Osteoporosis in Cage Layers

Abstract

Osteoporosis in laying hens is a condition that involves the progressive loss of structural bone during the laying period. This bone loss results in increased bone fragility and susceptibility to fracture, with fracture incidences of up to 30% over the laying period and depopulation not uncommon under commercial conditions. A major cause of osteoporosis is the switch in bone formation from structural to medullary bone at the onset of sexual maturity, but structural bone loss is accelerated by the relative inactivity of-caged birds. Allowing birds more exercise, as in aviary systems, results in better bone quality but may not decrease the overall fracture incidence. Good nutrition can help to minimize osteoporosis but is unable to prevent it. Best nutritional practice involves transferring birds to a higher calcium diet at lighting up rather than at first egg, providing a source of calcium in particulate form, and not withdrawing feed some days before depopulation. Breeding may be an effective way of combating ostoporosis. Some bone strength traits have been shown to be heritable, and divergent selection for resistance or susceptibility to osteoporosis has resulted in lines with markedly different bone characteristics. After three generations of selection, the lines differ by 19% for keel bone mineral density, 13% for humerus breaking strength, and 25% for tibia breaking strength and show a sixfold difference in fracture incidence under commercial breeding conditions. The difference in bone quality among the lines is maintained under different housing systems.

Gender identification of the Mesozoic bird Confuciusornis sanctus

“…2). This well vascularized, endosteally formed tissue characteristically has a cancellous or spongy texture and consists of woven bone [9][10][11][12][13] . Endosteal deposits are sometimes caused by disease (for example, avian osteopetrosis) and in such cases they are usually accompanied by bony periosteal outgrowths 13 .…”

“…Several studies have shown that the deposition of avian medullary bone is directly linked to the maturation of the ovarian follicles before egg laying, and that it acts as a calcium reservoir for the production of the calcareous eggshell [9][10][11][12][13][14][15] . The deposition of medullary bone is considered to be an adaptation to compensate for the thin-walled bones of birds, from which extensive bone resorption leads to brittleness and susceptibility to fractures 11,14,15 .…”

“…The deposition of medullary bone is considered to be an adaptation to compensate for the thin-walled bones of birds, from which extensive bone resorption leads to brittleness and susceptibility to fractures 11,14,15 . Thus, our discovery of medullary bone directly indicates that DNHM-D1874, a specimen lacking ornamental rectrices, is a reproductive female.…”

Identification of quantitative trait loci associated with bone traits and body weight in an F2 resource population of chickens

“…Welfare issues associated with osteoporosis have become more urgent due to the increasing use of battery cages, which contributes to a decrease in structural bone, leading to bone fragility and susceptibility to fracture [2,13,60]. It has been estimated that bone fragility is responsible for 35% of hen mortalities in caged systems [33], and bone fractures due to production, handling, and transportation have been reported in 29% of birds that reach processing facilities [15] and 98% of birds by the end of the processing line [3].…”

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

“…Thus, temperature measurements and profiles from IRT images were constructed and compared among housing conditions. Osteoporosis in laying hens is common, and is generally regarded as occurring due to loss of calcium from structural bone to support formation of eggshells over the course of the production cycle [13]. Breakage of leg and wing bones frequently occurs at the end the production cycle when hens are removed from their cages [14,15].…”