When determining a diet for a pig population the goal has traditionally been to reduce the costs of the diets while maintaining the minimum nutrient requirements to promote growth. This method has led to expensive nutrients like phosphorus and nitrogen to be under used because while some pigs in a herd require high amounts of P and N, some pigs in the same herd do not require as much, and therefore do not digested nutrients and excrete them. This is problematic for two reasons, the excretion causes inefficiency in feed use because costly nutrients are essentially wasted and when the slurry with high amounts of P and N is spread over a field it saturates the soil and water systems which is considered bad for the environment. Precision feeding is proposed as a way to make feeding more efficient and less harmful to the environment. By giving each pig specific diets that meet their individual nutrient requirements for the day reduces the amount of excreted nutrients thus saving money and protecting soils and water systems. Determining individual diet requirements can be a challenging task but can be achieved using linear programming that computes an objective value while considering several constraints that must be met. One way to utilize precision feeding is by way of phase feeding. The introduction of phase feeding was proven to reduce feed costs by as much as 4.6% and to reduce excretion by 38%. New technology in Spain is able to estimate each pigs dietary requirements for that day and deposit that amount to the specific pig, although this method still needs to be presented in an economically viable way and accuracy of predictions must be improved.  Precision feeding has multiple benefits and is constantly being pursued as a way to make swine production economically and environmentally sustainable.