Behaviour of free-range laying hens in distinct outdoor environments

Early and late cognitive and behavioral aspects associated with range use in free-range laying hens (Gallus gallus domesticus)

Individual differences in free-range chicken systems are important factors influencing how birds use the range (or not), even if individuals are reared in the same environmental conditions. Here, we investigated how various aspects of the birds' behavioral and cognitive tendencies, including their optimism/pessimism, cognitive flexibility, sociability, and exploration levels, are associated with range use and how they may change over time (before and after range access). To achieve this, 100 White Leghorn laying hen chicks underwent three distinct behavioral/cognitive tests-the cognitive bias test, the detour test, and the multivariate test-prior to gaining access to the range, between 9 and 39 days of age. After range access was allowed (from day 71), birds' range use was evaluated over 7 nonconsecutive days (from 74-91 days of age). Subsequently, a subset of birds, classified as high rangers (n = 15) and low rangers (n = 15) based on their range use, underwent retesting on the same three previous tests between 94 and 108 days of age. Our results unveiled a negative correlation trend between birds' evaluation of the ambiguous cue and their subsequent range use (rho = -0.19, p = 0.07). Furthermore, low rangers were faster to learn the detour task (χ2 = 7.34, df = 1, p = 0.006), coupled with increased sociability during the multivariate test (rho = -0.23, p = 0.02), contrasting with their high-ranging counterparts, who displayed more exploratory behaviors (F[1,27] = 3.64, p = 0.06). These behavioral patterns fluctuated over time (before and after range access); however, conclusively attributing these changes to birds' aging and development or the access to the range remains challenging. Overall, our results corroborate that behavioral and cognitive individual differences may be linked to range use and offer novel perspectives on the early behavioral and cognitive traits that may be linked to range use. These findings may serve as a foundation for adapting environments to meet individual needs and improve animal welfare in the future.

Easier said than done! Organic farmers consider free-ranging important for laying hen welfare but outdoor areas need more shelter - important gaps between research and practice

1. The aim of the present study was to investigate the design and management of free-range areas and their use by birds on commercial organic laying hen farms in Sweden and to document farmers' perspectives on outdoor access for poultry.2. Eleven Swedish organic laying hen farms were visited. The farmers were interviewed about general farm management, bird health and behaviour and outdoor access. The free-range areas were assessed in terms of proportion covered by protective (high) vegetation and any artificial shelters provided. The numbers of hens ranging at different distances from the house were recorded twice during the day.3. The outdoor area within 250m from the house contained 0-5% vegetation cover on six of the farms and at least 80% pasture on seven farms. On 10 farms, no more than 13% of the flock was observed outdoors. Of the hens observed in the free-range area, the median proportion ranging within 20m from the house or veranda per observation event was 99% (IQR=55-100%), confirming reports by the farmers.4. Free-range access was considered important by all farmers, primarily for welfare reasons and most agreed that protective vegetation cover and/or artificial shelters were important in encouraging free-ranging. However, there was marked variation among the farmers in their suggestions on how to attract hens outside.

Influence of an Automatic Enrichment Device on Laying Hen Behavior and Plumage Condition

Feather pecking and cannibalism are prominent problems in modern laying hen husbandry. Among the various approaches to address this issue, environmental enrichment plays a crucial role. In this on-farm study, four winter gardens of an organic farm henhouse were equipped with an automatic enrichment device. Different quantities of downpipes dosing grain on rough-coated pecking plates (PPs) were tested. One group served as a control (CG) without an automatic enrichment device, while the others were offered different numbers of PPs, with one equipped with a doubled amount of PPs (DEG) compared to the other two groups (SEG). Video analyses of the hens’ duration of stay and behaviors in the recorded winter garden area and around the PPs were performed, and regular assessments of the plumage condition were conducted. By the end of the production cycle, no hens with intact plumage were found, with hens in the CG and DEG showing worse scores and earlier deterioration in the plumage condition than in the SEG. The offer of PPs showed a significant influence on the duration of stay in the filmed area. Hens in the DEG stayed significantly longer (mean: 129 s, SD: 126 s) than those in the CG (mean: 79 s, SD: 91 s; p < 0.05) and SEG (mean: 75 s, SD: 83 s; p < 0.005). On the performed behavioral bouts per hen and minute (CG mean bouts/minute (SD): 5.47 (2.92); SEG mean (SD): 5.33 (2.76); SEG mean (SD): 5.81 (3.24)), no significant influences were detected. Environmental pecking was the behavior most frequently observed in all winter gardens, where, particularly around the PPs, pecking at the device was observed. Therefore, the enrichment device can be assessed as well accepted by the hens in winter gardens. The effect of the device on the plumage condition remains unclear, with external factors probably showing a greater influence than the enrichment.

