This review, which focuses on foie gras production from ducks in France, highlights welfare problems that may arise in the final (third) stage of production, when force-feeding occurs and which lasts 12 to 15 days. Welfare problems arising in the first two stages are also considered. The male mulard duck, a non-migratory hybrid between a muscovy drake (Cairina moschata) and a female domestic duck (Anas platyrhynchos), is used most frequently despite being fearful, nervous and maladapted to force-feeding conditions. During the period of force-feeding, mortality is 2 to 6%, higher than in fattening units for meat production. Welfare deteriorates markedly as ducks progress through the three production stages. Posture and gait abnormalities and wing lesions develop, and contact dermatitis is widespread and often severe. Oesophagitis and other injuries are documented. Steatosis and other liver changes are pathological and can limit duck survival. Group housing necessitates the use of crowd-gates to facilitate force-feeding of birds, which show aversive behaviour towards the force-feeder. Cages are small, with a mesh floor without litter or a rest area. Access to open water for bathing or full immersion of the head may be insufficient and make thermoregulation difficult. We conclude that forcefeeding causes very poor welfare in ducks and should not be practised. Should foie gras production without force-feeding become possible, duck livers should not reach a weight at which there are pathological effects. Inadequate housing and management conditions should be prevented by establishing limits for the prevalences of contact dermatitis (foot-pad and digits), breast lesions and gait abnormalities, which should not be exceeded prior to slaughter. Limits should also be established for the prevalence of wing and other body lesions after slaughter.

In order to avoid excess feed consumption during the force-feeding period in foie gras production, a dose-response experiment with seven feed consumption levels (450, 540, 630, 720, 810, 900, 990 g/day per bird) was conducted to evaluate the effects of feed consumption levels on growth performance and carcass composition of male Mule ducks from 91 to 102 days of age. One-day-old Mule ducklings (sterile and artificial hybrid of male Albatre Muscovy duck and female Pekin duck were fed a two-phase commercial diets for ad libitum intake from hatching to 91 days of age, followed by graded feeding levels of a corn diet by force-feeding from 91 to 102 days of age. Fifty-six 91-day-old male Mule ducks with similar BW were randomly assigned to seven treatments, with eight birds per treatment. Birds were housed in individual pens. At 102 days of age, final BW was measured and BW gain and feed conversion ratio of ducks from each treatment were calculated from day 91 to 102, and then all ducks were slaughtered to evaluate the yields of skin with subcutaneous fat, abdominal fat, breast meat (including pectoralis major and pectoralis minor), leg meat (including thigh and drum stick), and liver. Significant differences in BW gain, total liver weight and liver relative weight were observed among the treatments (P<0.001). According to the broken-line regression analysis, the optimal feed consumption levels of male Mule ducks from 91 to 102 days of age for maximum BW gain, total liver weight and liver relative weight were 217, 227 and 216 g feed/kg BW0.75·per day, respectively.