A walk through the broiler breeder life: how do footpad dermatitis and gait scores develop from rearing to slaughter?

The two most common animal-based indicators used to evaluate leg health in broiler chickens are footpad dermatitis (FPD) and gait scoring, but these indicators are less explored in broiler breeders. This study is the first to investigate FPD and gait scoring in broiler breeders during their lifespan from rearing to end of life. In total, eight flocks were monitored (four Ross and four Hubbard) at five different timepoints, in rearing (5 and 15 weeks of age), during the production period (25 and 45 weeks of age) and at the end of the production period (approximately 60 weeks of age). At each visit, 50 hens and 25 roosters were gait scored (six-point scale) and footpads from another 50 hens and 25 roosters were evaluated (five-point scale) (total n = 3000 breeders, 2000 hens and 1000 roosters). Litter quality and air quality were measured at each visit. The results showed that the overall prevalence of FPD in rearing was low and that it increased towards the end of the production, with a mean FPD score of 2 out of a maximum 4 in the hens, indicating moderate lesions and 1.5 in the roosters. In all houses, the litter was dry and loose. FPD was not related to the litter quality, but to air quality, especially the ammonia concentration (P < 0.001). Overall, the gait score were good, and increased with age in both hens (P < 0.001) and roosters of both hybrids (P < 0.001).

Mortality risk on farm and during transport: a comparison of 2 broiler hybrids with different growth rates.

Mortality in broilers is often associated with poor health and welfare and has a complex and multifactorial etiology. Recent studies under experimental conditions indicated that genetic selection for fast growth is an important risk factor for mortality in broiler chickens. However, the knowledge on broiler mortality in general, and in slower growing broilers in particular, under commercial conditions is still limited. This retrospective cohort study aimed to describe mortality risk on farm and during transport in 2 broiler hybrids with different growth rates, Ross 308, and Hubbard JA787, and to estimate the association between hybrid and mortality at different stages of the production cycle. The study sample consisted of 64,651,804 broilers from 4,228 flocks and 139 farms slaughtered from January 1st, 2015, to June 22nd, 2021. Analysis of on-farm mortality was restricted to broiler flocks slaughtered in the period July 2017 to July 2018 due to changes known to affect FWM. The effect of hybrid on mortality during 3 different production stages (first week mortality (FWM), mortality after the first week (MAFW), and mortality during transport (DOA)), was assessed using mixed effect negative binomial regression models. Descriptively, there were notable differences in mortality at all stages of the production cycle, with higher mean mortalities in Ross 308 (1.40% FWM, 3.05% MAFW, and 0.063% DOA) than in Hubbard JA787 (0.76% FWM, 1.49% MAFW, and 0.015% DOA). In the analysis, the largest estimated difference was found for dead on arrival under cold conditions, where mortality was almost 5 times higher in Ross 308 compared to Hubbard JA 787 (IRR: 4.70, 95% CI: 3.74-5.90). The estimated difference in FWM between hybrids was highest during autumn, with an estimated risk approximately 1.6 times higher in Ross than in Hubbard (IRR: 1.56, 95% CI: 1.30-1.86). For MAFW, the estimated risk was approximately 2 times higher in Ross than in Hubbard (IRR: 2.13 95% CI: 1.82-2.49). The findings in this study emphasize the need for more knowledge on causes of mortality in broilers including effects of genetic factors as basis for preventive measures.

Health effects of feed dilution and roughage in Ross 308 broiler breeder cockerels.

