The transition of piglets at weaning from a liquid milk diet to a solid feed is dramatic and can result in low intake and poor growth post-weaning. The digestive tract has been accustomed to milk and as a result is still relatively immature. It has the capability of digesting components of milk, such as milk fat, protein, and lactose, very well. However, the digestibility of nutrients from plant sources and other ingredients used in baby pig diets is low at the time of weaning. As the pig consumes more feed, the levels of digestive enzymes responsible for the breakdown of starches, proteins, and fats increase. Therefore, getting the pig to consume feed quickly is extremely important in getting off to a good start.
A comparison between the nutrient composition of sows milk and a common early weaning ration is presented in Table 1. The main difference between the two sources is the level of fat, and therefore the level of energy the pig has available for growth. This high level of fat, physically cannot be attained in a practical pig ration. In addition, fat in sow milk is very well digested by the pig compared to fat sources added to nursery diets (particularly animal fats).