Technologies and practices to improve feed and nutrient utilization by pigs.

This review aims to summarize the current practices producers can use to improve feed and nutrient utilization with a focus on providing critical information for use within future life cycle assessments of the swine industry. Nutrient utilization by pigs can be improved by closely meeting the nutrient requirements for maintenance, growth, and reproduction, which reduces nutrient excretion. For example, N excretion can be reduced by 8% and 3.7% for every percentage unit reduction in crude protein for growing pigs and lactating sows, respectively. Similarly, reducing excess trace minerals or replacing inorganic Cu, Zn, and Mn with lower additions of organic sources can reduce excretion by 28% to 42%, 38% to 53%, and 12% to 20%, respectively. Adoption of precision feeding strategies can lower N and P excretion by at least 11%. Ingredient selection and use of feed additives that enhance nutrient digestibility are also an important component in improving feed efficiency and nutrient utilization. The use of exogenous carbohydrase and protease can improve feed efficiency by 1.8%, while phytase can enhance P digestibility by 30% to 50%. At the feed mill, feed efficiency can be improved by 1% for every 100-µm reduction in particle size and by 8% with pelleting. At the farm, management practices such as reducing overfeeding of developing gilts and sows, increasing meal frequency, and minimizing feed wastage can also improve feed utilization. For example, feed wastage is estimated to represent 5% to 6% of total feed disappearance, and feeder type can reduce this by 1% to 10%. Lastly, non-nutritional strategies to improve feed efficiency should be considered, including genetic selection, managing thermal environment, and improving herd health. Current genetic selection results in a reduction in greenhouse gas production by 0.5% to 1.5% per year. Likewise, compared to healthy pigs, disease-challenged pigs have 6.3%, 7.9%, 7.4%, 5.8%, and 5.8% greater climate change potential, soil and water acidification potential, eutrophication potential, cumulative energy demand, and land application requirements, respectively. Currently, the swine industry primarily focuses on feed and management practices that optimize growth and minimize production costs. The challenge to future swine production will be to find emerging technologies that further reduce environmental impacts while still optimizing performance and production costs.