Individual perching behavior of laying hens and its effects in cages.

1. ISA Brown hens were housed, from 18 to 71 weeks of age, as groups of 4 in cages with 675 cm2/bird. There were 7 treatments: control cages and 6 treatments with perches fitted across the rear of the cage. Five treatments had 450 mm wide cages, with perches made from hardwood, textured metal, smooth plastic, softwood and padded vinyl, and one treatment had a 600 mm wide cage, with a softwood perch. There were 4 cages in each of the first 6 treatments and 6 in the last. 2. Overall, birds spent about 25% of the day time on perches. Most time (28 to 41%) was spent perching on the 600 mm softwood perches. Among 450 mm perches, most time (25 to 30%) was spent on the softwood perch and least (13 to 23%) on the plastic; the results suggested that a slightly rough surface was preferred. Individual birds varied considerably in the proportion of day time they spent perching; this variation was relatively consistent over time. 3. Overall, the proportion of birds roosting on the perches at night was 85% in period 1; declined to 76% by period 6, probably because increased body size made it almost impossible for 4 birds to perch in the 450 mm cages. Birds roosting on the floor tended always to be the same individuals. 4. Damage to the soles of the feet was less in all treatments with perches than in control cages. It was least in 600 mm wide cages and showed a negative correlation with time spent perching, both within and between treatments. Long or twisted claws, in contrast, tended to be slightly worse in treatments where there was most perching. 5. Downgraded eggs tended to be slightly more frequent in cages with perches; the greatest proportion (cracked 1.4%, dirty 3.6%) was from the 600 mm wide cages, as a result of hens laying from the perch and a build-up of manure behind it. 6. Although problems remain the findings suggest that provision of perches is important for the welfare of hens; perch space should be sufficient to allow all birds to perch simultaneously.