To ensure reproductivity and prevent obesity, broiler breeder's growth rate is controlled by quantitative feed restriction. However, feed restriction is associated with chronic hunger, frustration, and abnormal behaviors, thus representing a welfare problem. Feed diluted with insoluble fiber is an alternative, allowing larger amounts of feed and more gut filling, increasing satiety without increasing the caloric intake. Previous research on feed dilution has focused on pullets not cockerels. In addition, the health effects of diluted feed are less explored. The aim of this study was to investigate the effects of feed dilution and roughage on health indicators in broiler breeder cockerels, 5 to 10 wk of age (WOA), a very feed restricted period. In total, 200 Ross 308 broiler breeder cockerels were housed in 12 pens (6 pens/treatment), 16 to 17 birds per pen. The treatments were standard feed (Control) and feed diluted with (20%) insoluble oat hulls and 150 g of roughage (lucerne/alfalfa) daily per pen (D + R). The D + R birds received 20% more feed per day. Body weight, pecking injuries, footpad dermatitis (FPD), and litter quality were recorded weekly between 5 and 9 WOA. At 10 WOA all birds were euthanized and subjected to postmortem assessment. D + R birds tended to weigh more than controls (P = 0.055), but diet did not affect flock uniformity (P = 0.57). The weekly assessment showed no effect of treatment on foot pad lesion scores (P = 0.31). However, an effect on FPD was observed postmortem (P = 0.04), where Control had slightly better footpad condition compared to the D + R group. Litter had to be completely changed in 2 control pens during the trial, due to quality deterioration. There was no effect of treatment on the weight of specific organs, the length of the gut, the intestinal mucosa, nor on the incidence of wounds on the head (P = 0.15). Overall, these results indicate that feed dilution and roughage have neither adverse nor beneficial health effects on Ross 308 broiler breeder cockerels.

Causes of carcass condemnation in Norwegian aviary housed layers.

BACKGROUND: Meat inspection data is commonly used to monitor health and welfare in commercial broiler production; however, less used in layers. Slaughterhouse records can provide insight into animal and herd health and identify important health and welfare challenges. To gain knowledge of health issues in commercial aviary housed laying hens, the aim of this repeated cross-sectional study was to describe the occurrence and causes of carcass condemnation, including dead-on-arrivals (DOA), in commercial aviary housed layers in Norway, and to explore seasonal patterns and correlation between DOA and number of carcass condemnations. RESULTS: Data from January 2018 to December 2020 were collected from one poultry abattoir in Norway. In total, 759,584 layers were slaughtered during this period in 101 slaughter batches from 98 flocks and 56 farms. In total, 33,754 (4.4%) layers were condemned, including the DOA. The most common carcass condemnation causes were (percent of all slaughtered layers): abscess/cellulitis (2.03%), peritonitis (0.38%), DOA (0.22%), emaciation (0.22%), discoloration/smell (0.21%), acute skin lesions (0.21%) and ascites (0.17%). Regression analysis showed an estimated higher prevalence of total carcass condemnation during winter compared to the other seasons. CONCLUSIONS: The three most common condemnation causes found in the present study were: abscess/cellulitis, peritonitis, and DOA. We found a large between-batch variation in causes of condemnation and DOA indicating that prevention might be possible. The results can be used to inform and guide further studies on layer health and welfare.

The Aviary Transect-a practical welfare assessment tool to improve the management of cage-free laying hens.

The Aviary Transect (AT) is a method for assessing welfare in cage-free laying hen flocks, and comprises standardized walks along each aisle screening the flock for selected welfare indicators: feather loss (FL) on head, back, breast, and tail, wounds on head, back, tail, and feet, dirty plumage, enlarged crop, sickness, and birds found dead. The method is quick (20 min for a flock of 7,500 hens), has good interobserver agreement and shows positive correlations with individual bird sampling methods. However, it is less clear whether AT can be used to detect differences in flock health and welfare related to housing and management. The aim of this study was to evaluate how AT findings varied in relation to 23 selected housing, management, environmental, and production factors. The study was conducted on 33 commercial nonbeak-trimmed, white-feathered layer flocks of similar age (70-76 wk) kept in multitiered aviaries in Norway. The most prevalent findings across flocks were feather loss on the back (mean 0.97% of flock) and breast (0.94%) followed by feather loss on the head (0.45%) and tail (0.36%) with differences in feather pecking damage according to the hybrid used (P < 0.05). Better litter quality was associated with a lower prevalence of feather loss on the head and breast (P < 0.05), and addition of fresh litter during the production cycle resulted in fewer birds with feather loss on the head (P < 0.05) and tail (P < 0.001). Lower dust levels were linked to a lower prevalence of feather loss on the head, back, and breast (P < 0.05), and when access to the floor area underneath the aviary was provided at an earlier stage of production, fewer birds had wounds (P < 0.001), but more birds were observed with an enlarged crop (P < 0.05) and found dead (P < 0.05). In conclusion, findings from AT showed that results of the assessment varied according to housing conditions. These results support the validity of AT as a relevant welfare assessment tool for evaluating cage-free management practices.