Health in poultry- immunity and microbiome with regard to a concept of one health

The overall concept of OneHealth focuses on health and infectious disease in the context of the relationship between humans, animals, and the environment. In poultry production, there are many opportunities to implement OneHealth by organizing work and introducing appropriate engineering solutions. It is recommended that future research directions include designing and testing solutions to improve air quality and the elimination of antibiotics in the poultry industry. For this to be possible, it is essential to understand the indigenous microbiota of poultry, which plays a crucial role in nutrients, but also restricts the growth of pathogenic organisms. In poultry production, the most important thing is disease control in the herd, high product quality, and product efficiency. Food safety is key for consumers, as some zoonoses are transmitted through the food chain. Moreover, antibiotic resistance of bacteria is becoming a growing threat. For this reason, it is essential to maintain the proper immune status in the herd. Virus disease control in poultry is based on vaccination programs and the maintenance of biosecurity. This chapter aims to present the current state of knowledge in the field of immunity and microbiome of poultry in the context of the OneHealth concept.

Welfare issues and potential solutions for laying hens in free range and organic production systems: A review based on literature and interviews

In free-range and organic production systems, hens can make choices according to their needs and desires, which is in accordance with welfare definitions. Nonetheless, health and behavioral problems are also encountered in these systems. The aim of this article was to identify welfare challenges observed in these production systems in the EU and the most promising solutions to overcome these challenges. It is based on a review of published literature and research projects complemented by interviews with experts. We selected EU specific information for welfare problems, however, the selected literature regarding solutions is global. Free range use may increase the risk of infection by some bacteria, viruses and parasites. Preventive methods include avoiding contamination thanks to biosecurity measures and strengthening animals' natural defenses against these diseases which can be based on nutritional means with new diet components such as insect-derived products, probiotics and prebiotics. Phytotherapy and aromatherapy can be used as preventive and curative medicine and vaccines as alternatives to antibiotics and pesticides. Bone quality in pullets and hens prevents keel deviations and is favored by exercise in the outdoor range. Free range use also lead to higher exposure to variable weather conditions and predators, therefore shadow, fences and guard animals can be used to prevent heat stress and predation respectively. Granting a free range provides opportunities for the expression of many behaviors and yet many hens usually stay close to the house. Providing the birds with trees, shelters or attractive plants can increase range use. Small flock sizes, early experiences of enrichment and personality traits have also been found to enhance range use. Severe feather pecking can occur in free range production systems, although flocks using the outdoor area have better plumage than indoors. While many prevention strategies are facilitated in free range systems, the influence of genetics, prenatal and nutritional factors in free range hens still need to be investigated. This review provides information about practices that have been tested or still need to be explored and this information can be used by stakeholders and researchers to help them evaluate the applicability of these solutions for welfare improvement.

