Influences of Fermentable Carbohydrates on Shifting Nitrogen Excretion and Reducing Ammonia Emission of Pigs

Abstract

There is increasing evidence that nitrogen (N) excretion is shifted from urea in urine to bacterial protein in feces when fibrous feedstuffs are included in the diet. Carbohydrates also beneficially affect the host by selectively stimulating the growth and activity of one or a limited number of bacterial species that are already resident in the cecum and colon of pigs and are known to extend health-promoting properties. Ammonia emissions were reduced significantly in monogastric animal manure by adding a variety of carbohydrate sources to the basal diet, although certain fractions of carbohydrates are not involved or are less involved in reducing these emissions. When sucrose thermal oligosacchride caramel (STOP) was added to the basal diet of pigs at 2%, both stored manure and fresh manure had reductions of 62 and 37%, respectively, in NH3-N, while total Kjeldahl nitrogen (TKN) in the stored manure and fresh manure declined by 55 and 35%, respectively. The addition of cellulose at 5% to the pigs basal diet resulted in NH3-N reductions of 73 and 68% in stored and fresh manure, respectively. TKN levels were reduced by 35 and 61%, respectively, in stored manure and fresh manure. The addition of paper products at 2.5 to 5.0% reduced ammonia emission by 29 to 47%. Soybean hulls added at 10% reduced emissions 21 to 41%. When sugar beets were added at 6.1% of the diet, ammonia reduction was 45%. A 0.15% addition of lactosucrose resulted in a 50% reduction in ammonia emissions from the cecal contents of chicks. Lactosucrose when supplemented at 1.5 g/day to the dog and 0.175 g/day to the cat resulted in ammonia reductions of 53% and 47%, respectively, in their feces. The inclusion of fermentable carbohydrates in pig diets can be a practical method for ammonia emission control and reducing nitrogen excretion. However, these effects on ammonia emission and nitrogen excretion need to be verified in practical situations. Primary odor-causing compounds evolve from excess degradable proteins and lack of specific fermentable carbohydrates during microbial fermentation. Continued research to incorporate protein degradation with fermentable carbohydrates in the lower gastrointestinal tracts of pigs will further control odors and N excretion from swine manure.