Thi Hiep Dao

• Doctor of Philosophy
• Postdoctoral Research Fellow at University of New England

Soybean meal has traditionally dominated poultry diets as the protein source. However, its widespread use raises concerns regarding economic costs, environmental impact and social sustainability. As a result, there is growing interest in alternative protein sources, such as canola meal, which may reduce feed costs while sustaining productivity. Thi...

This study evaluated the optimal energy-to-protein ratio in practical reduced-protein diets to evaluate the production performance, nutrient digestibility, and egg quality parameters of laying hens between 20 and 35 weeks of age. The best feed conversion ratio (FCR) of 2.548 was achieved at 15.5% crude protein (CP) and 100% recommended apparent met...

The effects of precision feeding regimes on broiler performance, organ weight, nutrient utilization, carcass yield, and calculated wholesale returns were investigated over 42 days. The treatments consisted of a standard four-phase commercial diet as the control, a precision nutrition blend diet based on a daily nutrient requirement, a precision nut...

Coccidiosis is a major economic threat in poultry, and with anticoccidials being phased out, cost-effective alternatives like copper (Cu) supplementation are of interest. This study investigated whether in-feed monovalent Cu (100 ppm) could mitigate the effects of a mild Eimeria challenge in broilers. A total of 216 broiler chicks were randomly ass...

Context AM/PM feeding (also known as ‘split-feeding’) is designed to meet a hens’ nutrient requirement via two diets, namely, high protein and energy in the morning/early afternoon (AM) and high calcium during the mid-afternoon/evening (PM), compared with a single conventional diet over 24 h. Aims The study aimed to investigate the effects of AM/P...

Laying hens’ metabolism goes through a cyclic process to produce eggs, which requires higher dietary protein and energy in the morning (AM) and higher calcium (Ca) in the afternoon/evening (PM) than the rest of the day. Therefore, poultry scientists are trying to adopt a new feeding strategy called AM/PM or split feeding to precisely meet hen’s req...

A modified AM/PM strategy was evaluated in this study by supplementing calcium (Ca) in afternoon/evening (PM) drinking water instead of feed, offering an alternative to supplying two diets. A 10-week trial was conducted with 288 Hy-Line Brown hens (56 weeks old) housed on the floor in 18 pens (16 hens per pen; 9 replicate pens per treatment). The c...

This study investigated the effects of the dietary supplementation of mineral methionine hydroxyl analogue chelates (MMHACs) zinc (Zn), copper (Cu), and manganese (Mn) on excreta nitrogen and mineral levels, housing conditions, and the welfare status of broilers. Three-hundred eighty-four day-old Ross 308 male chicks were randomly distributed to fo...

This floor pen study explored the effects of feeding mineral methionine hydroxyl analogue chelates (MMHACs) zinc (Zn), copper (Cu), and manganese (Mn) on growth performance, carcass processing weight and quality, nutrient digestibility, gizzard erosion score, and bone parameters of broilers. One-day-old Ross 308 male chicks (n = 384) were randomly...

A survey of industry groups including nutritionists, producers, feed manufacturers, and technical personnel in broiler and layer operations within the Australian poultry industry was completed to determine the industry’s present views of max-profit and stochastic feed formulation and the barriers they see to implementing these techniques. A total o...

Currently, there are no guidelines on housing or recommendations for practical environmental enrichments for chickens used for research and teaching purposes. This study was conducted to identify optimal enrichment programs to improve the health and welfare of caged hens used for teaching and research purposes. The 24-week-old Hy-line Brown laying...

This study explored feeding recycled food waste-based diets for gut health, nutrient digestibility, bone morphology, and bone mineral level in laying hens. Hy-Line Brown laying hens (n = 150) were randomly allocated to three experimental treatments consisting of a commercial control diet, a recycled food waste-based diet, and a 50:50 blend of the c...

Laying hen nutrient requirements change throughout the day, due to the cyclic nature of egg formation. Generally, more energy and protein are required in the morning when the albumen is deposited around the yolk, and more calcium is required in the evening when the eggshell is formed. The aim of this study was to determine if feeding laying hens di...

Understanding the order of limiting amino acids (AA) in reduced-protein (RP) diets for laying hens will facilitate precise feed formulation and ensure that AA requirements are met cost-effectively. The order of the first three limiting AAs—lysine (Lys), methionine (Met), and threonine (Thr)—has been well established in RP laying hen diets. This stu...

The alterations in feed ingredients and the nutrient matrix to produce reduced-protein diets may affect bone morphology and mineralization in laying hens. This study was implemented to determine the effects of L-arginine (Arg), guanidinoacetic acid (GAA), and L-citrulline (Cit) supplementation to Arg-deficient reduced-protein diets on bone morpholo...