Relationship between sunlight and range use of commercial free-range hens in Australia

In Australia, summer brings intense, bright sunlight with high ultraviolet (UV) radiation and hot temperatures, which might impact free-range hens’ ranging outside. To determine how range use was correlated with different sunlight variables and weather factors, a study was carried out on three commercial free-range layer farms during the summer/autumn period (December-May) across diverse regions of Australia in Tasmania (TAS), Queensland (QLD), and Western Australia (WA). Hens’ range distribution was determined by counting the number of hens in the direct sunlight (‘sun’) or ‘cloud’ and shaded areas (‘sun-shade’ or ‘cloud-shade’, in sunny or cloudy conditions, respectively) using image snapshots taken at 30 min intervals from video recordings of a portion of one shed comprising 20,000–30,000 hens on each farm during the production phase of the laying cycle. The solar radiation spectrum [UV radiation (UV_AB) (288–432 nm), photosynthetically active radiation (PAR; visible light) (400–700 nm), and total solar radiation (TSR) (285 nm-3000 nm)] and weather data (ambient temperature and relative humidity) were recorded through an on-site weather station. Data were analysed separately due to discrepancies between the farms’ layouts. The effects of time of day and months on range use were analysed using General Linear Models in JMP^® 16.0 and the relationship of sunlight and weather variables with hens’ distribution in ‘sun’/’sun-shade’ and ‘cloud’/’cloud-shade’ in sunny and cloudy conditions respectively was determined by fitting linear ridge regression models using the ‘lmridge’ package in R. Overall, the time of day and month had significant effects on hens’ distribution on the range (all p < 0.0001). Hens’ range occupancy in the ‘sun’ decreased during the midday period with gradual increases in the late afternoon to evening, and the opposite pattern in the ‘sun-shade’. A linear increase in the number of hens on the range over the months indicated the seasonal effects on hen ranging patterns. Temperature, UV_AB and PAR were the most important factors for discouraging hens’ range use in the ‘sun’ suggesting free-range systems in Australia should be designed to account for the extreme sunlight using adequate shade for optimum ranging across summer.

Foraging Behavior Shows Individual-Consistency Over Time, and Predicts Range Use in Slow-Growing Free-Range Male Broiler Chickens

Recent research on free-range chickens shows that individual behavioral differences may link to range use. However, most of these studies explored individual behavioral differences only at one time point or during a short time window, assessed differences when animals were out of their social group and home environment (barn and range), and in specific tests or situations. Therefore, it is yet unclear how different behaviors relate to range use and how consistent these behaviors are at the individual level. To fill this gap, we here aimed to describe the behavioral budget of slow-growing male broiler chickens (S757N) when in their social group and home environment during the whole rearing period (from the second week of life to the twelfth week, before slaughter), and to relate observed behavioral differences to range use. For this, we followed a sample of individuals in two flocks (n = 60 focal chickens out of 200 chickens per flock), over two seasons, during three periods: before range access (from 14 to 25 days old), during early range access (first weeks of range access, from 37 to 53 days old), and during late range access (last weeks of range access, from 63 to 87 days old). By the end of each period, individual tests of exploration and social motivation were also performed, measuring exploration/activity and sociability propensities. Our results show that foraging (i.e., pecking and scratching at the ground) was the only behavior that correlated to range use for all three rearing periods, independent of the season. Foraging was also the only behavior that showed within-individual consistency from an early age and across the three rearing periods. Foraging may, therefore, serve as a useful behavioral predictor of range use in free-range broiler chickens. Our study increases the knowledge of how behaviors develop and relate to each other in a domesticated and intensely selected species, and improves our understanding of the biology of free-range broiler chickens. These findings can, ultimately, serve as a foundation to increase range use and improve chicken welfare.

Commercial Free-Range Laying Hens’ Preferences for Shelters with Different Sunlight Filtering Percentages

