Mitigating the impact of ammonia emissions from poultry

Sustainability and safeguarding the environment are key issues for the poultry industry. The industry is proactively managing its environmental obligations in the face of toughening environmental legislation and governmental initiatives, particularly where ammonia and nitrogen output is a focus. There are several approaches the industry can use including the use of feed additives that can directly influence ammonia production and therefore improve nitrogen utilisation.

David Harrington
teamTWO Solutions, Denmark
Sebastián Decap
Plantae Labs, Chile

Livestock production produces gaseous emissions. It’s a simple, clear, unavoidable fact. Whether it’s methane from belching and flatulent cattle, hydrogen sulphide from swine manure or ammonia from poultry droppings, pollutant gases from livestock production make their way into the environment and potentially damage ecosystems.

Sustainability and safeguarding the environment are key issues for many industries, including livestock. But the livestock industry is already taking proactive steps to manage its environmental impact while legislation and governmental initiatives push hard at the heels to make quicker progress. There are several tools available to help lower emissions and meet environmental obligations and feed additives, such as Quillaja saponaria, are one such example.

Estimates on the level of different pollutants from livestock are highly variable and subject to different interpretation but estimates suggest 0.4 to 15 kg of CO2 equivalents are produced for 100 g of animal protein alone, before considering the contribution of processing and supporting industries, such as cereal production for feed etc. If we look at green-house gases (GHG) as a group, the literature suggest livestock production contributes anywhere from 7 to 18% of GHG emissions.

While levels of pollutants are open to discussion, there is one area of consensus: pollutants such as ammonia can cause considerable damage to the environment. Excess nitrogen in manure spread onto land leads to acidification of soil and environmental eutrophication. High ammonia levels in animal sheds can affect animal welfare and performance and pose a risk to human health.

While it’s easy to focus on livestock production as the villain for many environmental woes, there is another 82 to 93% of GHG’s attributable to industries other than livestock. However, livestock production is in the environmental crosshairs of governments and several initiatives have been implemented to combat increasing emissions e.g. EU Directive 2010/75/EU or the stance taken by the Netherlands to aggressively decrease nitrogen pollution.

While poultry and egg production are amongst the lowest producers of GHG’s, the industry still has an obligation to do all it can to reduce its environmental impact. In many countries the poultry industry is tackling this problem head-on and improving nitrogen utilisation is a focus.

Nutrition is a key focus to improve nitrogen utilisation. For example, we can use more digestible ingredients, alternative protein sources or add more essential amino acids to improve the efficiency of nitrogen use. We can also look at reducing dietary crude protein (CP) by using nitrogen-balanced diets based on digestible amino acids. Insoluble fibre can influence digestibility of protein and other nutrients, but consideration needs to be given to fibre type if used in fibre-rich diets. Multi-phase feeding programmes can balance the diet to changing nutritional demands of the birds and have been shown to have no detrimental impact on performance while lowering overall faecal nitrogen content.

Feed additives are a diverse group including enzymes, organic acids, probiotics, phytogenics, etc. Enzymes clearly have a role improving nutrient utilisation in poultry feed and have been used for many years. Proteases can support the reduction of dietary crude protein and reduced nitrogen excretion via improving protein digestion.

Many types of feed additive have typically been used with a focus to support intestinal health. By helping birds to have a balanced microbiota, gut health and therefore feed utilisation is improved. It is a well-told story of poor gut health in birds leading to protein fermentation in the hindgut and subsequent proliferation of Clostridium perfringens and production of endotoxin resulting in necrotic enteritis. However, as the importance of environmental sustainability grows, so feed additives look to broaden the scope of their modes of action beyond managing the gut microbiota alone, from modulating specific immune mechanisms to indeed, improving nutrient digestibility with data to support matrix values to include in feed formulations.

Plants and plant extracts are highly complex containing hundreds of compounds, each compound can exert a different effect. Often, trying to fully understand the mode of action is difficult and furthermore, is it always necessary? After all, if a product is effective and safe and does the job, isn’t that enough? Issues can arise if more than one additive type is to be combined in feed. Do they have complementary modes of action, for example? Are they synergistic? Some plant combinations can interact antagonistically. Sometimes it can be useful to have a single component product, with a clear purpose and mode of action that is easier to fit into a production system with other products. Quillaja saponins are a good example of a single source, targeted phytogenic.

