Theo van Kempen North Carolina State University

Publish Date: March 25, 2010

Animal production involves the feeding and care of animals to obtain usable end products, such as meat or milk. Since the efficiency with which animals use nutrients is less than 100%, a portion of the nutrients supplied to the animal is excreted as feces. The end/byproducts of metabolism are excreted in urine. Traditionally, these excreta were used as fertilizers for crops and thus were an integral part of the nutrient cycle. Over the last decade, animal production has expanded significantly in areas without adequate local feed production. To sustain expanding animal agriculture, feed ingredients were shipped in from major crop producing regions, initiating the import of nutrients, including nitrogen and phosphorus into animal producing regions. Due to the bulk of animal manure relative to its weight, shipping it to the feed producing regions for use as a fertilizer was not economically viable. Alternative methods to deal with manure were thus sought. Some are focused on different processing and storage techniques after manure production, while others deal with reducing the excretion of nutrients in manure. This factsheet outlines some of the underlying principles for modifying pig diets with the objective of reducing nutrient excretion and ammonia and odor emissions.

Publish Date: July 8, 2006

North Carolina State University Swine Nutrition Research from 2003. Corn constitutes a major portion of swine (and poultry) feeds. As such, its impact on manure production by animals can be expected to be substantial. Indeed, sieving fresh feces obtained from grower pigs (Kasper et al., unpublished) demonstrated that approximately 40% of the fecal dry weight was corn hulls (pericarp). This suggests that removing pericarp (indigestible fiber) prior to feeding pigs may result in a substantial reduction in manure production.

Publish Date: July 18, 2006

North Carolina State University Swine Nutrient Management Research from 2001. The objective of this study was to investigate the effect of different sources of calcium and phosphorus in swine diets on urine pH and ammonia emission. Experiment 1 evaluated the impact of acidogenic calcium and phosphorus sources on urine pH. In Exp. 2, the effect of acidogenic calcium and phosphorus sources on in vivo ammonia emission were determined. In Exp. 1, urine pH was decreased (P<.05) in animals consuming diets containing phosphoric acid+calcium sulfate (PA) and monocalcium phosphate+calcium sulfate (MCP). In Exp. 2, the ammonia concentration (NH3), ammonia emission per feed intake (NH3/FI), and ammonia emission per nitrogen uptake (NH3/NI) were significantly decreased in the pigs fed the phosphoric acid+calcium sulfate grower diet (PA-G) compared with the control diet. The ammonia reduction percentages of PA-G diet were 27.7, 30.6, and 30.4%, respectively. The phosphoric acid+calcium sulfate finishing diet (PA-F) decreased NH3 concentration only (25.3%, P=.06) as feed intake was decreased with this treatment. Also, the combination of calcium sources (50% CaCO3 + 50% CaCl2) with monocalcium phosphate (MCPCl) diet led to a decreased NH3 (18.8%, P=.07), NH3/FI (16.1%, P=.07), and NH3/NI (15.7%, P=.07) emission. It is concluded that diet manipulation of acidogenic agents can reduce ammonia emission from swine manure.

Publish Date: July 18, 2006

North Carolina State University Swine Nutrient Management Research from 2001. Ammonia is one of the gases produced in greatest volume from swine waste. It constitutes a serious environmental threat due to its potential for ground water nitrification and adverse effects on animal and human health. Engineering microorganisms to be more efficient in removing ammonia from their environment and in converting this ammonia to stable, non-odorous compounds is one way to reduce the ammonia problem. These engineered microbes can be added to feed as probiotics (direct fed microbials) or used in biofiltration systems. In order to reduce ammonia levels from animal production, a novel chimeric enzyme has been created to efficiently utilize ammonia and fix it in stable organic compounds. The chimera consists of the carbamoyl phosphate synthetase/aspartate transcarbamoylase cDNA except that the portion encoding the aspartate binding domain has been replaced by the ornithine binding domain sequence of porcine ornithine transcarbamoylase in order to alter substrate specificity. The chimera has been synthesized, cloned, and identified by plasmid size and restriction pattern. By creating the chimera, we hope to avoid the inhibition normally exercised by pyrimidine pathway metabolites thereby establishing a system for continual ammonia removal and conversion to useful, stable compounds.

Publish Date: July 17, 2006

North Carolina State University Swine Nutrition Research from 1998-2000. Adipic acid is available as an odorless and pleasant tasting crystalline powder approved for feed acidification. Beyond acidification of the feed, adipic acid may have certain other characteristics of interest to animal production. When consumed, a portion is excreted in urine, and this may lower the urine pH, and thus ammonia emission. Adipic acid also shows a great structural similarity to several of the key intermediates in the lysine degradation cascade, and Cerdan (1988) hypothesized that adipic acid may inhibit lysine degradation.