Associations among gait score, production data, abattoir registrations, and postmortem tibia measurements in broiler chickens

On-farm study of walking ability in conventional broilers and those labelled as being higher welfare

BACKGROUND

Multiple factors, including genetics and management practices, are known to influence the walking ability of broilers. This field survey aimed to assess the walking ability of broilers in two different production systems.

METHODS

Thirty flocks of conventional (Ross 308) and 26 flocks of welfare-labelled (Level 1; Ranger Gold/Rustic Gold) broilers were evaluated, with maximum stocking densities of 40 and 38/38 kg/m2 and growth rates of 62-63 g/day and 43-45/47-51 g/day, respectively. Gait scores were obtained for approximately 120 birds/flock prior to slaughter using the six-point Bristol scale, with scores ranging from 0 (no detectable abnormality) to 5 (complete lameness). Data on broiler age, target bodyweight on day of assessment and genotype were collected.

RESULTS

The odds of birds having gait scores greater than 0 (p = 0.011), 1 (p < 0.001) and 2 (p = 0.033) increased significantly with a 100 g increase in bodyweight for conventional broilers, whereas no such effect was found for level 1 broilers. Within the level 1 system, the slower-growing Ranger Gold birds had lower odds of having gait scores greater than 1 than the faster-growing Rustic Gold birds (p = 0.022).

LIMITATIONS

Data on the bodyweight of individual birds were not collected.

CONCLUSION

The results obtained in this study are in line with previous research showing that walking ability is negatively associated with growth rate.

Valine and isoleucine deficiency in necrotic enteritis challenge impact growth performance, intestinal health, and muscle growth in broilers

Necrotic enteritis (NE), an enteric disease caused by Clostridium perfringens, and antagonistic effects due to dietary branched-chain amino acid (BCAA) imbalance are key factors that negatively affect chicken growth. The current study was conducted to investigate the effects of valine and isoleucine deficiency in NE challenged broilers. A total of 336 seven-d-old male Cobb 500 were allotted to four treatments with six replicates. The four treatments were as follows: (1) non-challenged control (NC; leucine:lysine = 1.31, valine:lysine = 0.73, and isoleucine:lysine = 0.63), (2) NE-challenged group (NE), (3) NE-challenged with 85 % valine deficiency group (NE-VAL; valine:lysine = 0.62), and (4) NE-challenged with 85 % isoleucine deficiency group (NE-ILE; isoleucine:lysine = 0.54). E. maxima and C. perfringens were administered on d 14 and 18, respectively, and the experiment lasted until d 21. The NE-VAL group had the lowest growth performance measurements compared to the other groups (P < 0.001). All NE-challenged groups had significantly reduced overall growth performance measurements compared to the NC group (P < 0.001). The NE-ILE group showed no difference in any of the measurements compared to the NE group. On d 21, the NE group had significantly increased intestinal permeability, jejunal lesion scores, C. perfringens colony counts, and jejunal chemokine and cytokine gene expression levels, along with decreased intestinal morphology compared to the NC group (P < 0.05). The NE-VAL group had significantly decreased breast muscle yield, reduced lean and total tissue weight, and increased expression levels of mechanistic target of rapamycin pathway and BCAA catabolism-related genes compared to the NE group (P < 0.05). This may explain why the NE-VAL group had the lowest growth performance, as the two negative effects of NE infection and valine deficiency are separated. In conclusion, the negative effects of NE challenge and valine deficiency were independent; valine deficiency showed a similar response to that exhibited by high leucine levels, despite reduced feed intake caused by NE challenge.

Valine deficiency has a greater impact on broiler growth and bone health than isoleucine deficiency

Valine and isoleucine are not only two of the indispensable amino acids (AAs) in chickens but also have special mechanisms with leucine within the branched-chain AA (BCAA) category. Therefore, we aimed to investigate how valine or isoleucine deficiency could specifically affect growth performance in broilers through various analyses. A total of 252 seven-day (d)-old male Cobb 500 broilers were allotted to three treatments with six replicates and reared until d 21. The three treatments were as follows: (1) Control group (CON; 1.31 leucine:lysine ratio), (2) valine deficiency group (-VAL; 0.62 valine:lysine ratio and 85% valine level compared to the CON group), and (3) isoleucine deficiency group (-ILE; 0.54 isoleucine:lysine ratio and 85% isoleucine level compared to the CON group). The -VAL group had significantly decreased d 7, 14, and 21 body weight (BW), BW gain (BWG), feed intake (FI), and feed efficiency from d 7 to 21 compared to the CON and -ILE groups (P < 0.001). The -ILE group showed no difference in d 14 and 18 BW; however, they showed significantly reduced BW and BWG at d 21 and feed efficiency from d 7 to 21 compared to the CON group (P < 0.001). Daily FI in the -VAL group significantly decreased from the beginning compared to the two groups, and this gap further expanded until d 21. The -VAL group also had significantly decreased breast muscle weight, total tissue weight, bone mineral density, bone mineral content, and walking ability (P < 0.01). The expression levels of mechanistic target of rapamycin and BCAA catabolism-related genes were highest in the -VAL group (P < 0.05), whereas the -ILE group did not show any difference compared to the CON group (P > 0.05). In conclusion, about 85% valine deficiency is accompanied by a substantial reduction in chicken growth, which has a much greater effect than isoleucine. Valine deficiency can also lead to increased utilization of leucine, which may result in BCAA antagonism.

