaves), low value crops, fruits and by-products (peels and pulps), oil cakes (copra and palm kernel), by-products from the brewery, livestock/poultry slaughter, hatchery and fish processing and insect meal are readily available in most countries of the region. With adequate processing and correct diet formulation, these materials could replace reasonable proportions of the conventional energy and protein ingredients and reduce feed cost. Several factors including the type and source of material, processing method, diet composition, species, age and class of poultry affect the dietary recommendations of alternative ingredients. Currently however, the use of these resources in feed production in the region is limited due to lack of processing and analytical facilities, likely presence of antinutritional substances and poor knowledge on their nutritive value. Continued research into processing technology, regular training for farmers and extension staff and establishment of community owned feed processing units for optimum utilisation of locally available resources will benefits the poultry industry in the region.

The aim of this review paper is to review the data on tea tree (Melaleuca alternifolia) as an antimicrobial, antioxidant and acaricidal in poultry production. Tea tree exhibits a wide spectrum of antimicrobial activities with minimal inhibitory concentrations between 0.12 and 4 mg/ml. Its modes of action against Gram-negative bacterium Escherichia coli (0.12 to 1.5 mg/ml), Gram-positive bacterium Staphylococcus aureus (0.12 to 1 mg/ml), Aspergillus fumigatus (1.78 mg/ml) and yeast, Candida albicans (0.05 to 0.5 mg/ml) have been investigated using a range of different methods. As an antimicrobial, tea tree has high antifungal, bacteriostatic and germicidal activity (e.g. a decrease of 73.8% in Candida sp.), because of its components such as terpinen-4-ol, α-terpineol, linalool, α-pinene, β-pinene, β-myrcene and 1,8-cineole. Its bioactive compounds such as α-terpinene, α-terpinolene and γ-terpinene show high antioxidant activity when applied in concentrations of 100 and 200 µl/ml, while its essential oils demonstrated free radical scavenging activity of 60 to 80%. Tea trees insecticidal and acaricidal properties have been tested for tick control. The mortality of ticks (Ixodes ricinus) and poultry red mites (Dermanyssus gallinae) have been recorded at levels over 60% and 80%, respectively, when used in concentrations of 0.15 to 0.30 mg/cm2 during in vitro testing, and in vivo, when sprayed in poultry houses. When tea tree was used in a form of essential oils as a dietary supplement in concentrations of 50 to 150 mg/kg in broiler chicken diets, a significant increase in daily weight (by around 7%) and decrease in morbidity and mortality were seen. Additionally, when applied in laying hen nutrition, a significant increase in daily egg production has been recorded. Tea tree essential oils when supplemented in poultry diets have high positive effects regarding productivity performance, but this requires further field experiments to clarify standardisation of the material and effective inclusion levels.

Man has been in interrelationship with wild water fowl for thousands of years. Yet, in that time, only two species of wild geese have been domesticated (13.3% of all true geese); the Greylag goose (Anser anser) in the fourth millennium B.C. and the swan goose (Anser cygnoides) in the second millennium B.C. From these two species, numerous breeds (181) have been developed. Compared to other domestic animals, the goose has varied less during domestication, aside from a few modifications in appearance, reproductive traits, internal organs and behaviour. It has increased in body weight, and hence became a non-migratory bird. Compare to the greylag goose (gander 2.8-4.1 kg, goose 2.5-3.8 kg body weight), the body weight of the Toulouse gander has increased by 331-421%, and the Toulouse goose by 286-364%. The African goose developed higher body weights (gander by 285-362%, goose by 292-311%) compared to the weight of the swan goose (gander 3.5 kg, goose 2.8-3.5 kg body weight). Conformation traits have changed, whereby the natural grey feather colour has changed to white in some breeds. Furthermore, sexual maturity has accelerated, and prolificacy increased. Egg production of a significant proportion of the European goose breeds has increased by 600-1000% compared to the greylag goose (5-6 eggs/goose). For example, egg production of the Chinese goose has increased by 875-1200% compare to the wild swan goose (5-8 eggs/goose), and the monogamous partnership typical of wild geese has turned into polygamous matings.

The poultry industry is mainly scared by affected by infections due to microorganisms which reduce the growth rate and cause economic losses. Currently, vaccines and antibiotics are utilised to combat these infectious microorganisms, but irresponsible use of antibiotics may pose health risks to consumers, and there is a need for drug-free alternatives. Nanotechnology could reduce such risks and can improve the wholesomeness of poultry meat. This review discusses the current status of nanotechnology as it relates to improving poultry health by using various nano-particles (NPs). Silver-NPs at a dose rate of 900 ppm have been used in poultry to improve their growth performance in terms of body weight, feed intake and feed conversion ratio. NPs are thought to boost immunity in birds against numerous diseases. Gold-NPs improved the growth performance of poultry birds as well as detecting avian influenza virus with a detection limit of 2.2 pg/ml. Similarly, Copper-loaded chitosan-NPs supplementation at dose rate of 100 mg/kg feed improved growth performance, immunity, protein synthesis and caecal microbiota in broilers. Zinc oxide-NPs improved growth performance and showed anti-oxidative properties in broilers at the dose rate of 20 mg/kg. While, montmorillonite nano-composites at a level of 3 g/kg feed decreased the toxicity of aflatoxins in poultry birds. In conclusion, nanotechnology has the potential to reduce microbial load without resulting drug residues in poultry products, thus improving performance and immune status of poultry birds.

