G. Guy

Role of hepatic lipogenesis in the susceptibility to fatty liver in the goose (Anser anser).

In response to overfeeding, the Landes goose develops a fatty liver that is twice as large as that of the Poland goose, despite similar food intake. The role of hepatic lipogenesis in the genetic susceptibility to fatty liver was assessed in male overfed geese of the two breeds. For a similar hepatic protein content, total activities of malic enzyme, glucose-6-phosphate dehydrogenase, acetyl-Coa-carboxylase and fatty acid synthase, and specific activity and mRNA level of malic enzyme were about two-fold higher in the Landes goose. In the Poland goose, the weight of the fatty liver was correlated positively with the specific activity of ME and the VLDL concentration, which was not the case in the Landes breed. These results show that: (1) hepatic lipogenesis remains very active until the end of the overfeeding period; (2) the pentose-phosphate pathway may function in birds, contrary to what is assumed usually; (3) the level of hepatic lipogenesis is a major factor in the susceptibility to hepatic steatosis in different breeds of geese; and (4) ME activity may be a limiting factor of lipid synthesis in the less susceptible Poland breed.

Differential channelling of liver lipids in relation to susceptibility to hepatic steatosis in two species of ducks

In the human, hepatic steatosis can be associated with an imbalance between synthesis, secretion and storage of hepatic lipids, and exhibits a genetic susceptibility. The effect of overfeeding on hepatic lipid channelling was investigated in two genotypes of ducks that differ in their susceptibility to fatty liver, i.e. the common duck, Anas platyrhynchos, and the Muscovy duck, Cairina moschata. Before overfeeeding, the Muscovy duck exhibited a lower subcutaneous adiposity and a higher muscular development, whereas hepatic composition was similar in both genotypes (>5% lipids and triglycerides accounting for 6-10% lipids). In the plasma lipoprotein profile, HDL predominated (5.5-7.8 g/l) over VLDL (0.09-0.25 g/l) and LDL (0.65-1.06 g/l). All lipid and lipoprotein concentrations were lower in the Muscovy duck. In response to overfeeding, the Muscovy duck exhibited a higher degree of hepatic steatosis (62 vs. 50% lipids), and a lower increase in adiposity and in the concentration of plasma triglycerides (6-fold vs. 10-fold) and VLDL (23-fold vs. 34-fold). Thus, certain genotypes may be more responsive to the dietary induction of fatty liver because of a less efficient channelling of hepatic lipids towards secretion into plasma and adipose storage, and the duck may represent a suitable model in which to study the development of hepatic steatosis and its pathogenesis.

Welfare of ducks in European duck husbandry systems

European duck meat production is based on the use of Pekin, Muscovy and Mule duck genotypes that vary in their behavioural and physiological characteristics. Furthermore, large differences exist in their housing and management conditions. The aim of this review is to discuss the welfare of these different genotypes in typical husbandry systems, focusing on ducks kept for meat production. Firstly, factors that can affect duck welfare, such as stocking density and group size, access to straw, an outdoor run, or open water, are described. Secondly, welfare problems such as feather pecking, fear and stress, and health problems are assessed. Thirdly, the various systems used in Europe are described for these aspects. Giving ducks access to straw, an outdoor run, or open water increases the behavioural opportunities of the ducks (foraging, preening, bathing, and swimming), but can also lead to poor hygiene and increased health- and food safety risks. Therefore, practical solutions that allow expression of natural behaviour, but do not lead to hygiene or health problems have to be found and some practical suggestions are provided.