Effects of different environmental enrichment tools to improve behavior, welfare, and growth performance of broiler chickens

This study was performed to evaluate the effect of various environmental enrichment (EE) tools on broiler growth, welfare, behavior, carcass, and meat quality. A total of 300 commercial broilers were randomly divided into 05 treatments. The treatments include various EE tools such as perches, balls, hanging bottles, and laser lights placed for birds and a control group. The birds kept with perches and hanging bottles had the lowest feed intake, while the birds in the control group showed the poor feed conversion ratio compared to all EE treatments. Broilers raised under different EE were more active and exhibited frequent maintenance behavior (i.e., walking, jumping, running, wing flapping and aggressiveness) than the control group which spent more time in feeding and drinking. Moreover, the birds with EE had reduced incidence of toe injuries and footpad dermatitis than those in the control group. Birds reared with perches had higher meat lightness, whereas meat from the birds in the control group had lower cooking loss and shear force. It can be concluded that the use of various EE tools improved the welfare and behavior of the birds without affecting bodyweight of the birds. Furthermore, the use of hanging bottles and placing perches reduced feed intake and improved feed conversion ratio.

Effects of branched-chain amino acid imbalance and dietary valine and isoleucine supplementation in modified corn-soybean meal diets with corn distillers dried grains with solubles on growth performance, carcass quality, intestinal health, and cecal microbiome in Cobb 500

One important feature of corn distillers dried grains with solubles (DDGS) is its high leucine:lysine ratio, which can inhibit chicken growth by causing branched-chain amino acid (BCAA) antagonism. The current study was conducted to investigate the effects of BCAA imbalance of inclusion of DDGS and whether additional dietary valine and isoleucine could alleviate the negative effects in broilers. A total of 640 0-d-old male Cobb 500 broilers were allocated into 4 treatments with 8 replicates and reared until d 42. The four different dietary groups were as follows: 1) control (CON) group (corn-soybean meal-based diet); 2) 30% DDGS (30D) group (replacing soybean meal with 30% DDGS); 3) 30D + additional valine and isoleucine (30DB) group; and 4) the group of 30DB + additional valine and isoleucine to provide the same leucine:valine and leucine:isoleucine ratios as the CON group (30DBB). The analyzed leucine:lysine ratios of the CON group were 1.36/1.41/1.46 (starter/grower/finisher phase), whereas the average leucine:lysine ratios of the 30% DDGS groups were 1.61/1.70/1.78 (starter/grower/finisher phase). The 30% DDGS groups (30D, 30DB, and 30DBB) negatively affected body weight (BW) from d 7 to 42 and BW gain (BWG), feed intake, carcass weight, breast muscle weight, and jejunal and ileal villus height:crypt depth during the overall period (d 0 to 42) (P < 0.05). Furthermore, the 30% DDGS groups significantly altered expression levels of jejunal tight junction proteins, breast muscle mechanistic target of rapamycin (mTOR) pathway-related genes, BCAA catabolism genes, and AA transporters compared to the CON (P < 0.01). The 30% DDGS groups showed differences in beta-diversity indices compared to the CON group (P < 0.05). The 30DBB group showing the lowest d 21 and 42 BW and overall BWG had the largest differences compared to the CON group in most measurements. In conclusion, excessive replacement of soybean meal with DDGS can significantly increase leucine levels, which may negatively affect chicken growth. Additionally, inappropriate ratios of valine and isoleucine can further decrease growth performance.

Plasma exosome-derived miR-455-5p targets RPS6KB1 to regulate cartilage homeostasis in valgus-varus deformity (Gallus gallus)

Valgus-varus deformity (VVD) is a common long bone deformity in broilers. Imbalance in cartilage homeostasis is the main feature of leg disease. Exosomes act as an important intercellular communication vector that regulates chondrogenesis by encapsulating specific nucleic acids and proteins. However, the exact mechanism of how plasma exosomal miRNAs regulate cartilage homeostasis in VVD broilers remains unclear. This study first demonstrated the structural disorder, growth retardation, and reduced proliferative capacity of VVD cartilage in vitro and in vivo. Subsequently, VVD and Normal broiler plasma exosomes were collected for miRNA sequencing. Cartilage-specific miR-455-5p was extraordinarily emphasized by performing bioinformatics analysis on differential miRNA target genes and further validated by tissue expression profiling. PKH67 fluorescently labeled plasma exosomes were shown to be taken up by chondrocytes, deliver miR-455-5p, inhibit chondrocyte proliferation, and disrupt their homeostasis, and these effects could be inhibited by the miR-inhibitors. Mechanistically, MiR-455-5p targets Ribosomal Protein S6 Kinase B1 (RPS6KB1) to inhibit RPS6 phosphorylation and reduce the synthesis of key proteins for cartilage proliferation, which in turn inhibits cartilage proliferation and disrupts its homeostasis. In conclusion, the present study identified abnormalities in VVD cartilage tissue and clarified the specific mechanism by which plasma exosome-derived miR-455-5p regulates cartilage homeostasis.

The potential of decision trees as a tool to simplify broiler chicken welfare assessments

To simplify fast-growth broiler welfare assessments and use them as a benchmarking tool, decision trees were used to identify iceberg indicators discriminating flocks passing/failing welfare assessments as with the complete AWIN protocol. A dataset was constructed with data from 57 flocks and 3 previous projects. A final flock assessment score, previously not included in the dataset, was calculated and used as the benchmarking assessment classifier (pass/fail). A decision tree to classify flocks was built using the Chi-square Automatic Interaction Detection (CHAID) criterion. Cost-complexity pruning, and tenfold cross-validation were used. The final decision tree included cumulative mortality (%), immobile, lame birds (%), and birds with back wounds (%). Values were (mean ± se) 2.77 ± 0.14%, 0.16 ± 0.02%, 0.25 ± 0.02%, and 0.003 ± 0.001% for flocks passing the assessment; and 4.39 ± 0.49%, 0.24 ± 0.05%, 0.49 ± 0.09%, and 0.015 ± 0.006% for flocks failing. Cumulative mortality had the highest relative importance. The validated model correctly predicted 80.70% of benchmarking assessment outcomes. Model specificity was 0.8696; sensitivity was 0.5455. Decision trees can be useful to simplify welfare assessments. Model improvements will be possible as more information becomes available, and predictions are based on more samples.

