Today, there is a great interest in Swedish agriculture in recycled manure solids (RMS) since it can provide a safe supply of cheap bedding material. However, there are hygiene risks associated with its use, which can, however, be controlled through proper handling at the farm. Disturbed animal health and increased ammonia emissions can also occur using RMS. For biogas plants, the digestate is often associated with high costs and there is great potential to produce large quantities of hygienic bedding material at the biogas plants. It is therefore of great importance to develop knowledge about and guidelines for the use of RMS as bedding material in Sweden. Used correctly, RMS can contribute to a positive effect on the competitiveness of farmers. The project is a collaboration between Hushållningssällskapet Halland, Växa Sverige and SLU.
By separating manure into a solid and a liquid fraction, the solid fraction can directly, or after storage and/or hygienisation, be used as bedding material in cattle houses. The use of recycled manure solids (RMS) as bedding material is quite new in Sweden, but more common in e.g. UK, USA, Netherlands and Denmark. The interest of using RMS for bedding material is increasing due to the decreased availability and increased price of other common bedding materials. The climate scenarios indicate that the rainfall during the summer will decrease in the southern Sweden, increasing risk for drought and reduced harvest. This can cause a shortage of straw that is the most common bedding material in Sweden. The summer of 2018 was extremely dry in Sweden and many neighbor countries, and the use of RMS as bedding is therefore highly topical. The present project deals with the crucial issues about the effect of RMS on hygiene, animal health, milk quality, economy and environment. Results from other countries are not consistent and cannot directly be transformed to Swedish conditions, production system, economy and climate.
RMS can also be produced after anaerobic digestion at a biogas plant. Depending on substrate, including manure from other farms etc., the spread of contagious bacteria may be a risk. Today this is not allowed by the animal by-product regulation. The project will investigate the possibility to hygienise RMS from biogas plants by heat and acid for use as bedding material.
The project has a multidisciplinary research effort and is expected to give more knowledge on the following questions:
- To what extent will hygiene, animal health and milk quality be affected by the use of RMS as bedding material in Swedish dairy barns?
- To what extent will the treatments anaerobic digestion, hygienisation and acidification reduce the bacteria load in RMS. The results are expected to act as a scientific support for a possible change in the “Animal by-product regulation” to enable the use of RMS from selected biogas plants.
- How will different types and treatments of RMS affect the ammonia emission from Swedish dairy cow houses?
- Can the use of RMS decrease the risk for methane emission production during storage of manure or digestate?
- What are the production costs using RMS as bedding material depending on treatment compared to other materials?
Aims and objectives
The aim of the project is to develop the use of recycled manure solids (RMS) as a bedding material for Swedish dairy farmers. Furthermore, to examine how different types and management of RMS affect hygiene, animal health, milk quality, methane potential of manure, production economy, as well as environmental impact. An additional aim is to investigate whether RMS from extern biogas plants is a possible, future product to use as bedding material, and if addition of acid can be used for hygienisation and reduction of ammonia emission.
The objective is to propose appropriate guidelines for the production, storage and use of RMS as bedding for Swedish dairy farmers to preserve biosecurity, animal health, milk quality, economic viability and minimal climate impact.