Lesions can occur on the sternum of the birds due to necrosis of the skin. This is observed more frequently in birds reared in cages rather than on the floor. The prevalence is higher in Mulard ducks (40–70%) compared to under 6% in Muscovy ducks. This is due to the larger pectoralis profundus major and minor muscles in Muscovy ducks compared to Mulards. The relatively new Mulard breed used in foie gras production seems more prone to developing lesions in the area of the sternum when kept in small cages, and to bone breakage during transport and slaughter.