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).

Water deprivation in poultry in connection with transport to slaughter-a review

Poultry are deprived of water when transported to slaughter, beginning shortly prior to catching of the first bird and lasting through catching and loading, the journey on the vehicle, time spent in lairage, and up until time of death. Our aim was to review existing knowledge on variables which may be useful in determining the length of time that poultry may go without water in connection with transport before their welfare begins to deteriorate. During transport, it is likely that birds experience a motivation to drink, which may transition into the negative emotional state of thirst if water is unavailable. Determining when drinking motivation reaches a threshold where welfare is negatively impacted is challenging. In the absence of water, birds may over time experience dehydration which may be detected through physiological indicators as their body attempts to maintain homeostasis. In poultry, plasma osmolality, arginine vasotocin, and chloride have been suggested as being most suitable for assessing dehydration resulting from periods of water deprivation that correspond with typical transport durations, due to their particular sensitivity during this period. While initial dehydration may not be associated with negative emotional states, it is likely that it eventually leads to discomfort, but additional behavioral and motivational studies are necessary to infer when this begins. Impacts of thermal conditions, genetics, and the condition of the individual bird on the development of a dehydrated state were also assessed, though more information is needed to fully understand these interactions. With the available literature, this review concludes that total transport (i.e., from the initial deprivation from water until time of slaughter) durations of longer than 6 h are likely associated with measurable physiological indicators of dehydration and may potentially be associated with negative emotional states, although more research is needed to clarify this. Current available knowledge and assessment tools are not sufficient to detect the degradation of welfare derived from thirst itself, which should be further examined to protect poultry welfare during transport.

Evaluating broiler welfare and behavior as affected by growth rate and stocking density

This study evaluated the welfare and behaviors of Cobb 700 broilers as affected by growth rate (GR) and stocking density (SD). Slower-growth (weight gain < 50 g/d) and medium-growth (weight gain = 50-60 g/d) broilers were produced by providing 57.1% and 78.6% of the feed intake listed in the Cobb 700 production manual for standard (fed ad libitum) broilers (weight gain > 60 g/d). Broilers at all 3 GRs were reared at 2 SDs of 30 and 40 kg/m2. Broiler welfare indicators, including gait score, tibia strength, feather coverage, and footpad condition were evaluated when birds reached 1, 2, and 3 kg of body weight. The activity index was determined by overhead cameras and image processing, and the time spent at feeders was recorded using the radio-frequency identification (RFID) systems. The results show that it took 45 d for standard, 52 d for medium-growth, and 62 d for slower-growth broilers to reach a 3 kg market body weight. Feed conversion ratios (FCR, kg/kg) were 1.57 for standard, 1.67 for medium-growth, and 1.80 for slower-growth broilers. Growth rate and SD had an interaction effect on feather cleanliness (P = 0.03), and belly feather coverage (P = 0.02). Slower-growth broilers were more active and had better feather coverage and gait scores than medium-growth and standard broilers (all P < 0.01) but may feel hungry and depressed, medium-growth broilers spent the most time at the feeder among the 3 growth groups (P = 0.02), and standard broilers showed the best production performance. Broilers at 30 kg/m2 showed better bone strength (P = 0.04), and footpad condition (P < 0.01) compared to those at 40 kg/m2. In conclusion, reducing GR and SD may slightly improve broiler leg health at the high expense of compromised production performance and prolonged production cycles.

Active walking in broiler chickens: a flagship for good welfare, a goal for smart farming and a practical starting point for automated welfare recognition

Automated assessment of broiler chicken welfare poses particular problems due to the large numbers of birds involved and the variety of different welfare measures that have been proposed. Active (sustained, defect-free) walking is both a universally agreed measure of bird health and a behavior that can be recognized by existing technology. This makes active walking an ideal starting point for automated assessment of chicken welfare at both individual and flock level.

Leg disorders in broiler chickens: a review of current knowledge

Ensuring improved leg health is an important prerequisite for broilers to achieve optimal production performance and welfare status. Broiler leg disease is characterized by leg muscle weakness, leg bone deformation, joint cysts, arthritis, femoral head necrosis, and other symptoms that result in lameness or paralysis. These conditions significantly affect movement, feeding and broiler growth performance. Nowadays, the high incidence of leg abnormalities in broiler chickens has become an important issue that hampers the development of broiler farming. Therefore, it is imperative to prevent leg diseases and improve the health of broiler legs. This review mainly discusses the current prevalence of broiler leg diseases and describes the risk factors, diagnosis, and prevention of leg diseases to provide a scientific basis for addressing broiler leg health problems.

