Cameron Jose

The iron content of pork meat is low in relation to lamb and beef even though it can vary considerably according to muscle type, with the ‘redder’ (more aerobic) muscles generally possessing higher iron levels. Australian pork currently does not meet the Australian Food Standards Code requirements of being a food that is “a good source” of iron, for to achieve such a rating the food must contain no less than 25% of the recommended daily intake (RDI) for that mineral. Furthermore, it appears that the iron content of Australian pork may be lower than that reported by other major pig-producing countries such as Canada and the USA. Evidence to date indicates that various nutritional strategies (e.g., adding more iron to the diet) to elevate the iron content in pork been largely unsuccessful suggesting that muscle iron storage is refractory to dietary iron content, the amount of which can vary in the diet according to the age and feeding phase of the pig. In this context, muscle-specific manipulation of iron levels by examination of the effects housing systems or dietary formulation may be possible assuming any increased iron absorption directly relates to a deposition in the muscle in redder/more aerobic fibre types. Three experiments were conducted to test the general propositions that (i) pigs raised in deep-litter/eco-shelter systems will have more iron and myoglobin than their counterparts that are raised indoors (“conventional”); (ii) feeding diets lower in iron (to induce mild iron depletion) followed by feeding diets higher in iron (to induce iron repletion) will increase circulating serum iron levels and will increase levels of iron in a redder muscle type; and (iii) there will be differential expression of candidate genes implicated in muscle iron metabolism in relation to feeding different iron concentrations throughout the grower finisher stages of growth.