Digestibility of Several Known Dietary Manipulations Used in Combination to Reduce Nutrient Excretion in Pigs
Purdue University 2002 Swine Research Report. The concern associated with the effect of excess nutrient excretion on the environment, as well as odor emissions, continues to grow as suburban communities are beginning to develop in many rural areas. Historically, livestock operations have served as a source of balancing nutrients for cropland which in turn can be recycled back to the animal through grain sources. With the large increase in use of commercial fertilizers and the intensification of livestock production, nutrients are being concentrated to a smaller land mass and present the potential for runoff and leaching of nutrients such as nitrogen (N), phosphorus (P), and potassium (K). It is predicted that agricultural practices in the Mississippi River Basin contribute approximately 2-3 lbs of nitrogen per agricultural acre to the Mississippi River each year. The fertilizer value of this lost nitrogen is valued at $410 million. (CAST, June 1999). Not only does this lost nitrogen have the potential to accumulate and cause low dissolved oxygen levels in waterways, it is a great loss of fertilizer to the farmer. Similarly, phosphorus can pollute waterways through soil erosion and sedimentation. It has been well documented that manipulation of dietary components can significantly increase nutrient utilization and therefore reduce nutrient excretion in growing pigs. In a previous growth trial at Purdue University conducted by Kendall et al. (2000), pigs were housed in environmentally controlled rooms with separate pits and fed a low crude protein (CP) highavailable phosphorus (HAP) corn diet with synthetic amino acids, 5% soybean hulls, 0.05% phytase, and reduced mineral sulfates. The combination diet resulted in lower aerial ammonia concentrations, as well as lower total and ammonium nitrogen in pit manure contents. There was also a 53% reduction in P content of manure. To further analyze the nutrient utilization of these diets by growing pigs, a digestibility trial using similar diets was conducted to determine the effect of dietary manipulations used in combination on nutrient excretion in feces and urine.