Bone Metabolite Profile Differs between Normal and Femur Head Necrosis (FHN/BCO)-Affected Broilers: Implications for Dysregulated Metabolic Cascades in FHN Pathophysiology

Femur head necrosis (FHN), also known as bacterial chondronecrosis with osteomyelitis (BCO), has remained an animal welfare and production concern for modern broilers regardless of efforts to select against it in primary breeder flocks. Characterized by the bacterial infection of weak bone, FHN has been found in birds without clinical lameness and remains only detectable via necropsy. This presents an opportunity to utilize untargeted metabolomics to elucidate potential non-invasive biomarkers and key causative pathways involved in FHN pathology. The current study used ultra-performance liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS) and identified a total of 152 metabolites. Mean intensity differences at p < 0.05 were found in 44 metabolites, with 3 significantly down-regulated and 41 up-regulated in FHN-affected bone. Multivariate analysis and a partial least squares discriminant analysis (PLS-DA) scores plot showed the distinct clustering of metabolite profiles from FHN-affected vs. normal bone. Biologically related molecular networks were predicted using an ingenuity pathway analysis (IPA) knowledge base. Using a fold-change cut off of -1.5 and 1.5, top canonical pathways, networks, diseases, molecular functions, and upstream regulators were generated using the 44 differentially abundant metabolites. The results showed the metabolites NAD+, NADP+, and NADH to be downregulated, while 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) and histamine were significantly increased in FHN. Ascorbate recycling and purine nucleotides degradation were the top canonical pathways, indicating the potential dysregulation of redox homeostasis and osteogenesis. Lipid metabolism and cellular growth and proliferation were some of the top molecular functions predicted based on the metabolite profile in FHN-affected bone. Network analysis showed significant overlap across metabolites and predicted upstream and downstream complexes, including AMP-activated protein kinase (AMPK), insulin, collagen type IV, mitochondrial complex, c-Jun N-terminal kinase (Jnk), extracellular signal-regulated kinase (ERK), and 3β-hydroxysteroid dehydrogenase (3β HSD). The qPCR analysis of relevant factors showed a significant decrease in AMPKα2 mRNA expression in FHN-affected bone, supporting the predicted downregulation found in the IPA network analysis. Taken as a whole, these results demonstrate a shift in energy production, bone homeostasis, and bone cell differentiation that is distinct in FHN-affected bone, with implications for how metabolites drive the pathology of FHN.

EFSA AHAW Panel (EFSA Panel on Animal Health and Welfare), Nielsen SS, Alvarez J, Bicout DJ, Calistri P, Canali E, Drewe JA, Garin‐Bastuji B, Gonzales Rojas JL, Schmidt CG, Herskin MS, Miranda Chueca MÁ, Padalino B, Pasquali P, Roberts HC, Spoolder H, Stahl K, Velarde A, Viltrop A, Winckler C, Tiemann I, de Jong I, Gebhardt‐Henrich SG, Keeling L, Riber AB, Ashe S, Candiani D, García Matas R, Hempen M, Mosbach‐Schulz O, Rojo Gimeno C, Van der Stede Y, Vitali M, Bailly‐Caumette E, Michel V. 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.

Review on skeletal disorders caused by Staphylococcus spp. in poultry

Lameness or leg weakness is the main cause of poor poultry welfare and serious economic losses in meat-type poultry production worldwide. Disorders related to the legs are often associated with multifactorial aetiology which makes diagnosis and proper treatment difficult. Among the infectious agents, bacteria of genus Staphylococcus are one of the most common causes of bone infections in poultry and are some of the oldest bacterial infections described in poultry. Staphylococci readily infect bones and joints and are associated with bacterial chondronecrosis with osteomyelitis (BCO), spondylitis, arthritis, tendinitis, tenosynovitis, osteomyelitis, turkey osteomyelitis complex (TOC), bumblefoot, dyschondroplasia with osteomyelitis and amyloid arthropathy. Overall, 61 staphylococcal species have been described so far, and 56% of them (34/61) have been isolated from clinical cases in poultry. Although Staphylococcus aureus is the principal cause of poultry staphylococcosis, other Staphylococcus species, such as S. agnetis, S. cohnii, S. epidermidis, S. hyicus, S. simulans, have also been isolated from skeletal lesions. Antimicrobial treatment of staphylococcosis is usually ineffective due to the location and type of lesion, as well as the possible occurrence of multidrug-resistant strains. Increasing demand for antibiotic-free farming has contributed to the use of alternatives to antibiotics. Other prevention methods, such as better management strategies, early feed restriction or use of slow growing broilers should be implemented to avoid rapid growth rate, which is associated with locomotor problems. This review aims to summarise and address current knowledge on skeletal disorders associated with Staphylococcus spp. infection in poultry.

Practical Application of the Five Domains Animal Welfare Framework for Supply Food Animal Chain Managers

The author has worked as a consultant with global commercial supply managers for over 20 years. The focus of this commentary will be practical application of The Five Domains Model in commercial systems. Commercial buyers of meat need simple easy-to-use guidelines. They have to use auditors that can be trained in a workshop that lasts for only a few days. Auditing of slaughter plants by major buyers has resulted in great improvements. Supply chain managers need clear guidance on conditions that would result in a failed audit. Animal based outcome measures that can be easily assessed should be emphasized in commercial systems. Some examples of these key animal welfare indicators are: percentage of animals stunned effectively with a single application of the stunner, percentage of lame animals, foot pad lesions on poultry, and body condition scoring. A farm that supplies a buyer must also comply with housing specifications. The farm either has the specified housing or does not have it. It will be removed from the approved supplier list if housing does not comply. These types of easy to assess indicators can be easily evaluated within the four domains of nutrition, environment, health and behavioral interactions. The Five Domains Framework can also be used in a program for continuous improvement of animal welfare.

