The effect of experience of ramps at rear on the subsequent ability of layer pullets to negotiate a ramp transition

The development of laying hen locomotion in 3D space is affected by early environmental complexity and genetic strain

Adult laying hens are increasingly housed in spatially complex systems, e.g., non-cage aviaries, where locomotion between elevated structures can be challenging for these gallinaceous birds. This study assessed the effect of early environmental complexity on spatial skills in two genetic strains. Brown (B) and white (W) feathered birds were raised in: Conventional cages with minimal complexity (Conv) or rearing aviaries with low (Low), intermediate (Mid), or high complexity (High). Birds from each housing treatment were challenged at three different time points in three different, age-appropriate vertical spatial tasks. Whites performed better than brown birds in all tests regardless of rearing environment. In chicks, test performance was predominantly explained by variation between replicates and differences in motivation for test participation. Treatment effects were seen in pubertal birds (pullets), with pullets from aviaries performing better than those from Conv. White High pullets performed better than white Mid or Low, an effect that was not found in browns. Pullets preferred to use a ramp to move downwards, but only when ramps had previously been experienced and when the ramp was not too steep. Overall, early environmental complexity affected spatial skills of laying hen pullets with stronger effects in white than brown feathered birds.

Farm Environmental Enrichments Improve the Welfare of Layer Chicks and Pullets: A Comprehensive Review

Currently, cage housing is regarded as a global mainstream production system for laying hens. However, limited living space and confinement of birds in cages cause welfare and health problems, such as feather pecking, osteoporosis, obesity, and premature aging. Many studies have been conducted to alleviate layer welfare problems by providing farm environmental enrichments such as litter, sand, alfalfa bales, chick papers, pecking stones, pecking strings, perches, slopes, elevated platforms, aviaries and outdoor access with a trend towards complex enrichments. The provision of appropriate enrichments continuously attracts layers towards pecking, foraging, dust bathing, and locomotion, thereby giving lifelong benefits to laying hens. Hence, raising chicks and pullets under such conditions may reduce feather and skin damage, as well as accumulation of abdominal fat, and improve several biological features such as health, productivity, quality products, and docility of laying hens. Therefore, providing enrichment during the first few days of the layer’s life without any interruption is crucial. In addition, due to different farm conditions, environmental enrichment should be managed by well-trained farm staff. For example, in preventing feather pecking among the birds, litter materials for foraging are superior to dust bath materials or new items. However, a limited supply of litter creates competition and challenges among birds. Therefore, providing farm environmental enrichment for layers requires proper handling, especially in commercial layer farms. Hence, improving the welfare of chicks and pullets through optimizing on-farm environmental enrichments is essential for production systems practicing cage housing.

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.

Rearing experience with ramps improves specific learning and behaviour and welfare on a commercial laying farm

To access resources in commercial laying houses hens must move between levels with agility to avoid injury. This study considered whether providing ramps during rear improved the ability of birds to transition between levels. Twelve commercial flocks (2000 birds/flock) on a multi-age site were examined between 1 and 40 weeks of age. All birds had access to elevated perching structures from 4 days of age. Six treatment flocks were also provided with ramps during rear to facilitate access to these structures. Flocks were visited three times during rear and three times at lay to record transitioning behaviour and use of the elevated structures, together with scores for keel bone and feather damage. Ramp reared flocks used the elevated structures to a greater extent at rear (P = 0.001) and at lay, when all flocks had ramps, showed less hesitancy [i.e. pacing (P = 0.002), crouching (P = 0.001) and wing-flapping (P = 0.001)] in accessing levels. Mean levels of keel bone damage were reduced in ramp reared flocks (52%) compared with control flocks (64.8%) at 40 weeks of age (P = 0.028). The early life experience of the ramp reared flocks enabled specific learning that translated and persisted in later life and resulted in overall welfare benefits.

Skeletal health of layers across all housing systems and future research directions for Australia

Modern laying hens have been selected for an astounding rate of egg production, but the physiological calcium demand takes a significant toll on their skeletal health. Bones can be assessed both in vivo and ex vivo, using a combination of different structural and mechanical analysis methods. Typically, the properties of leg, wing and keel bones are measured. Conventional caged layers are restricted in movement, which imbalances structural bone resorption and new bone formation, resulting in osteoporosis. Hens within alternative housing systems have opportunities to exercise for strengthening bones, but they can also suffer from higher rates of keel fractures and/or deviations that are likely to have resulted from collisions or pressure force. Limited research has been conducted within Australian commercial housing systems to assess hen skeletal health, including prevalence of keel damage across different system types. Research conducted on both brown and white hen strains approximately within the past decade internationally (2009 onward) has shown that skeletal health is impaired across all housing systems. Keel-bone damage is of specific concern as it occurs at high rates, particularly in multi-tiered systems, is painful, can alter hen behaviour, and reduce both production and egg quality. Management strategies such as the provision of ramps to access perches and tiers can reduce the incidence of keel-bone damage to a degree. Bone strength can be improved through exercise opportunities, particularly when available during pullet rearing. Genetic selection for high bone strength may be necessary for hens to adequately adapt to loose-housed systems, but the best strategy for improving skeletal health is likely to be multifactorial.

The impact of early structural enrichment on spatial cognition in layer chicks

The aim of the study was to determine whether early access to elevated structures affects spatial navigational abilities. Ninety six day-old chicks were reared in 16 pens. Eight pens were provided with A-frame perches with an attached platform and a ramp. Eight pens had no elevated structures. At 14-15 days of age 48 chicks were tested in a battery of navigational tasks: a detour test, jump test and rotated floor test (RFT). The remaining 48 chicks received the same tests at 28-29 days of age. Chicks reared with elevated structures were faster at completing the detour test (P = 0.045). Older chicks were more likely to turn left in the detour test (p = 0.013) and were more successful in the jump test (69% vs 31% completion, p = 0.001). There was no treatment effect on use of intra or extra-maze cues in the RFT, but the proportion of chicks using intra-maze cues declined between the first (0.76) and second (0.43) repeat of the RFT (p = 0.038), particularly for chicks reared with elevated structures. We conclude that bird age or developmental stage may have a predominant influence on spatial navigation and physical ability, but early experience of elevated structures had some mediating effects which require further investigation.