Comparison of carcass condemnation causes in two broiler hybrids differing in growth rates.

Experimental studies concluded that genetic factors enabling fast growth rate might negatively affect broiler health and welfare. Recently, the proportion of slower-growing broilers has been increasing. However, studies of health in broilers with different growth rates in commercial systems are still scarce. This repeated cross-sectional study aimed to describe causes of carcass condemnations in two broiler hybrids with different growth rates, Ross 308, and Hubbard JA787, and to estimate the effect of hybrid. The study sample consisted of 63,209,415 broilers slaughtered in 4295 batches from 139 farms. All broilers were slaughtered from January 1st, 2015, to June 22nd, 2021, by the same company (Norsk Kylling). All causes of condemnation, except fractures, were more prevalent in Ross 308. The five most common causes (ascites, discolouration, hepatitis, small and skin lesions) were investigated in greater detail, and the effect of hybrid was assessed using mixed effects negative binomial models with the condemnation codes as outcome variables. For the five selected causes, variation in prevalence between slaughter batches was considerable for Ross and minor for Hubbard. The notable differences between hybrids in prevalence and causes of condemnation have important implications for animal health, welfare, economy, and sustainability in broiler production.

Keel bone fractures in broiler breeders: is palpation a reliable diagnostic method?

The aim of this study was to estimate the sensitivity and specificity of palpation relative to necropsy for detection of keel bone fractures (KBF) in broiler breeders. In addition, the study investigated observer reliability of palpation. Four commercial breeder flocks (Ross 308 n = 2, Ranger Gold n = 1, Hubbard JA 757, n = 1) were included in the study. A total of 400 hens and 60 roosters were examined after culling or slaughter, at end of lay (63 weeks). Keel bones were first palpated independently by two raters with a varying degree of experience in palpation of keel bones in laying hens. After palpation, a necropsy with investigation of the keel bone was conducted. The prevalence of KBF at end of lay for hens, as diagnosed by necropsy, varied from 14-58%, while only one in 60 assessed roosters had KBF. Palpation had poor sensitivity, with differences between raters ranging from 56% to 36% when hybrid is not considered. The specificity of palpation for all hybrids together was 85% and 88%, for the two raters, respectively. The two raters had moderate agreement, Gwet's agreement coefficient (95% confidence interval): 0.60 (0.52-0.69). In conclusion, palpation has poor diagnostic accuracy for detection of KBF in broiler breeders, and other methods, like necropsy, must be applied for reliable assessments. KBF appears to be a prevalent condition in different hybrids of broiler breeder hens, but not in roosters.RESEARCH HIGHLIGHTS This is the first study to investigate palpation as a diagnostic method for detection of KBF in broiler breeders.Palpation has poor diagnostic accuracy for detection of KBF in broiler breeder hens with differences between raters.KBF can be a prevalent problem in broiler breeder hens of several hybrids, but not in roosters.

End of lay postmortem findings in aviary housed laying hens.

