Bone Mineral Density and Breaking Strength of White Leghorns Housed in Conventional, Modified, and Commercially Available Colony Battery Cages

Abstract

Limited opportunity for movement and load-bearing exercise for conventionally caged laying hens leads to bone loss and increased susceptibility to osteoporosis, bone fractures, and cage layer fatigue, all of which compromise hen welfare and have negative consequences for production. The objective of this study was to compare bone mineral density (BMD) and strength measures of White Leghorns housed in conventional battery cages (CONV), cages modified to incorporate a nest box and perch (MOD), and commercially available, furnished colony cages with (CWDB) or without (CWODB) a raised dust bath. Hens reared on floor litter were randomly allocated to 1 of 4 cage systems at 19 wk of age. Hen-day production and egg quality were measured between 20 and 64 wk. At 65 wk, hens were killed, and right femur, tibia, and humerus were excised. Bone mineral density was assessed using quantitative computed tomography, and breaking strength was measured with an Instron Materials Tester. In the femur and tibia, CONV hens exhibited lower total BMD, bone mass, cortical bone area, cortical bone mass, and bone-breaking strength than CWDB, CWODB, and MOD hens. Density and cross-sectional area of bone in the trabecular space was highest in CONV. In the humerus, total and cortical BMD and mass and breaking strength values were higher for colony-housed birds than hens in CONV and MOD. The MOD birds did not exhibit increased humeral BMD or strength measures over CONV hens. These findings provide evidence that hens housed in modified and colony cages, furnished systems that promote load-bearing movement, are better able to preserve cortical structural bone than conventionally caged hens and simultaneously have stronger bones. Furthermore, inclusion of raised amenities that encourage wing loading is necessary to reduce humeral cortical bone loss. The overall absence of correlation between egg production or quality and bone quality measures also suggests that improved bone quality in CWDB, CWODB, and MOD furnished cages is not the result of lowered egg production or quality.

Effects of calcium to non-phytate phosphorus ratio and different sources of vitamin D on growth performance and bone mineralization in broiler chickens

“…Tibiae were cradled on two support points measuring 4 cm apart. A force was applied to the midpoint of the same face of each tibia using a 50 kg load cell with a crosshead speed of 10 mm min -1 (Jendral et al, 2008).…”

Interaction between housing system and genotype in relation to internal and external egg quality parameters

“…Data from a number of studies revealed differences in egg quality depending on the housing system. Moorthy et al (2000), Leyendecker et al (2001a) and Jenderal et al (2004) reported higher egg weights in cages, while Tůmová and Ebeid (2005), Pištěková et al (2006), Zemková et al (2007) found out heavier eggs on litter. Quality traits such as egg shell thickness, Haugh unit score and yolk index were reported to be higher in cages than on litter (Roland et al, 1997;Moorthy et al, 2000;Tůmová and Ebeid, 2005;Lichovníková and Zeman, 2008).…”

Minimally-Invasive Assessments of the Behavioural and Physiological Effects of Enriched Colony Cages on Laying Hens

“…Previous studies have suggested that perch use can maintain the strength of the leg bones of laying hens [16,18] and that this is a function of maintaining bone volume [17] and density [20]. Nevertheless, in a comparison among laying hens housed in unfurnished and furnished cages there were no significant affects of the housing conditions on the weight, breaking strength, elastic strain or stiffness of the humerus [21].…”

“…Bone mineralization can be accurately and precisely measured by quantitative computer tomography (QCT) scans. This technique has previously been used to assess mineralization of the bones of laying hens at the end of the production cycle [19] and in response to housing conditions [20]. In the present study, the effect of cage enrichment, i.e.…”