Fat use by the pig
The digestibility of fat is low in weanling pigs but the ability to digest fat increases with age, particularly for animal fats compared with vegetable oils. Therefore, the young pig seems to require a more digestible fat source rich in unsaturated and short-chain fatty acids for an efficient energy utilization than the growing-finishing pig (Gu and Li, 2003). Soybean oil and coconut oil are good sources of energy for weanling pigs (Weng, 2016).
The pig deposits fat in the same fatty acid profile as the dietary fat. This characteristic is particularly important in growing-finishing pigs because the composition of dietary fat is a determinant of carcass fat quality. Diets with vegetable oils or rich in unsaturated fatty acids increase the iodine value and softness of carcass fat. The iodine value estimates the degree of unsaturation of carcass fat, with higher iodine value associated with softer pork fat (Benz et al., 2011). Soft pork fat is undesirable because it affects the ability to process pork bellies and to meet specifications of fresh cuts of pork. Some pork processing plants have established a maximum allowable iodine value cutoff, which may limit the amount of fat sources, especially unsaturated fats or oils, in finishing diets.