There is renewed interest in utilizing food waste as animal feed due to its potential benefits in reducing feed cost and environmental impact while improving global food security. This study was conducted to examine the efficacy of recycled food waste-based feed for laying hen performance, egg quality, and nutrient digestibility. Hy-Line Brown hens...

Precision nutrition regimes currently rely on the assumption that broilers will grow in a steady and predictable way on a daily basis, with the continuous deposition of nutrients into muscle or, in the case of laying hens, into an egg. However, it has been observed that this is not the case for egg production, with Ca requirements being aligned wit...

Reduced protein (RP) diets have received increasing interest in poultry nutrition due to the potential benefits in feed cost and environmental footprint (Liu et al., 2021). Understanding the order of limiting amino acids (AA) in RP diets is critical to ensure requirements are met cost effectively. To date, only the first three limiting AA (includin...

Feeding recycled food waste-based feed to poultry promotes sustainability, the circular economy and improves food security. A study was conducted to examine the nutrient composition, chemical residue and efficacy of processed and sterilized recycled food waste (RFW) as a feed for laying hens. Performance, egg quality and nutrient digestibility were...

Re-emergence of enteric diseases in the post-antibiotic era has imposed severe loss to the poultry industry leading to the urgent need for appropriate additives to maintain gut health. Recently, more attention has been paid to animal plasma due to its high concentrations of active components such as albumins and globulins. The objective of this stu...

The effects of L-arginine (Arg) and L-citrulline (Cit) supplementation in an Arg-deficient reduced protein diet on tibia morphology and mineral composition were investigated in broilers maintained at the thermo-neutral (NT) and cyclic warm temperature (WT). Seven hundred and twenty Ross 308 male broilers were brooded together for the first 7 days a...

Context The impact of necrotic enteritis (NE) on acute-phase proteins, interleukins, blood mineral profiles, and gene expression have not been well documented. Aims This study aimed to determine the effects of l-arginine (Arg) or l-citrulline (Cit) supplementation on serum immunological parameters, serum mineral composition and gene expression in...

In Australia alone, some 7.3 million tonnes of food waste are disposed in landfills each year leading to substantial environmental concerns and economic losses. Each tonne of food waste going to landfill is estimated to produce 1.9 tonnes of carbon dioxide equivalents in the form of methane. If this food waste could be fed to poultry, such concerns...

Context Necrotic enteritis (NE) has been considered a major threat to broiler gut health and growth performance. Aims This study aimed at investigating the effects of l-arginine (Arg) or l-citrulline (Cit) supplementation on intestinal morphology, short-chain fatty acid (SCFA), microbiota count, gut permeability, and pH in broilers fed reduced-pro...

Context Improving immune status through nutritional adjustments may be part of an effective strategy to reduce reliance on antibiotic growth promoters for controlling necrotic enteritis (NE) in broiler chickens. Aims This study examined the effect of dietary protein level and the replacement of crystalline l-arginine (Arg) with l-citrulline (Cit)...

Context Mineralisation of the bone matrix is a pivotal factor affecting bone strength in broilers. Reduced bone strength might cause fracture during catching and transportation to slaughterhouses, leading to economic loss. Aims This study was conducted to investigate the effects of l-arginine (Arg), guanidinoacetic acid (GAA), and l-citrulline (Ci...

A trial was conducted to determine if full matrix values for phytase alone or in combination with xylanase and beta-glucanase (XB) were appropriate across multiple inclusion levels and combinations. It may be concluded that these matrix values are appropriate, with birds offered diets containing either phytase alone or in combination with XB overal...

An estimated 7.3 million tonnes of food waste are dumped annually in Australia, leading to substantial environmental and economic losses (Arcadis, 2019). Additionally, poultry feed represents the majority of production cost. Therefore, an experiment was designed to evaluate food waste as a feed for laying hens. A total of 150 Isa Brown laying hens...

Feeding reduced protein diets may influence the microbial fermentation in the ceca due to the differences in the diet composition and nutrient digestibility compared to the standard protein diets. Two experiments were conducted to investigate the effects of L-arginine (Arg) and L-citrulline (Cit) supplementations in reduced protein diets on cecal f...

Chickens have a high dietary Arg requirement compared to mammalians as they have an incomplete urea cycle and therefore cannot synthesise Arg. Arginine is important for protein synthesis and is also involved in immunity being converted to nitric oxide (NO) at the macrophage level. Nitric oxide is secreted as a free radical during an immune response...

