Effect of stocking density on performance, welfare and environmental conditions in meat-turkey production.

After the approval of a specific Directive on broiler chicken protection in EU, the debate on welfare has been focusing on turkey production. The aim of the trial was to evaluate if a stocking density lower than that applied under commercial conditions improves the production and welfare indexes of turkey as well as air and litter quality of the poultry house. 22,800 female one-d-old BUT turkeys were split in 2 experimental groups of 2 replicates each and allotted in 4 boxes of the same environmental controlled poultry house at a stocking density of 5 birds/sqm (Welfare=WLF) and 6 birds/sqm (Standard=STD). Feeder space allowances was of 2.7 and 2.0 cm/bird respectively for WLF and STD groups as well as drinker space was 1.4 and 1.2 cm/bird. Both groups were submitted to the same light and feeding regimens. WLF birds grew up faster and at the slaughtered age (100 d) weighted 300 g more than STD (8.6 vs 8.3 kg/bird). Feed intake and conversion were unaffected by the rearing conditions. Final stocking densities were 37.0 and 45.5 kg/sqm respectively for WLF and STD. The incidence of foot pad lesions (score 0= no lesion, 1= mild lesion and 2= severe lesion) and hock burns, indicators used to measure the welfare status, resulted slightly lower in WLF group reflecting the little differences observed in the moisture content of litter collected at 60, 90 and 100 days in WLF and in STD houses (39 vs 43 , 46 vs 47and 46 vs 47% respectively). The total nitrogen and pH of litter were respectively lower and higher in WLF than STD (3.68 vs 4.54% DM and 8.39 vs 7.91). Ammonia concentration of air was 39% higher in WLF boxes due either to the reduced ventilation rate (less animal heat production) or to the higher release from the litter due to its higher pH value. Reduced stocking density while improving the growth rate of animal worsen both litter and air quality of turkey houses.