How does the presence of excreta affect the behavior of laying hens on scratch pads?

Measuring Chronic Stress in Broiler Chickens: Effects of Environmental Complexity and Stocking Density on Immunoglobulin-A Levels

Commercial housing conditions may contribute to chronic negative stress in broiler chickens, reducing their animal welfare. The objective of this study was to determine how secretory (fecal) and plasma immunoglobulin-A (IgA) levels in fast-growing broilers respond to positive and negative housing conditions. In three replicated experiments, male Ross 708 broilers (n = 1650/experiment) were housed in a 2 × 2 factorial study of high or low environmental complexity and high or low stocking density. In experiments 1 and 3 but not in experiment 2, high complexity tended to positively impact day 48 plasma IgA concentrations. When three experiments were combined, high complexity positively impacted day 48 plasma IgA concentrations. Stocking density and the complexity × density interaction did not impact day 48 plasma IgA concentrations. Environmental complexity and the complexity × density interaction did not impact day 48 secretory IgA concentrations. A high stocking density negatively impacted day 48 secretory IgA concentrations overall but not in individual experiments. These results suggest that environmental complexity decreased chronic stress, while a high stocking density increased chronic stress. Thus, plasma IgA levels increased under high-complexity housing conditions (at day 48), and secretory IgA levels (at day 48) decreased under high-density conditions, suggesting that chronic stress differed among treatments. Therefore, these measures may be useful for quantifying chronic stress but only if the statistical power is high. Future research should replicate these findings under similar and different housing conditions to confirm the suitability of IgA as a measure of chronic stress in broiler chickens.

Welfare of broilers on farm

This Scientific Opinion considers the welfare of domestic fowl (Gallus gallus) related to the production of meat (broilers) and includes the keeping of day-old chicks, broiler breeders, and broiler chickens. Currently used husbandry systems in the EU are described. Overall, 19 highly relevant welfare consequences (WCs) were identified based on severity, duration and frequency of occurrence: 'bone lesions', 'cold stress', 'gastro-enteric disorders', 'group stress', 'handling stress', 'heat stress', 'isolation stress', 'inability to perform comfort behaviour', 'inability to perform exploratory or foraging behaviour', 'inability to avoid unwanted sexual behaviour', 'locomotory disorders', 'prolonged hunger', 'prolonged thirst', 'predation stress', 'restriction of movement', 'resting problems', 'sensory under- and overstimulation', 'soft tissue and integument damage' and 'umbilical disorders'. These WCs and their animal-based measures (ABMs) that can identify them are described in detail. A variety of hazards related to the different husbandry systems were identified as well as ABMs for assessing the different WCs. Measures to prevent or correct the hazards and/or mitigate each of the WCs are listed. Recommendations are provided on quantitative or qualitative criteria to answer specific questions on the welfare of broilers and related to genetic selection, temperature, feed and water restriction, use of cages, light, air quality and mutilations in breeders such as beak trimming, de-toeing and comb dubbing. In addition, minimal requirements (e.g. stocking density, group size, nests, provision of litter, perches and platforms, drinkers and feeders, of covered veranda and outdoor range) for an enclosure for keeping broiler chickens (fast-growing, slower-growing and broiler breeders) are recommended. Finally, 'total mortality', 'wounds', 'carcass condemnation' and 'footpad dermatitis' are proposed as indicators for monitoring at slaughter the welfare of broilers on-farm.

Environmental complexity positively impacts affective states of broiler chickens

Affective state can bias an animal's judgement. Animals in positive affective states can interpret ambiguous cues more positively ("optimistically") than animals in negative affective states. Thus, judgement bias tests can determine an animal's affective state through their responses to ambiguous cues. We tested the effects of environmental complexity and stocking density on affective states of broiler chickens through a multimodal judgement bias test. Broilers were trained to approach reinforced locations signaled by one color and not to approach unreinforced locations signaled by a different color. Trained birds were tested for latencies to approach three ambiguous cues of intermediate color and location. Broilers discriminated between cues, with shorter latencies to approach ambiguous cues closest to the reinforced cue than cues closest to the unreinforced cue, validating the use of the test in this context. Broilers housed in high-complexity pens approached ambiguous cues faster than birds in low-complexity pens-an optimistic judgement bias, suggesting the former were in a more positive affective state. Broilers from high-density pens tended to approach all cues faster than birds from low-density pens, possibly because resource competition in their home pen increased food motivation. Overall, our study suggests that environmental complexity improves broilers' affective states, implying animal welfare benefits of environmental enrichment.

