Risk factors for smothering in three commercial free-range layer poultry farms, Australia 2019-2022

In intensively managed poultry production systems the term 'smothering' refers to deaths from suffocation that occur as a consequence of piling behaviour where birds crowd together into densely packed groups. Smothering is a non-negligible source of loss in free-range layer hens, having both negative welfare and economic effects. Smothering events are rarely observed and are usually detected by the discovery of groups of dead hens. The aim of this study was to identify risk factors for smothering deaths in three commercial free-range layer poultry farms in Australia. This was a prospective cohort study of poultry flocks managed by three commercial free-range layer farms in eastern Australia. Flocks were enrolled into the study from 1 January 2019-29 March 2021 and were followed until the end of lay or until the end of the study on 31 March 2022, whichever occurred first. Throughout the follow-up period of the study, daily production and weather data, details of flock management and details of the place and time of smothering events were recorded. Time to event (survival) analyses were used to quantify the association between hypothesised risk factors and the number of days in lay at the time of smothering. Shed and bird level characteristics associated with time to event were quantified using a stratified Cox proportional hazards model which included a frailty term to account for birds clustered within sheds within farm. Across the three farms, for every 100 birds placed into a shed, there were 12 deaths over the duration of the production period. Of the 12 deaths per 100 birds, 2 were due to smothering. Our Cox proportional hazards regression analyses showed that the daily hazard of smothering was increased for birds housed in aviary sheds compared with flat-deck sheds (HR 4.0, 95 % CI 1.7-9.7). The daily hazard of smothering mortality was increased on warm, humid and rainy days, and in birds with low fear of humans and high fear of novel objects. Rainy days on which outdoor daily average humidity was greater than or equal to 70 % were associated with a 3.7 (95 % CI 3.5-3.9) fold increase in the daily hazard of indoor smothering deaths, compared with days when outdoor daily average humidity was less than 70 % and no rain. This study provides useful insight into the determinants of smothering in Australian free-range layer hens, in particular risk factors that do not change over time (e.g., shed type) and those that change daily (e.g., weather conditions). This information allows flock management strategies to be adapted accordingly.

Recognition of Abnormal-Laying Hens Based on Fast Continuous Wavelet and Deep Learning Using Hyperspectral Images

The egg production of laying hens is crucial to breeding enterprises in the laying hen breeding industry. However, there is currently no systematic or accurate method to identify low-egg-production-laying hens in commercial farms, and the majority of these hens are identified by breeders based on their experience. In order to address this issue, we propose a method that is widely applicable and highly precise. First, breeders themselves separate low-egg-production-laying hens and normal-laying hens. Then, under a halogen lamp, hyperspectral images of the two different types of hens are captured via hyperspectral imaging equipment. The vertex component analysis (VCA) algorithm is used to extract the cockscomb end member spectrum to obtain the cockscomb spectral feature curves of low-egg-production-laying hens and normal ones. Next, fast continuous wavelet transform (FCWT) is employed to analyze the data of the feature curves in order to obtain the two-dimensional spectral feature image dataset. Finally, referring to the two-dimensional spectral image dataset of the low-egg-production-laying hens and normal ones, we developed a deep learning model based on a convolutional neural network (CNN). When we tested the model's accuracy by using the prepared dataset, we found that it was 0.975 percent accurate. This outcome demonstrates our identification method, which combines hyperspectral imaging technology, an FCWT data analysis method, and a CNN deep learning model, and is highly effective and precise in laying-hen breeding plants. Furthermore, the attempt to use FCWT for the analysis and processing of hyperspectral data will have a significant impact on the research and application of hyperspectral technology in other fields due to its high efficiency and resolution characteristics for data signal analysis and processing.

Flock Factors Correlated with Elevated Mortality in Non-Beak Trimmed Aviary-Housed Layers

The use of non-cage housing systems for layers is increasing in Europe and elsewhere. Knowledge of factors that may affect mortality in these systems is important to be able to improve animal welfare, reduce mortality and enhance sustainability. The aim of this study was to investigate factors that may contribute to increased mortality in non-beak trimmed aviary-housed laying hens in Norway. A total of 39 non-beak trimmed commercial flocks (Lohmann LSL (n = 25) and Dekalb White (n = 14)) were visited between week 70 to 76 of life, and factors related to health, behaviour and management were recorded. Mean mortality in the flocks was 3% (range: 0.5−9%) and increased flock mortality was correlated with total feather loss (p < 0.05); feather loss on the breast (p < 0.02) and feather loss on the head (p < 0.003). There was an association between layer hybrid line and mortality (p = 0.055). Furthermore, a low positive correlation between mortality and dust level inside the barn was found (p < 0.04), showing that mortality was higher when dust level was also high. No correlation between mortality and the provision of environmental enrichment was found. In conclusion, this study found an association between flocks with elevated mortality (>3.0%) and increased feather loss which may indicate feather pecking. The results underline the importance of regularly assessment of plumage condition in commercial layer farms, as a tool to detect early signs of feather pecking in commercial aviary-housed layer flocks. This may help to target feather pecking before cannibalism breaks out.

