Kinetic examination of femoral bone development in modern broiler chickens

Abstract

BACKGROUDLameness in broiler chickens often presents as femoral head separation, degeneration and necrosis. The etiologies of these disorders are unknown and may results from compromised blood flow to femora and/or imbalances in bone resorption and formation.METHODSWe examined developmental changes in femoral bone volume and metabolism, via histomorphometry, at 7, 15, 21, 28, and 42 days. Bone volume (BV/TV, %), osteoid surface (OS/BS, %), osteoblast activity (Ob.S/BS, %) and osteoclast activity (Oc.S/BS) were evaluated.RESULTSBody mass increased 23‐fold from 7 to 42 days. BV/TV remained stagnate (range: 5%–8%) and reached its highest value at day 28. Bone volume‐to‐body mass ratio (range: 0.057%–0.002%), Ob.S/BS (range: 1.3%–0.5%) and OS/BS (range: 22.9%–5.6%) declined significantly (p < 0.05) with age and Oc.S/BS was so excessive throughout development that analysis was not possible. In addition, vast areas of chondrocyte columns often expanded into the secondary spongiosa.CONCLUSIONSDevelopment of broiler femora failed to sufficiently match overall body growth. The lack of bone development corresponded to diminished osteoblast and augmented osteoclast activity. The large chondrocyte columns possibly coincide with a lack of blood vessel penetration that is necessary for calcification of the cartilage template and subsequent bone development. Supported by Cobb‐Vantress Inc.