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.

Keywords: aviary; locomotion; musculoskeletal development; poultry welfare; rearing.

Figure 1

Brooding compartment for (a) style one; (b) style two; (c) and style three rearing aviaries.

Figure 2

Aerial view of camera placements for (a) Style 1 and Style 2; (b) Style 3 rearing aviaries; (c) still shot from a low view into a Style 2 brooding compartment; (d) a still shot from a “wall” long view of a Style 2 rearing aviary. Blacked out areas are walkways for human traffic, unoccupied by pullets. The shaded sections are the aviary structures, and the white section is the litter area. Black lines separate rows of aviary structures. Cameras (represented by boxes) were located at the brooding compartment or panel section ¼ (A,D), ½ (B,E) and ¾ (C,F) down the aisle. At each letter location, one camera was positioned to view the litter floor and the bottom tier, and one viewed the top tiers of the system. Camera-labelled wall and middle viewed the litter area lengthwise. In style three, the camera-labelled aisle viewed the system lengthwise. Arrows indicate the direction in which cameras were facing.

Figure 3

Least squares means of the visit by style interaction of state behaviours. Percentage of time (a) standing; (b) sitting; (c) running; (d) wing-assisted running; (e) the rate per 30 min of group locomotion. Visits one, two, and three were when the pullets were 25.9 ± 6.67; 68.0 ± 4.78 days of age; 112.1 ± 3.34 days of age. During visit one, the brooding compartments were closed, whereas during visits two and three, the brooding compartments were open into the litter areas. Error bars represent standard error. ^a–f Indicate significant differences between means (p < 0.05).

Figure 4

Least square means of the visit by colour interactions of state behaviours. Percentage of observed of time (a) sitting; (b) standing; (c) wing-assisted running. Visits one, two, and three were when the pullets were 25.9 ± 6.67; 68.0 ± 4.78 days of age; 112.1 ± 3.34 days of age. During visit one, the brooding compartments were closed, whereas during visits two and three, the brooding compartments were open into the litter areas. Error bars represent standard error. ^a–c Indicate significant differences between means (p < 0.05).

Figure 5

Least square means of the style by colour interactions of locomotory events. Rate per 30 min of (a) wing flaps; (b) aerial transitions; (c) vertical transitions. Visits one, two, and three were when the pullets were 25.9 ± 6.67; 68.0 ± 4.78 days of age; 112.1 ± 3.34 days of age. During visit one, the brooding compartments were closed, whereas during visits two and three, the brooding compartments were open into the litter areas. Error bars represent standard error. ^a–c Indicate significant differences between means (p < 0.05).

Figure 6

Visit by colour interaction of (a) tibia breaking strength; (b) bicep weight. Pullets were 68.5 ± 4.94 and 111.5 ± 3.45 days of age, respectively, when euthanised by cervical dislocation during visits two and three. Error bars represent standard error.

Figure 7

Aviary style by strain colour interaction of pectoral minor weights. Error bars represent standard error. ^a–d Indicate significant differences between means (p < 0.05).