A history of the WWG

The 1^st International Congress on Goose Production was held in 1967 in Jouy en Josas, France, organised by Mr. Georges Monachon, ex-director of the experimental goose farm in Domaine d'Artiguères, France. At this Congress the fields of development, reproduction, nutrition, technology and pathology of geese were discussed, mostly focused on goose liver production. Working Group 8 ‘Goose Keeping’ of the European Federation (EF), WPSA was established on 7 February, 1969, two years later, and was confirmed in the WPSA World Congress in Madrid in September 1970. The first chairperson of the Working Group 8 was Mr. Georges Monachon, who served as chairman from 1969 to 1976. Later, the 2^nd International Congress was held in Budapest, Hungary, on 24-30 October, 1971, and focused on ‘Feeding and Hygiene in Geese’ (Stasko, Reference STASKO1978).

The second chairperson of the Working Group 8 was Dr. Jozef Stasko of Czechoslovakia, elected in 1976. The 3^rd International Congress was held on 29 March-2 April 1976 in Bratislava, Czechoslovakia, with the theme of ‘Actual Problems in Large-scale Production of Geese’. In 1978, there was a seminar on ‘Genetics and Keeping of Geese’ organised by Dr. Jozef Stasko on 28-31 May in Bratislava–Harmonia, Czechoslovakia (Stasko, Reference STASKO1978). The 4^th International Conference, which focused on ‘Breeding and Geese Production’ was organised by Prof. Stanisław Wężyk and was held on 11-13 September, 1979 in Torun and Koluda Wielka, Poland.

The third chairperson of the Working Group 8, elected in 1979, was Prof. Stanisław Wężyk. The 5^th-7^th waterfowl conferences seem not to have had clearly defined themes. During this time, waterfowl probably only occupied a single session in World Poultry Congresses. On 17-19 December 1981, there was an international poultry symposium together with the WWG on ‘Problems of Breeding, Reproduction and Production of Waterfowl’ held at the University Leipzig, Germany, which was organised by Prof. Heinz Pingel. This meeting could be considered the 5^th symposium, because all members of the WWG were invited. In the 1980s, there was a further conference in Krakow, Poland, again organised by Prof. Stanisław Wężyk.

The orientation of WWG was changed in the 1980s. Gaudry (Reference GAUDRY1987) reported that ‘The activities of the waterfowl group are changing direction, thus confirming the proposals made in Helsinki two years ago’. After the establishment of the WWG, it was structured into six sub-groups (feed, genetics, pathology etc.). Because of little activity by the sub-groups, the EF decided to change this structure. On 21 August 1986, the General Assembly decided to start a committee responsible for international activities, with Dr. Daniel Gaudry and Prof. Stanisław Wężyk being elected president and vice-president respectively (Gaudry, Reference GAUDRY1987). The 8^th International Waterfowl Symposium was held on 12-14 September, 1989 in Budapest, Hungary. Three years later, on 16-18 September, 1992 the 9^th International Symposium on Waterfowl was held in Pisa, Italy, and was organised by Prof. Carlotta Fedeli-Avanci and her team. Between the 9^th and 10^th Symposiums, in 1993, a workshop was organised by Prof. Stanisław Wężyk in Pawlowice, Poland, at which ‘Quality and Standardisation of Waterfowl Products’ was discussed. The 10^th European Symposium on Waterfowl was held on 26-31 March, 1995 in Halle, Germany. This meeting was organised by Prof. Heinz Pingel and Dr. Rainer Timmler. Dr. Roger Rouvier organised the 11^th European Symposium on Waterfowl on 8-10 September, 1997, in Nantes, France, and on 18-20 October, 1999 the 12^th European Symposium on Waterfowl, organised by Prof. Ahmed Testik, was held in Adana, Turkey.