Data evaluation of broiler chicken rearing and slaughter-An exploratory study

To process and evaluate the data from broiler fattening and slaughtering, we investigated the production data of 107 straight run flocks of the commercial meat-type breed Ross 308 (Aviagen, EU). All flocks were raised and slaughtered in Germany and the average slaughter age was 37 days. The health outcomes of interest were mortality, average weight, and the slaughter results. First-week mortality, cumulative mortality, stocking density, flock size, season, production week of the parental flock, farm, antibiotic treatment, and the interaction between antibiotic treatment and season were considered as possible influencing factors. The average first-week mortality (FWM) and cumulative mortality percentages were 0.66 and 2.74%, respectively. First-week mortality was influenced by flock size, production week of the parental flock, and the interaction between antibiotic treatment and season, whereas cumulative mortality was influenced by antibiotic treatment, farm, and first-week mortality. The average weight (mean 2.30 kg) was influenced by season, stocking density, flock size, farm, and the interaction between antibiotic treatment and season. The condemnation rate was on average 1.48%, with the most common causes being deep dermatitis (mean 0.63%), ascites (mean 0.53%), and not suitable for production/general disease (mean 0.25%). Several factors influenced the causes of condemnation, with season being the most predominant one, followed by the interaction between antibiotic treatment and season, the antibiotic treatment alone, and stocking density.

In pursuit of a better broiler: walking ability and incidence of contact dermatitis in conventional and slower growing strains of broiler chickens

In this study, the mobility, incidence, and severity of contact dermatitis and litter moisture content were assessed in 14 strains of broiler chickens differing in growth rate. The strains encompassed 2 conventional (CONV; ADG0-48 > 60 g/d) and 12 slower growing (SG) strains categorized as FAST (ADG0-62 = 53-55 g/d), MOD (ADG0-62 = 50-51 g/d), and SLOW (ADG0-62 < 50 g/d), with 4 strains in each category. A total of 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m2) in a randomized incomplete block design, with each strain represented in 8 to 12 pens over 2-3 trials. From each pen, 4 to 6 birds were tested in the latency-to-lie (LTL) and group obstacle tests 1 wk prior to the birds reaching 2 target weights (TWs) of approximately 2.1 kg (TW1: 34 d for CONV and 48 d for SG strains) and 3.2 kg (TW2: 48 d for CONV and 62 d for SG strains). The incidence of footpad dermatitis (FPD) and hock burns (HB) were evaluated a day prior to each TW. Litter moisture content was determined biweekly from d 14 to d 56. At TW1, CONV and SLOW had longer LTL than FAST birds. At TW2, CONV, MOD, and FAST birds had similar LTL. At both TWs, CONV birds were lighter than FAST birds in the group obstacle test, yet their number of obstacle crossings was similar. At TW1, CONV birds had greater incidence of FPD than FAST and MOD, while at TW2, CONV birds had greater incidence than the other categories. The incidence of HB in CONV and MOD was greater than SLOW birds at TW1, while at TW2, the incidence of HB was greater in CONV and FAST birds vs. MOD and SLOW birds. Litter moisture content was high in all categories from d 28 onward. Our results indicate that both BW and growth rate influence leg strength and walking ability, whereas the overall high litter moisture content and to a lesser extent growth rate influenced the incidence of contact dermatitis.

In pursuit of a better broiler: tibial morphology, breaking strength, and ash content in conventional and slower-growing strains of broiler chickens

This study was conducted to determine the differences in bone traits in 14 strains of broiler chickens differing in growth rate. The strains encompassed 2 conventional (CONV; ADG_0-48 >60 g/d) and 12 slower-growing (SG) strains classified as FAST (ADG_0-62 = 53-55 g/d), MOD (ADG_0-62 = 50-51 g/d), and SLOW (ADG_0-62 <50 g/d), with 4 strains represented in each SG category. A total of 7,216 mixed-sex birds were equally allocated into 164 pens (44 birds/pen; 30 kg/m²) in a randomized incomplete block design, with each strain represented in 8 to 12 pens over 2-3 trials. From each pen, 4 birds (2 males and 2 females) were individually weighed and euthanized at 2 target weights (TWs) according to their time to reach approximately 2.1 kg (TW1: 34 d for CONV and 48 d for SG strains) and 3.2 kg (TW2: 48 d for CONV and 62 d for SG strains). Tibiae samples were dissected, and length and diameter were recorded. Left tibiae were used for tibial breaking strength (TBS) at both TWs and tibial ash at TW2. At TW1, CONV birds' tibiae were narrowest and shortest (P < 0.001), yet had similar TBS compared to the other categories (P > 0.69). At TW2, category (P > 0.50) had no effect on tibial diameter, yet CONV birds had the shortest tibiae (P < 0.001). The CONV birds had greater TBS:BW ratio than FAST and MOD birds at both TWs 1 and 2 (P < 0.039) and similar ash content as the other categories at TW2 (P > 0.220). At 48 d of age, CONV birds had the greatest absolute TBS (P < 0.003), yet lower TBS:BW ratio than SLOW birds (P < 0.001). Tibiae from CONV birds were longer than MOD and SLOW birds, and thicker in diameter than the other categories, yet CONV birds had the lowest dimensions relative to BW (P < 0.001) at 48 d, indicating a negative association between accelerated growth and tibial dimensions. These results indicate that differences in functional abilities among categories may be due to differences in morphometric traits rather than differences in bone strength and mineralization.

