Poultry farming involves a variety of risks associated with the environment and constant exposure to various contaminants: viruses, bacteria, parasites, fungi and dust, which affect weight gain and increase mortality. This is why poultry house disinfection is an important aspect to take into account.

Contaminants in poultry farming cause the immune system to be constantly and increasingly active, since it tries to prevent diseases, and it increases the need for more protein and energy. It causes higher feed consumption, with less daily weight gain, delayed growth of the birds and an increase of the prevalence of infectious diseases. It, therefore, increases production costs and contamination of meat for human consumption.

Therefore, the cleaning of the facilities and equipment and, generally, poultry house disinfection is a useful action to prevent diseases and reduce environmental pollution in livestock facilities.

The evaluation of the cleaning and disinfection of poultry facilities is an action that ensures cleaning with the least degree of contamination and helps to decrease the infective pressure.  When evaluating cleaning and poultry house disinfection programmes, the aim is to detect the most contaminated sites, those that require special attention, to improve the process and, thus, significantly reduce contamination and the infectious agents that may cause diseases and make sure there is a better environment for the next flock.

Methods to evaluate the contamination level in poultry house disinfection programmes

The existing methods to evaluate the level of contamination of the facilities are classified into indirect and direct.

The indirect methods relate to health status of the birds and the level of contamination of the houses. They do not indicate the degree of contamination or which contaminants are involved. Among them, we can mention daily weight gain, necropsies, trace checks and visual and olfactory inspection.

On the other hand, direct methods can determine the degree of surface contamination; it is related to the presence of adenosine triphosphate proteins or measures the number of bacterial colony forming units involved.

Poultry house disinfection should be carried out until the entire house is completely clean, dry and all the repairs to the house have been completed, since disinfectants reduce their power or are not effective in the presence of dirt or organic matter.

Disinfection methods in poultry house disinfection

The most used methods for disinfection with chemical agents in poultry houses are spraying, foaming and thermo-misting.

During disinfection, a methodology should be followed to ensure that all areas, equipment and materials present within the stalls are covered. After disinfection, the house should be kept closed if possible, to avoid entrance of harmful fauna.

We must make clear that disinfection is not a substitute for cleaning and that it must also have certain characteristics:

• Highly germicidal.
• Non-toxic for man and birds.
• Effective in the presence of moderate amounts of organic material.
• They must not stain or be corrosive.
• Soluble in water.
• Capable of penetrating materials and crevices.
• Not associated with foul odors.
• Cheap and easily available.

Kinds of disinfectants

There are different kinds of disinfectants among which we could name phenols, quaternary ammonium, halogens, oxidizing agents, chlorexidine compounds and alcohols.

The main objective of these disinfectants is to reduce microbial populations as much as possible by acting on the microorganisms to destroy their membranes, inhibit their metabolism or lysing the cell.

• Phenols

These are coal tar derivatives with a carbonic acid base. Such disinfectants are effective against fungi, gram-positive and negative bacteria, but they are not effective against bacterial spores and only control some viruses. In high concentrations, phenols act as a protoplasmic toxicant, penetrating and disrupting the cell wall and precipitating cell proteins, but in low concentrations only the enzyme systems of the cell are affected.

• Ammonium Quaternaries

These are odorless, transparent, non-irritating compounds with deodorizing and detergent action; they are extremely soluble in water and their germicidal property is reduced in the presence of organic matter. These substances are effective against gram-positive organisms, moderately effective against gram-negative ones and control some fungi and viruses.

• Aldehydes

They react with proteins of the capsid and compounds of the nucleic acid inside the viral particle, but their degree of diffusion is given by the time, potential, pH and nature of the water. Formaldehyde is usually a 40% dilution of formalin. It is widely used to disinfect in the form of steam when mixed with potassium permanganate, thus producing a very toxic steam. To be effective, this vapor must be maintained at temperatures above 22°C and a relative humidity of 65% for several hours before being used.

In some countries, formalin has already been banned because it is a carcinogenic and extremely irritating agent to the skin and eye. It also causes headaches, especially in the workers who apply it.

The productive and economic benefits of a biosecurity program that includes a strict cleaning and poultry house disinfection protocols are of utmost importance in poultry production.

Cleaning and disinfection of poultry houses are very important, meticulous and time-consuming activities, where in addition to evaluating the disinfection processes, it is important to evaluate the quality of the water, its mineral content and its purification, as well as to wash and disinfect water tanks, pipes and food stores.