Different stocking densities in Swiss broiler production

In a trial with 4’200 broilers (Ross PM3, male : female = 1 : 1) the effect of different stocking densities (25, 27,5, 30, 32,5 and 35 kg live weight per m2) was studied in 20 units of 16 m2, each. The trial was conducted from day 1 to day 41. Growth perfor-mance, carcass charac-teristics and behaviour parameters were recorded.Due to the different stocking densities, no significant differences were ob-served in live weight (? 2395 g), feed conversion ratio (? 1,75 kg feed per kg weight gain) and total mortality rate (? 4,8%) up to day 41. Above 30 kg per m2,- dirtiness of broilers and litter quality were slightly impaired with increasing stocking density, whereas no differences were seen in foot-pad dermatitis on day 40 (? 25,5% of the animals with lesions). Behaviour characteris-tics on days 32 and 38 were also similar for all stocking densities (? 11,5% standing, ? 3,9% eating, ? 3,8% drinking). Percentage of lower classified slaugh-ter bodies increased with a growing number of birds per m2 (25 to 30 kg per m2: 5,6%, 32,5 kg per m2: 7,5%, 35 kg per m2: 12,4%). This is the main reason why increasing stocking densities from 30 to 35 kg per m2 had hardly no effect on economics, whereas the lower densities of 27,5 and 25 kg were followed by a major reduction of the economical result by 24,7 and 47,2%, respectively (100% = economical result at 30 kg/m2).