Effect of Protein-Energy Relationships on the Performance and Carcass Quality of Growing Swine

Abstract
The effect of protein level, energy level, sex and slaughter weight on growth, feed efficiency and carcass characteristics was studied in growing pigs. As protein level increased above 13% average daily gain and feed required per lb of gain decreased. Increasing the protein level decreased carcass backfat thickness, carcass yield (dressing percent) and intramuscular fat but increased yield of lean cuts (percent of chilled carcass wt.). Energy level of ration had no significant effect on tissue N but increased fat in longissimus dorsi. Barrows gained faster than gilts. Little difference in rate of gain was observed between boars and gilts, although boars were more efficient than gilts. Pigs marketed at 200 lb. gained faster and had a higher dressing percent than did pigs slaughtered at 150 lb.; however, the 150 lb. pigs had less carcass backfat, a higher percent of lean cuts, a higher percent of tissue N and less intramuscular fat.