Pathogenic micro-organisms are a continuous threat for broilers as they can cause illness, immunosuppression and poor performance. A good start of a broiler flock begins with healthy chicks in a clean house. It is important to prevent poultry from becoming infected with pathogens, especially young chicks, with cleaning and disinfection (C&D) of empty broiler houses playing an important role here.

Visual inspection doesn’t give information on the success of the disinfection. Bacterial sampling and ATP-testing provides more information about the results of the C&D regarding bacteria, but representativeness is questionable as only very small parts of the broiler house are sampled. Bacteriological testing provides also limited information about the efficacy of the C&D against viruses, especially the resistant nonenveloped viruses. PCR tests can’t distinguish between inactivated and still infectious virus particles.

With a test where the broilers act as incubator, a much better indication is generated on what was still infectious in the house at the time the day-old-chicks arrive. Viruses quite resistant to disinfectants would fit best to test for. When these resistant viruses are not prevalent anymore, other less resistant pathogens will be inactivated as well.

Based on recent results in a field study, these scores are now divided into four colours: green, yellow, orange and red. This recent field study revealed a significant correlation between the four groups within the VIR check and daily growth rates. Flocks with an yellow, orange or red score showed a reduction of the average daily growth (ADG) of 0.8, 1.6, and 2.4 grams a day over the fattening period compared to flocks with a green score. This showed that by reducing the virus pressure in the house, on average, the flocks performed significantly better. The new VIR check score with the four categories provides farmers, veterinarians, and other involved parties further tools for a more focused approach to farm hygiene and disinfection.