Effects of Fiber Addition (10% Soybean Hulls) to a Reduced Crude Protein Diet Supplemented With Synthetic Amino Acids Versus a Standard Commercial Diet on Pig Performance, Pit Composition, Odor and Ammonia Levels in Swine Buildings

Purdue University 1999 Swine Research Report. The swine industry is facing many challenges. Environmental awareness and stewardship fall near the top of the list. Producers have to incorporate these criteria into any management decision on the farm. If not, they face the possibility of odor complaints and/or fines levied by state regulatory agencies. In efforts to reduce the amount of odor emission, researchers in industry and academia have designed many different ways to combat this problem. Pit additives, ventilation systems, manure treatment systems, and dietary manipulation are all ways currently available to reduce odor, with some more effective than others. While many of the ventilation system and manure treatment system alternatives are effective, they are capital intensive. With these methods, there is no reduction in initial nutrient excretion from pigs, but the nutrients are in a more stable, less odorous form. Pit additives can be effective, but again there is no real reduction in the volume of nutrients that must be removed from the operation and it can be a significant increase in diet cost. Dietary manipulation has shown much promise, with most of the research attempting to reduce the crude protein of swine diets by including synthetic amino acids to more closely meet the actual needs of the pig. Some research with this type of dietary manipulation has shown a reduction in performance and an increase in backfat accretion. The poor performance has been attributed to many things, and is perhaps due to an amino acid deficiency, changes in the essential to nonessential amino acid ratio or an upset in the acid-base balance of the animal. Differences in backfat accretion are presumably due to the increased net energy content of the reduced crude protein diets. Adding a fiber source to the reduced crude protein diets should bring net energy into equilibrium. Previous research at Purdue University has shown that the addition of fiber (soybean hulls) will serve to give microorganisms in the hindgut of the pig an energy source for the production of microbial crude protein (MCP) and volatile fatty acids (VFA). This benefits in three ways. First, additional energy is available to the pig in the form of VFAs for protein or lipid synthesis; second, the increased VFAs will decrease manure pH and reduce volatilization of odorous compounds; and third, more of the excreted nitrogen is incorporated into MCP. By shifting nitrogen excretion from the traditional form of urea in the urine to MCP in the feces, the nitrogen is not volatilized into ammonia. This creates a better building environment for pigs and people, less complaints of ammonia, and more usable N for field application. This trial was conducted to test whether a reduced crude protein diet with the addition of 10% soybean hulls could reduce odor while maintaining similar performance in a production setting.