Across-Species Pose Estimation in Poultry Based on Images Using Deep Learning

Animal pose-estimation networks enable automated estimation of key body points in images or videos. This enables animal breeders to collect pose information repeatedly on a large number of animals. However, the success of pose-estimation networks depends in part on the availability of data to learn the representation of key body points. Especially with animals, data collection is not always easy, and data annotation is laborious and time-consuming. The available data is therefore often limited, but data from other species might be useful, either by itself or in combination with the target species. In this study, the across-species performance of animal pose-estimation networks and the performance of an animal pose-estimation network trained on multi-species data (turkeys and broilers) were investigated. Broilers and turkeys were video recorded during a walkway test representative of the situation in practice. Two single-species and one multi-species model were trained by using DeepLabCut and tested on two single-species test sets. Overall, the within-species models outperformed the multi-species model, and the models applied across species, as shown by a lower raw pixel error, normalized pixel error, and higher percentage of keypoints remaining (PKR). The multi-species model had slightly higher errors with a lower PKR than the within-species models but had less than half the number of annotated frames available from each species. Compared to the single-species broiler model, the multi-species model achieved lower errors for the head, left foot, and right knee keypoints, although with a lower PKR. Across species, keypoint predictions resulted in high errors and low to moderate PKRs and are unlikely to be of direct use for pose and gait assessments. A multi-species model may reduce annotation needs without a large impact on performance for pose assessment, however, with the recommendation to only be used if the species are comparable. If a single-species model exists it could be used as a pre-trained model for training a new model, and possibly require a limited amount of new data. Future studies should investigate the accuracy needed for pose and gait assessments and estimate genetic parameters for the new phenotypes before pose-estimation networks can be applied in practice.

Post-mortem examination of fast-growing broilers with different degrees of identifiable gait defects

BACKGROUND

The walking ability of many broilers is characterised by slight or definite defects categorised as gait scores (GS) 1 and 2. The present study aimed to examine potential relationships between GSs and indicators of body morphology, leg pathology, tibia strength and wooden breast in Ross 308 broilers assessed as GS ≤ 2.

METHODS

At 38 days of age, GS and live body weight of 179 birds was recorded. Each bird was examined post-mortem for signs of wooden breast, contact dermatitis and a range of leg pathologies. Weights of different body parts and tibia strength were quantified.

RESULTS

Within sex, GS increased with increasing live body weight (p = 0.020). There was a tendency for an effect of GS on prevalence of footpad dermatitis (p = 0.086) and dislocated femoral joint cartilage (p = 0.059) where both pathologies increased in frequency with increasing GS. Greater load was required to fracture tibia from GS2 than GS0 birds (p = 0.040).

CONCLUSIONS

Within this relatively small data set, no strong relationships between GS ≤ 2 and indicators of body morphology, leg pathology, tibia strength and wooden breast in Ross 308 broilers were found, except for the live terminal body weight. Further studies, involving larger data sets are required for full clarification.

In pursuit of a better broiler: growth, efficiency, and mortality of 16 strains of broiler chickens

To meet the growing consumer demand for chicken meat, the poultry industry has selected broiler chickens for increasing efficiency and breast yield. While this high productivity means affordable and consistent product, it has come at a cost to broiler welfare. There has been increasing advocacy and consumer pressure on primary breeders, producers, processors, and retailers to improve the welfare of the billions of chickens processed annually. Several small-scale studies have reported better welfare outcomes for slower-growing strains compared to fast-growing, conventional strains. However, these studies often housed birds with range access or used strains with vastly different growth rates. Additionally, there may be traits other than growth, such as body conformation, that influence welfare. As the global poultry industries consider the implications of using slower growing strains, there was a need for a comprehensive, multidisciplinary examination of broiler chickens with a wide range of genotypes differing in growth rate and other phenotypic traits. To meet this need, our team designed a study to benchmark data on conventional and slower-growing strains of broiler chickens reared in standardized laboratory conditions. Over a 2-year period, we studied 7,528 broilers from 16 different genetic strains. In this paper, we compare the growth, efficiency, and mortality of broilers to one of two target weights (TW): 2.1 kg (TW1) and 3.2 kg (TW2). We categorized strains by their growth rate to TW2 as conventional (CONV), fastest-slow strains (FAST), moderate-slow strains (MOD), and slowest-slow strains (SLOW). When incubated, hatched, housed, managed, and fed the same, the categories of strains differed in body weights, growth rates, feed intake, and feed efficiency. At 48 d of age, strains in the CONV category were 835 to 1,264 g heavier than strains in the other categories. By TW2, differences in body weights and feed intake resulted in a 22 to 43-point difference in feed conversion ratios. Categories of strains did not differ in their overall mortality rates.

Over-processed meat and bone meal and phytase effects on broilers challenged with subclinical necrotic enteritis: Part 3. Bone mineralization and litter quality

This study was conducted to determine the effect of necrotic enteritis (NE), phytase level and meat and bone meal (MBM) processing on bone mineralization of broilers and litter quality. Ross 308 male broiler chicks (n = 768) were allotted to 48 pens with 16 birds each. There were 8 dietary treatments in a 2 × 2 × 2 factorial arrangement. Factors were NE challenge (no or yes), phytase level (500 or 5,000 FTU/kg), and MBM (as-received or over-processed). Half of the birds were challenged with field strains of Eimeria spp. at d 9 and 10⁸ CFU per mL of Clostridium perfringens strain EHE-NE18 on d 14 and 15. The middle toe, tibia and femur of 2 birds per pen were excised at d 16 and 29 for determination of ash, breaking strength (BS) and bone mineralization. At d 42, all were assessed for hock burns and litter was scored and assessed for dry matter (DM). At d 16, challenged birds had lower toe ash (P < 0.01), femur ash (P < 0.001), tibia ash (P < 0.001) and tibial BS (P < 0.001) than unchallenged birds. At d 16, challenged birds fed high phytase and over-processed MBM had higher toe Mn than those fed low phytase and as-received MBM. At d 29 unchallenged birds fed high phytase and as-received MBM had a higher toe Mn than those fed over-processed MBM. At d 16, a phytase × MBM interaction was detected for femur Zn concentration (P < 0.05), where a higher level of Zn was observed in the high phytase group fed over-processed MBM. At d 16, tibial Ca (P < 0.05) and P (P < 0.05) were lower in the challenged whereas the femur K (P < 0.001), Mn (P < 0.01) and Na (P < 0.001) were higher in the challenged at d 16. At d 42, challenged birds had higher litter DM (P = 0.058) and fewer hock burns than those unchallenged (P < 0.05). In conclusion, NE impaired bone traits but high phytase and over-processed MBM increased bone mineral contents. Cases of hock burns may be lower under NE incidences due to lower livability of birds reducing litter wetness.

