Pork characteristics as affected by two populations of swine and six crude protein levels.

Previous research has investigated the effect of genetic line and dietary CP on gilt growth and carcass composition. The aim of this research was to characterize lean tissue composition, color, tenderness, and water-holding capacity as affected by protein level and genetic lines. Thirty-six Gene Pool pigs, a population with low lean growth potential, and 36 Hampshire pigs, a population with a high lean growth potential, had ad libitum access to diets consisting of 10, 13, 16, 19, 22, or 25% CP. Longissimus muscles of Hampshire pigs were lighter, more red, and more yellow than those from Gene Pool pigs (P <.01). Redness and yellowness of longissimus muscles decreased linearly (P <.01) as protein level increased. Chops from Hampshire pigs required less force and less total energy to shear but had lower cooking yields and water-holding capacity than chops from Gene Pool pigs (P <.01). Chops from pigs fed 19 and 22% protein required greater force (quadratic, P <.01) and more total energy (quadratic, P <.05) to shear. Objective color differences revealed that restructured, cured hams from Hampshire pigs were lighter, less red, and had a less intense cured color ( P <.01). The Hampshire line of gilts produced pork muscle that was leaner, more pale in color, more tender, and lower in water-holding capacity than the Gene Pool line. Level of dietary CP caused alterations in tenderness and lean composition, especially when diets contained less protein.