#05-130

Complete

Date Full Report Received

04/16/2007

Date Abstract Report Received

04/16/2007

Investigation

Institution:
Primary Investigator:
Co-Investigators: Doug Hamilton

Results from these experiments suggest that dietary manipulation can have dramatic effects on the mass balance of nutrients during the finishing phase. Altering the dietary crude protein and phosphorus concentration in the diet reduced nitrogen and phosphorus excretion by 30 and 35%, respectively. Lowering the trace minerals in the diet reduced the excretion of iron, zinc, copper, and manganese by 40 to 60%. Additionally, the reduction in dietary crude protein resulted in a 59% reduction in ammonia emissions during the finishing phase for pigs housed in a facility with a shallow pit, pull-plug, recharge system. However, dietary treatment did not effect hydrogen sulfide emissions. When the inputs and outputs of nitrogen and phosphorus for the finishing phase were evaluated, dietary manipulation can markedly increase the percentage of nitrogen and phosphorus leaving the finishing phase via the pigs compared to the slurry. These reductions were observed without any effects on growth performance, carcass traits, or whole body composition of finishing pigs. Furthermore, feed costs per pig were not affected by the dietary manipulations employed in this experiment. Current models for predicting excretion appear to accurately estimate nitrogen excretion, but may underestimate P excretion for finishing pigs. Results from the nursery phase suggest that excretion increases with age and feed intake, and that trace mineral supplementation can have profound effects on excretion. The waste treatment system employed at a particular site can markedly affect nutrient concentration of the effluent and affect the mass balance of nutrients for the whole production system.