As a result of increasing production of waterfowl in Asian countries, it was decided to hold waterfowl conferences away from Europe. Therefore, the 1^st World Waterfowl Conference was shifted from Europe to Asia, and was held on 1-4 December, 1999 in Taichung, Taiwan. Interestingly, a workshop on waterfowl, organised by Prof. Heinz Pingel and Dr. Rainer Timmler was held on 13-15 November, 2001 in Halle/Wermsdorf, Germany. The 2^nd World Waterfowl Conference was held on 7-9 October, 2003 in Alexandria, Egypt. Two years later, the 3^rd World Waterfowl Conference was held on 3-6 November, 2005 in Guangzhou, China, focusing on ‘Sustainable Development of Waterfowl Production’. The 4^th World Waterfowl Conference, with its theme of ‘Waterfowl Production for Food Security’, was held on 11-13 November, 2009 in Kerala, India. On the last day of this conference, a meeting was held to discuss the formation of a WWG in the Asia Pacific region. During this meeting, the president of the APF, Mr. Alan Gibbins, explained that the EF had closed its Working Group 8 because the waterfowl industry and the research effort in that region had diminished and there were not enough people interested in waterfowl to sustain a viable working group there. The EF made the suggestion that the group be ‘transferred’ to the Asian Pacific region. Waterfowl production in the Asian Pacific region is a very important sector of the poultry industry and on a global scale the region accounts for more than 80% of waterfowl production. Furthermore, waterfowl research and development is still very active in the region. This ‘transfer’ proposal was put to the meeting and it was agreed that the APF should inaugurate its second working group. A recommendation to this effect was presented to the general meeting of the APF committee on 22 March 2011 during the 9^th Asia Pacific Poultry Congress in Taipei, Taiwan where it was accepted. The new working group was named the APF Working Group 2 on waterfowl. Dr. Jeng-Fang Huang from Taiwan was elected as the first chairperson of Working Group 2. It was also thought appropriate that the new Working Group 2 assumes responsibility for future World Waterfowl Conferences and that it should be the body to select the host country for subsequent events. Following a formal process involving all APF branches, Vietnam was selected to host the 5^th World Waterfowl Conference, which will be held in Hanoi from 25-27 October 2013.

Apart from helping in the dissemination of scientific and technical information by organising conferences and symposia, the main task of the WWG is to help coordinate research and development and stimulate international cooperation. The waterfowl conferences, the sessions on waterfowl at the World Poultry Congresses, the European Poultry Conferences, and the Asian Pacific Poultry Conferences have brought scientists and producers from around the world together to exchange knowledge, technology as well as to inspire critical thinking about the industry. The major achievements in different fields of waterfowl knowledge are reviewed below.

Progress of performance

The progress in duck growth performance improvement has been spectacular. The live weights of Pekin ducks increased linearly from about 1.7 kg in 1928 to approximately 4.5 kg in 2001 at seven weeks of age. It took 75 days to reach a live weight of 2.7 kg in 1928, which decreased to 35 days to achieve the same weight in 1993. Over the period 1928-1993, the feed consumption required to produce 1 kg of body weight was reduced by approximately 27 g annually (Cherry and Morris, Reference CHERRY and MORRIS2008a). Today, intensively fed Pekin ducks are generally slaughtered at 6-8 weeks, weighing 3.3-3.7 kg.

Muscovy ducks, which are typical meat-birds, are much bigger than those of Mallard origin. They are also sexually dimorphic: an adult male reaches 4.6-6.8 kg, (and maybe as much as 8 kg), while females reach 2.7-3.6 kg. Muscovies reach maturity at 28-29 weeks of age, and, during two reproductive cycles, a female lays 150-180 eggs. Muscovy females reared up to 65 days weigh around 2.5 kg, while males reared for 80 days weigh 4.7-5.1 kg. As a result of improvements in nutrition and breeding, the weight of 10-week-old mule ducks (black Muscovy ♂ x Brown Tsaiya ♀) in Taiwan was 1.4 kg in 1966, which increased to over 2.9 kg in 1986 at which time the mule ducks were produced by white Muscovy ♂ x Kaiya ♀ (the progeny of Pekin ♂ x White Tsaiya ♀). Feed conversion ratio improved from 4.95 to 3.09 from 1966 to 1986 (Huang et al., Reference HUANG, LEE, LIN, LIN, LIU, LIN, HSIAO and WANG2007). In France, mule ducks (Muscovy ♂ x Pekin ♀) for fatty liver production can reach 4.2 kg before overfeeding occurs, even after a specific feed restriction alimentary schedule during the rearing period.

