Wing-feather loss in white-feathered laying hens decreases pectoralis thickness but does not increase risk of keel bone fracture

Abstract

Feather loss in domestic chickens can occur due to wear and tear, disease or bird-to-bird pecking. Flight feather loss may decrease wing use, cause pectoral muscle loss and adversely impact the keel bone to which these muscles anchor. Feather loss and muscle weakness are hypothesized risk factors for keel bone fractures that are reported in up to 98% of chickens. We used ultrasound to measure changes in pectoral muscle thickness and X-rays to assess keel bone fracture prevalence following symmetric clipping of primary and secondary feathers in white- and brown-feathered birds. Four and six weeks after flight feather clipping, pectoralis thickness decreased by approximately 5%, while lower leg thickness increased by approximately 5% in white-feathered birds. This pectoralis thickness decrease may reflect wing disuse followed by muscle atrophy, while the increased leg thickness may reflect increased bipedal locomotion. The lack of effect on muscle thickness in brown-feathered hens was probably due to their decreased tendency for aerial locomotion. Finally, pectoralis thickness was not associated with keel bone fractures in either white- or brown-feathered birds. This suggests that the white-feathered strain was more sensitive to feather loss. Future prevention strategies should focus on birds most susceptible to muscle loss associated with flight feather damage.

Does wing use and disuse cause behavioural and musculoskeletal changes in domestic fowl ( Gallus gallus domesticus )?

“…Directly before (week 0) and five weeks following immobilization treatment, cross-sectional images of the breast (pectoralis and supracoracoideus) and lower leg ( M. gastrocnemius pars medialis , M. fibularis lateralis and M. tibialis cranialis caput tibiale and femorale ) of each hen were obtained with a portable ultrasound unit (EBit 50 Unit, Digital Color Doppler Ultrasound System, Chison Medical Technologies, Bellevue, WA, USA). The procedure followed the same protocol as in Garant et al [ 48 ]. In brief, each hen was securely held in the lap of an assistant while a trained second person captured ultrasound images.…”

“…Thickness measurements were collected for the left and right muscles (pectoralis, supracoracoideus, lower leg muscles) of each bird. Thickness measurements were performed as described in Garant et al [ 48 ]. In brief, the thickness of the pectoralis was measured between the skin and epimysial fascia, and the supracoracoideus between the epimysial fascia and keel bone.…”

“…The presence and severity of keel bone fractures were assessed from X-ray images as described in Garant et al [ 48 ]. A Poskom VET-20BT portable X-ray unit (Promark Imaging, Toronto, ON, Canada) kept within a steel-doored, purpose concrete room (Research Station, University of Guelph) was used to obtain keel radiographs before (week 0), and five weeks post-treatment application.…”

“…Change in muscle thickness and body weight was calculated as the difference between muscle thickness at week 5 and baseline (week 0) expressed as a percentage of the baseline value at week 0 as per Garant et al [ 48 ]. Thus, these percentages of change could be negative (indicating reduction) or positive (indicating increase).…”

Reduction of wing area affects estimated stress in the primary flight muscles of chickens

“…Open Sci. 10: 230817 of wing-feather clipping on potential keel bone injuries [18], changes in behaviour [11], muscle depth [18] and flight kinematics [12]. The floor was covered in 5 cm of wood shavings and each pen included two high platforms (122 cm L × 31 cm W) 70 cm above the ground on either side of the pen.…”