27 27 LOHMANN TIERZUCHT › MANAGEMENT GUIDE Interesting hatcher graph with a good and a perfect hatch window contamination. For better control, a timed dosage of disinfectant is very useful. Disinfection which starts and finishes in one shot isn’t a perfect job because of the de- crease in terms of active ppm: the solution loses capacity over time. In a test, the value of disinfection is very high on day 19, at over 50 ppm, but near 0 on day 20.5. For this rea- son it is better to spread a higher dosage of the disinfectant that we have chosen. IMPORTANT: all disinfectants have to strictly follow the “technical sheet info” in terms of the right dosage and the systemof utilisation. Make sure to verify the activity with chicks’ fluff analysis and to check whether they are compatible and not aggressive with the ma- terial construction of our hatcher machine; some disinfectants are good for bacteria con- trol but extremely corrosive and dangerous.