The onset for the laying period of laying ducks derived from Anas platyrhynchos is at about 16 weeks of age, and laying rate can be about 90%. Huang et al. (Reference HUANG, LEE, LIN, LIN, LIU, LIN, HSIAO and WANG2007) reported that laying rate in laying Brown Tsaiya ducks in 1964 was 40%, with a feed conversion ratio for eggs of 6.72. After most of the major nutrient requirements for laying ducks were established, and improvements in breeding and production techniques had been brought in, laying rate improved to 87% during the 50-week period after point of lay, with a feed conversion ratio for eggs of 2.72.

For geese, genetic selection and improvements in environmental conditions shortened the maturity period of domestic geese from three years for wild ancestors, down to 9-11 months, and the laying period was extended from 4-6 weeks to 6-8 months, while the egg number increased from 6-12 to 50-80 in meat type geese, and as much as 210 eggs were produced by Chinese Huoyan geese in one laying period. The colour and weight of goose eggs remained unchanged (Pingel, Reference PINGEL2008). Commercial meat-type geese, reared intensively, can be slaughtered at 12-20 weeks, weighing from 3.5 to 8.0 kg, with a slaughter yield of around 68%.

To produce fatty liver, the main genotypes used are mule ducks and Landaise geese. The success of mule ducks is mainly based on the progress in artificial insemination favouring the production of this hybrid, and in the selection for white plumage birds. For both species, selection programs have aimed at increasing meat yield and fatty liver weight (545 g in 2009 vs. 449 g in 1987, Guerder et al., Reference GUERDER, CHINZI and KOEHL2000; Litt Reference LITT2010). Rearing conditions and equipment have been modified, allowing an increase in the number of mule ducks reared together as a flock (2,523 in 2009 vs. 971 in 1987) and a decrease in the rearing period before overfeeding (88 days in 2009 vs. 93 days in 1987). New specific equipment for force feeding (individual cages during overfeeding, hydraulic and pneumatic equipment for the overfeeding procedure) has led to further progress (770 birds force-fed per producer in 2009 vs. 120 heads in 1987). In addition, the overfeeding period was reduced (12.7 days in 2009 vs. 15.6 days in 1987), and the corresponding amount of maize for overfeeding was decreased (9.8 kg in 2009 vs. 12.4 kg in 1987). In France, at present, geese are reared for 12 to 14 weeks, overfed for 15 to 21 days with 15 to 20 kg of maize, and produce fatty livers weighing 750 to 850 g. In Hungary, the production of goose fatty liver yields lighter carcasses and fatty livers of about 600 g, these livers being solely dedicated for canned products.

Genetics and breeding

Major genetic impacts in waterfowl during the process of domestication occurred mainly in plumage colour and in some morphological and biochemical traits. Until the first part of the 20th century there were standards for breeds for exhibition based on plumage colour, type and size. The first pedigree farms were established and selection for body weight and egg number based on individual trapnesting records was introduced. In the second part of the 20th century a few multinational breeding companies for meat ducks were developed. In addition, there were some small breeding farms for ducks and geese of local importance. Comprehensive reviews of breeding and genetics of growth and meat production as well as egg production and reproduction have been presented by Pingel (Reference PINGEL1990a; Reference PINGEL1990b) and Rouvier (Reference ROUVIER1999). Hutt (Reference HUTT1952) reported that in the Jansen-farm in the Netherlands with 50,000 Khaki Campbell ducks the laying performance was increased to 335-340 eggs per laying season. In Taiwan the small-sized Brown Tsaiya ducks were selected by index and achieved 330 eggs up to 500 days of age. The use of individual cages for laying test has necessitated the application of artificial insemination (Tai et al., Reference TAI, CHENG, LEE and WANG1997). The egg production of small body sized Huoyan goose in China was improved from 83 to 118 eggs by Ning and Qu (Reference NING and QU1988) after four generations. In Europe a new approach to increase egg production in geese by selection for longer laying duration was introduced under applying short light-day to delay photo-refractoriness.

