Effects of Rearing Aviary Style and Genetic Strain on the Locomotion and Musculoskeletal Characteristics of Layer Pullets

Abstract

Previous research indicates that the musculoskeletal development of pullets is improved when pullets are reared in aviaries compared to conventional rearing cages. However, there are considerable differences in rearing aviary design. To measure locomotion and musculoskeletal development of brown (n = 7) and white-feathered (n = 8) strains of pullets, 15 commercial flocks in three styles of rearing aviaries differing in structural complexity (n = 5 per style) were visited three times: 25.9 ± 6.67, 68.0 ± 4.78, and 112.1 ± 3.34 days of age. Locomotion (duration of standing, sitting, walking, running, flying, and rates jumping, flying, group running and walking) was analysed from videos recorded three times per day: at the beginning, middle, and end of the light cycle. Pullets for dissection were taken on visits 2 and 3. Pullets in the most complex system (style 3; S3) spent the most time locomoting throughout rearing (p < 0.05). Pullets in S3, particularly white-feathered strains, performed the highest rate of vertical transitions (p < 0.05). There were no differences in any of the proportional muscle weights between aviaries styles (p > 0.05) despite the differences in locomotion. White-feathered strains, however, had proportionally heavier pectoralis major (p < 0.0001), pectoralis minor (p < 0.0001), and lighter leg muscles (p < 0.0001) than brown-feathered strains. White-feathered strains and pullets in S3 also had proportionally stronger tibiae and femurs than brown-feathered strains and pullets housed in the least structurally complex system (style 1; S1) (p < 0.05). However, there were no differences found in the breaking strength of the radius and humerus between strain colours or aviary styles (p < 0.05). Therefore, strain, as well as differences in rearing aviary design, can affect the types of locomotion that growing pullets perform, which may, in turn, impact their skeletal development.

Effects of clipping of flight feathers on resource use in Gallus gallus domesticus

“…Ground-level feeders were used over elevated feeders in brown-feathered birds regardless of clipping treatment. This result expands on the general results of other studies where brown-feathered birds are less aerial than white-feathered birds [ 14 , 16 , 43 ]. Unexpectedly, there was no difference in half-clipped and fully clipped brown-feathered birds in their usage of the ground feeder.…”

“…In contrast with many flying species of birds, ground-dwelling species, such as chickens, will only fly infrequently, mainly to avoid predation and locate safe sleeping or roosting spaces [11][12][13]. Domestic birds kept for egg-laying (Gallus gallus domesticus) navigate their living space by walking, running, climbing, wing-assisted running and short-burst flapping flight [14][15][16]. Despite being ground birds, laying hens are highly motivated to roost using an elevated perch [17].…”

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

“…By contrast to their white-feathered counterparts, brown-feathered caged birds only displayed a significant thickness increase of the supracoracoideus. Potentially, the ground-dwelling nature of brown-feathered birds [ 43 , 44 , 65 ] resulted in the minimal load-bearing activity of the wings prior to treatment, and the disuse of the wings did not differ enough to produce changes. Under partial immobilization, birds were still able to use one wing and walk around, which we hypothesized would reduce flight muscle (ipsilateral) but increase leg muscle thickness.…”

Farm Environmental Enrichments Improve the Welfare of Layer Chicks and Pullets: A Comprehensive Review

“…There are considerable differences in rearing aviary design. A recent study found that strain, as well as differences in rearing aviary design, can affect the types of locomotion that growing pullets perform, which may, in turn, impact their skeletal development [ 115 ]. Thus, it is recommended to raise pullets in a complex aviary system or a diverse environment during the early rearing period, regardless of the stereoscopic enrichment provided during the laying period [ 97 ].…”