Fat composition
Fats and oils are mainly composed of fatty acids, which differ in chain length and degree of saturation. The number of carbons in the chain determines the classification of fatty acids in short-chain (C1-5), medium-chain (C6-12), or long-chain fatty acids (C13-21). The bond between carbons determines the degree of saturation of fatty acids as saturated (single bonds) or unsaturated (double bounds). Animal fats contains more saturated fatty acids and are solid at room temperature, whereas vegetable oils have more unsaturated fatty acids and are liquid at room temperature.
Animal fats, such as choice white grease, beef tallow, and poultry fat, are derived from rendering whereas vegetable oils are extracted from seeds, such as corn oil, soybean oil, and canola oil. Also, waste cooking oil or yellow grease is produced from rendering. These sources of fat and oils are available for feed-grade use in swine diets either as a single source or as a blend.