Accessing an outdoor range may affect broiler welfare. The degree of these effects is likely related to individual ranging behaviour. However little is known about the ranging behaviour of individual free-range broiler chickens or the effects of seasonal variation. This study investigated ranging patterns of ROSS 308 broiler chickens on a commercial free-range farm.

Valid reliable indicators of positive affective state are a critical component of welfare assessments, however, these are currently lacking for laying hens. Pharmacological interventions that disrupt specific neural pathways have shown to be a useful tool when validating indicators of affective states. As such, we utilised and validated the μ-opioid receptor antagonist nalmefene to block the reward pathway in laying hens.

The demand for free-range chicken meat in Australia is increasing. Free-range products are usually perceived as more welfare friendly by consumers (Department for Environment Food and Rural Affairs, 2011) and particularly fulfill the belief that the ability to perform natural behaviour leads to better welfare. However, there is a lack of scientific knowledge relative to the use of the outdoor range by broilers and its implications, advantages or disadvantages, in terms of bird behaviour and welfare. Therefore this study investigated behavioural time budgets of broiler chickens on two Australian commercial farms. Behaviour was monitored inside the shed and in four range areas, differing in resource availability (tree, shade cloth or no resource present) and distance from the shed (adjacent to the shed wall or 7.5m from the shed). Results indicated that distance is a deterrent for range use, as few broiler chickens were seen in areas 7.5m from the shed. Furthermore, behavioural time budgets differed between broiler chickens observed in the shed compared to those in the range; there was more active, exploratory and vigilant behaviours seen in the range and more resting and comfort behaviors observed in the shed. However the implications of such behavioural differences remain unknown.

Environments lacking complexity can decrease exploratory behaviour and adaptation to fearful experiences. We investigated the effects of increased environment complexity on fear responses of broiler chickens. Day-old mixed-sex ROSS 308 broilers (n=108) were randomly allocated to either a control ( C), physical environmental complexity (P) or human contact (H) group.

Little is known about broiler chicken ranging behaviour. Previous studies have monitored ranging behaviour at flock level but whether individual ranging behaviour varies within a flock is unknown. Using Radio Frequency Identification technology, we tracked 1200 individual ROSS 308 broiler chickens across four mixed sex flocks in two seasons on one commercial farm. Ranging behaviour was tracked from first day of range access (21 days of age) until 35 days of age in winter flocks and 44 days of age in summer flocks. We identified groups of chickens that differed in frequency of range visits: chickens that never accessed the range (13 to 67% of tagged chickens), low ranging chickens (15 to 44% of tagged chickens) that accounted for <15% of all range visits and included chickens that used the range only once (6 to 12% of tagged chickens), and high ranging chickens (3 to 9% of tagged chickens) that accounted for 33 to 50% of all range visits. Males spent longer on the range than females in winter (p < 0.05). Identifying the causes of inter-individual variation in ranging behaviour may help optimise ranging opportunities in free-range systems and is important to elucidate the potential welfare implications of ranging.

Little is known about the ranging behaviour of chickens. Understanding ranging behaviour is required to improve management and shed and range design to ensure optimal ranging opportunities. Using Radio Frequency Identification technology, we tracked 300 individual broiler chickens in each of four mixed sex ROSS 308 flocks on one commercial farm across two seasons. Ranging behaviour was tracked from the first day of range access (21 days of age) until 35 days of age in winter and 44 days of age in summer. Range use was higher than previously reported from scan sampling studies. More chickens accessed the range in summer (81%) than winter (32%; p < 0.05). On average, daily frequency and duration of range use was greater in summer flocks (4.4 ± 0.1 visits for a total of 26.3 ± 0.8 min/day) than winter flocks (3.2 ± 0.2 visits for a total of 7.9 ± 1.0 min/day). Seasonal differences were only marginally explained by weather conditions and may reflect the reduction in range exposure between seasons (number of days, hours per day, and time of day). Specific times of the day (p < 0.01) and pop-holes were favoured (p < 0.05). We provide evidence of relationships between ranging and external factors that may explain ranging preferences.

Fear is a response to a known threat, anxiety is a response to a perceived threat. Both of these affective states can be detrimental to animal welfare in modern housing environments. In comparison to the well-validated tests for assessing fear in laying hens, tests for measuring anxiety are less developed. Perception of a threat can result in an attention bias that may indicate anxious affective states in individual hens following playback of an alarm call. In Experiment 1, an attention bias test was applied to hens that differed in their range access to show that hens that never ranged were more vigilant (stretching of the neck and looking around: P < 0.001) and slower to feed following the second alarm call playback (P = 0.01) compared with hens that ranged daily. All hens showed a reduction in comb temperature following the first alarm call (P < 0.001). In Experiment 2, an open field test was used to determine an effective dose of 2 mg/kg for the anxiogenic drug meta-Chlorophenylpiperazine (m-CPP) in adult laying hens. Hens dosed with 2 mg/kg showed reduced locomotion compared with a saline solution (P < 0.05). In Experiment 3, 2 mg/kg m-CPP or saline was administered to adult hens previously habituated to the open field arena to pharmacologically validate an attention bias test as a measure of anxiety. Hens dosed with m-CPP were slower to feed (P = 0.02) and faster to vocalize following a second alarm call playback (P = 0.03) but these hens did not exhibit the same vigilance behavior as documented in Experiment 1. The m-CPP hens also spent more time stepping and vocalizing (both P < 0.001) than the saline hens. An attention bias test could be used to assess anxiety. However, behavioral responses of hens may vary depending on their age or test environment familiarity, thus further refinement of the test is required. In these tests, 2 mg/kg of m-CPP resulted in motionless behavior when the environment was novel, but more movement and vocalizing when the environment was familiar. The extreme behavioral phenotypes exhibited by individually-tested birds may both be indicators of negative states.

Individual broiler chicken range access was monitored until final pick up for slaughter. Birds were weighed and gait scored prior to and post range access (35 and 45 days of age) to investigate the relationships between body weight, leg health and range use. There were no weight differences prior to range access between birds that did and those that did not access the range. Birds that did access the range more than once had lower body weights at first and final pick up than birds that did not access the range. No birds were observed with a gait score ⋝ 3 prior to range access. However by final pick up, birds that used the range more than once had more normal gaits than birds that never used the range. This study provides evidence of relationships between accessing an outdoor range and production and welfare characteristics in commercial free-range broiler chickens.