Ability of laying hens to jump between perches: individual variation and the effects of perch separation and motivation on behaviour

Perch Positioning Affects both Laying Hen Locomotion and Forces Experienced at the Keel

The aim of this study was to assess the effect of perch positioning on laying hens' locomotion and the resulting energy experienced at the keel. Twenty Nick Chick and 20 Brown Nick hens were trained to transition from a platform to a perch in several configurations. Three variables of perch positioning were tested in a 2 × 2 × 2 factorial design: direction (upward vs. downward), angle (flat vs. steep), and distance (50 cm vs. 100 cm). All hens were tested for five jumps of each treatment combination at 27-28 weeks of age. As predicted, we found steep angles and long distances to result in higher peak forces and impulse during take-off, flight, and landing; longer latency to jump; a higher likelihood to perform balancing movements; and a longer latency to peck at the provided food reward. The effect of perch positioning on locomotion and force at the keel during downwards jumps and flight was more pronounced in Brown Nick hens than in Nick Chick hens. Although we cannot state how the observed forces at the keel relate to the risk for keel bone fractures, our results indicated that optimizing perch positioning can reduce accumulated forced at the keel and consequent risk for fracture due to unsuccessful transitions.

Prevalence of keel bone deformities in Swiss laying hens

The goal of this study was to evaluate the prevalence of keel bone deformities of laying hens in Switzerland. The keel bones of 100 end-of-lay hens from each of 39 flocks (3900 in total) were palpated. On average, 25·4% of the hens had moderately or severely deformed keel bones and the overall prevalence including slight deformities was 55%. 3. Variation between flocks was considerable. Thus, the prevalence of moderately or severely deformed keel bones ranged from 6 to 48%, and the overall prevalence including slight deformities ranged from 20 to 83%. Aviary housing was associated with a higher prevalence of total, and severe or moderate deformations, compared with floor pens. There were no significant differences in the number of deformities between the different plumage colours, hybrids or perch materials.

Poultry housing and husbandry

1. In order to conduct this anniversary review, 10 excellent papers were carefully selected from the 148 available papers published on housing and husbandry in British Poultry Science (BPS) over the past 50 years. 2. The 10 selected papers on this subject covered mainly the housing and husbandry of laying hens, but two of them dealt with various aspects of broiler production. 3. Aspects of housing considered included a wide range of intensive and extensive systems of broiler and egg production. Specific topics included the effects of husbandry system on bird welfare, including skeletal damage in laying hens and contact dermatitis in broiler chickens, as well as the design and management of nest boxes, perches, feeders and drinkers, conventional laying cages (CCs), furnished laying cages (FCs) and non-cage systems (NCs). 4. A variety of the findings in these and related papers have enlightened our understanding of many aspects of poultry housing and husbandry; most of them have found application in the poultry industry and thus improved its efficiency.

Providing laying hens with perches: fulfilling behavioural needs but causing injury?

1. The EU laying hen directive, which bans standard battery cages from 2012, has implications for animal welfare, particularly since housing laying hens in extensive systems, while increasing natural behaviour and improving bone strength, is associated with a greater level of bone fractures, predominantly of the keel bone, compared to birds housed in cages. 2. The aetiology and welfare consequences of keel and other bone fractures are not well understood and could have important implications for housing system designs. While proposed alterations to layer housing are based on the desire to fulfil behavioural needs and increase bone strength, there appears to have been little consideration of the effect of system on potential injury. 3. In addition, there are variations in how the directive is interpreted. For example, egg producers housing hens in extensive systems in Scotland and Northern Ireland must provide hens with aerial perches, whereas in England and Wales they do not. Aerial perches may be implicated in bone fracture injuries. 4. This paper reviews the prevalence of bone fractures in the egg-laying sector of the poultry industry and the literature on perches. It also explores how bone fractures may be occurring. 5. We propose some means of reducing bone fracture, namely through improved housing designs and genetic selection.

Effects of perch design on behaviour and health of laying hens

EU-Directive 1999/74/EC stipulates that furnished cages and non-cage systems for laying hens should be provided with perches. This Directive allows for a wide variety in perch design features possibly affecting perch use and hen health. Perch material and shape mainly affect slipperiness and grip quality and, in this regard, plastic, metal and circular perches are inferior. The incidence of bumble-foot and keel bone deformities can be influenced by perch shape. Perch shapes which reduce localised pressure on the foot pad and the keel-bone are recommended. Several aspects of the arrangement of the perches in the cage or non-cage system are also important. A consistent preference for high perches is seen, provided there is a minimal distance of 19–24 cm between perch and roof. Accessibility of high perches should be ensured, for example by incorporating lower level perches from which hens can reach the higher levels. Such multi-height perch designs also allow behavioural differentiation according to perch height (with most passive behaviour on the higher perches). In non-cage systems, good accessibility can be achieved by minimising the angles between perches at different heights to smaller than 45° and by limiting the distance between horizontal perches to 1 m. The legislated minimum perch length provided per hen (15 cm) adequately allows for synchronised roosting behaviour on straight perches. However, in crosswise perch designs, hens require more perch length per hen as the area close to the cross cannot be used optimally.

Welfare, Health, and Hygiene of Laying Hens Housed in Furnished Cages and in Alternative Housing Systems

The aim of this review was to compare welfare, health, and hygienic status of laying hens housed in furnished cages and in alternative systems. In alternative systems (floor housing and aviaries), birds have more freedom of movement and a more complex environment than in furnished cages. However, housing birds in much larger flocks in alternative systems leads to an increased risk of feather-pecking. Furthermore, air quality can be poorer in alternative systems than in furnished cages. This can affect health and hygienic status. There are only limited data on a direct comparison between furnished cages and alternative systems. Therefore, there is a need for an on-farm comparison of welfare, health, and hygienic status in these systems.

The ability of laying hens to negotiate perches of different materials with clean or dirty surfaces

Increasingly, perches for laying hens are being made from metals and plastics. There is nothing in the literature regarding how easily birds jump between perches of different materials, or how their ability to do so changes with faecal contamination of the perches. Forty-four medium hybrid brown hens negotiated perches of wood (5 cm × 5 cm, rounded edges), metal (half-round section, diameter 4 cm) or poly-vinyl-chloride (PVC: circular section, diameter 4 cm), which were either clean or dirty (poultry manure 0.5–1.0 cm deep). The time to jump to the destination perch (0.75 m from the start perch), number of squats (pre-jumping behaviour), slips, failures to jump (in 300 s) and crashes were recorded. Compared to wood and metal perches, birds took significantly longer to jump from PVC perches when they were clean, but there was no difference when the perches were dirty. Birds slipped significantly more on clean metal or PVC perches compared to clean wood perches. The birds took significantly longer to jump from metal or wooden perches when they were dirty compared to when they were clean. These data may suggest that PVC is not a suitable material for perches. Slipperiness is important. The birds apparently found the metal and PVC perch more slippery than the wooden perch, although the metal perch did not cause the birds to delay jumping. A slippery perch may deter the birds from attempting to jump. Manure on the perches reduced the slipperiness of the metal and PVC perches. Once perches become dirty, any welfare issues concerning the risk of injury from slippery perches cease to be as important as the potential slipperiness of the manure itself.