Effects of litter substrate and genotype on layers' use of litter, exterior appearance, and heterophil:lymphocyte ratios in furnished cages.

Effects of sand versus sawdust as a litter bath substrate in furnished cages for laying hens were studied. The study used 112 Hy-Line White (HYW) and 140 Hy-Line Brown (HYB) layers housed in 18 furnished cages with 14 hens in each cage, generating 4 or 5 replicates per combination of genotype and litter substrate. Traits studied were mortality, feather cover, hygiene of hens, pecking wounds, heterophil/lymphocyte ratios, and hens' use of litter baths. Hens' litter bath use was measured by direct observations and by use of the passive integrated transponder technique. The latter technique allowed for recording of an individual hen's visits to litter baths during the 420-d study. There were no indications of differences between sand and sawdust as litter substrates in mortality rates, exterior appearance, or heterophil/lymphocyte ratios. Litter baths with sand or sawdust were occupied to the same extent but dustbathing behaviors were more frequently seen in baths with sawdust. Hens of both lines visited the litter bath to the same extent but HYB performed more dustbathing. There was large variation in the number of days that individual hens visited litter baths; in fact, 30% of the hens never entered litter baths, whereas some hens visited baths almost every day. The HYB hens had inferior feather cover compared with HYW, indicating that feather pecking occurred more frequently in cages with brown hens. The HYW hens had lower body weight, longer claws, and more comb wounds than HYB. In conclusion, sawdust seems to be an acceptable alternative to sand as a litter substrate in furnished cages.