The Soap Bark Tree (Quillaja saponaria Molina) from Chile provides a sustainable source of saponins for use as a feed additive, either in the raw form (pulverised bark) or as a concentrated, water extract. Quillaja is comprised of over 100 triterpenoid saponins (molecules that have a non-polar aglycone core attached to two monosaccharide moieties) that have a broad range of activity from immunomodulatory to antifungal and antiprotozoal. When used in the raw form, Quillaja also contains polyphenols, salts, and carbohydrates amongst other compounds.

Quillaja saponins are used in many industries from soap and beverages to vaccine adjuvants; their application is diverse. Quillaja saponins are also very good at reducing ammonia emissions in livestock production systems and supporting gut health which is where our interest in them in poultry production lies.

Quillaja saponins have dual mode of action. They bind ammonia but they also interfere with the microbial conversion of uric acid to ammonia that occurs in the faeces in the litter. Reducing ammonia in the litter helps improve litter quality with a consequent reduction in possible footpad burns.

Fig 1a. In vitro reduction of ammonia after 48 hours following addition of Quillaja saponaria (Feed Sap 3.5)

In in vitro assays, Quillaja saponins (Feed Sap 3.5, Plantae Labs) have been shown to bind ammonia, reducing ammonia levels by up to 92% (Figure 1a). In real world, on farm testing, Quillaja has been demonstrated to be highly effective at lowering environmental ammonia, irrespective of season. In two studies run over 4 months in winter and spring, ammonia levels in the laying shed were reduced by 57 to 63%; the reduction in ammonia can be observed quickly, sometimes within 5 days.

Fig 1b. A rapid reduction in daily ammonia concentration can be observed in the poultry shed following supplementation of Quillaja

The benefits of Quillaja also extend to bird performance, particularly when birds see enteric challenges from parasite such as Eimeria and recover. This has been observed where Eimeria infected birds fed Quillaja saponins demonstrate improved zootechnical performance (11% better weight gain, 14% improved FCR) and 45% lower oocyst output and lower lesion scores versus infected controls.

Figure 2. Bird weight gain 7 days post Eimeria oral challenge / Columns with different letters are significantly different at P<0.05

The benefits of Quillaja in these scenarios are unsurprising. Quillaja supports the bird immune system and modulates inflammatory responses while also disrupting the membranes of the invading Eimeria sporozoites, likely interfering with their ability to invade intestinal cells and ultimately cause disease.

The poultry industry is under increased scrutiny by Regulatory authorities and consumers to play an active role in reducing its already low environmental footprint. Ammonia is a significant gaseous pollutant from growing and laying birds and there are numerous interventions the industry can take to lower ammonia output and improve nitrogen utilisation. Quillaja saponins offer a low cost, effective tool to help manage ammonia emissions in addition to supporting gut health, particularly during periods of intestinal stress and pathogen challenge.

About Dr Sebastian Decap
Dr Sebastian Decap is the Technical Director of Plantae Labs, Chile, a company applying new technologies to the production of Quillaja saponins to enhance efficacy and sustainability. He obtained his veterinary degree from Universidad de Chile and his MSc in Animal Science from Wageningen University, Netherlands. He has worked as a consultant and nutritionist for Chilean beef and dairy operations before moving into feed additives with Chile Botanicals. He stayed with the organisation as during their acquisition by Naturex and recent spin out into Plantae Labs, where he is responsible for managing R&D activities and developing the business in the agricultural space.

About Dr David Harrington
Dr David Harrington is the Managing Director at teamTWO Solutions. He obtained his BSc and MSc from Edinburgh University, UK, and his PhD from Newcastle University, UK researching avian immune responses to ectoparasite infections. During his early career he worked in the development and commercial support of swine and poultry vaccines. For the last 10 years he has worked with feed additives from probiotics and organic acids to phytogenics in both commercial/strategic and technical roles globally.