Extreme sunlight might be aversive to free-range laying hens, discouraging them from going outside. Range enrichment with artificial shelters may protect hens from sunlight and increase range use. The preferences of 34–40-week-old Hy-Line Brown laying hens for artificial shelters were assessed by counting the number of hens under three densities of individual shelters (three replicates/density) from video recordings for 14 to 17 days for two flocks. The artificial shelters used shade cloth marketed as blocking 50%, 70%, and 90% of ultraviolet light, although other sunlight wavelengths were also reduced. Different sunlight spectral irradiances (ultraviolet radiation (UVAB) (288–432 nm), photosynthetically active radiation (PAR) (400–700 nm), and total solar radiation (TSR) (285 nm–3000 nm), ambient temperature, and relative humidity were recorded with an on-site weather station. There was a significant interaction between sunlight-filtering shelter and time of day (both Flocks, p < 0.0001), i.e., hens preferred shelters with the highest amount of sunlight-filtering at most time points. Regression models showed that the most variance in shelter use throughout the day resulted from the ambient temperature in both flocks, while sunlight parameters had different degrees of effect depending on the shelter type and flock. However, fewer hens under the shelters during the midday period suggest that during periods of intense sunlight, hens prefer to remain indoors, and artificial structures might not be sufficient to attract more hens outside.

Impacts of Rearing Enrichments on Pullets and Free-Range Hens’ Positive Behaviors across the Flock Cycle

Simple Summary

Enrichment during the indoor rearing of young laying hens (pullets) destined for free-range systems may improve pullet development and increase motivated natural behaviors (termed ‘positive behaviors’) such as foraging, dust bathing and chick play. Hy-Line Brown® chicks (n = 1700) were floor-reared indoors across 16 weeks with three enrichment treatments (n = 3 pens/treatment): (1) standard control, (2) weekly novel objects—‘novelty’, (3) perching/navigation structures—‘structural’. Pullets (16 weeks old: n = 1386) were then transferred to nine identical pens within rearing treatments, with outdoor range access from 25 to 65 weeks. Video cameras recorded the pullet pens, adult indoor pens, and outside range. During rearing, observations of play behavior in chicks at 2, 4 and 6 weeks showed no overall effect of rearing treatment. At 11 and 14 weeks only the novelty hens were observed to increase their foraging across age with no differences between treatments in dust bathing. Observations of adult hens at 26, 31, 41, 50, 60 and 64 weeks showed that the structural hens exhibited more dust bathing and foraging overall than the control hens, but that both novelty and/or structural hens showed small increases relative to control hens depending on the behavior and location. Across age, adult hens differed in the degree of dust bathing performed inside or outside and foraging outside but not inside. For litter-reared pullets, additional enrichments may result in some long-term increases in positive behaviors.

Abstract

Enrichment during the indoor rearing of pullets destined for free-range systems may optimize pullet development including increasing motivated natural behaviors (termed ‘positive behaviors’) including foraging, dust bathing and chick play. Hy-Line Brown® chicks (n = 1700) were floor-reared indoors across 16 weeks with three enrichment treatments (n = 3 pens/treatment): (1) standard control, (2) weekly novel objects—‘novelty’, (3) perching/navigation structures—‘structural’. At 16 weeks, pullets (n = 1386) were transferred to nine identical pens within rearing treatments with outdoor range access from 25 to 65 weeks. Video cameras recorded the pullet pens, adult indoor pens, and outside range. During rearing, observations of play behavior (running, frolicking, wing-flapping, sparring) in chicks at 2, 4 and 6 weeks (total of 432 thirty-second scans: 16 observations × 3 days × 9 pens) showed no overall effect of rearing treatment (p = 0.16). At 11 and 14 weeks only the ‘novelty’ hens were observed to increase their foraging across age (p = 0.009; dust bathing: p = 0.40) (total of 612 thirty-second scans per behavior: 17 observations × 2 days × 2 age points × 9 pens). Observations of adult hens at 26, 31, 41, 50, 60 and 64 weeks showed that the structural hens exhibited overall more dust bathing and foraging than the control hens (both p < 0.04) but both novelty and/or structural hens showed small increases depending on the behavior and location (total of 4104 scans per behavior: 17 observations × 2 days × 6 age points × 9 pens × 2 locations = 3672 + an additional 432 observations following daylight saving). Across age, adult hens differed in the degree of dust bathing performed inside or outside (both p ≤ 0.001) and foraging outside (p < 0.001) but not inside (p = 0.15). For litter-reared pullets, additional enrichments may result in some long-term increases in positive behaviors.