Are changes in behavior of fast-growing broilers with slight gait impairment (GS0-2) related to pain?

Impaired walking ability in terms of slight or definite defects is more common in broiler production than lameness that obviously hinders movement, but it has received limited scientific attention. This study aimed to compare behavior of conventional broilers with impaired walking ability (assessed as gait score (GS) 2) with those walking normally (GS0) and those with only a slight gait defect (GS1). Behavior in the home environment was registered, and an analgesic intervention to quantify changes in time budgets indicating pain relief was applied. The study included 192 Ross 308 broilers. On day 27 of age, the birds were distributed as evenly as possible into birds of GS0 and GS2 of each sex based on obtained gait score. Following this, each experimental bird was housed with 3 companion birds. On days 30 and 32 of age, the behavior in the home pens was recorded. All experimental birds were injected with the NSAID carprofen on one of the 2 d and saline on the other. The statistical analyses used the GS scored on the day of recording as explanatory factor. Compared to GS0 birds, GS2 birds tended to be more inactive (mean (CI): 4,193 (3,971–4416) vs. 4,005 (3,753–4,257) s; P = 0.074), spent more time sitting while feeding (306 (266–353) vs. 213 (180–251) s; P = 0.026), were less likely to perch (probability: 0.78 (0.69–0.85) vs. 0.91 (0.85–0.95); P = 0.012), and spent less time performing comfort behavior (749 (689–814) s vs. 875 (792–967) s; P = 0.043). Compared to GS1 birds, GS2 birds spent more time inactive (GS1: 4,022 (3,818–4225) s; P = 0.027), less time foraging (289 (253–329) vs. 347 (309–388) s; P = 0.047), and were less likely to perch (GS1: 0.90 (0.86–0.93); P = 0.001). For some of these behavioral variables, administration of carprofen led to behavioral changes across the GSs, which may suggest that the behavioral expression of the broilers was limited by pain. These findings are of relevance to animal welfare, but the underlying causes are still not fully clarified.

Long-term access to live black soldier fly larvae (Hermetia illucens) stimulates activity and reduces fearfulness of broilers, without affecting health

Commercially housed broilers frequently experience limited environmental stimulation and various health issues, compromising their welfare. Providing environmental enrichment can alleviate these problems by facilitating natural behaviour and activity. We investigated the effect of providing live black soldier fly larvae (BSFL) to broilers housed at commercial densities (33 kg/m²) on behaviour, fearfulness, health and performance. One-day-old broilers were distributed over five treatments with eight pens/treatment: a control treatment without BSFL; two treatments where 5% of the daily nutrient intake was replaced with live BSFL, provided four or seven times a day; and two treatments where 10% of the daily dietary intake was replaced with live BSFL provided four times a day or in transparent, movable tubes with holes. In all BSFL treatments foraging behaviour, and thereby broiler activity, was increased. Prolonged access to live BSFL, either by providing larvae seven times a day or in tubes, caused the largest increase in activity while also decreasing the time spend in tonic immobility, indicating reduced fearfulness. Broiler final weight and health were not affected. Overall, long-term access to live BSFL seems most effective in improving broiler welfare by facilitating natural behaviour and reducing fearfulness, without hindering broiler performance and health.

Effects of dietary organic minerals, fish oil, and hydrolyzed collagen on growth performance and tibia characteristics of broiler chickens

Nutrition is a crucial factor for growth and bone development in broiler chickens. Adjustments in dietary ingredients might affect bone development and consequently locomotion related problems. This study was designed to evaluate effects of dietary organic minerals (ORM), fish oil (FISH), and hydrolyzed collagen (COL) on growth performance and tibia characteristics of broiler chickens. A total of three hundred eighty four 1-day-old Ross 308 male broiler chickens were used in a complete randomized block design with 4 diet groups and 8 replicates per diet group. In the ORM diet, the inorganic macro and trace minerals were replaced by their organic varieties. In the FISH diet, palm oil and soybean oil were partly replaced by FISH. In the COL diet, soybean meal was partly replaced by COL. Results showed that the ORM and COL diet groups reached a higher body weight (BW) at 42 D of age than the FISH diet group, whereas the control group was in between. The feed conversion ratio between day 1 and 42 was lower in the ORM and COL diet groups than in both other diet groups. On day 28, 35, and 42, gait score (GS), Varus Valgus deformity, tibia length (TL), thickness, femoral and metatarsal head thickness (THT), mineral content (TMC), mineral density (TMD), breaking strength (TBS), stiffness (TSF), and energy to fracture (TEF) were measured (n = 3/replicate). The ORM diet group had higher TL at day 42, higher THT at day 28, higher TMC at day 42, higher TMD at day 28, 35, and 42, higher TBS at day 42, higher TSF at day 35 and 42, and higher TEF at day 42 compared to the FISH diet group, with the COL and control diet groups in between. It can be concluded that replacing dietary inorganic macro and trace minerals by their organic varieties seems to stimulate tibia dimensions, strength, and mineral content of broiler chickens. On the contrary, FISH appears to negatively affect tibia characteristics.