With regard to meat ducks and geese, the market demands white-feathered birds. Therefore, mainly white Pekin ducks and white Chinese geese with the recessive genes for white plumage (cc) and white Muscovy ducks with the dominant white gene (P) are used. Tai et al. (Reference TAI, CHENG, LEE and WANG1997) developed mule ducks with white plumage by parental selection. The white plumage in goose breeds descending from Greylag geese is the result of a combination of genes for recessive spotting (sp) and dominant dilution (Sd) (Crawford, Reference CRAWFORD1990).

The antagonistic relationship of rapid growth with high fecundity demands breeding programs for meat ducks and geese with completely closed specialised male and female lines. The most important traits in sire lines are body weight at the slaughter age, breast meat percentage, feed conversion ratio and fertility (mating activity). In dam lines more attention is paid to egg number and hatchability. With regard to body growth and breast meat percentage, measured by breast layer thickness, rapid gains have been made (Pingel and Heimpold, Reference PINGEL and HEIMPOLD1983; Powell, Reference POWELL1985). Direct selection towards feed conversion ratio based on individual feed intake has been introduced in duck breeding, which increased biological and ecological efficiency of production by decreasing production costs and environmental pollution (Pingel, Reference PINGEL2001). This can improve the adaptability of birds to hot climates.

In commercial breeding programs three and four-way crosses as well as back-crosses are applied to utilise maternal heterosis resulting in increasing number of offspring for meat production. The commercial stocks are multiplied via grandparent and parent stocks. The most important inter-specific hybrids used in poultry production is the cross between a Muscovy drake and a common duck, sometimes with short fertility persistency. Cheng et al. (Reference CHENG, HUANG and ROUVIER1999) have increased the duration of fertility after insemination by selection from 6.5 days to 8 days. In France the male mule ducks are used for fatty liver production by overfeeding. Guy (Reference GUY2009) reported that a new program was started for selection of quiet birds better adapted to the specific process of overfeeding.

Reproduction

Artificial insemination (AI) is important in many aspects for both ducks and geese. For ducks, it not only plays an important role in the production of hybrid mule ducks from crossing Cairina moschata with Anas platyrhynchos, but also for breeding efficiency. The AI techniques for mule duck production have been applied by the duck industry in Taiwan for decades. Training courses for AI in Taiwan can be traced back to 1967 (Huang, Reference HUANG1972). Since then AI has become very popular in Taiwan. At that time fertility from AI was 10-15% higher than that from natural mating (Huang, Reference HUANG1972). Three-way mule ducks are produced by crossbreeding Muscovy drakes with Kaiya ducks in Taiwan. However, mule ducks produced in other countries are mostly derived from crossbreeding Muscovy drakes and Pekin ducks. The conditions for both intra- and inter-generic crossbreeding were reviewed by Tai and Tai (Reference TAI and TAI1991). Countries employ different measures and tools for AI. Lighting regimes are also important for reproduction. It affects not only sexual maturity but also egg production. Sauveur and de Carville (Reference SAUVEUR and DE CARVILLE1985) indicated that increasing the photoperiod by only 15 minutes per week was not enough to stimulate precocity; however increases of 30-60 minutes per week seemed enough. Cherry and Morris (Reference CHERRY and MORRIS2008b) reported that age of sexual maturity in Pekin ducks was reduced by increasing the photoperiod during rearing, or reducing the age when artificial light was first increased. In subtropical Taiwan, the off-season for Muscovy ducks is between October and April, when semen can be successfully collected from only about 20% of the drakes. Prolonging the photoperiod from 11 hours to 17 hours per day for Muscovy drakes can increase the proportion of drakes that semen could successfully be collected from, sperm concentration and yield (Wei et al., Reference WEI, CHUANG, LIU, LEE and HUANG2011). The progress in cryopreservation of duck semen is relatively successful for Pekin and Brown Tsaiya ducks, but it is not as satisfactory for Muscovy ducks (Blesbois, Reference BLESBOIS2007; Hsu et al., Reference HSU, CHUANG, HSIAO, WEI, LIU and HUANG2010).

