Preparing for life : effects of environmental choice and change during rearing on adaptability in laying hens

The importance of the early environment for later animal behaviour, health and welfare is well known. Hens (Gallus gallus domesticus) kept for egg production are exposed to various challenges and opportunities during their life time, such as relocation from a rearing to a laying facility or access to free range. Promoting greater adaptability in young laying hens could lead to improved welfare, especially considering the increasing complexity of commercial loose housing and aviary systems. However, early environmental inputs that could improve laying hen adaptability have not been clearly identified. This thesis investigated the impact of two environmental inputs (“choice” and “change”) during rearing, based upon well-established theories on the effects of controllability and predictability on coping ability. Experiments using two relevant environmental resources, litter and perches, showed that young laying hens with regular changes of litter and perch type were less fearful when placed in a novel environment. Young laying hens given the option to choose between different litter and perch types during rearing, showed increased exploration in a novel environment, were better able to locate a hidden feed reward and showed improved stress coping and immunocompetence. Both short- and long-term effects were seen among hens reared with different levels of environmental choice and change, depending on the stage of rearing in which hens were exposed to the environments and when the evaluations were conducted. In particular, providing greater possibilities for environmental choice could be a biologically relevant approach for a rearing environment that goes beyond simply providing basic resources and can enhance laying hen adaptability and welfare

Comb size, shape complexity and laterality of laying hens reared in environments varying in resource choice

The comb is an ornament involved in signalling condition in domestic fowl. We hypothesised that comb size, comb shape complexity (i.e., rugosity, the comb perimeter jaggedness), and comb laterality of laying hens would be influenced by the degree of environmental enrichment experienced during juvenile development in the form of resource choice. We conducted a 2 x 2 factorial crossover experiment with pullets reared in pens containing four perches of equal length and four litter areas of equal size. Pullets were exposed to a single choice vs multiple choices of perch and litter types (i.e., all the same vs all different) during Weeks 1-4 (Period 1) and/or Weeks 5-15 (Period 2) of rearing (n = 4 pens/treatment combination) prior to transfer to standard adult laying pens for Weeks 16-27 (Period 3). In Week 27, combs were photographed, and comb laterality (hanging on left or right side) was noted. Using a custom-made image analysis programme, we captured comb area (mm 2 ), perimeter length (mm), and rugosity ((perimeter length - horizontal length) / horizontal length) from comb photographs of 6-7 randomly selected hens/pen. We predicted that hens reared in the multi -choice environment during Periods 1 and 2 would have larger, more complex, and left -side -biased combs than those in the other treatment groups, reflecting lower allostatic load. The predicted comb side bias was based on a possible bias in head posture/movements associated with greater right eye/ear use and left -brain hemispheric dominance. Contrary to our predictions, we detected an overall right -side bias in comb laterality, and no associations between resource choice treatment in Period 1 or Period 2 and comb area, perimeter length, rugosity, or laterality of the adult hens. Thus, variation in allostatic load resulting from the rearing treatments was insufficient to modify the trajectory of comb morphological development, possibly due to a ceiling effect when comparing environmental treatments on the positive end of the welfare spectrum. We found that left -lopping combs had shorter perimeters than right -lopping combs. However, among hens with left -lopping combs, those with larger combs were heavier and had less feather damage, while among hens with right -lopping combs, those with longer -perimeter combs were heavier and tended to have less comb damage. In conclusion, comb characteristics were related to physical condition at the individual level but did not serve as sensitive integrated indicators of hen welfare in response to basic vs enhanced resource choice during rearing. (c) 2024 The Author(s). Published by Elsevier B.V. on behalf of The Animal Consortium. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Changes in the behaviour of sheltered cats when coping with a new environment: focus on individuality and effects on sickness behaviour

