By the time a pig reaches 250 pounds, the animal will have generated 1.5 tons of waste. That waste includes such things as manure, urine, bedding material, feed and water, and it doesn’t always stay put as you intended.

Animal waste can be transmitted through runoff of nutrients, organic matter and pathogens to surface water; nitrogen and pathogens leaching to ground water; and gas and odor volatilization into the atmosphere. Pollutants can start at production facilities, manure-storage structures (lagoons and ponds) or on land where manure is collected or applied. The main contaminants are excess nutrients, ammonia, hydrogen sulfide, methane, odor and pathogens, such as Salmonella, E. coli and Campylobacter.

They have varying degrees of impact. Excess ammonia, for example, has been correlated with delayed onset of puberty in gilts, and continuous exposure to high levels can damage the epithelial cells that line the respiratory tract. So, for multiple reasons, they are worth addressing.

Indicators of a facility’s potential environmental impact include the total nitrogen excreted, as well as excess nitrogen and phosphorus. Evaluating the total excreted nitrogen levels can help identify problems for the whole operation, from the production facility to land application.

Because nutrients that exceed a crop’s needs can leach off into the field and water resources, it’s always best to match the nutrients to the crop needs, and then find a place to use the extra manure elsewhere. Some ways to align nutrients are to sample the manure in storage to determine its nutrient content, and test the soil type, as well as the nutrient concentration of land application sites, to better match the crop’s needs.

Handling Manure and Gases

Odor and gas emissions are, of course, big issues worth addressing. You can add chemicals to the manure during the collection stage, which bind nutrients and reduce odorous compounds and ammonia emissions. By decreasing atmospheric emissions you increase the manure’s nitrogen content, which also increases its fertilizer value.

Trapping air vented from production facilities and treating it before it discharges also can minimize odor and gas release. For example, the North Carolina Extension Service has design criteria for ventilation systems that move particles into pits and trap them in the liquids, which then move to a lagoon for treatment.

Covering manure-storage tanks and lagoons greatly reduce ammonia and other discharges such as hydrogen sulfide, nitrous oxide, methane and carbon dioxide. Covers create a physical barrier at the liquid/air interface. They also help keep volatile chemical compounds in the liquid phase and minimize emissions into the air. According to USDA, conserving nitrogen in tank and lagoon waste increases the effluent’s fertilizer value, but it can increase manure-management costs to protect water quality.

Another tactic is to separate the urea from solid fecal matter, using sedimentation basins or mechanical methods, which can prevent some of the reactions that cause ammonia and odor to form. This can help reduce the cost of moving waste to land for disposal. Incorporating or injecting manure into the soil also can help reduce ammonia and odor, but it can increase the risk of nitrogen getting into the ground water.

Taking a Nutritional Approach

In the Netherlands, several research projects have studied ways to reduce swine manure’s environmental impact. The more substantial reductions have come through nutritional approaches. These have focused on improving the efficiency of dietary nitrogen and phosphorus utilization. The fact is, growing pigs use between 30 percent to 35 percent of the nitrogen and phosphorus they ingest. It's possible to greatly cut ammonia emissions through nutrition that’s directed at reducing the urea content and pH of urine and slurry. Cutting slurry’s urea and pH levels can reduce ammonia emission by 11 percent to 45 percent.

Many pork producers are turning to new technologies such as computer modeling, and feeding enzymes and organic minerals to improve production efficiencies and reduce costs. However, many of those technologies also help minimize environmental impacts. Some feed additives can boost a diet’s nutrient utilization, thereby reducing nitrogen and phosphorus needs.

You can reduce phosphorus excretions if it’s supplied through the diet at a level and in a form that best meet the pig’s needs, considering the pig’s genotype and physiological stage. For example, during the growth phase, a very lean pig will require 5 percent to 6 percent more phosphorus than a more “typical” pig. Phytase, an enzyme naturally present in wheat, barley and rye, and produced by microbial flora, can greatly improve the assimilation of the phosphorus from phytate phosphorus. Diet formulation based on wheat or barley will reduce the phosphorus excretion compared to corn-based diets. Adding phytase to feed is another way to reduce phosphorus excretion.

One way to increase digestibility is by creating unique enzyme complexes with solid-state fermentation technology. This results in improved feed utilization and reduces the impact of anti-nutritional components.

Organic minerals offer yet another approach. In a 2001 North CarolinaStateUniversity study, 18 pens of pigs were divided among three treatments, beginning at 63 days of age through 112 days of age. The diets were based on Phase II and Phase III grower diets. Researchers measured animal weights, feed intake, weight gain, mortality and copper content of fecal samples. Two copper supplementation treatments — copper sulfate and organic copper — were compared to a control diet.

The two copper treatments showed no significant differences for feed conversion, with a significant reduction in feed intake when compared to the control group. There was a 46 percent decline in fecal copper from pigs fed the organic copper, compared with those fed copper sulfate.  The results tell us that organic copper is an effective way to reduce manure copper concentrations while maintaining optimal animal performance.

Another new technology that some have embraced is the use of nature-made products to address ammonia challenges. Ammonia release from nitrogenous compounds and ammonia uptake for microbial protein synthesis are continual processes. When bacteria are overwhelmed, release outpaces uptake and ammonia accumulates. Using a yucca-extract product can moderate the ammonia supply to bacteria and maintain steady bacterial growth and ammonia assimilation.

There is increasing pressure on the pork industry world-wide to become more efficient, reduce production costs and reduce the industry’s environmental impact. Today’s consumers expect the products that they buy to provide environmental responsibility assurances. At the same time, the industry needs to continue to improve the eating quality and nutrient value of its product to meet consumers’ expectations. Embracing new technologies and developing a manure-management plan can help pork operations handle both product and environmental challenges effectively.