The physiology of goose reproduction is different to that of other poultry species. At European latitudes, the initiation of reproduction occurs just after the shortest day, towards the end of December, and depending on ambient temperature, the first eggs are laid in mid-January. Contrary to laying hens, shorter light periods of 8-10 hours per day stimulate and sustain laying intensity much better than 14-17 hours per day (Elminowska-Wenda, Reference ELMINOWSKA-WENDA1988). Lighting programs should thus be applied to obtain optimum reproductive performance. In subtropical areas, in order to get maximum response in laying period from a lighting program, a 12 to 13 hour light period for geese raised in open-sided houses, or an 8 to 10 hour period in lightproof houses, with 40 lux light intensity, are recommended (Huang et al., Reference HUANG, HU and HSU2008). Although breeding goose flocks can be kept for four and more cycles, the best quality goslings are produced by two-year-old parents. Later on, as the age of the flock increases, the number of eggs, fertility and hatchability decrease. Further, during one reproductive cycle, fluctuations in reproduction performance have been observed, which together with a low male to female ratio and poor semen quality made goose production less effective. Some of these problems can be eliminated or at least reduced by the application of AI with freshly collected or cryopreserved semen (Łukaszewicz, Reference ŁUKASZEWICZ2010).

Nutrition

In comparison with chickens, waterfowl nutrition research has lagged behind. Very little information on the nutritional requirements of waterfowl was published in early editions of the NRC's Nutrient Requirements of Poultry. The first edition of this book was published in 1944, with data for ducks being first included in 1954 and for geese in 1977 (NRC, 1977). For Pekin ducks, the requirements for only six items were estimated and listed in the 6^th revised edition of the book. The same requirements were used for ducks in the starting and growing stages (NRC, 1971). In the 7^th revised edition, nutritional requirements of breeding ducks were added and ‘increased protein level to 22% for the first 2 weeks will increase early growth’ was noted, which meant that the notion of phased feeding was introduced at this time (NRC, 1977). In the advent of the growth of the duck industry, more attention was paid to the nutrition of ducks, and a separate chapter on ducks began appearing in the 8^th editions of Nutrient Requirements of Poultry (NRC, 1984). Ten years later more detailed information was included in the 9^th edition (NRC, 1994a). Taiwan began nutrition research for mule ducks and laying Brown Tsaiya ducks in the 1970s, and the results were compiled in the Manual of Nutrient Requirements for Ducks (Shen, Reference SHEN1988). For Muscovy ducks, the most comprehensive nutritional research was carried out in France. This breed raised interest in poultry production because of its reddish, lean and tasty meat, but only in some countries, for example France, Taiwan, Germany, Egypt and Italy. Initially, the recommendations for Muscovy production were inspired by knowledge of chicken nutrition, or that of common ducks where it existed. Major nutritional requirements for Muscovy ducks such as energy, protein, lysine, sulphur amino acids, calcium and phosphorus were established in 1970-1980s (Leclercq and De Carville, Reference LECLERCQ and DE CARVILLE1985; Leclercq et al., Reference LECLERCQ, BLUM, SAUVEUR and STEVENS1987; Leclercq et al., Reference LECLERCQ, DE CARVILLE and GUY1990). Globally, knowledge about Muscovy nutrition and the appreciation of growth lead to a breeding period was divided into three phases with specific diets: starting, growing and finishing periods. Recently, energy and amino acid utilisation of feedstuffs have been studied to evaluate non-traditional nutrient sources and determine their optimal inclusion levels in feed formulation (Adeola, Reference ADEOLA2005).

