|Cheng, Heng Wei|
Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2003
Publication Date: 7/1/2003
Citation: KOPKA, M.N., CHENG, H., HESTER, P.Y. BONE MINERAL DENSITY OF LAYING HENS HOUSED IN ENRICHED VERSUS CONVENTIONAL CAGES. POULTRY SCIENCE. 2003. Interpretive Summary:
Technical Abstract: Cages enriched with nests, perches, scratch pads, and dust baths may allow birds to display behaviors that they normally cannot express in conventional cages. In addition, these enrichments may increase bird activity and subsequently improve skeletal integrity. The objective of the current study was to determine the effect of cage enrichments on bone mineral density (BMD) of White Leghorns. Hens were housed in three caged environments: 1) conventional cages with 3 hens/cage (645 cm² of floor space/bird), 2) conventional cages with 6 hens/cage (645 cm² of floor space/bird), and 3) enriched cages with perches, dust bath, scratch pad, and nest box with 10 birds/cage (610 cm² of floor space/hen). For BMD, repeated measurements of the left leg (tibia and fibula) and wing (humerus) were taken from 12 live, unanaesthetized birds from each of the cage environments at 30, 40, and 50 wk of age using a Norland pDexa X-ray bone densitometer (Model No. 476D014). Using the mixed model procedure of SAS and body weight as a covariant, an analysis of covariance with repeated measurements (30, 40, and 50 wk of age) was conducted using the cage environment as the whole plot with the type of bone (tibia and humerus) within a bird as a sub-plot. Although the BMD of the tibia tended to be greater for hens housed in enriched cages as compared to hens of conventional cages at 30, 40, and 50 wk of age (P=0.08), the increase was significant only at 40 wk of age (P<0.05). The humerus showed an increase in BMD at 30 but not at 40 and 50 wk of age (treatment x bone x age interaction, (P<0.05). There was no difference in the BMD of the tibia and humerus between the 3 hens/cages vs. the 6 hens/cage of conventional cages at any age. It is concluded that cage enrichments improved skeletal integrity perhaps through increased activity.