The VIR-check is a test used for assessing the effectiveness of broiler house cleaning and disinfection. This test determines the viral pressure in a broiler house. Based on 10 swabs from 6-7 day old chicks, a quantitative multiplex PCR test assesses how many common resistant intestinal viruses the chicks picked up in the first days of life. The VIR-check score is easy to interpret with four color coded categories (green, yellow, orange and red). This tool shows the result of farm hygiene and disinfection and it also stimulates to continuously improve this process. Research shows that chicks with a lower VIR-check score grow faster. If a farm improves from category red to category green, this will result in more than 100 grams of extra growth per chick in 6 weeks.