Integrating Manure Into Feed Ration Optimization.

The value of manure supplied nutrients (nitrogen, phosphorus and potassium) has increased significantly over the past decade. Feedstuffs, such as distiller’s grains (DDGS) have been incorporated into the diets in ways that reduce the need for P supplementation. These developments have moved manure from a waste product to a co-product in livestock production. By integrating feed and manure management decisions it was hypothesized that profit could be improved. This project evaluated least cost swine rations and how they might have changed during the past 10 years if manure value had been incorporated into the ration optimization decision. We examined rations for 50-100 lb. and 200-250 lb. pigs. Rations were optimized with the following limitations: 1) manure was/was not included in the objective function; 2) DDGS were/were not allowed as a feedstuff in the rations. Assuming that the full value of the manure could be obtained, incorporating manure into the least cost ration optimization had no effect in 2002 to 2006 but reduced net diet cost four of the next five years for 50-100 lb. and 200-250 lb. pigs. The ten-year mean improvement in net diet cost was $0.18/ton with a range from $0 to $0.58/ton of feed when DDGS were allowed in the diets. Increasing manure value required increasing feed cost by a 10-year average of $0.44/ton.  The least cost ration always included DDGS’s at the maximum allowable percentage independent of the inclusion or exclusion of manure value. Phytase was never needed to obtain the least cost ration when manure value was considered.