Geese are one of the most rapidly growing domesticated poultry species in the world (Leeson and Summers, Reference LEESON and SUMMERS1997). These birds can utilise grass and weeds efficiently, and are marketable from 10 to 18 weeks of age, depending on the feeding programs or on the nutrient concentrations in the diet. The higher the intake of good quality feedstuffs, the more abundant the final geese products. However, since the middle of the 20th century little information on the nutritional requirements of geese has been published. As for ducks, an individual chapter on geese was included from the 8^th edition of Nutrient Requirements of Poultry (NRC, 1984). The basic knowledge of the nutrient requirements for geese in terms of nitrogen or amino acids, minerals, vitamins and metabolisable energy had been established by the end of 20th century. The editors of National Research Council collected the experimental data and published guidelines on the nutritional requirements of geese at different physical stages (NRC, 1994b). This book established the principles of goose feeding. Later, Leeson and Summers (Reference LEESON and SUMMERS1997) published feeding programs for geese. Since the price of grain has increased and the concept of decreasing the carbon mileage on agricultural products began to be emphasized at the beginning of 21st century, the research on the effective utilisation of grass by geese began to be appreciated. In the past two decades, work has been conducted on the nutrition of goslings in their early stage, which focused on the physiological development of the gastrointestinal tract and digestive organs, as well as the utilisation of the yolk sac or the variation of digestive enzymes. At the same time feed additives like L-carnitine and probiotics were investigated to understand the effect of these substances on the growth performance and carcass evaluation. Research data on geese for breeding remained scarcer than that for growth. Bogenfürst (Reference BOGENFÜRST2005) reported on papers dealing with elements of nutrition and reproduction. More recently, a technique for using photoperiodic control to adjust the reproduction of geese has been developed, which stimulates laying behaviour in the non-reproductive season. Further experiments on the nutritional requirements of geese need to be carried out because of the different environmental conditions used in management. Furthermore, it is necessary that the nutritional requirements must be determined from the viewpoint of animal welfare, and that the welfare aspects of production of goose down, feathers and fatty liver should be paid more attention in the future (Kozák et al., Reference KOZÁK, GARA and KAWADA2010; Kozák, Reference KOZÁK2012).

Management and housing

Depending of locality, the type of bird, and the market purpose, management and housing systems vary considerable. From a general point of view, modern husbandry, and high market demand has led to intensive production, accompanied by high stocking densities inside specifically designed buildings. However, the situation is not exactly the same everywhere. In Asia, goose and duck production has been carried out in extensive conditions for a long time, including watered areas. Soon after the starting period, when ducklings are raised in a more or less sophisticated shelter, they are accommodated in the open. One of the advantages of this system is that birds are often encouraged to find their own food, which does not compete with human requirements. For example, it is very popular to let birds out on paddy fields after harvesting, where they can find spilled rice, as well as much other food including snails, worms, fishes, crabs, insects and aquatic plants (Jalaludeen et al., Reference JALALUDEEN, PEETHAMBARAN, LEO and MANOMOHAN2004). When the amount of food available in the paddy field is not sufficient, birds are provided a complement of additive food, generally of low cost. Other advantages of these systems are that their droppings contribute to the fertilisation of the fields for crops; and the birds help to control pests present in the watered areas. The main objective of this style of production is not optimising yield, but rather to produce at low cost. Other than rice fields, waterfowl are sometimes grown on deeper lakes, under integrated breeding systems which combine fish production (Varadi, Reference VARADI1995). Although these extensive breeding systems are still very popular in Asia, there is a new tendency to develop intensive production in modern poultry houses. In China, waterfowl meat and egg demand is on the increase. For meat production there has been considerable increase in high-performance occidental duck breeds, but these ducks are in fact as poorly suited to extensive breeding compared to the local strains. Furthermore, in the north of the country there is a paucity of available watered areas. The development of intensive production is therefore occurring in the south of China, under warmer climatic conditions. The general equipment of the buildings used in the south is not particularly different to those found in developed western countries. A portion of the floor is generally mixed biological bedding which contributes to reduced feed consumption and produces heat as a result of bacterial fermentation. The rest of the building has slatted floors where drinking takes place, so as to avoid wet litter, and to reduce the husbandry requirements for the farmer. To limit the effects of temperature, specific equipment is often installed, including galvanised iron bathing tubes, ventilation systems, pad cooling, and black curtains to prevent entrance of the sunlight. These two types of production, extensive or intensive have been adapted for both meat geese and ducks as well as layer ducks (Guémené et al., Reference GUÉMENÉ, SHI and GUY2012).

