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

Abstract

Domestic chickens may live in environments which restrict wing muscle usage. Notably, reduced wing activity and accompanying muscle weakness are hypothesized risk factors for keel bone fractures and deviations. We used radio-frequency identification (RFID) to measure duration spent at elevated resources (feeders, nest-boxes), ultrasonography to measure muscle thickness (breast and lower leg) changes, radiography and palpation to determine fractures and deviations, respectively, following no, partial (one-sided wing sling) and full (cage) immobilization in white- and brown-feathered birds. We hypothesized partially immobilized hens would reduce elevated resource usage and that both immobilization groups would show decreased pectoralis thickness (disuse) and increased prevalence of fractures and deviations. Elevated nest-box usage was 42% lower following five weeks of partial immobilization for brown-feathered hens but no change in resource usage in white-feathered birds was observed. Fully immobilized, white-feathered hens showed a 17% reduction in pectoralis thickness, while the brown-feathered counterparts showed no change. Lastly, fractures and deviations were not affected in either strain or form of wing immobilization; however, overall low numbers of birds presented with these issues. Altogether, this study shows a profound difference between white- and brown-feathered hens in response to wing immobilization and associated muscle physiology.

Keywords: flapping flight; keel bone damage; limb immobilization; muscle adaptations; resource use.

Figure 1.

Series of three images displaying a hen with one wing slinged (partial immobilization). (a) Dorsal view of a right-wing immobilization via sling, (b) lateral view of a right-wing immobilization via sling and (c) close-up of one wing sling secured through 3M Vetrap and elastic bands secured around the wing and silicone backpack worn for individual identification.

Figure 2.

Plastic chicken leg bands (20 mm) modified to include a PIT tag encased within a layer of duct tape and bound to the band with a layer of steel-enforced epoxy. A soft layer of elastic bandage was included.

Figure 3.

Placement of hens during ultrasound imaging of the lower leg. Hens were gently laid in the lap of a bird handler to image the left or right leg. The current figure shows placement for the left leg, the head of the hen is out of view at the top of the figure and the vent located in the right bottom of the figure. (a) The shank and lower leg were held such that they formed a 90° angle by holding the tarsometatarsus with one hand while the other hand gently parted the feathers. (b) A plastic vernier calliper was placed just below the knee and perpendicular to the length of the tibiotarsus and the transducer placed caudal to the calliper to obtain lower leg cross-section.