Effect of Dietary Protein and Fat on Growth, Protein Utilization and Carcass Composition of Pigs Fed Purified Diets

Thirty-two baby pigs were used to study the effect of added calories in the form of corn oil on protein utilization, growth and carcass composition. Purified diets containing 5% or 18% protein either as casein or purified wheat gluten were used. Levels of 3%, 13% and 23% corn oil were employed with each protein source. An increase in growth rate was observed on the casein diets as the energy level was increased; however, a depression in growth rate occurred with the gluten diets, especially at the 23% corn oil level. Grams of feed required per gram of gain were reduced by the addition of corn oil; however, number of calories required per gram of gain was not influenced by energy level. Apparent protein digestibility was not affected by either source of protein or level of energy in the diet. Added energy had no significant effect on grams of nitrogen retained. All the animals maintained a positive nitrogen balance throughout the 21-day experimental period even on the gluten diets. Animals consuming the casein diets exhibited greater nitrogen retention than those on the gluten diets. The addition of corn oil resulted in an increased carcass fat content of animals receiving the casein diets but not in those on the gluten diets. Carcasses of animals on the casein diets contained a greater percent of protein than did animals on gluten regardless of energy level.