The relationship between breast blisters and the availability and use of perches by organic broilers

Summary

Organic broiler producers are concerned that the occurrence of breast blisters is associated with perching. This was investigated together with a comparison between two strains. Four groups of each 60 Labresse broilers and 12 groups of each 60 i657 broilers where housed indoors in straw bedded pens (9.5 m2) and fed ad libitum with standard organic broiler feed. The birds were subjected to one of three perch availabilities: 15 cm per bird (Labresse and i657), 7.5 cm per bird (i657 only), and 0 cm per bird (i657 only) with four replicates per treatment. At 43 days of age 52 birds from each group were moved to outdoor housing facilities with access to grass-covered outdoor areas (each 9m by 22m). The use of perches was monitored via video recordings throughout the experimental period until slaughter on day 84. The incidence and severity of breast blisters were recorded on a scale from 0 to 2 at slaughter. Data were analysed using GLM.
Groups of i657 with the highest perch availability used these more than groups with half the perch length (9.5 vs. 3.9 birds perching at midnight; P<0.001) and groups of i657 with perches had a higher breast blister score than groups with no access to perches (0.24 vs. 0.12; P<0.05). Labresse had a higher breast blister score than i657 (0.58 vs. 0.24; P<0.001), but used the perches significantly less (0.1 vs. 9.5 birds perching at midnight; P<0.001) and weighed less (2011g vs. 2246g; P<0.01) than i657. Males had a higher breast blister score than females, and this was most prominent in the Labresse strain (1.06 vs. 0.08; P<0.001). In some broiler strains access to perches may increase the occurrence of breast blisters, but significant strain differences in the occurrence of breast blisters are also found independent of perch use.