Housing conditions alter properties of the tibia and humerus during the laying phase in Lohmann white Leghorn hens

Abstract

Osteoporosis in caged hens is one driving factor for the United States egg industry to explore options regarding alternative housing systems for laying hens. The aim of our research was to study the influence of housing systems on tibiae and humeri of 77-week-old Lohmann White hens. Pullets raised in an aviary system were either continued in aviary hen systems (AV) or conventional cages (AC) whereas pullets reared in conventional cages continued in conventional hen cages (CC) or enriched colony cages (EN) at 19 weeks. From each group, 120 hens were randomly euthanized and right and left tibae and humeri were excised for structural and mechanical analysis. Volumetric density of the cortical bone was measured using quantitative computed tomography (QCT). Aviary (AV) hens had greater cortical thickness and density but similar outer dimensions to AC hens (P < 0.05). Hens in EN system had humeri with similar cortical thickness and density but wider outer dimensions than the humeri of CC hens (P < 0.05). Cortical geometry of the tibiae was the same for the EN and CC hens, whereas EN hens had denser tibial cortex than CC hens (P < 0.05). Geometrical changes in the humeri suggest that hens in the AV system were better able to protect their structure from endosteal resorption during the laying phase. Humeri of AV and EN hens had increased second moment of area compared to the AC and CC hens; however, the changes were not observed in tibiae. Mechanical property differences were observed, with bones of AV hens having greater failure moment and stiffness than AC hens and the same difference was observed between the EN and CC hens, (P < 0.05). These findings indicate that movement limitation causes loss of bone mass and density whereas provision of moderate movement increases certain bone quality parameters during adulthood in laying hens.

Influence of physical activity on tibial bone material properties in laying hens

“…The improved bone mechanical properties of aviary birds should be directly related to greater physical activity of these birds in this type of housing (Fleming et al, 2006) which have been confirmed during lay (Leyendecker et al, 2001;Regmi et al, 2016) and during rear (Regmi et al, 2015). Prolonged immobility in cage hens increases bone resorption whereas increased physical activity (as in aviary birds) stimulate bone formation and remodeling.…”

A metabolite of leucine (β-hydroxy-β-methylbutyrate) given to sows during pregnancy alters bone development of their newborn offspring by hormonal modulation

“…Bending moment can be described as a yield load adjusted to the bone length and it indicates bone elastic load capability [30]. The elastic stress reflects the elastic strength of midshaft cortical bone, the ultimate stress is equal to the maximum stress a bone can withstand in bending before fracture [30, 31]. …”

Reproductive management of poultry

“…111 There are also differences in leg bone characteristics with hens under the cage free conditions having increased cortical cross-sectional area and cortical density of their humerus and tibia compared to those maintained in conventional cages. 112 Moreover, there was there was greater stiffness of both humerus and tibia and increased percentage ash in the humerus in hens in a cage free system. 112,113 However, in another study, there were little differences between tibia and humerus parameters between hens in cage-free or conventional cage systems.…”

“…112 Moreover, there was there was greater stiffness of both humerus and tibia and increased percentage ash in the humerus in hens in a cage free system. 112,113 However, in another study, there were little differences between tibia and humerus parameters between hens in cage-free or conventional cage systems. 111 In laying hens at the end of the laying cycle, there were differences in bone characteristics depending on the environment under which the pullets were raised.…”

“…111 In laying hens at the end of the laying cycle, there were differences in bone characteristics depending on the environment under which the pullets were raised. 112 Production has been compared between Lohmann Brown layer hens in convention layer housing, enriched convention layer housing and free-range systems. Perhaps unexpectedly, egg production was greater in hens in a freerange system (average production over cycle 89.3%) compared to conventional layer housing (87.3% with enrichment and 87.1% without).…”