Swine nutrition and pork quality: A review

The rapidly expanding body of information concerning swine nutritional impacts on pork quality was reviewed. Energy is required to support muscle growth, but excess energy intake increases fatness. Energy restriction increases leanness but reduces marbling. If amino acid intake is inadequate to maximize protein accretion rate, pigs grow slowly and produce fatter carcasses but have more marbling. Supplementation of the diet with chromium increases muscling, but recent data do not support the early observations of reduced backfat thickness. Addition of conjugated linoleic acid (CLA) to the diet produces leaner carcasses. The softness of fat is related to the composition and level of dietary fat. Dietary fats containing a high level of n-3 fatty acids appear to increase the incidence of off-flavors in pork. Dietary CLA increases the firmness of carcass fat, but a high dietary level of copper decreases it. A high dietary level of vitamin E consistently improves the oxidative stability of pork. It appears that under some circumstances a preslaughter feed deprivation reduces the incidence of PSE. Specific inhibitors of key glycolytic enzymes appear to improve quality characteristics of pork muscle, including pH, waterholding capacity, and color. Addition of a high level of magnesium to the diet for a few days before slaughter markedly reduces the incidence of PSE. Supplemental dietary creatine may improve some muscle quality characteristics. Supplementing the diet with a high level of vitamin D has not been shown to increase tenderness of pork, as it has for beef. However, it may be that further research will identify a combination of dietary concentration and duration of feeding that will improve tenderness. Nutritional means to improve pork quality exist.