Floor Substrate Preferences of Chickens: A Meta-Analysis

Environmental enrichment promotes sensory and motor stimulation for species-typical behaviors, which in turn enhance animal well-being. For farmed Galliformes, housing systems often limit enrichment to bedding and litter, that simultaneously act as material for dustbathing and foraging. Therefore, this meta-analysis sought to systematically review and synthesize the substrate preference test literature for Galliformes. Data based on the following four welfare-related behaviors were extracted for analysis: (1) dustbathing, (2) foraging, (3) pecking, and (4) time spent on a given substrate. Literature searches in CAB Direct, Web of Science, and Google Scholar yielded 239 articles, and hand searching yielded an additional five articles. Ten publications that used different chicken strains as test subjects, met the criteria to be included in the systematic review. The effects of bedding type, the number of days birds had access to tested substrates, enclosure area, and substrate area, on the examined behaviors were determined. We found that birds preferred dustbathing in sand and peat moss more than on any other substrates. The bedding type, size of the enclosure, and size of the substrate area affected the amount of time that birds spent on the tested substrates. When provided the choice between bedding materials, birds spent more time on sand or peat moss than on any other substrate or on no substrate. Notably, most studies did not report relevant physical or chemical characteristics of substrate that may influence birds' preferences, such as grain size, moisture content and the level of soiling. Focusing future studies on identifying substrate characteristics that influence preferences can lead to the discovery of new, practical, enriching beddings that can be easily implemented in housing systems for Galliformes.

Are Turkeys (Meleagris gallopavo) Motivated to Avoid Excreta-Soiled Substrate?

Simple Summary

Commercial turkeys are raised in large barns at stocking densities that cause excreta (or feces) to quickly accrue in the turkeys’ environment. Even though commercial turkeys spend most, if not all, of their time in contact with their excreta, we do not know how turkeys perceive this soiled environment. Therefore, our study used six pens of four turkeys, dividing each pen with a barrier that contained two one-way push-doors. This created two compartments: a “home” compartment containing soiled wood shavings, and a “treatment” (T) compartment containing fresh pine and spruce wood shavings (FP), soiled pine and spruce wood shavings (SP), ammonia reductant-treated soiled pine and spruce wood shavings (TSP), no substrate (NS), or a feed treatment. To establish the turkeys’ motivation to access these resources, we weighed the door to T with 0%, 20% or 40% of the turkeys’ body weight. The number of turkeys that pushed the maximum door weight was used as an indicator for their motivation. Additionally, time spent in T and the odds of visiting T were examined to determine how the turkeys responded to increasing challenge. We found that the turkeys preferred feed over all other resources and showed equal motivation for all floor substrate treatments.

Abstract

The soiling of bedding on modern turkey farms combined with turkeys’ reduced ability and opportunity to perch and roost at elevation, forces them to spend most, if not all, of their time in contact with their excreta. To determine turkeys’ perspective on these conditions and the value they place on unsoiled bedding vs. soiled litter (collectively, substrates), we used twenty-four eleven-week-old turkey hens divided into six two-compartment pens. In the “home” compartment (H), we placed soiled wood shavings, while the “treatment” compartment (T) contained no substrate (NS), fresh pine and spruce wood shavings (FP), soiled pine and spruce wood shavings (SP), ammonia reductant-treated soiled pine and spruce wood shavings (TSP), or a feed treatment. One-way push-doors separated the two compartments. The door leading to T weighed an additional 0%, 20% or 40% of the turkeys’ body weight while the door to H remained unweighted. All birds were exposed to each resource and door weight combination in a systematic order. We measured the turkeys’ motivation based on the number of birds that pushed the maximum weight to access each resource, the amount of time spent in T, and the number of visits to T. Our findings show that turkeys worked harder to access feed compared to all the floor substrate treatments. Additionally, they were equally motivated to access all the substrate treatments.

