In Finland, broilers are bred under the All- in/ All-Out principle without thinning the flocks. The method is a requirement for ensuring biosecurity, it improves food safety (prevents the spread of campylobacter and salmonella) and reduces stress and injuries among the broiler chickens, as fasting and loading only occurs once during their life. With this method disease pressure is lower, the birds are doing better and are healthier. As we do not thin the flocks, maximum stocking density is 42 kg / m2. The number of placed chicks is limited and there is clear target weight for the chicks. That makes the growth more optimal not maximal and that have positive impact of health. Healthier birds grow better, and feed efficiency is better. No need for antibiotics. Prevention is cheaper than the consequences of the disease. When maximum stocking density is 42 kg/m2 and no thinning, a stocking density of 30 kg/m2 is exceeded during an approximate period of 5 days preceding the date of slaughter. This means that each broiler chicken is only subjected to a stocking density above 30 kg/m2 for less than seven days during their life. The method includes the monitoring of production and slaughter results, as well sanctions if the goals are not reached. Higher stocking density in the end of growing period requires good rearing conditions and good management. The producer must be competent.