Manganese (Mn) is an element required in nutrition, functioning largely in the enzyme systems involved in lipid and carbohydrate metabolism. It plays an important role in growth, bone development, perosis prevention, optimal eggshell quality and performance maintenance of poultry. The current NRC (1994) guidelines recommend 20 and 60 mg/kg of Mn for laying hens and broilers, respectively. In practical poultry feeds, however, the dietary requirement of Mn is considered higher than these values. Traditionally, Mn is added to the diet in the sulphate form, which is typically used as the standard in nutritional studies. However, in recent times, other, more natural forms have been made available to the feed industry, e.g. organic chelates. From this current review of published data, it appears that inorganic Mn supplementation up to 200 mg/kg is ineffective on the performance of both laying hens and broilers but at lower levels it improves eggshell quality. The dietary Mn requirement of laying hens and broilers appears to be 90 mg/kg, and the availability of Mn-sulphate is higher than that of other inorganic Mn sources but lower than its organic sources. More studies should be undertaken to determine the optimum Mn requirement in its various forms for laying hens and broilers.
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