Broiler Chicks' Motivation for Different Wood Beddings and Amounts of Soiling

Simple Summary

Many animals move excreta—or feces—away from resting areas to avoid attracting predators and spreading disease. However, today’s farms raise broiler (meat) chickens in large barns with stocking densities that prevent the birds from segregating their excreta. Moreover, whether or not chickens would prefer to avoid their excreta is unknown. Understanding what litter conditions chickens prefer can help inform farming practices. Therefore, this experiment aimed to assess chicks’ motivation to access unsoiled bedding or soiled litter. We used six pens of six to seven broiler chicks—each pen divided into two compartments by a barrier containing two one-way push-doors. The ‘home’ compartment contained soiled wood shavings, while the ‘treatment’ (T) compartment contained either aspen wood shavings, pine and spruce wood shavings, soiled pine and spruce wood shavings, ammonia reductant treated soiled pine and spruce wood shavings, or a feed treatment as a gold standard. To determine the chicks’ motivation to access the resources, the door leading into T weighed 0% (lifted), 10%, 20%, or 30% of the chicks’ body weight. The combination of time spent in T, number of visits to T, and average maximum weight pushed to access T were used to measure motivation. Chicks showed equal motivation for all substrates and preferred feed over all substrates. However, future experiments must explore chicks’ preference and motivation over the long-term in commercial conditions.

Abstract

In the wild, excreta soiled surroundings can attract predators and spread disease. Yet, farmers rear broiler chicks in large barns with stocking densities that prevent excreta segregation. To measure chicks’ motivation to access unsoiled bedding or soiled litter (collectively, substrates) we used 40 16-day-old broiler chicks who were divided into six two-compartment pens. The ‘home’ compartment (H) contained soiled wood shavings, while the ‘treatment’ compartment (T) contained either aspen wood shavings, pine and spruce wood shavings, soiled pine and spruce wood shavings, ammonia reductant treated soiled pine and spruce wood shavings, or a feed treatment as a gold standard. The barrier separating the compartments had two one-way push-doors that chicks pushed to access a resource. The chicks’ motivation was measured by the average maximum weight pushed to access each resource. The door leading to T weighed 0% (raised), 10%, 20%, or 30% of the chicks’ body weight, and chicks could return to H via a raised (for 0%) or unweighted door. Our findings indicate that chicks worked hardest for feed, but paid a lower, equal price to access all substrates. With increasing door weight, chicks visited less and spent less time with the substrates. Therefore, as chicks themselves do not avoid litter that could have potential negative effects on their well-being, it is important that farmers diligently monitor litter conditions as their primary care-takers.

Effects of different claw-shortening devices on claw condition, fear, stress, and feather coverage of layer breeders

Natural mating colony cage systems for parent-stock layer breeders have been widely adopted by many commercial farms in China. However, the environment is still relatively barren, so enrichment devices such as claw abrasives can be provided. Hens living in wire cages lack the opportunity to abrade their claws, resulting in uncontrolled claw growth. The objective of this study was to investigate the effects of claw abrasive devices (CADs). Three different CADs were investigated: abrasive strips (T1), metal plates with holes (T2) and rubber mats with grooves (T3); cages without CADs acted as controls (T4). Claw length and sharpness, foot health, feather coverage, fear and physiological stress and mortality of the layer breeders were evaluated. Twelve replicates were used for each treatment, a total of 48 identical cages. Results showed that CADs had significant effects on claw length and sharpness of both hens and roosters. Birds in the T1 group had the shortest claw length and bluntest claw sharpness at 22, 32, 42, and 52 wk of age (P < 0.05). T1, T2, and T3 had higher scores for claw condition and significantly better overall plumage condition on the back and rump than T4 (P < 0.05). Hens in the T4 group were more susceptible to the tonic immobility, novel object, and avoidance distance tests. No significant differences were found between groups in concentration of triiodothyronine, thyroxine or 5-HT, except a significantly higher concentration of corticosterone in T4 compared to T1, T2, and T3 (P < 0.05). Overall mortality and mortality from cannibalism were both significantly higher in T4 than in T1, T2, and T3 (P < 0.05). In conclusion, hens with access to CADs during the laying period had shorter and blunter claws, less damaged plumage, a lower plasma corticosterone secretion and mortality rate and were less fearful.

An Investigation of Associations Between Management and Feather Damage in Canadian Laying Hens Housed in Furnished Cages

Feather pecking is a continuous welfare challenge in the housing of egg-laying hens. Canada is currently making the transition from conventional cages to alternative housing systems. However, feather damage (FD) among laying hens due to feather pecking remains a welfare concern. An explorative approach was taken to assess bird, housing, and management associations with FD in Canadian laying hens housed in alternative systems. A questionnaire focused on housing and management practices was administered to 122 laying farms across Canada in autumn of 2017 (response rate of 52.5%), yielding information on a subset of 26 flocks housed in furnished cages. Additionally, a three-point feather cover scoring system was developed to estimate the prevalence of FD. Farmers assessed FD by sampling 50 birds per flock. Linear regression modeling was applied to explain FD as a function of 6 variables (out of an available 54). Of the 6 modeled variables, "increased age", "brown feather colour", "midnight feeding", and "no scratch area" were associated with higher levels of FD at farm level (R² = 0.77). The results indicated that FD resulting from feather pecking is a multifactorial problem, and supported existing evidence that FD increases as birds age. These results also suggested that "feather colour", "midnight feeding", and "access to (or lack of) a scratch area or additional substrate" play a role in FD prevalence in furnished cages.

