Herbage intake and use of outdoor area by organic broilers: effects of vegetation type and shelter addition

The herbage intake and use of outdoor areas by organic broilers were investigated in an experiment laid out in two fields, i.e., a grass?clover pasture and wheat stubble with undersown clover. Each field was divided into two plots, one with and one without extra shelter consisting of camouflaging nets around huts constructed from straw bales where the broilers were housed during the night. Five hundred birds were assigned to each of the four treatment combinations. To analyse the use of outdoor areas with respect to herbage intake, plots were divided into three smaller areas surrounding the night house: P1 (most intensively used area), P2 (intermediate area) and P3 (least intensively used area). The mean daily herbage dry matter intake per broiler between 25 and 80 days of age was 10.7 g, irrespective of vegetation type. The amount of herbage consumed represented up to 7 and 3% of the birds’ daily protein and energy requirements, respectively. When extra shelter was provided, the area of P1 increased, suggesting that some extra protection gave the broilers more confidence to explore further areas of the plots. However, the total frequently-used area (P1+P2) was not affected by the presence of extra shelter, indicating that there was a critical distance (about 20 m in this study) that was seldom surpassed. It is concluded that adding shelter in the field contributes only marginally to a more even distribution of the excreta