Use of horizontal and angled perches by broiler chickens

Abstract

Roosting increases the survival of wild relatives of domestic birds. Thus, we expected chickens to choose to roost on perches. We predicted that birds would use angled perches more than horizontal ones because an angled roost would be more similar to tree branches and thus more attractive to the birds, and also easier for the birds to access. We assigned 768 male broilers to 16 pens in a 4 treatment×4 replication randomized complete block design. Each of the four pens within each block contained one of the following treatments: 0° treatment (three 0° perches); 20° treatment (three 20° perches); mixed angle treatment (one 0°, 10° and 20° perch); and a control (no perches). Angled perches were designed to slope upward from the floor to facilitate access to the perches by broilers at all ages. A combination of differently angled perches within the same pen (mixed angled treatment) provided more roosting choices at all ages, as well as allowed the birds to use different angled perches as their size and strength changed with age. The perch designs differed significantly only in height at one end (slope). Perches were constructed of 1.9 cm inside diameter polyvinyl chloride (PVC) pipes, and were 91 cm in length with 5 equally spaced 28 cm long PVC crossbars. Perch use was recorded every 15 min for three consecutive hours, 4 days each week from day 3 to 42 using instantaneous scan sampling. Mean perch use was low across all treatments (2%), possibly due to heavy body weight and high ambient temperature in later weeks. However, distinct perching patterns were identified. Perch use was highest in the 0° treatment and lowest in the 20° treatment. Within the mixed angle treatment, 0° perch use was highest, followed by 10° and 20° perch use, respectively. Perching generally increased with age but peaked at week 5. A decline in perching occurred at week 6, a period during which the birds had the heaviest body weights and ambient temperatures remained high. We determined that perching increased with age of bird (through week 5), decreased with hotter temperatures, was greater for perches with lower angles (0° and 10°), and followed a daily crepuscular pattern.