Effect of rearing environment on bone growth of pullets

Abstract

Alternative housing systems for laying hens provide mechanical loading and help reduce bone loss. Moreover, achieving greater peak bone mass during pullet phase can be crucial to prevent fractures in the production period. The aim of this study was to determine the housing system effects on bone quality of pullets. Tibiae and humeri of White Leghorn pullets reared in conventional cages (CCs) and a cage-free aviary (AV) system were studied. At 16 wk, 120 birds at random from each housing system were euthanized. Right and left tibiae and humeri were collected and further analyzed. Cortical bone density and thickness were measured using computed tomography. Periosteal and endosteal dimensions were measured at the fracture site during mechanical testing. At 4, 8, 12, and 16 wk, serum concentrations of osteocalcin and hydroxylysyl pyridinoline were analyzed as markers of bone formation and resorption. Cortical bone density was higher (P < 0.05) in humeri of AV pullets, and tibiae were denser (P < 0.05) for AV pullets in the distal section of the bone compared to CC pullets. Ash content was higher (P < 0.05) in AV humeri with no difference in tibiae ash content. Tibiae and humeri of AV pullets had a thicker cortex than the CC pullets (P < 0.05). Additionally, the tibiae and humeri of AV pullets had greater (P < 0.05) second moment of areas than the CC pullets. While some bone material properties between groups were different (P < 0.05), the differences were so small (< 7%) that they likely have no clinical significance. Serum osteocalcin concentrations were not different between the treatments, but hydroxylsyl pyridinoline concentrations were higher in CC pullets at 12 wk compared to the AV pullets and the effect reversed at 16 wk (P < 0.05). These findings indicate that tibiae and humeri respond differently to load bearing activities during growth. The improved load bearing capability and stiffness in bones of AV pullets were related to increased cross-sectional geometry.

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.…”

Pathological characterization of keel bone fractures in laying hens does not support external trauma as the underlying cause

“…As previously demonstrated CT scanning is a useful research tool to study the morphology and the number of fractures and exact location [37]. CT scanning allows the investigation of the external appearance of the fractures thought the 3D models, as well accurate inspection of what happened inside the bone.…”

Quadratic Indirect Effect of National TVET Expenditure on Economic Growth Through Social Inclusion Indicators

“…The human capital approach is a key economic rationale for the policy makers to enhance the national investment in education to widen individuals' participation in the education (Gale & Molla, 2015). The human capital theory explains that national investment in education and training for developing competent citizens is positively associated with economic growth (Dean, 2003;Regmi et al, 2015). The "education" as a strategy of economic revival attracted the significant attention of policy makers after the 2008 Global Financial Crisis (Antolin & Stewart, 2009).…”

“…The "education" as a strategy of economic revival attracted the significant attention of policy makers after the 2008 Global Financial Crisis (Antolin & Stewart, 2009). The human capital theory provides a perspective of the education as a capital good for developing human resources to cope with socioeconomic changes (Olaniyan & Okemakinde, 2008;Regmi et al, 2015). The human capital outcomes resulting from the imperative role of educational institutions (Biesta, 2006) as the engine for economic growth (Gowlett, 2012) are driving the recent educational policies (Walker, 2012).…”