Good health and low mortality are constitutive elements of good animal welfare. In laying hens, mortality and pathological findings are usually reported as cumulative proportions from onset of lay to culling. However, knowledge of pathological lesions and causes of death specifically toward the end of the production period are scarce. This study aimed to investigate the occurrence of postmortem lesions and tentative causes of death in non-beak trimmed, end of lay hens, housed in multitiered aviary systems. A convenience sample of 48 flocks was recruited. In each flock, layers dead between wk 65 and 70 were necropsied in the field. In total, 482 layers were subjected to postmortem examination. The 4 most common pathological lesions were keel bone fracture (KBF) (92%), fatty liver (42%), emaciation (23%), and salpingitis (22%). Apart from keel bone fracture, the relative frequency of the pathological lesions variated between flocks, indicating that flock is an important factor. Common tentative causes of death were salpingitis (18%) and fatty liver hemorrhagic syndrome (FLHS) (13%). This study sheds light on health challenges aviary housed layers are facing end of lay, which is crucial knowledge in the development of preventive measures to secure good health and welfare.

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.

Description of Light Environment in Broiler Breeder Houses with Different Light Sources-And How It Differs from Natural Forest Light.

Light is a key factor in poultry production; however, there is still a lack of knowledge as to describing the light quality, how to measure the light environment as perceived by birds, and how artificial light compares with the light in the natural forest habitats of their wild ancestors. The aim of this study was to describe the light environment in broiler breeder houses with three different light sources, using two different methods of light assessment. We also aimed to compare an artificial light environment with the light in a range of relevant natural forest habitats. A total of 9 commercial broiler breeder houses with one of three different light sources-Lumilux 830 CFL (n = 3), Biolux 965 CFL (n = 3) or LED Evolys with UVA (n = 3) were visited. Assessments of the light environment in the breeder houses were conducted using both a spectrometer and the environmental light field (ELF) method. ELF measurements from three forest types in south India (Kerala) were also included. We found that most aspects of the light environment were similar between the nine breeder houses and were not dependent on the type of light sources. The only clear difference related to the light source was the spectral balance, wherein 830 CFL had the most red-dominated light, 965 CFL had the most blue-dominated light and Evolys was intermediate but with more UV than the latter two. Plumage color had minimal effect on the light environment. Both the spectrometer and the ELF method provided valuable information. The spectrometer gave detailed values about certain aspects of the light environment, while the ELF described the light more in line with human and avian visual perception. We also found that the light environment in the investigated broiler breeder houses differs dramatically in all measured aspects from the natural light habitats of wild junglefowl, suggesting improvement possibilities in artificial lighting systems.

Environmental enrichment in commercial flocks of aviary housed laying hens: relationship with plumage condition and fearfulness.

Management strategies can have positive effects on laying hen welfare, including prevention of damaging behavior, aggression, and fear, particularly by using environmental enrichment (EE). However, few studies have investigated the effects of the provision of EE in commercial aviary flocks. This knowledge gap is particularly significant considering the increasing numbers of non-beak trimmed hens worldwide kept in aviaries. The aim of this study was to survey and investigate the relationship between commercially applied EE and plumage condition and fearfulness in Norwegian flocks of loose-housed laying hens. Forty-five indoor multi-tiered aviary-system flocks of laying hens from across Norway were visited at the end of lay (range: 70-76 wk of age). The flocks consisted of either Lohmann LSL (n = 30) or Dekalb White (n = 15) non-beak-trimmed hens. During the visit, the researchers collected data on the farmers' use of the following five types of enrichment: pecking stones, gravel, oyster shells, grains scattered in the litter, and "toys". Feather loss was assessed individually in approximately 50 hens per flock and scores were awarded using a 3-point scale (0-2) for each of the following body parts: head, back/wings, breast, and tail. Finally, a novel object test was performed in 4 different locations in each house. The results showed that damage to the tail feathers was correlated positively to the first age of provision of toys (Pearson correlation coefficient = 0.41; P = 0.051) and negatively to the amounts of gravel stones provided (Pearson correlation coefficient = -0.43, P = 0.02). No other associations between the welfare indicators and the provision of EE objects were found, likely because of the low variation of enrichment provision. The present study showed that the provision of EE objects such as toys and gravel stones can have significant benefits to the condition of laying hen plumage. This study also adds to the body of literature supporting the importance of early life experiences on the behavioral development of laying hens and on their welfare at older ages.