Published literature indicates that L-arginine (L-Arg), guanidinoacetic acid (GAA) and L-citrulline (L-Cit) can all provide Arg activity in broiler diets (Su and Austic, 1999; Dilger et al., 2013; DeGroot, 2018) and all are commercially available. GAA has been reported to have 77% Arg equivalence for feed conversion (Ringel et al., 2013). This stud...

Necrotic enteritis (NE) is an enteric disease of poultry caused mainly by a spore-forming gram-positive bacterium, Clostridium perfringens, resulting in decreased growth, high mortality, and increased veterinary costs (Wade and Keyburn, 2015). While supplementing poultry diets with antibiotics can control NE, emerging antibiotic-resistant microbes...

This survey was conducted in 10 households in the Red River Delta: Xuan Quan cornmune, Van Giang district, Hung Yen province, from August 2010 to November 2011 to evaluate the growth performance and economic efficiency of crossbred [(Brahman × (Vietnam Yellow × Sindhi)] cattle. The results of body length, chest size, fin-height and body weight show...

This study was conducted to provide informations of the growth performance of Dong Tao chicken raising under household conditions in Dong Tao commune, Khoai Chau district, Hung Yen province. A total of 250 Dong Tao chickens were observed from 1 day old to 24 weeks old among 5 families with following traits: body weight, relative growth rate, averag...

Swine production in Vietnam is increasingly threatened by a large range of swine infectious diseases (PRRS, FMD, Pneumonia….) with significant economic impacts on the national economy and local producers' livelihood. Under this context early detection of disease through efficient surveillance system is critical. Previous studies have highlighted th...

South-East Asia, and especially Vietnam, is known for its high human, poultry and pig population density. Located in Northern Vietnam, the Red River Delta region (RRD) alone includes about a quarter of the human, pig and poultry population of the country in just 6.4% of its area [1]. This high density along with familial production practices could...

The recent occurrence of the swine-origin pandemic influenza H1N1 in 2009 stressed the importance of the surveillance of emerging zoonotic diseases in swine at the global level. South-East Asia has been identified as a high risk zone for such emergences due to the farming practices and the high population density. The analysis of the pig value chai...

Literature evidence has indicated that L-arginine, guanidinoacetic acid (GAA) and citrulline can all provide arginine activity in broiler diets (Su and Austic, 1999; Dilger et al., 2013; DeGroot, 2018) and all are commercially available. GAA has been reported to have 77% arginine equivalence for feed conversion (Ringel et al., 2013). This study was...

In Australia and many other countries, free-range eggs can be sold at significantly higher prices than cage eggs. The mislabeling of cage eggs as free-range eggs and vice versa has been documented, and has a significant impact on consumer confidence and therefore egg consumption. The development of methods to distinguish eggs produced from differen...

Heat stress causes significant economic losses in the broiler industry. Dietary supplementation of arginine (Arg) and citrulline (Cit) might increase the performance of broilers raised under warm temperature due to vasodilation effects. This study investigated the effects of L-Arg or L- Cit supplementation in broilers fed a reduced protein wheat-ba...

Organic production system has been increasing significantly in both production scale, market size, and sales volume in many parts of the world. However, many politicians and academics are still anxious about the potential contributions of the organic production systems to the future development of the agriculture sector. This overview focuses on an...

A study was conducted with Hy-Line Brown laying hens to examine the effects of reduced protein diet, deficiency of Arg, and addition of crystalline Arg, citrulline (Cit) and guanidinoacetic acid (GAA) as substitutes for Arg. Hen performance, egg quality, serum uric acid, liver and reproductive organ weights, and energy and protein digestibility wer...

Necrotic enteritis (NE) has been estimated to cause up to 6 billion in losses to the global broiler industry annually. The toxin producing variant of Clostridium perfringens is responsible and gut injury as a result of cocci infection may trigger the onset. Early feeding of spray dried porcine plasma (SDP) is a potential replacement for AGP as it c...

Arginine activity in broiler diets can be supplied by L‐arginine (Arg), guanidinoacetic acid (GAA) and L‐citrulline (Cit), all of which are commercially available. This study was conducted to assess the effects of Arg source and level on broiler performance, nutrient digestibility and carcass parameters. Day‐old Ross 308 cockerels (n = 768) were as...

Background: Hepatitis E virus (HEV) is a zoonotic disease and has been reported around the world. The main objective of this study was to evaluate the sero-prevalence and phylogenetic analysis of HEV in Vietnam. Pig blood and fecal pooled samples were collected to assess the prevalence of HEV. We assessed the true prevalence (TP) of HEV from appar...

