Concerns over low levels of intramuscular fat and poor eating quality of meat from modern lean lines of pigs have focused attention on approaches to increasing the marbling fat content of pork. A number of techniques to increase intramuscular fat by manipulation of the nutrient composition of the diet have been evaluated. These have included feeding of protein deficient diets and of excess dietary leucine levels (Cisneros et al., 1996). Leucine is a ketogenic amino acid, the carbon skeleton of which can be used to synthesize fatty acids in muscle. In a previous study (Cisneros et al., 1996) feeding excess dietary leucine increased intramuscular fat and also improved muscle color. This study was carried out to validate those findings.