While Asian countries evolve more intensive systems, the situation is a little bit different in Europe. Intensive waterfowl breeding in closed buildings was developed widely in the 1970-1980's in a number of European countries. Pekin ducks (Great Britain, Netherland and Germany), Muscovy ducks (Germany and France) and mule ducks (France) are currently raised in confined conditions (Rodenburg et al., Reference RODENBURG, BRACKE, BERCK, COOPER, FAURE, GUÉMENÉ, GUY, HARLANDER, JONES, KNIERIM, KUHNT, PINGEL, REITER, SERVIÈRE and RUIS2005). Pekin ducks are generally raised on litter, often straw, and Muscovy ducks on slatted floors. These intensive breeding systems allow high stocking densities. Slatted floors improve hygiene, and reduce disease problems, but constitute a poor environment for the birds, and most of the time both mule ducks and Muscovy ducks raised on slats must be submitted to claw and beak trimming to avoid cannibalism. A combination of both a slatted floor and litter seems to be a good balance between animal welfare and hygiene, and is consistent with European regulations. Nowadays, total confinement systems are becoming less popular in Europe. One of the reasons is that intensive production conveys a negative picture of the welfare of the animals, and the products are generally considered low quality. Market demand is progressively focussed on high quality products (organic or others sustainable production under quality control) which requires free range conditions. To take into account welfare demands, producers have no choice other than to move back to less intensive systems of production.

Product quality and utilisation

Ducks are reared mainly for meat, eggs and fatty liver production, with feathers and down as by-products. The main species used to produce duck meat are Pekin ducks, Muscovy ducks and mule ducks (mostly in France for the production of fatty liver). As for chickens and turkeys, the industry tends to develop more cut (49% of slaughtered ducks in France in 2009, Braine, Reference BRAINE2010) and processed products. As a result of selection programs and improvements in nutritional and rearing conditions, the body weight at slaughter and meat yield of Pekin and Muscovy ducks were largely increased whereas the carcass fatness was decreased. For example, at 12 weeks of age, the difference in breast muscle weight between control and selected Muscovy ducks was 39% (Baéza et al., Reference BAÉZA, DE CARVILLE, SALICHON, MARCHÉ and LECLERCQ1997; Reference BAÉZA, DESSAY, WACRENIER, MARCHÉ and LISTRAT A.2002). However, it was not possible to decrease slaughter age as development of breast muscles occurs relatively late - at 7-8 weeks for Pekin ducks, 10 weeks for female Muscovy and mule ducks, and 12 weeks for male Muscovy ducks. At present, body weight at slaughter is 3.3-3.7 kg for Pekin ducks and 4.7-5.1 kg for male Muscovy ducks, and the yield of breasts with skin in relation to body weight are 15-16% and 16-17% for Pekin and Muscovy ducks, respectively. In France, a large proportion of duck meat is provided by overfed ducks (about 58%, Braine, Reference BRAINE2010). This meat is characterised by its high lipid content (about 4% in breast muscle), which is double that in ad libitum fed ducks (Chartrin et al., Reference CHARTRIN, MÉTEAU, JUIN, BERNADET, GUY, LARZUL, RÉMIGNON, MOUROT, DUCLOS and BAÉZA2006). In this case, breast muscles are marketed under the name ‘magrets’ according to French regulations, and thighs and shanks with thigh meat are mostly processed into ‘confits’ corresponding to meat cooked for two hours with duck fat (internal temperature of 100°C).