The Impact of Probiotic Bacillus subtilis on Injurious Behavior in Laying Hens

Simple Summary

Injurious behavior prevention is a critical issue in the poultry industry due to increasing social stress, leading to negative effects on bird production and survivability, consequently enhancing gut microbiota dysbiosis and neuroinflammation via the microbiota–gut–brain axis. Probiotics have been used as potential therapeutic psychobiotics to treat or improve neuropsychiatric disorders or symptoms by boosting cognitive and behavioral processes and reducing stress reactions in humans and various experimental animals. The current data will first report that probiotic Bacillus subtilis reduces stress-induced injurious behavior in laying hens via regulating microbiota–gut–brain function with the potential to be an alternative to beak trimming during poultry egg production.

Abstract

Intestinal microbiota functions such as an endocrine organ to regulate host physiological homeostasis and behavioral exhibition in stress responses via regulating the gut–brain axis in humans and other mammals. In humans, stress-induced dysbiosis of the gut microbiota leads to intestinal permeability, subsequently affecting the clinical course of neuropsychiatric disorders, increasing the frequency of aggression and related violent behaviors. Probiotics, as direct-fed microorganism, have been used as dietary supplements or functional foods to target gut microbiota (microbiome) for the prevention or therapeutic treatment of mental diseases including social stress-induced psychiatric disorders such as depression, anxiety, impulsivity, and schizophrenia. Similar function of the probiotics may present in laying hens due to the intestinal microbiota having a similar function between avian and mammals. In laying hens, some management practices such as hens reared in conventional cages or at a high stocking density may cause stress, leading to injurious behaviors such as aggressive pecking, severe feather pecking, and cannibalism, which is a critical issue facing the poultry industry due to negative effects on hen health and welfare with devastating economic consequences. We discuss the current development of using probiotic Bacillus subtilis to prevent or reduce injurious behavior in laying hens.

Myeloperoxidase expression in diencephalon is potentially associated with fear‐related behavior in chicks of laying hen

Preventing feather pecking (FP) in adult laying hens is important for the welfare of intensively poultry farming. Fear-related behavior in growing female layer chicks may predict FP in adult hens. In this study, in two representative laying breeds (White Leghorn [WL] and Rhode Island Red [RIR]) that have different FP frequencies, we identified a candidate gene associated with fear-related behavior in chicks and FP in adult hens. In the tonic immobility test and open-field test, the behavioral activity was lower in WL chicks than in RIR chicks (P < 0.01), suggesting that WL chicks were more fearful than RIR chicks. Based on previous studies, 51 genes that have been found to be differentially expressed in the brain between high- and low-FP populations were chosen, and their expression levels were screened in the chick diencephalon. This analysis revealed that myeloperoxidase (MPO) gene expression level was higher in WL chicks than that in RIR chicks (P < 0.05). Furthermore, STRING analysis predicted the gene network including MPO and MPO-related genes and revealed the association of these genes with fear-related behavior. These results suggest that MPO is potentially associated with fear-related behavior in growing female layer chicks and FP in adult hens.

Feather Pecking in Non-Beak-Trimmed and Beak-Trimmed Laying Hens on Commercial Farms with Aviaries

Simple Summary

Severe feather pecking (SFP) is a major animal welfare problem in layers. It results in pain and injuries in the affected animal. SFP is a behavioral disorder and should not be confused with aggressive pecking. The aim of our study was to observe the pecking behavior of layers on farms with flock sizes common in practice and to identify possible influencing factors. We found that SFP occurred in all flocks, but the pecking rate varied widely between flocks. A low stocking density and the provision of a winter garden or free range (or both) had a positive effect and reduced SFP. Keeping mixed flocks of brown and white layers was a risk factor for SFP. SFP occurred mainly in the litter area and only rarely on perches. This finding emphasizes the importance of providing enough litter, litter areas and environmental enrichment. Aggressive pecking and SFP were correlated, which may indicate a higher stress level in the flock. Beak trimming reduced pecking rates but did not entirely prevent SFP. Instead of subjecting chicks to this potentially painful procedure, reasons for SFP should be addressed. SFP remains a multifactorial problem, but in recent years, many risk factors have been identified and included in best-practice recommendations, allowing the housing of non-beak-trimmed layers.