The red yeast Phaffia rhodozyma is considered as a useful source of astaxanthin (ASX) which is a carotenoid pigment widely used in the feed industry. Poultry cannot synthesise carotenoids, so they must obtain these pigments from diet supplementation with sources such as red yeast, as a source of ASX. Astaxanthin has health benefits including the protection against oxidative damage in cells, enhancement of the immune response and protection against diseases by scavenging oxygen free radicals. It has activities approximately 10 times stronger than that of other carotenoids and 100 times greater than α-tocopherol against reactive oxygen species. In recent years, Phaffia rhodozyma has become an important microorganism for its use in both the pharmaceutical industries and food. Dietary Phaffia rhodozyma addition at the level of 10 and 20 mg/kg in broiler diets positively increased weight gain by 4.12 and 6.41% respectively. The inclusion of ASX rich red yeast (100 mg/kg) in broiler diets for 14 days improved T-cell proliferation and IgG production by 111.1 and 34.6% respectively. However, the optimum level or feeding duration of dietary ASX rich red yeast addition for enhancing poultry productive, physiological and immunological responses has not been determined.

Increased pressure on the poultry industry by animal-rights organisations and environmentally-conscious consumers has led to the rising popularity of cage-free housing system for hens. One of the main dangers of cage-free housing systems is the possibility for laying hens to damage their keels. Keel bone fracture incidence rate ranges up to 85%, and can lead to extensive pain in any bird, and potentially be the cause of the death for a hen in a cage-free environment. It was reported that kneel bone damage observed in flocks housed in non-cage systems was 30 to 95% while in furnished cages it was 15 to 55%. The purpose of this review is to compare the prevalence of the problem found in the three main housing systems (conventional, enriched cage, and cage-free), discuss if such damage could affect the behaviour and production of laying hens, and provide potential solutions for reducing the prevalence of keel bone damage. Keel fractures can negatively affect a hen in its day-to-day life by causing pain and restricting its movements. The prevalence of keel bone damage varies considerably among the studies due to differences in the system design, genetic line, age and method for determining the keel damage, which makes difficult to compare the systems. The genetic selection, adequate nutrition and modifications in the house design have shown to be useful tools in reducing keel bone damage in laying hens.

Supplementation of poultry diets with medicinal plants containing bioactive molecules have shown promising results in promoting growth performance, enhancing feed efficiency, and improving carcass traits and meat quality. There are many studies using herbal plants and their derivatives involving liquorice (Glycyrrhiza glabra), while studies using only liquorice are very limited. Liquorice contains bioactive components such as glycyrrhizin and flavonoids, and has been linked to many pharmacological effects like immunomodulatory, anti-oxidant, antiviral and anti-inflammatory activity. Supplementation of liquorice in poultry diets had beneficial impacts on growth and performance by improving organ development. In addition, there are appetite and digestion stimulating factors in liquorice. Dietary liquorice supplementation at level of 2.5 g/kg showed the best results in broiler chicken, and demonstrated it can be safely used in poultry diets. Addition of liquorice in diets up to 0.5% inclusion before sexual maturity enhanced performance of laying hens. Furthermore, broilers receiving drinking water containing 450 mg/l liquorice under heat stress significantly improved feed conversion and economic efficiency. Abdominal fat in broiler chickens was decreased when liquorice was included at 2 g/kg in feed or 0.3 g/l in drinking water. Broiler chickens with access to drinking water containing 450 mg/l of liquorice increased the dressing percentage, with or without giblets. Carcass organoleptics were improved in birds receiving drinking water with liquorice at levels of either 1, 2 and 4 mg/ kg body weight. This review describes the chemical composition, health benefits and beneficial applications of the liquorice herb and its effect on growth and productive performance, carcasses and meat quality, which will be useful for researchers, physiologists, nutritionists, veterinarians, scientists, pharmacists, pharmaceutical industries, and poultry breeders.

Chlorella (vulgaris spp.; CLV) is a genus of unicellular freshwater microalgae that are fit for human consumption and are used as additives with high nutritional value in feed for agriculturally important animals. Chlorella spp. are characterised by their simple cultivation, high productivity and levels of protein and other nutrients. Investigations have shown that the growth performance of broilers can be positively affected by the addition of very low amounts of CLV biomass (0.5-1.0% of the diet) to feed. The effect of CLV on growth and development is considered to stem from its high protein content (60.6%) and nutritional value. Results have shown enhanced body weight gain (2.7%), better feed conversion ratio (lowered by 2.8%), meat colour and breast muscle weight (20.1%) in CLV-supplemented chicks compared to control birds (control breast weight 19.1%). Additionally, a significant decrease in drip loss (2.26%) from breast muscle was observed with CLV supplementation and levels of blood total protein, albumin, and high-density lipoprotein (HDL) cholesterol significantly increased (P<0.05), while the levels of liver enzymes indicative of oxidative damage (alanine aminotransferase, ALT) decreased by 23.2%, indicating better liver function. In terms of immunity, blood lymphocytes were increased in broilers fed a diet supplemented with liquid CLV (17.9 x 103/µl) compared with birds supplemented with dry CLV (13.5 x 103/µl). Additionally, the levels of IgA, IgG, and IgM were elevated by 29.7%, 69.1%, and 32.3%, respectively, in broilers that consumed feed containing CLV. Similarly, the intestinal diversity and abundance of Lactobacillus spp. were significantly increased (9.9 ± 1.88 and 8.99 log10 CFU/g, respectively) by dietary supplementation with liquid CLV compared to that in non-treated chicks (8.7 ± 1.22 and 8.51 log10 CFU/g, respectively). Energy digestibility was increased significantly by 1.29% in CLV-treated chicks compared to the control chicks. This review highlights the findings associated with the utilisation of CLV biomass as a feed supplement and its effect on broiler growth and health.

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.