Foot and keel bone disorders in laying hens - Effects of artificial perch material and hybrid

The studies reported cover two experiments comprising 684 layers of the hybrids Dekalb XL, LSL and Shaver 288 (Expt. I) and 744 ISA Brown and LSL layers (Expt. 2) kept in Get-away cages with 15 birds per cage, and in conventional cages with 4 birds per cage. At 35 and 55 weeks of age birds were scored for the appearance of bumble foot, toe pad hyperkeratosis, keel bone lesions, claw length, foot hygiene and hygiene of perch and cage floor (Get-away cages). Birds' use of perches was recorded by visual observation. Expt. 1 made use of a circular profile perch with flattened upper and lower surfaces made of European beech hardwood or of plastic, and Expt. 2 utilized the same hardwood perch and the same design but with a reduced diameter covered with a 4 mm rubber layer. All perches had equal exterior measurements, 38 x 33 mm. Bumble foot and keel bone lesions appeared only in Get-away cages and toe pad hyperkeratosis only in conventional cages. Scores for bumble foot were significantly different between all three white hybrids and between LSL and ISA, always being inferior in LSL. In Expt. 1, the plastic perch resulted in more bumble foot than the hardwood design. In Expt. 2 there was no significant effect of perch design on toe pad hyperkeratosis, keel bone lesions or bumble foot. Hygiene of feet was better in conventional cages than in Get-away cages. Although artificial materials were easier to keep clean than hardwood perches, it is concluded that plastic is not a suitable material because it increases the incidence of bumble foot, and that a soft rubber cover does not reduce bumble foot or keel bone lesions compared with plain European beech hardwood perches of equal diameter. Significant interaction effects between hybrid and perch design/keeping system, especially regarding bumble foot and toe pad hyperkeratosis, indicate that genotypes are differently adapted to environmental designs in terms of the clinical health aspects studies.