EFFECTS OF CAGE VERSUS FLOOR REARING ENVIRONMENTS AND CAGE FLOOR MESH SIZE ON BONE STRENGTH, FEARFULNESS, AND PRODUCTION OF SINGLE COMB WHITE LEGHORN HENS

Fourteen hundred pullets were reared at densities of 304 and 735 cm2 in cages and floor pens with litter, respectively. Feeder spaces of 2.7,4.0, and 5.4 cm per bird were held constant during the brooding growing period. At 18 wk of age, the birds were housed four birds per cage (348 cm2 per bird) in a force-ventilated, light-controlled house with two rows of stair-step cages. In two rows, the standard 2.5 x 5.0 cm welded wire flooring was replaced randomly with 2.5 x 2.5 cm welded wire in eight-cage sections. Egg production, egg quality, feed conversion, and mortality were measured over a 48-wk production cycle. At 68 wk of age, a sample of hens was selected and euthanatized, and the right leg was excised for further evaluation. Rearing environment, rearing feeder space, or type of layer floor mesh had no significant effects on hen-day production or feed conversion. Hens reared in cages produced heavier (P < .001) eggs with a higher percentage of Grade A eggs and had fewer body checks than floor-reared birds' Femur, tibia, and shank lengths were not affected by the rearing treatments or the type of flooring in the layer cage. Tibia breaking strength was not different for the rearing systems or hens maintained on 2.5 x 2.5 vs 2.5 x 5.0 cm welded wire mesh flooring. Hens reared in floor pens on litter displayed a higher level of fearfulness at the end of the production cycle. The reduced (P < .05) body weights associated with cage rearing and reduced feeder space did not negatively affect the production variables. Alteration of the mesh size of layer cage floor had no effect on the production levels of the hens.