Environmental Nutrition: Nutrient Management Strategies to Reduce Nutrient Excretion of Swine

Intensive production of swine has brought an increase in the volume of manure produced on farms with limited land area. Exceeding the capacity of soil and crops to handle this volume of manure results in nutrient accumulation in and on the soil that can produce leakage of nutrients to the environment and pollution could result. Environmental nutrition is defined as the concept of formulating cost-effective diets and feeding animals to meet their minimum mineral needs for acceptable performance, reproduction, and carcass quality with minimal excretion of minerals. Pigs normally excrete 45 to 60% of N, 50 to 80% of Ca and P, and 70 to 95% of K, Na, Mg, Cu, Zn, Mn, and Fe when fed diets containing commonly used feedstuffs. Although it is not possible to make pigs 100% efficient in utilization of nutrients, it is possible to reduce the amount of nutrients excreted through careful nutrient management. Several strategies are possible for reducing nutrients excreted: 1) improvements in feed efficiency, 2) more accurate nutrient requirement information for animals and compositional data for feed ingredients, 3) reduced feeding of excess nutrients through overformulation, 4) feeding for optimal rather than maximum performance, 5) use of crystalline amino acids and high quality protein, 6) improving the availability of P and some other minerals, 7) use of phase feeding and separate-sex feeding, and 8) reduced feed waste. Some strategies have a much greater potential for reducing nutrients excreted than other strategies. In the future, diet formulation and feeding must be integrated into total production systems so that swine production systems are environmentally safe as well as economically viable.