Project news Ammonia reduction in pig farming: first results of promising techniques

20/01/2025 Source: Ammoniakreductie in de varkenshouderij

How can livestock farmers reduce ammonia emissions from their farms? There are several recognized techniques on the RAV list in the Netherlands and the PAS list in Flanders. But are there other solutions that are practically feasible, affordable, and scientifically substantiated? The RAMBO project researches, tests, and evaluates promising techniques for pig and poultry farming. In this article we give an intermediate status of the research on ammonia reduction in pig farming.

The RAMBO project selected five promising measures for pig farming. Research is still in progress, but some measures are already showing promising results. During the second sounding board group meeting of the RAMBO project on 07/11/2024 and the study day "The road to less emissions in pig and poultry farming" on Jan 17 2025, the first findings of one year of research and practical experiences were shared.

From feed to manure management: interim results

1. Feed adjustment (lowering electrolyte balance)

The RAMBO project is investigating whether lowering the electrolyte balance in feed can help reduce ammonia emissions. This is done by reducing potassium and sodium in the feed while increasing chlorine levels. This change lowers the pH of the urine, which slows the conversion of urea to ammonia in the manure. Initial results indicate a modest reduction in ammonia emissions. No significant effect on animal health or growth was measured, but there are concerns about possible effects on feed price and potential impact on feed palatability. Further research is needed to evaluate long-term effects.

Additional research planned: Further research will be conducted to evaluate the long-term effects on animal health and the economic feasibility of this measure.

2. Zeolites in feed

Zeolites that can absorb ammonia can be used both as litter on the floor and in the feed. The use of zeolites in the feed appears promising because it requires less zeolites compared to litter application, which was tested in a previous project. Initial tests show that adding zeolites to feed contributes to ammonia emission reduction. However, there is still insufficient data to give specific reduction rates, as only one trial has been conducted. The cost-effectiveness and long-term feasibility of this technique need further investigation. Practical implementation is also under consideration, as the cost of zeolites can be significant.

Additional research planned: Further study is planned on the practical applicability of zeolites on a larger scale and the economic impact of using zeolites in feed, especially considering the additional cost of feed due to the addition of zeolites

3. Air filter (research stopped)

The technique of air filters with zeolites was tested as a way to capture ammonia from the air. In the preliminary tests at ILVO, the air filter, despite its potential, proved to be not effective enough in the pork houses. The filter had too low a capacity for the specific conditions in the pig house, leading to limited ammonia reductions. This result was no better than the control, and therefore it was decided not to continue the test with this air filter. Although air filters with zeolites could potentially be more effective in other contexts, the initial findings for pig farming are less positive.

4. Manure pit additive

Manure pit additives are added to manure to reduce ammonia emissions. The RAMBO project is looking at both bacterial and chemical additives. An exploratory test in manure containers with microbial and biostimulant additives yielded mixed results: some products gave significant reductions in ammonia but were accompanied by increases in methane emissions. Other products gave more stable but smaller reductions in ammonia. The variation in results makes it difficult to draw conclusions. A manure container also does not provide an ideal replication of the barn situation. There is a slight preference for biological additives, as they may be better accepted by society than chemical alternatives.

Additional research planned: Further research is underway to determine how effective the additives are in practical use in the pig barn. This will look specifically at how the additives affect ammonia and other emissions.

5. Daily manure removal

Daily manure removal is a source-based measure in which manure is removed from stables daily to reduce the amount of time it is in contact with the air. This prevents the formation of ammonia by reducing the emitting surface area. The first results of the application of daily manure removal in swine stables are promising, especially in piglet departments. Here a reduction of more than 85% in ammonia and 95% in methane was measured. In fattening pigs, a 60% reduction is achieved because older pigs produce more manure, which reduces the effect of daily manure removal. Nevertheless, daily manure removal remains a promising technique, especially in younger pig units. It also offers benefits for methane reduction and improving indoor air quality.

Additional research planned: Further research is being conducted into the practical feasibility of daily manure removal and what can be done in management to optimize the effects. Another line of investigation is how to further optimize the technique for fattening pigs and what the cost-benefit ratio is for different animal species.

A system is also under development for free-range stall pens. Most free-range stall pens have a large proportion of slatted floor. By increasing the proportion of closed floor, creating a dedicated manure area and removing the manure daily, it is expected that a good emission reduction can be achieved. In addition, the animals will get more comfort through a good large lying area.

Important feedback from the sector

During the sounding board meeting workshop, interim research results were discussed with participants. daily manure removal received broad support because of its proven effectiveness in piglets and potential for wider application. Organic manure pit additives were also viewed positively, provided they are affordable.

With feed optimization, questions were raised about the impact on animal health and cost, underscoring the importance of tailoring to specific farm conditions. The importance of social acceptance and easy assurance of results was also pointed out. These insights will help to further refine the research and make the techniques more applicable.

Hope for the future

The RAMBO project offers pig farmers and other actors in the sector tools to make emission reduction feasible and affordable. Through a combination of source-oriented and supplementary measures, such as feed optimization and daily manure removal, the pig farming industry is developing into a sustainable and profitable livestock industry. Innovation and cooperation remain essential for success.