Metabolic disorders: Limitations to growth of and mineral deposition into the broiler skeleton after hatch and potential implications for leg problems

Metabolic diseases are associated with a rapid early growth rate in poultry, especially in broilers, and their incidence can be decreased by slowing early growth. Leg problems seen in the absence of infectious agents are often the result of fast early growth and thus can be related to metabolic diseases. At hatch, the broiler skeleton is poorly mineralized; growth and mineralization occur most rapidly in the first 2 wk of life. Except for Ca, the embryo has limited access to minerals. Most minerals in the egg cannot be influenced by maternal diet, but embryo mineral uptake can be improved by dietary mineral source selection. The use of management tools to reduce metabolic diseases that rely primarily on decreasing feed consumption, without increasing prestarter mineral density, may have negative unintended consequences on skeletal development. Incidence of losses due to leg problems during growout and processing have decreased since the early 1990s, in part due to breeding programs, but not enough information is available to estimate the proportion of losses related to metabolic diseases. This information is needed if improvements are to be made.