Nutrition-Gene Interactions (Post-Genomics): Changes in gene expression through nutritional manipulations

This paper discusses the effects of severe nutritional restriction, both pre- and post-weaning, on development of skeletal muscle in food animals. Given recent predictions about growth in demand for muscle-foods in developing countries, the global community will need to face the food-feed dilemma, and balance efficiency of production against the quality-of-life aspects of local livestock husbandry. It is likely that production animals will be grown in successively more marginal environments and at higher stocking rates on unimproved pastures. Understanding the nutritional limits to animal growth at the level of muscle gene networks will help us find optima for nutrition, growth rate and meat yield. Genomic approaches give us unprecedented capacity to map the networks of control under nutritionally restricted conditions, though the challenges remain of identifying steps that regulate substrate flux. The paper describes some approaches currently being taken to understanding muscle development, and concludes that the genes contributing to two ruminant phenotypes should be mapped and characterized. These are: the capacity to depress metabolic rate in response to nutritional restriction; and the capacity to exhibit compensatory growth after restriction is relieved.