Behaviour in Slower-Growing Broilers and Free-Range Access on Organic Farms in Sweden

Two slower-growing hybrids (Rowan Ranger and Hubbard) are currently reared in organic broiler production in Sweden, but knowledge of bird welfare on commercial farms is limited. This study examined chicken behaviour, including free-range use and features of this, in order to enhance knowledge, describe the current situation and identify practical solutions on Swedish organic broiler farms. Eight of 12 available farms were visited once each, when average flock age was 55 ± 6 days. Farmer interviews were followed by avoidance distance tests, group behavioural observations, and assessment of use of environmental enrichment and free-range by the chickens. On average, almost half of all birds observed indoors were in a sitting posture. However, even when approaching slaughter age, the chickens were agile enough to perch and used some of the variety of items provided for perching, but the quantity of environmental enrichment equipment appeared to be insufficient. Free-range areas generally lacked sufficient vegetation cover or artificial shelters, and chickens were predominantly observed ranging near the house. Further research should explore feasible ways for farmers to make key improvements to the indoor and outdoor environment, in order to improve broiler welfare.

The Benefit of Hedgerow Access on the Health and Growth Rate of Pasture Raised Broiler Chickens

Pasture rearing is an increasingly common option for small farms to produce humanely raised poultry products for an expanding market, however profit margins tend to be much lower for pastured poultry producers than for those that opt for conventional indoor rearing. Research into simple methods to optimize the growth and health of pasture-raised poultry can help small farmers maximize meat yields and decrease the morbidity and mortality of their flock, ultimately leading to higher profit margins and improved animal welfare. The objective of this study was to measure how the inclusion of mature, native foliage into pastures can impact the production performance and overall health status of two different popular breeds of commercial broiler chickens; fast-growing Cornish cross and slower growing Red rangers. During the finisher phase (30–78 days old), pastured chickens were separated by breed into either a treatment population with access to a mature bordering hedgerow, or a control population without access to a hedgerow. Weekly weight gain, daily feed intake and basic hematologic values were used to evaluate differences in the production performance and health status between each population. We found that hedge access led to a significant improvement in the rate of gain of the Cornish cross without an associated increase in feed intake, suggesting that the addition of hedges can increase meat yields in fast-growing broilers without increasing feed costs. Red rangers with hedge access demonstrated an improved ability to neutralize bacterial pathogens in whole blood and a lesser degree of hemodilution compared to control populations, suggesting improved immune function and a lower degree of heat stress in these populations. We conclude that the addition of natural environmental enrichment such as mature foliage to grass pastures can lead to improved production performance in fast-growing broilers and improvements in the health and immune function of slower growing broiler chickens.

Preference testing for UV light spectrum and intensity in laying hens

Sunlight intensity and UV radiation may affect free-range hens' use of the outside range, particularly when sunlight is intense with a high UV index. However, it is uncertain what aspect of sunlight (brightness or UV) may be most aversive to hens to discourage them from leaving standard indoor lighting conditions to venture outdoors. A controlled indoor-based choice study was conducted to determine whether hens showed preferences for different light wavelengths and intensities that may affect outdoor range usage. Cage-reared ISA Brown laying hens (n = 84) at 44 wk of age in 3 groups (28 hens/group) were tested for preferences of indoor standard light emitting diode (LED) white light (control) vs. one of three different treatment lights: 1) visible spectrum plus infrared wavelengths (VIS); 2) visible spectrum plus UVA wavelengths (UVA); and (iii) visible spectrum plus UVA and UVB wavelengths (UVA/B) presented successively at low, medium, or high levels of intensity. Hens within each group were individually tested for 2 h in an apparatus with 2 compartments (control vs. treatment) connected by a tunnel on both sides. Videos of hens' time spent in each compartment and behaviors were decoded and analyzed using GLMM. Hens spent more time under the low intensity of the UVA/B light treatment (62%), the low intensity of VIS light (61%), medium intensities of both UVA/B light (60%), and UVA light (59%), and the high intensity of the VIS light (58%) when compared with control light (all P ≤ 0.05). Hens spent less time feeding under all intensities of UVA light (all P ≤ 0.03) and showed more foraging, ground pecking, and preening at lower levels of UVA/B light (P < 0.05). The study suggests that UVA/B light (sunlight) may have positive effects for hen range use, but during peak sun intensities, hens may need additional measures (e.g., shelter) to protect themselves. Confirmation of these findings in a free-range setting is needed.