A Description of Laying Hen Husbandry and Management Practices in Canada

Simple Summary

Furnished cage and non-cage (single-tier or multi-tier) housing systems are increasingly used worldwide in efforts to improve laying hen welfare. Canadian laying hen farms are undergoing a similar transition, however, little is known about the housing and management of laying hens in these housing systems in Canada. Data collected through farmer questionnaires from 65 laying hen flocks across Canada revealed commonly used management practices in furnished cage (26), single-tier (17) and multi-tier systems (22). Non-cage systems should allow hens to perform natural behavior (e.g., foraging/dustbathing). However, a proportion of non-cage systems either did not provide litter or considered manure as a litter substrate, which could have implications for consumer perspectives on these systems. Daily flock inspections and vaccination schemes were the main practices used to maintain flock health, whereas veterinarian involvement on-farm and in the development and implementation of a flock health plan was less common. Further research is needed to make clear recommendations and to investigate how to facilitate management changes by farmers currently transitioning to furnished cage and non-cage housing systems.

Abstract

Canadian laying hen farms are transitioning from conventional cage housing to furnished cage and non-cage housing systems to improve laying hen welfare. However, little is known about the current housing and management systems in Canada. This study addresses this knowledge gap by describing different housing and management practices used on farms where laying hens were housed in furnished cages or non-cage housing systems. A questionnaire covering farm and housing conditions, litter management, nutrition and feeding, environmental control, flock characteristics, rearing and placement, health, egg production and performance were distributed through provincial egg boards to 122 producers across Canada. Data were collected from 65 laying hen flocks (52.5% response rate) in 26 furnished cage, 17 single-tier and 22 multi-tier systems. Flocks were on average 45.1 ± 14.59 weeks old (range: 19–69 weeks). Frequencies of different management practices were calculated according to housing system. Most flocks were reared in the same housing system as they were housed in during lay, with the exception of furnished cage layers which were reared in conventional cage systems. Results indicated that a large proportion of non-cage systems were either fully slatted or had manure as a litter substrate, which could have implications for consumer perspectives on these systems. Further research is needed to develop clear recommendations on proper litter management for farmers. In general, flock health was managed through daily inspections and vaccination schemes, whereas veterinarian involvement on-farm was less common. Vaccination, hygiene, and effective biosecurity should be maintained to ensure good health in laying hens in furnished cage and non-cage systems during the transition to these systems.

Do laying hens eat and forage in excreta from other hens?

Worldwide, farm animals are kept on litter or foraging substrate that becomes increasingly soiled throughout the production cycle. For animals like laying hens, this means that it is likely they would scratch, forage and consume portions of excreta found in the litter or foraging substrate. However, no study has investigated the relative preference of laying hens for foraging and consumption of feed mixed with different percentages of excreta. A total of 48 White Leghorn laying hens of two strains, a commercial strain (Lohmann LSL-Lite (LSL), n=24) and UCD-003 strain (susceptible to liver damage, n=24), were individually housed and given access to feed mixed with increasing percentages of hen excreta (0%, 33%, 66% and 100% excreta diets) and corn as a luxury food reward (four corn kernels per diet daily). The amount of substrate and number of corn kernels consumed from each diet was recorded for a period of 3 weeks. Both LSL and UCD-003 hens preferred to consume and forage in diets with 0% excreta, followed by 33% and finally diets containing 66% and 100% excreta. Despite the presence of excreta-free diets, birds consumed on average 61.3 g per day of the diets containing excreta. Neither physical health, measured by plasma enzyme activity levels, nor cognitive differences, assessed by recalling a visual discrimination task, was associated with relative feeding or foraging preference. In conclusion, this study demonstrated a clear preference for feeding and foraging on substrate without excreta in laying hens. However, considering the amount of excreta diets consumed, further studies are needed to understand the causes and consequences of excreta consumption on physiological and psychological functioning, and how this information can be used to allow adjustments in the management of foraging substrates in farmed birds.