The utilisation of duck meat in Asian countries is very different from that in western countries. Varieties of manufacturing processes have been developed, like ‘eight-treasure duck’, ‘crispy-skin duck’, ‘camphor-’ and ‘tea-smoked duck’, ‘ginger-root duck’, ‘smoked duck steak’, ‘duck roll’, ‘Pekin roasted duck’, ‘pressed salted duck’, ‘hanging-roasted duck’, ‘roasted squashed duck’, and so on (Chen, Reference CHEN1999). Measures to improve duck meat quality have been reviewed by Huang et al. (Reference HUANG, LEE, LIN, LIN, LIU, LIN, HSIAO and WANG2007). Because of the size of China, there are many ways to utilise duck meat and by-products. In addition to edible viscera, duck heads, necks, tongues, intestines, and even bone may be sold after specialist processing or cooking, and there are some 700 different ways of cooking duck, with recipes for duck meat and edible viscera (Lee, Reference LEE2003).

Other duck species, such as Jinding and Shao ducks in China, Brown Tsaiya ducks in Taiwan, Khaki Campbell, Indian runner and Desi ducks in India, Vietnam, Cambodia and Indonesia, are mainly used for egg production with meat as a by-product. Duck eggs are consumed as table eggs in many countries. There are many varieties of duck egg recipes, for example boiled, stuffed or devilled eggs, coddle eggs, roasted eggs, egg omelette, scrambled eggs, poached eggs, and so on (Jalaludeen et al., Reference JALALUDEEN, CHURCHILL, JOSEPH and ANITHA2009). In addition, duck eggs are processed into alkalized eggs (‘pidan’, ‘pedant’, century egg, thousand-year eggs) and salted eggs. Many studies have been carried out to improve duck eggs, such as, for example, the measures taken to enhance the stability of alkalized eggs (Huang and Lin, Reference HUANG and LIN2011). Fertilised duck eggs incubated to approximately 17 days are boiled and eaten as a delicacy in the Philippines, Vietnam, Laos, and so on.

Geese are mainly reared for meat, fatty liver, feather and down production. For meat production, there is a large variety of goose breeds and strains. The production of goslings is highly seasonal, occurring mainly from February to July in Europe, and from October to April in Asia under natural photoperiods. If lighting programs are used in closed buildings, goslings can be produced all year round. Therefore, the production system is quite variable, very often using pasture extensively and yielding slaughter ages varying from 9 to 24 weeks. Geese are usually sold as whole carcasses. For example, White Koluda geese, slaughtered at 17 weeks of age, in Poland, are characterised by high body weight (6.7 kg) and muscle yield (30% in relation to carcass weight; Łukaszewicz et al., Reference ŁUKASZEWICZ, ADAMSKI and KOWALCZYK2008). Chinese breeds are lighter than the Embden breed (USA), at 3.9-4.3 kg vs. 4.9 kg at 12 weeks of age (Grunder et al., Reference GRUNDER, CAVE, PAWLUCZUK, BUTLER and POSTE1991). Bielinski et al. (Reference BIELINSKI, BIELINSKA and KASZYNSKI1970) recommended slaughtering White Italian geese at 11.5-12 weeks of age, when they weigh 4.5-5.0 kg.