Developing a novel welfare assessment tool for loose-housed laying hens - the Aviary Transect method.

This study compared welfare assessment results in aviary flocks using 3 approaches: 1) A novel Aviary Transect method, 2) AssureWel, and 3) the Norwegian farm advisors' NorWel method. The Aviary Transect time requirement, interobserver reliability, and within- and across-house sensitivity to detect welfare indicators were also evaluated. The study was conducted on 6 randomly chosen commercial white-strain layer flocks of similar age and flock size, kept in multitiered aviaries. The Aviary Transect method comprised standardized walks along each aisle while screening the whole flock for 12 welfare indicators: feather loss (FL) on head, back, breast, and tail, wounds on head, back, tail, and feet, dirty birds, enlarged crop, sick birds, and dead birds. AssureWel involved scoring FL on head and back, and dirtiness of 50 random birds, and flock-level evaluation of beak trimming, antagonistic behavior, flightiness, birds needing further care, and mortality. NorWel involved scoring 8 welfare indicators on 50 random birds: FL on head, back, breast, and tail, dirtiness, and wounds on head, back, and tail. The AssureWel detected flock differences in both minor and major FL on the back (P < 0.01) as well as somewhat dirty birds (P < 0.01). The NorWel method detected flock differences in both minor and major FL on the head (P < 0.01), back (P < 0.001), breast (P < 0.001), and tail (P < 0.001) and somewhat (score 1) dirty birds (P < 0.05). The Aviary Transect method detected flock differences in FL on head, back, breast, and tail (all P < 0.001), dirty birds (P < 0.05) and enlarged crop (P < 0.001). More birds with FL on breast, and more dirty birds, were found in wall vs. central transects (P < 0.05). There was good interobserver agreement, except for dirty birds (P < 0.01), and positive correlations (P < 0.05) were identified between the Aviary Transect method and the other sampling methods for FL on head and back, and dirtiness. The three methods took similar time to complete (about 20 min/flock). In conclusion, all 3 methods detected significant differences in welfare indicator prevalence between flocks. The new Aviary Transect method provides egg producers with an efficient and sensitive whole-flock assessment of hen welfare status in multitiered aviaries.

Keel bone fractures are more prevalent in White Leghorn hens than in Red Jungle fowl hens-A pilot study.

Fractures and deviations to the keel bone are common in commercial laying hens, with reported variations in occurrence across strains and breeds. The aetiology is not fully understood, however, modern genetics and selection for efficient egg production has been claimed to be important factors for the keel bone fractures. To explore this further, we investigated keel bones from two different breeds, representing different degrees of selection for egg production: Red jungle fowl (n = 82), and White Leghorn (n = 32), where the latter is a selected laying breed which is the origin for many modern laying hen hybrids. Keel bones from a total of 116 birds, 53 hens and 63 roosters, were examined by necropsy at 80 weeks of age. All birds were raised in modified aviaries in the same holding facility. Overall, 24.5% of the hens had one or more fractures to the keel, with a difference in the prevalence between hens from the two breeds (p<0.01): 10% (95% CI: 3.7-24%) in the Red Jungle fowl hens and 69% (95% CI: 37-90%) in the White Leghorn hens. No roosters, regardless of breed, had keel bone fractures. Mild to moderate keel bone deviations were present in 54% (95% CI: 25-80%) of the hens and 4.7% (95% CI: 0.5-30%) of the roosters, all White Leghorns.

A Descriptive Study of Keel Bone Fractures in Hens and Roosters from Four Non-Commercial Laying Breeds Housed in Furnished Cages.

