The cleaning and disinfection of poultry houses, alongside other measures—including those relating to the area outside the house, which are explained below—is essential for maintaining animal health, ensuring food safety, and achieving good animal performance. Under EU regulations (EU Regulation 2016/429 Animal Health Law (AHL)¹⁹) and German legislation (Section 3 of the Animal Health Act (TierGesG)¹⁴), the livestock keeper must ensure that no animal diseases are introduced into or spread from the herd. However, the obligation to carry out proper cleaning and disinfection applies not only in the event of an outbreak, but also to the routine maintenance of clean livestock housing before and after each batch (EU Directive 2007/43/EC (Annex 1, para. 10)¹³, TierSchNutztV²⁰). This not only reduces the risk of diseases and animal epidemics such as avian influenza^8,9, but also of food safety-relevant pathogens such as salmonella and campylobacter. An effective hygiene concept reduces the bacterial load, lowers the number of sick animals and animal losses, and consequently also reduces financial ^losses3. 

By drawing up a biosecurity plan, farmers actively contribute to the United Nations’ 2030 Agenda (Sustainable Development Goals, SDGs)²⁸. A suitable plan, such as the ‘Lower Saxony Poultry Biosecurity Plan’³¹, can help to prevent disease outbreaks and reduce the use of antibiotics. The production of safe, sufficient and nutrient-rich food helps to prevent hunger (SDG 2.1 – Zero Hunger). Furthermore, reducing the use of antibiotics in animal husbandry can help to limit the spread of resistance and ensure that available active substances can still be used effectively in both humans and animals (part of SDG 3.8 – Good Health and Well-being)¹⁰.
The use of chemical cleaning and disinfectant agents, which are necessary for the safe and hygienic production of animal-based food, can have environmental impacts that can be reduced through proper and responsible use. Well-considered cleaning and disinfection procedures tailored to the specific farm not only support global sustainability goals but also provide additional protection for people by ensuring occupational safety.
The following article aims to provide a brief overview of potential environmental impacts, the correct cleaning and disinfection procedures for optimal animal health, and the steps to be taken to ensure occupational safety.

Cleaning and disinfection tailored to the farm’s operations help to maintain animal health throughout the production cycle, thereby minimising the occurrence of sick animals and animal losses. Maintaining a healthy and stable herd is essential not only for animal welfare reasons24, but also for economic reasons.

Active substances used in livestock housing, such as aldehydes (e.g. glutaraldehyde, formaldehyde), quaternary ammonium compounds, organic acids, peracetic acid and ketones, are biocides used to combat undesirable microorganisms. They are effective against pathogens but can enter the environment via wash water, slurry, solid manure and aerosols, where they ^may harm non-target organisms1, which is why they are often subject to the European Biocidal Products ^{Regulation11,12}. In particular, the use of formaldehyde – which may only be applied for disinfection in the veterinary sector with appropriate expertise and following authorisation – must be viewed critically for occupational health and safety and environmental protection reasons. 
A study by the German Federal Environment Agency (UBA)^¹ shows that unnecessary environmental releases can result from incorrect application – for example, due to incorrect dosage, the wrong product, or errors in application or temperature during use. Integrating the substances used into a holistic hygiene management system to reduce unnecessary use is therefore crucial¹⁶. 
To minimise waste of the products used and ensure occupational safety, it is necessary first to check the shelf life of the products, as they may lose their effectiveness if stored for too long1. To avoid packaging waste, bulk containers, concentrates and refill systems are recommended. When stockpiling, however, care should be taken to ensure that the products are used up completely within their shelf life. If expired products and empty containers are disposed of improperly, microplastics can enter soil and water. Empty containers and those with residual contents should be returned to the recycling cycle via local recycling collection points. In the European Union, waste classification is regulated by the European Waste Catalogue (EWC). In Germany, the relevant requirements are set out in the Waste Catalogue Ordinance (AVV²⁵). All waste types classified as hazardous in the EAV are marked with an asterisk (*) after the waste code number. Corresponding disposal instructions can also be found on the cleaning/disinfectant container (see Fig. 2). In those federal states where there is a so-called ‘duty to deliver and hand over’ for hazardous waste (under the Circular Economy Act (KrWG²⁶)), the waste-generating business must inform its competent authority of the type, quantity and composition of the waste, as well as the intended disposal facility. The authority then assigns the waste to a suitable facility²⁷. As a general rule, only products with a current BAuA registration number (Federal Institute for Occupational Safety and Health)¹⁸ should be used to ensure legal and economic compliance. If there is any uncertainty regarding disposal, it is advisable to consult the relevant waste management authority.
Approved products with recommendations for their respective applications, including for organic livestock farming, are listed on the website of the German Veterinary Medical Society (DVG)⁷.

Effective barn hygiene does not rely solely on the appropriate use of cleaning or disinfectant products, but on a systematic, comprehensive approach. First and foremost, careful planning of cleaning and disinfection measures is essential. This must be tailored to the barn environment, size and system, the animal species, as well as the frequency of use and (where known) the presence of pathogens and their resistance. DLG Fact Sheet 364¹⁷ contains a list of critical control points to which particular attention should be paid during cleaning and disinfection.

The recommended stand-down periods for each system and animal species should be observed. During the stand-down period between two cleaning cycles, sufficient time should always be allowed for effective (e.g. contact times) and proper (e.g. drying) cleaning and disinfection. Where necessary, time should also be set aside for any repair work.