Abstract

Severe feather pecking (SFP) is a major animal welfare problem in layers. It results in pain and injuries in the affected animal. It was the aim of this study to gain insight into the actual pecking behavior of laying hens kept on commercial farms with flock sizes common in practice. We observed aggressive pecking and SFP in non-beak-trimmed and beak-trimmed flocks of laying hens and investigated possible influencing factors. The study took place on eight conventional farms in Germany with aviaries, including three farms with a free range and a winter garden, one with a free range and one with a winter garden. Pecking behavior was observed during three observational periods (OPs): OP 1, at the peak of the laying period between the 28th and 33rd week of life; OP 2, in the middle of the laying period between the 42nd and 48th week of life; and OP 3, at the end of the laying period between the 63rd and 68th week of life in one laying period. Videos were analyzed using behavior sampling and continuous recording. We found that SFP occurred in all flocks, but the pecking rate differed significantly between the flocks. SFP correlated positively with the number of hens per square meter of usable area, with statistical significance in the litter area (r = 0.564; p = 0.045). The multivariate analysis revealed that access to a winter garden or free range significantly reduced the SFP rate on perches (p = 0.001). The stocking density (number of birds per usable square meter) had a significant influence on the SPF rate in the nest-box area (p = 0.001). The hybrid line had a significant effect on the SFP rate on perches and in the nest-box area (p = 0.001 each). Lohmann Brown hens in mixed flocks had a higher SFP rate (significant in OP 2) than those in homogeneous flocks, indicating that mixed flocks may be a risk factor for SFP. Lohmann Brown hens pecked significantly less than Dekalb White hens in the litter area (p = 0.010) and in the nest-box area (p = 0.025) and less than Lohmann Selected Leghorn hens in the litter area (p = 0.010). Lohmann Brown and Lohmann Selected Leghorn hens showed increasing SFP rates during the laying period. All hybrid lines had significantly higher SFP rates in the litter area, followed by the nest-box area and perches. These findings emphasize the importance of providing enough litter, litter areas and environmental enrichment. We found a significant positive correlation between aggressive pecking and SFP—in OP 1: rho (Spearman) = 0.580, p < 0.001; OP 2: rho = 0.486, p = 0.002; and OP 3: rho = 0.482, p = 0.002 (n = 39) —indicating that SFP may lead to a higher stress level in the flock. Beak trimming reduced pecking rates but did not entirely prevent SFP. Instead of subjecting chicks to this potentially painful procedure, reasons for SFP should be addressed. In conclusion, our data suggest a positive influence of a lower stocking density and the provision of a winter garden or free range for additional space. The hybrid line had a significant influence on the feather-pecking rate on perches and the nest-box area. Aggressive pecking and severe feather pecking correlated positively. We assume that vigorous and painful AP were an additional stress factor, especially in non-beak-trimmed flocks, leading to more SFP in due course. Beak trimming had a reducing effect on SFP. However, our results showed that non-beak-trimmed flocks could be kept without major outbreaks of SFP.

Extreme crowding in laying hens during a recurrent smothering outbreak

BACKGROUND

Piling, a behaviour where hens crowd together, is referred to as smothering if mortalities result. Smothering is a considerable concern for the egg industry, yet is vastly understudied.

METHODS

During an outbreak of recurrent smothering, continuous video footage captured a commercial, free-range flock over 35 days. We describe the piling behaviour observed and potential associations with productivity and flock health indicators.

RESULTS

Forty-eight piles were filmed, with a maximum density of 187.93 birds/m² and up to 1204 birds in one pile. Piling occurred in the same house location on 33 of 34 observation days, the first evidence of regularity in piling behaviour. Despite extreme bird densities, we did not find associations between piling extremity and productivity but did find associations with water:feed ratio and temperature range.

CONCLUSION

This study describes the most extreme level of piling reported in literature and offers new insights into this problem behaviour and its consequences.

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.

Effects of plastic antipecking devices on the production performance, beak length, and behavior in Chinese Wannan chickens

This study examined the effects of plastic antipecking devices (PAD) on the production performance, upper beak length, behavior, and plumage condition of a local Chinese chicken breed. Three hundred sixty 63-d-old Wannan chickens with intact beaks were randomly allocated into 3 groups. Birds were fitted with the PAD at 63 d (PAD63d) and at 77 d of age (PAD77d). Control birds were not fitted with PAD. The results showed that there were no significant effects of PAD on the BW, carcass traits, and meat quality (P > 0.05). The mortality in the PAD63d and PAD77d groups was lower than that in the control group. Compared with those in the PAD77d and control groups, the feed conversion ratio (FCR) from 63 to 112 d of age was lower in the PAD63d group. The ADFI of birds from 63 to 112 d of age was lowest in birds in the PAD63d group, intermediate in birds in the PAD77d group, and highest in control birds (P < 0.05). Birds in the PAD63d and PAD77d groups showed a lower frequency of walking and running, a higher frequency of sleeping, and higher plumage scores of the back and tail than those of control birds (P < 0.05). Birds' daily walking steps in the PAD77d group decreased compared with that of birds in the control group (P < 0.05). The upper beak length at 91 d and 112 d of age was longest in birds in the PAD63d group and shortest in control birds (P < 0.05). Overall, PAD appeared to be effective at reducing mortality, FCR, overall activity, and plumage damage and increasing the upper beak length.