Hormonal and metabolic responses to overfeeding in three genotypes of ducks

Muscovy, Pekin and Mule duck are different in their body weight. To make a valid comparison in the lipid metabolism between these three genotypes, overfeeding was carried out by providing the animals with amounts of food in proportion to their body weight. Under these conditions, Muscovy ducks developed a strong liver steatosis, whereas it was not very pronounced in the Mule ducks and even less in the Pekin ducks. On the contrary, Pekin ducks showed a much marked extrahepatic fattening. At the beginning of overfeeding, there was a similarity in the three genotypes as regards the post-heparin lipoprotein-lipase (LPL) activity and the insulin and glucagon concentrations. After 10 days of overfeeding, the LPL activity dramatically fell in Muscovy and in Mule ducks, whereas it remained steady in Pekin ducks. Compared to values found at the beginning of the overfeeding period, plasma glucagon and insulin shown no evolution, except for the insulin of Pekin ducks which was dramatically higher. Those data suggest that high plasma insulin concentrations measured in Pekin ducks after 10 days of overfeeding can be responsible for the maintenance of the LPL activity, which favors the extrahepatic fattening to the detriment of liver steatosis.

Metabolism in two breeds of geese with moderate or large overfeeding induced liver-steatosis.

Biochemical mechanisms which may control fat deposition in liver and/or peripheral tissues have been studied in Poland and Landes geese. Post-prandial plasma substrates and post-heparin lipoprotein-lipase (LPL) activity were measured in 10-week-old animals. At 23 weeks of age, geese were overfed for 14 days then slaughtered. Hepatic steatosis was more important in Landes geese, while muscle and subcutaneous adipose tissue were less developed. In this breed, fatty liver weight negatively scaled to LPL activity, suggesting that a low LPL activity is a limiting factor of peripheral fat deposition. Consequently, non-catabolized VLDL may return to liver and increase hepatic steatosis. In Poland geese, such a mechanism does not exist. On the other hand, fatty liver weight was positively correlated to very low density lipoproteins (VLDL) and triacylglycerols measured in overfed Poland geese, suggesting that lipids synthetized by liver are better transferred from liver to extrahepatic tissues. Kinetics of post-prandial plasma glucose, triacylglycerols, phospholipids and uric acid were similar in the two breeds. However, the marked decrease in post-prandial plasma glycerol in Poland geese suggests that an extrahepatic tissue lipolysis inhibition could contribute to the higher peripheral fattening in overfed Poland geese and could be a limiting factor of hepatic steatosis in this breed.

The past, present and future of force- feeding and "foie gras" production

Force-feeding is a very old practice, first recorded in ancient Egypt, but until the 1950′s foie gras production remained somewhat limited in volume. Foie gras is currently produced in various countries but approximately 80% of world production and consumption takes place in France. Geese, which were the most common specie been force-fed until recently, now account for less than 10% of the total world foie gras production. Ducks such as the Muscovy duck (Cairina moschata) account for less than 5%, and mule ducks for the rest. Thus, over 35 million mule ducks were force-fed in France in 2001, accounting for nearly 95% of the domestic foie gras production. This increase was made possible by technical progress in specific breeding programmes and force-feeding practice. However, the future of this production is uncertain, at least in Europe. Indeed, although a number of experimental approaches have shown that there is no scientific evidence that validates such adverse comment, this procedure is highly criticised in terms of animal welfare. The Council of Europe therefore adopted two specific recommendations in 1999 and although its practice is not banned at present, it is limited to the areas where it is already practised and only under specific rearing conditions. Therefore, the question is: will it be still possible to produce foie gras in France or elsewhere in Europe in the future and, if not, where and how will it be produced?

Force-feeding procedure and physiological indicators of stress in male mule ducks

1. The effects of the force-feeding procedure and its different components on various physiological indicators of acute and chronic stress were investigated in male mule ducks before and during a 12-d cramming period. 2. The highest concentration of corticosterone were measured after injection of ACTH agonist, during the pre-experimental period when the ducks were still housed in collective floor pens and at the time of transfer. 3. During the cramming period, corticosterone measured before and after force-feeding did not differ significantly though there was a non-significant trend towards an increase in certain cases. 4. The different components of force-feeding, including manipulation, intubation, force-feeding with a standard or a large amount of food had no significant effect upon corticosterone concentrations. 5. There was no indication from ACTH agonist challenge either of a change in adrenal sensitivity or a change in its responsiveness. 6. The heterocyte-lymphocyte ratio measured before and at the end of the cramming period did not differ significantly. 7. In conclusion, we observed no significant indication that force-feeding is perceived as an acute or chronic stress by male mule ducks, in our experimental conditions. Nevertheless, it remains to be shown that their adrenocorticotropic axis is responsive to acute stressors.