Preference for artificial range enrichment design features in free-range commercial laying hens

1. This study examined what elements of artificial enrichment structures attract hens in the outdoor range, and what behaviours hens perform around these structures. Three principles of cover design (height, orientation and visual density) were tested for laying hen preference in the outdoor range of a commercial egg farm using a 2 × 3 × 3 factorial design. The factors were height: 0.5 m or 1.5 m; orientation: vertical, horizontal or horizontal cover with one vertical side; and visual density: 0% (control), 50% or 90% UV blocking cloth.2. A significant three-way interaction between all factors was found (P < 0.001). The most preferred visual density of these structures was the 90%, followed by 50% UV blocking cloth. Horizontal structures with one vertical side, of either height, were highly preferred. Short horizontal structures were preferred to tall ones, and tall vertical structures were slightly preferred over short ones.3. The most common behaviours observed around the structures were interaction with the structure (pecks, scratches and vigilance directed at the structure; 32.7%), foraging (32.2%), locomotion (9.9%), and air foraging (pecks and snapping in the air; 9.0%). A three-way interaction between the design principles influenced the proportion of hens performing each of these behaviours (P < 0.001). Hens foraged more around structures with no shade cloth and interacted more with structures that had dense shade cloth.4. These results highlighted the complexity of designing attractive outdoor environments for laying hens. By testing the combination of elements that hens prefer it is possible to understand how to design attractive outdoor ranges that attract hens and promote a diverse range of behaviours on commercial farms.

Nutrition, feeding and laying hen welfare

The relationship between nutrition and welfare is usually considered to be a direct result of supplying the hen with adequate quantities of feed and water. This simple notion of freedom from hunger and thirst belies the fact that nutrients play a pivotal role in the body’s response to challenges whether they relate to ambient temperature, gastrointestinal health, pathogen exposure, metabolic disorders, or social and mental stress. In all instances, maintaining homeostasis and allowing for physiologic response is dependent on an adequate and balanced nutrient supply. It is accepted that most laying hens are fed a complete diet, formulated commercially to provide the required nutrients for optimal health, egg production and welfare. In other words, the laying hen, irrespective of her housing, does not experience hunger or thirst. However, despite adequate nutrient and water supply, certain senarios can significantly affect and alter the nutrient requirements of the hen. Furthermore, the chemical composition and also the physical form of feed can significantly contribute to prevent or treat welfare and health conditions and is, therefore, a highly relevant tool to ensure and maintain an adequate welfare status. Therefore, this review takes a broader perspective of nutritional welfare and considers the nutrition of hens managed in different production systems in relation to nutritional physiology, gut microbiota, stress, metabolic disorders and feeding management.

The impact of management, husbandry and stockperson decisions on the welfare of laying hens in Australia