Environmental change, such as an arrival to a cat shelter, is something that has been seen to affect the domestic cat by increasing stress levels and sickness behaviours e.g. food deprivation and diarrhoea, and thereby jeopardise its welfare. Measuring stress and welfare is of importance when evaluating a cat’s habituation and wellbeing in different situations. The invasive methods, such as measuring plasma cortisol as an indicator of stress, often cause discomfort to a cat. In this study, the method of observing behaviour when examining stress in cats is investigated. The first aim of this study was to see if cats’ behaviour changes between two periods where one is supposed to be more stressful. The second aim was to see if measuring sickness behaviours might work as an indicator of psychological stress. In this study 11 sheltered cats were observed in a cat shelter in Sweden. Behaviour elements and sickness behaviours were observed during cats’ first three days after their arrival to a new home environment. These behaviours were compared with behaviours observed during days when they had been in the new environment for longer than three days. The results showed that the relative frequency of observed behaviour elements such as body postures and activity, differs between the two periods suggesting that observing behaviour might be a valid method when investigating stress and welfare, although, the validity of the Cat-Stress-Score test used in research today could be questioned. The average amount of sickness behaviours decreased after the first three days after environmental change suggesting adaptation and that measuring sickness behaviour might be a valid method when investigating stress in sheltered cats. In this study sheltered cats were observed to hide 85 % more during the first three days after environmental change. A higher frequency of hiding behaviour was during this time period associated with a lower score of sickness behaviour. All cats except one were observed on a higher position, such as on top of a shelf or in a climbing-tree. The cats were observed to spend an average of 60 % of the time to be on higher positions during both periods. This might show that this is both a preferred coping strategy as well as a highly preferred position during everyday life for cats. Individual differences of strategies when coping with a new environment were shown. As a conclusion, this study shows that observing behaviour and measuring sickness behaviours such as diarrhoea, disruption of cage and food deprivation is useful when investigating cats’ welfare. Individuality should be considered when judging their welfare based on their behaviour and methods for doing so should be investigated further. Hiding places along with a complex enrichment and elevated surfaces should be provided to cats, especially during stressful situations such as environmental changes, in order to increase their welfare

Making the most of life: environmental choice during rearing enhances the ability of laying hens to take opportunities

Introduction: The potential of aviary housing for improving laying hen (Gallus gallus domesticus) welfare will be constrained if rearing conditions limit the hens’ behavioral ability to take opportunities. Incorporating theories on developmental plasticity and animal agency, this study aimed to determine: (1) whether a choice of litter and perch types during rearing would promote longlasting changes in use of novel locations and resources, and (2) the influence of timing of choice provision. Methods: Laying hen chicks were assigned to either a “Single-choice” (one litter and perch type) or “Multi-choice” environment (four litter and perch types) during “Early” (day 1-week 4) and “Late” rearing (week 5–15). The environments were switched in half of the 16 pens in week 5, resulting in a 2 × 2 factorial design with four choice environment by period combinations. The allocation of perch and litter space was the same across all treatment combinations. In week 16, all groups were moved to standard aviary laying pens (Laying period, week 16–27). Results: When first moved to the laying pens, hens with Multi-choice in either or both rearing periods were quicker to spread out in their pen than hens with Singlechoice throughout rearing. Multi-choice in Early rearing also reduced the latency to use novel elevated structures (perches and nests) in the laying pens. Multi-choice during Late rearing increased success in finding and consuming hidden mealworms (tested in weeks 9–17) and increased the proportion of eggs laid on elevated nesting trays. Numerically, hens switched from Multi-choice to Single-choice in week 5 used the outdoor range less than hens switched from Single-choice to Multi-choice. Discussion: These results support the hypothesis that offering multiple resource choices during rearing improves hens’ ability to make the most of new opportunities by being more proactive in exploring and exploiting newly available resources. In different opportunity challenges, hens showed positive outcomes in response to choice during Early, Late or both stages of rearing, suggesting that best results can be obtained by offering environmental choice throughout rearing

Litter and perch type matter already from the start: exploring preferences and perch balance in laying hen chicks

Early chick environment, such as provision of litter and perches, can be a predictor of laying hen welfare. Inadequate or nonpreferred litter and perch types could have similar negative effects as those seen when not providing these resources at an early stage, such as increased feather pecking and cannibalism in adult flocks. However, suitable litter and perch types for chicks are not well explored. In the present project, 6 different types of litter (crushed straw pellets, hemp shavings, peat, sand, straw, wood shavings) and 6 different types of perches (narrow or wide forms of rope, flat or round wood) were presented in a controlled way (3 at a time) to chicks in 6 pens. Usage was compared in 93 chicks of Lohmann Selected Leghorn Classic divided across the pens, during their first 3 wk after hatch. Different litter types were seen to be preferred for different behaviors. The majority of dustbathing bouts occurred in sand and peat. Chicks foraged more in wood shavings, hemp shavings, and sand than in peat and pellets (P < 0.05). Perch width and shape were found to affect both usage and perch balance, measured as the probability of successful or problematic landings. The wide rope was generally used more during the first week (P < 0.05) and was used more for sleeping or resting (P < 0.05) than the other wide perch types. Furthermore, birds were more likely to land on the wide rope or on flat perches successfully than they were to have a problematic landing (P < 0.05). That birds were more likely to be observed preening on flat perches than on the potentially shaky rope perches could further reflect a sense of security. Our results suggest that presenting several litter types could better fulfill chicks' behavioral needs and that flat perches or a wide rope (4.5-cm diameter) could be appropriate perch types for laying hen chicks and thereby promote early perch use and training

Environmental change or choice during early rearing improves behavioural adaptability in laying hen chicks