Genetic parameters of product quality and hepatic metabolism in fattened mule ducks.

Genetic parameters of traits related to hepatic lipid metabolism, carcass composition, and product quality of overfed mule ducks were estimated on both parental lines of this hybrid: the common duck line for the maternal side and the Muscovy line for the paternal side. The originality of the statistical model was to include simultaneously the additive genetic effect of the common ducks and that of the Muscovy ducks, revealing a greater genetic determinism in common than in Muscovy. Plasma metabolic indicators (glucose, triglyceride, and cholesterol contents) were heritable, in particular at the end of the overfeeding period, and heritabilities increased with the overfeeding stage. Carcass composition traits were highly heritable in the common line, with values ranging from 0.15 for liver weight, 0.21 for carcass weight, and 0.25 for abdominal fat weight to 0.32 for breast muscle weight. Heritabilities of technological outputs were greater for the fatty liver (0.19 and 0.08, respectively, on common and Muscovy sides for liver melting rate) than for the pectoralis major muscle (between 0.02 and 0.05 on both parental sides for cooking losses). Fortunately, the processing industry is mainly facing problems in liver quality, such as too high of a melting rate, than in meat quality. The meat quality appraisal criteria (such as texture and cooking losses), usually dependent on pH and the rate of decline of pH, were also very lowly heritable. This study demonstrated that genetic determinism of meat quality and ability of overfeeding is not similar in the common population and in the Muscovy population; traits related to fattening, muscle development, and BW have heritability values from 2 to 4 times greater on the common line than on the Muscovy line, which is relevant for considering different selection strategies.

Corticosterone plasma concentration in male mule ducks: Effects of sampling sites, repeated samplings and ACTH injections

1. Changes in plasma corticosterone concentrations according to puncture sites and various challenges including injections of an ACTH agonist (Immediate Synacthen) were investigated in male mule ducks. 2. Lower concentrations were measured in samples drawn by puncture from the occipital sinus than at a wing vein site. 3. Immobilisation and a single intramuscular injection of saline solution (1 ml, 0.9%) had no effect on plasma corticosterone after 15 min. 4. A single intramuscular injection of ACTH (5 microg/kg body weight) produced a rise (P<0.05) in corticosterone. Maximum concentrations were measured after 10 min and, in the absence of further sampling, a return to initial levels was observed by 1 h. 5. On the other hand, repeated bleedings following ACTH challenge maintained higher corticosterone concentrations. 6. A single intramuscular injection of ACTH at doses ranging between 0.625 to 20 microg/kg body weight increased corticosterone concentrations (P<0.05) in a dose-dependent manner, with the responses plateauing at doses of 1.25 microg/kg and higher.

A century of progress in waterfowl production, and a history of the WPSA Waterfowl Working Group

Waterfowl production has been on an upward trend and has become increasingly important around the world over time. The production of ducks worldwide in 2010 was 6-fold greater that of 1961, and that of geese was 9.8-fold over the same period. The progress in waterfowl production represents not only an increase in the quantity of the product, but also in quality. Waterfowl performance progress, genetics and breeding, reproduction, nutrition, management and housing, and product quality and utilisation are discussed in this article, alongside a review of the history of the Waterfowl Working Group (WWG) which was established in 1969 as Working Group 8 under the European Federation (EF). After moving to the Asian Pacific Federation (APF) in 2011, it became Working Group 2.