The present review examines the impact of management and husbandry decisions on the welfare of laying hens in Australia. The literature on many of these aspects is lacking for the Australian egg industry, and, indeed, for the egg industry in general. Management decisions that can affect hen welfare relate to the initial farm design, husbandry routines, and staff selection and training. As modern laying houses represent a considerable financial investment, the decisions made during the design phase are likely to affect both the hens and stockpeople for substantial periods. Hens in cage systems may benefit from fewer tiers and greater space allowances. In non-cage systems, the brown genotypes used in the Australian egg industry may benefit from lower structures that accommodate their heavier and less agile bodies. Keel fractures can be reduced by improving the skeletal health and spatial cognition of laying hens during the rearing period, in addition to minimising the distances they need to jump when navigating aviary structures. The addition of a wintergarden to fixed free-range systems appears to be beneficial. Housing hens in mobile units on free-range farms may challenge their welfare, particularly in relation to heat stress. There is also room for improvement in biosecurity practices and health monitoring of hens, as these appear to be lacking at some farms. The current strains of hen used in free-range systems may not be best suited to these conditions, on the basis of their body condition and flock uniformity. Feed quality may also need to be monitored for quality assurance and optimal hen nutrition. Hen welfare during depopulation can be improved through staff training and by reducing staff fatigue. Euthanising spent hens on farm offers welfare benefits over transporting spent hens to an abattoir. Both hen welfare and working conditions for stock people should be considered when designing laying houses to provide suitable conditions for both hens and stockpeople. This will help improve the job satisfaction of stockpeople, which may translate into better care for the hens and may aid in retaining quality staff. Stockpeople must be recognised as vital contributors to hen welfare in the egg industry, and it is important for the egg industry to continue to attract, train and retain skilled stockpeople to ensure that they enjoy their job and are motivated to apply best-practice care for their flocks. Promoting the animal-care aspect of stockmanship in combination with a supportive managerial environment with optimal working conditions may increase the attractiveness of the egg industry as a place to work.

Free-range egg production: its implications for hen welfare

Free-range laying hen housing systems are prevalent in Australia and perceived by consumers to provide greater opportunities for the expression of natural behaviour resulting in higher hen welfare. However, all housing systems have both benefits and risks and scientific evidence is needed on the welfare outcomes of free-range systems. In this review, the scientific literature is summarised from the past 10 years, from research conducted within Australia or internationally with brown laying-hen strains kept in free-range systems. It compiles information on range use by laying hens, hen behaviour while on the range, factors that affect range use, and impacts of ranging on hen health and other aspects of welfare. Novel insights have come from the use of radio-frequency identification systems that allow tracking of individual hens and have shown that the majority of hens access the range with multiple visits across the day, but a small proportion of hens within most flocks choose to remain indoors. Hens also vary in which areas of the range they use, and provision of natural or man-made shelters can increase both range access and range distribution. Hens spend most of their time foraging while outdoors, but the types and frequencies of behaviours vary depending on the resources available and other factors. Range access can be linked to health benefits such as improved plumage condition and reduced footpad dermatitis but there are also health risks associated with free-range systems such as greater susceptibility to disease (e.g. spotty liver disease), heat stress, predation, and potentially parasites in comparison to loose or cage housing systems. Design of the range area, indoor shed, management practices and rearing environments can all influence how hens utilise free-range housing systems. Further research is crucially needed on the impact of ranging on hen welfare in variable Australian climatic conditions, encompassing intense heat and sunlight as well as cooler or wet environments.

The association between range usage and tibial quality in commercial free-range laying hens

1. Bone tissue adapts continuously to metabolic calcium demands, as well as to external forces due to physical weight loading subject to hen movement. Limited calcium metabolism and, subsequently, its availability from the medullary bone, is a major factor contributing to reduced eggshell quality in hens in the late laying period (>60 weeks of age). 2. Increasing physical activity and biomechanical loading during hen rearing has been demonstrated to increase skeletal strength, enhancing bone mass as well as endocortical and periosteal bone metabolism. Presently, the consequences of range use during lay on bone quality characteristics in laying hens remain unknown. 3.The aims of this study were to characterise tibiotarsal bone indices and evaluate the impact of range access during lay on tibia bone quality in commercial free-range laying hens. 4. This exploratory study described and analysed the volumetric measurements, morphological mechanical and trabeculae indices of the tibiotarsal bone of 48 Lohmann Brown laying hens at 74 weeks of age. All bone parameters were obtained using micro-computed tomography and correlated with individual hen range use. 5. Range usage throughout lay was not associated with tibial trabecular architecture (bone volume and fraction, trabecular thickness, trabecular connectivity density and structural model index), or any other morphological characteristics (breaking strength, diaphyseal diameter, bone weight and bone mineral density) of the tibia (P > 0.05) when hens were 74 weeks of age. 6. The results demonstrated a large variation in individual bone characteristics and suggested that range usage was not associated with bone quality in commercial free-range laying hens used in this study. In conclusion, the bone health of free-range commercial laying hens may be positively impacted by other features, such as hen genetics, feed, the quality of pullet rearing, perch availability or other shed equipment, and the benefits of these variables exceed the benefit of range use.