Laying hens are typically moved to a novel environment after rearing, requiring adaptability to cope with change. We hypothesized that the standard rearing of laying hen chicks, in non-changing environments with limited choices (a single variant of each resource), impairs their ability to learn new routines, use new equipment and exploit new resources. On the contrary, rearing in a changing environment that also offers a choice of resource variants could better prepare chicks for the unexpected. To explore this hypothesis, environmental change and choice were manipulated in a 2 x 2 factorial experiment. Compared to standard rearing, greater change during early rearing, through repeatedly swapping litter and perch types, reduced initial freezing when exposed to a novel environment suggesting a lower fear response. Greater choice during rearing, through simultaneous access to multiple litter and perch types, resulted in shorter latencies to solve a detour task, more movement in novel environments and less spatial clustering, suggesting improved spatial skills and higher exploration. However, combining both change and choice did not generally result in greater improvement relative to providing one or the other alone. We conclude that environmental change and choice during rearing have different positive but non-synergistic effects on later adaptability potential

Increasing Environmental Complexity by Providing Different Types of Litter and Perches during Early Rearing Boosts Coping Abilities in Domestic Fowl Chicks

Early experience of a complex environment can improve biologically relevant traits related to coping abilities. However, the mechanisms underlying these positive effects have not been well explored. We hypothesized that giving chicks possibilities to express choices within relevant resources could be an important part of the mechanism, as well as a novel way to increase environmental complexity. In a balanced design, laying hen hatchlings of the white hybrid Bovans Robust were reared in a “single-choice” environment (single litter and perch type) or a “multi-choice” environment (four different litter and perch types). Immunological and behavioral indicators of chicks’ coping abilities were explored in this experimental study at three weeks of age. Chicks from “multi-choice” environments had shorter durations of tonic immobility, lower heterophil/lymphocyte ratios, higher natural antibody concentrations, and were more successful in gaining novel food rewards in a repeated opportunity test. These results imply that chicks having access to variation within resource types were less fearful, experienced less chronic stress, would be more able to cope with pathogenic challenges, and potentially had an improved learning ability. To conclude, the more complex environment, achieved by increasing chicks’ possibilities to choose, seemed to make chicks better prepared for potential challenges, boosting their adaptive capacities and their ability to make the most of opportunities

Resource choice during ontogeny enhances both the short- and longer-term welfare of laying hen pullets

We hypothesised that resource choice during early life contributes to both current and longer-term beneficial effects on animal welfare. We investigated this hypothesis in a longitudinal cross-over experiment with laying hen pullets (Gallus gallus domesticus) reared in pens with one or four litter and perch types, respectively (n = 8 pens/treatment, all providing ample and identical litter and perch space). After 4 weeks (chick period), half the pens were modified to provide the opposite treatment (juvenile period). After 11 more weeks, all groups were moved to novel, identical laying pens (adult period; Week 16–27). In support of our hypothesis, the opportunity to choose between multiple litter and perch variants was associated with higher levels of positively-valenced behaviours, including play as chicks and dustbathing as juveniles and adults, and lower levels of negatively-valenced behaviours, including feather pecking as chicks and juveniles and aggressive pecking as adults. Resource choice in the juvenile period also led to better juvenile and adult plumage condition, and greater growth as adults. We conclude that the opportunity to choose among different litter and perch types, instead of having only one type of each, had both short- and longer-term positive effects on the birds’ affective states and physical condition

Increasing Environmental Complexity by Providing Different Types of Litter and Perches during Early Rearing Boosts Coping Abilities in Domestic Fowl Chicks

Early experience of a complex environment can improve biologically relevant traits related to coping abilities. However, the mechanisms underlying these positive effects have not been well explored. We hypothesized that giving chicks possibilities to express choices within relevant resources could be an important part of the mechanism, as well as a novel way to increase environmental complexity. In a balanced design, laying hen hatchlings of the white hybrid Bovans Robust were reared in a &ldquo;single-choice&rdquo; environment (single litter and perch type) or a &ldquo;multi-choice&rdquo; environment (four different litter and perch types). Immunological and behavioral indicators of chicks&rsquo; coping abilities were explored in this experimental study at three weeks of age. Chicks from &ldquo;multi-choice&rdquo; environments had shorter durations of tonic immobility, lower heterophil/lymphocyte ratios, higher natural antibody concentrations, and were more successful in gaining novel food rewards in a repeated opportunity test. These results imply that chicks having access to variation within resource types were less fearful, experienced less chronic stress, would be more able to cope with pathogenic challenges, and potentially had an improved learning ability. To conclude, the more complex environment, achieved by increasing chicks&rsquo; possibilities to choose, seemed to make chicks better prepared for potential challenges, boosting their adaptive capacities and their ability to make the most of opportunities