Context In Australia and many other countries, free-range eggs can be sold at significantly higher prices than cage eggs. Mislabelling cage eggs as free-range eggs and vice versa has been documented, and has a significant impact on consumer trust and egg consumption. The development of methods to identify eggs produced from different production sys...

The annual food waste in Australia is estimated at 7.5 million tonnes with the majority disposed of in landfills. This not only causes significant economic loss but also has a negative environmental impact. This study aimed at investigating the possibility of recycling food waste into feed for poultry. Nutrient contents of various waste streams wer...

The annual food waste in Australia is estimated at 7.5 million tonnes with the majority disposed of in landfills. This not only causes significant economic loss but also has a negative environmental impact. This study aimed at investigating the possibility of recycling food waste into feed for poultry. Nutrient contents of various waste streams wer...

Background Evidence-based practice (EBP) enhances healthcare services and keeps providers current with best practices. EBP has been adopted and spread worldwide. However, people will not apply it if they do not know, understand, or believe it. Few studies have considered EBP application in Viet Nam. This study explores whether Vietnamese physical t...

Ascaridia galli is one of the most abundant nematode parasites in poultry. A. galli infections can significantly impact the profitability of egg farms and have negative implications for bird health and welfare. The main objectives of this study were to determine whether A. galli specific antibodies in egg yolks can be used to detect prior or curren...

Ascaridia galli is one of the most abundant nematode parasites of poultry. This study aimed at determining the relationship between the levels of anti-A. galli in the egg yolks and number of worm eggs in the hens’ excreta, which can then be used to develop a new method to detect A. galli infection in layer hens. The procedures to optimize the perfo...

The quality of eggshell remains a major concern for egg producers as 6 to 8% of the total egg production are unusable/unmarketable due to their insufficient shell qualities. This review focuses on analysing the effects of nutritional factors, including energy level, protein, lipid, minerals, vitamins, feed additives and water, on the egg production...

The main objective of this study is to provide an overview of Dong Tao chicken production, evaluate its economic efficiency and consumption situation. Since then, some solutions will be suggested for enhancing economic performance and sustainable development of Dong Tao chickens. From the interviews with key informants, 30 Dong Tao raisers in Dong...

This study was carried out on 34 rural households who raised Ho chickens from December 2012 to April 2013 to find out information on development status and economic efficiency of this chicken breed. A total of 181 (46 cocks and 135 hens) were used to identify morpho-biometric characteristics according to FAO standards. The Ho chicken population is...

This overview concerns the main characteristics of egg production systems in Australia. The scientific evidence indicates significant differences in terms of performance, welfare and disease management between current practices of egg production. Changing from conventional cage to alternative systems will lead to an increase of environmental comple...

Nghiên cứu được tiến hành nhằm đánh giá khả năng sinh trưởng, năng suất và chất lượng thịt của gà Đông Tảo nuôi theo phương thức bán chăn thả tại nông hộ. Trong chương trình bảo tồn và khai thác gà Đông Tảo của tỉnh Hưng Yên, 5 nông hộ tại xã Đông Tảo, huyện Khoái Châu, Hưng Yên được lựa chọn để nuôi 250 gà từ 1 ngày tuổi tới 24 tuần tuổi. Kết quả...

Purpose: Vaccination against avian influenza (AI) is currently applied worldwide with inactivated vaccines. Since November 2012, a novel recombinant HVT-AIH5 (Herpes virus of turkeys vector) vaccine has been commercialized and applied to day-old chicks (DOC) in Egypt and in Bangladesh. The objectives of this study were to assess the cost-effectiven...

The objectives of this study were to determine the morpho-biometric characteristics of Vietnamese indigenous Ho chicken breed and to evaluate its production, reproduction performance and egg quality. The study was carried out on 20 households raising purebred Ho chicken from September 2013 to April 2015 in Northern Vietnam. Morpho-biometric charact...

While swine production is rapidly growing in South-East Asia, the structure of the swine industry and the dynamic of pig movements have not been well-studied. However, this knowledge is a prerequisite for understanding the dynamic of disease transmission in swine populations and designing cost-effective surveillance strategies for infectious diseas...

The effectiveness of animal health surveillance systems depends on their capacity to gather sanitary information from the animal production sector. In order to assess this capacity we analyzed the flow of sanitary information regarding Highly Pathogenic Avian Influenza (HPAI) suspicions in poultry in Vietnam. Participatory methods were applied to a...

Pig production in Vietnam is threatened by a large range of swine infectious diseases (PRRS, FMD, pneumonia….) with significant impacts on pig producers’ livelihood. In this context identification of disease priority and disease management practices at swine holdings is essential for efficient surveillance of swine diseases. Under the framework of...