Light-based monitoring devices to assess range use by laying hens

Access to an outdoor range has many potential benefits for laying hens but range use can be poor due to factors only partly understood. Techniques to monitor individual range use within commercial flocks are crucial to increase our understanding of these factors. Direct observation of individual range use is difficult and time-consuming, and automatic monitoring currently relies on equipment that is difficult to use in an on-farm setting without itself influencing range use. We evaluated the performance of a novel small, light and readily portable light-based monitoring system by validating its output against direct observations. Six commercial houses (2000 hens/house) and their adjacent ranges were used, three of which were equipped with more structures on the range than the others (to determine whether cover would influence monitoring accuracy). In each house, 14 hens were equipped with light monitoring devices for 5 discrete monitoring cycles of 7 to 8 consecutive days (at 20, 26, 32, 36 and 41 weeks of age). Light levels were determined each minute: if the reading on the hen-mounted device exceeded indoor light levels, the hen was classified as outside. Focal hens were observed directly for 5 min/hen per week. Accuracy (% of samples where monitoring and direct observations were in agreement) was high both for ranges with more and with fewer structures, although slightly better for the latter (92% v. 96% ± 1 SEM, F1,19 = 5.2, P = 0.034). Furthermore, accuracy increased over time (89%, 94%, 95%, 98% ± 1 SEM for observations at 26, 32, 36 and 41 weeks, respectively, F3,19 = 3.2, P = 0.047), probably due to progressively reduced indoor light levels resulting from partial closing of ventilation openings to sustain indoor temperature. Light-based monitoring was sufficiently accurate to indicate a tendency for a greater percentage of monitored time spent outside when more range structures were provided (more: 67%, fewer: 56%, SEM: 4, $\chi_1^2 &#x003D; 2.9$, P = 0.089). Furthermore, clear and relatively consistent individual differences were detected. Individuals that were caught outside at the start of the experiment ranged more throughout its duration (caught outside: 72%, caught inside 51%, SEM: 4, $\chi_1^2 &#x003D; 10.0$, P = 0.002), and individual range use was correlated between monitoring cycles (for adjacent monitoring cycles: $r_s^2 &#x003D; 0.5-0.7$, P < 0.0001). This emphasizes the importance of studying range use on an individual level. In conclusion, our light-based monitoring system can assess individual range use accurately (although accuracy was affected by house characteristics to some extent) and was used to show that both cover availability and individual characteristics affected range use.

Behavioural repertoire of free-range laying hens indoors and outdoors, and in relation to distance from the shed

BACKGROUND

Access to an outdoor area is believed to allow free-range hens to express a greater behavioural repertoire. However, very little research has been done in this area. We hypothesised that the type and frequency of behaviours would differ between areas that vary in their characteristics and distance from the shed.

METHODS

This preliminary study investigated the behaviour of free-range laying hens in indoor and outdoor areas on one commercial free-range farm, through video recordings and scan sampling of focal hens, with the aim of determining their behavioural repertoire and time budget.

RESULTS

While ranging, hens spent most of their time foraging. Indoors, hens preened and rested. Behaviour in the wintergarden showed similarities to both the indoor and outdoor areas, with preening, resting and foraging behaviours. Differences were not in the main behavioural repertoire, but rather in terms of time budget, with access to the range and wintergarden encouraging exploration.

CONCLUSION

There was no difference in the types of behaviours that hens performed in the outdoor range compared with inside the shed, but access to a wintergarden and the outdoor range were favoured by the hens for foraging.