The presence of keel bone fractures (KBF) in laying hens has been documented and discussed by several authors, nevertheless the causative factors behind KBF remain uncertain. High prevalence of KBF have been reported in all commercial egg production systems, in different genetic lines and at different ages. Several of the proposed causal mechanisms behind KBF are linked to selection for efficient production. It is, therefore, of interest to explore whether less selected breeds have a lower occurrence of keel bone fractures compared to reports from highly selected, modern laying hen breeds. Thus, the aim of the current study was to investigate keel bones of hens from four non-commercial layer breeds. Birds were housed in furnished cages and keel bones examined at 30 and 63 weeks of age, using a portable X-ray equipment. The results from this descriptive study indicate a low prevalence of KBF at both ages in all four breeds, with only five KBF detected in 213 X-ray pictures taken from 126 birds. Of these, four of the KBF were observed in the most genetically selected breed, with an early onset of lay. None of the roosters examined exhibited KBF. The overall low numbers of KBF found indicate that genetic factors may be involved in KBF and, thus that selective breeding may help to reduce the susceptibility to KBF. Finally, this study highlights the importance of poultry conservation to secure genetic diversity, which may be an important resource in future selection schemes.

Prevalence of Keel Bone Damage in Red Jungle Fowls (Gallus gallus)-A Pilot Study.

Keel bone damage (KBD) is a highly prevalent problem in commercial egg production. KBD consists of two different conditions affecting the keel: Keel bone deviation and keel bone fractures (KBF). Deviations are linked to pressure on the keel, e.g., from perching. The causative factors for KBF are not clear; however, selection for efficient egg production has been suggested as a major contributing factor. An important step to shed light on the role of selective breeding as an underlying cause of KBF in modern laying hens is to evaluate the keel bones of the ancestor, the red jungle fowl. To the authors' knowledge, this has never previously been published. The aim of this study was therefore to describe the prevalence of KBD in a study group of red jungle hens and roosters housed in an aviary system. The present study examined 29 red jungle fowls 112 weeks of age post-mortem; 12 hens and 17 roosters. Keel bones were evaluated by external palpation for deviations and fractures. Palpation was followed by autopsy. No fractures were detected in the 17 roosters; one had a very slight deviation. Of the 12 red jungle hens in this pilot study, one had a single fracture and 10 hens had a very slight deviation.

Explanations for keel bone fractures in laying hens: are there explanations in addition to elevated egg production?

The current article served to provide the most up-to-date information regarding the causes of keel bone fracture. Although elevated and sustained egg production is likely a major contributing factor toward fractures, new information resulting from the development of novel methodologies suggests complementary causes that should be investigated. We identified 4 broad areas that could explain variation and increased fractures independent of or complementing elevated and sustained egg production: the age at first egg, late ossification of the keel, predisposing bone diseases, and inactivity leading to poor bone health. We also specified several topics that future research should target, which include continued efforts to link egg production and bone health, examination of noncommercial aves and traditional breeds, manipulating of age at first egg, a detailed histological and structural analysis of the keel, assessment of prefracture bone condition, and the relationship between individual activity patterns and bone health.

An Evaluation of Two Different Broiler Catching Methods.

Catching is the first step in the pre-slaughter chain for broiler chickens. The process may be detrimental for animal welfare due to the associated handling. The aim of this pilot study was to compare two different methods to manually catch broilers: Catching the broilers by two legs and carrying them inverted (LEGS) or catching the broilers under the abdomen and carrying them in an upright position (UPRIGHT). Wing and leg fractures upon arrival at the abattoir, animal density in the drawers, birds on their back, broilers dead-on-arrival and time to fill the transport modules were investigated. The results showed that mean crating time was shorter in the UPRIGHT method (p = 0.007). There was a tendency for more wing fractures in broilers caught by the LEGS (p = 0.06). The animal density in the drawers was lower and with a smaller range in the UPRIGHT method (p = 0.022). The results indicate that catching the broilers under the abdomen in an upright position may improve broiler welfare in terms of fewer wing fractures, more consistent stocking density in drawers and potentially reduced loading time.