Comparison of Chinese Broiler Production Systems in Economic Performance and Animal Welfare

Simple Summary

There are three main rearing systems for white-feathered broilers in China. They are the net floor system (NFS), the normal cage system (NCS), and the high standard cage system (HCS). This study compared the relationship between economic benefit and animal welfare between these systems. The high economic input, high output, and high profit in these three different rearing systems. The welfare scores were 778.24 ± 29.45, 691.09 ± 32.97, and 669.82 ± 22.79, respectively. As white-feathered broiler production in China has developed, from the conventional system to the latest system, both cost and economic profit have increased while the welfare score has decreased. This study explains why the level of animal welfare in China’s white-feathered broiler production is not high at present, and why breeders do not wish to improve the level of animal welfare production.

Abstract

Both proper animal welfare and economic benefit are important to the broiler industry, so it is better to consider these two factors together. The purpose of this study was to investigate the relationship between economic benefit and animal welfare in different production systems of white-feathered broilers in China. Based on the Welfare Quality Assessment (WQA) protocol for poultry, the authors compared and evaluated the results of the Welfare Quality model (WQM) and the deterministic model. The present study conducted welfare evaluations and investigations on 66 broiler chicken flocks on 52 farms in China. These flocks included three types: the net floor system (NFS), the normal cage system (NCS), and the high standard cage system (HCS). In terms of economy, the results were in line with high economic input, high output, and high profit. In terms of animal welfare assessment, the authors calculated the welfare scores per measure and the attributional WQ scores and WQ index scores of each production systems. The results showed that nine welfare measures from four welfare criteria presented different trends in the three production systems. WQ index scores were 778.24 ± 29.45, 691.09 ± 32.97, and 669.82 ± 22.79, respectively. According to Chow test results, significant differences were found between WQ index scores and total cost and profit (all p < 0.01). In conclusion, with the development of white-feathered broiler production in China, from the conventional system to the latest system, both cost and economic profit have been increased, but the welfare score has been decreased.

Effects of eggshell temperature pattern during incubation on tibia characteristics of broiler chickens at slaughter age

This study was designed to determine effects of eggshell temperature (EST) pattern in week 2 and week 3 of incubation on tibia development of broiler chickens at slaughter age. A total of 468 Ross 308 eggs were incubated at an EST of 37.8°C from incubation day (E) 0 to E7. Thereafter, a 2 × 2 factorial arrangement with 2 EST (37.8°C and 38.9°C) from E8 to E14 and 2 EST (36.7°C and 37.8°C) from E15 till hatch was applied. After hatching, chickens were reared until slaughter age with the 4 EST treatments and 8 replicates per treatment. At day 41 and 42, one male chicken per replicate per day was selected, and hock burn and food pad dermatitis were scored. Rotated tibia, tibia dyschondroplasia, epiphyseal plate abnormalities, bacterial chondronecrosis with osteomyelitis, and epiphysiolysis were assessed. Tibia weight, length, thickness, head thickness, and robusticity index were determined. X-ray analyses (osseous volume, pore volume, total volume, volume fraction, mineral content, and mineral density) and a 3-point bending test (ultimate strength, yield strength, stiffness, energy to fracture, and elastic modulus) were performed. A high EST (38.9°C) in week 2 of incubation, followed by a normal EST (37.8°C) in week 3 resulted in higher mineral content (P = 0.001), mineral density (P = 0.002), ultimate strength (P = 0.04), yield strength (P = 0.03), and stiffness (P = 0.05) compared with the other 3 EST groups (week 2 × week 3 interaction). A high EST (38.9°C) in week 2 of incubation, regardless of the EST in week 3, resulted in a higher tibia weight (P < 0.001), thickness (P = 0.05), osseous volume (P < 0.001), and total volume (P < 0.001) than a normal EST (37.8°C). It can be concluded that 1.1°C higher EST than normal in week 2 of incubation appears to stimulate tibia morphological, biophysical, and mechanical characteristics of broiler chickens at slaughter age. Additionally, a 1.1°C lower EST in week 3 of incubation appears to have negative effects on tibia characteristics, particularly in interaction with the EST in week 2 of incubation.

Effects of environmental complexity on welfare indicators of fast-growing broiler chickens

Increasing environmental complexity, e.g., by providing environmental enrichment, has been suggested as a way to increase activity levels and improve leg health in broilers. The aim of this study was to investigate the effects of different types of environmental complexity on leg health and measures of welfare of fast-growing broilers housed according to conventional European legislation. A total of 58 pens with approximately 500 broilers each (Ross 308), corresponding to a stocking density of 40 kg/m2, were used. A total of 8 treatment groups, of which 5 were enrichment treatments (roughage, vertical panels, straw bales, and elevated platforms at 5 and 30 cm) and 3 were standard resources manipulations [increased distances between feed and water (7 m and 3.5 m), stocking density reduced to 34 kg/m2, and 1 control group (1.5 m distance between feed and water and no enrichment objects)] were randomly assigned to each pen. At 35 D of age, 60 birds from each pen were assessed for gait, footpad dermatitis, hock burns, plumage cleanliness, presence of scratches, and leg deformities. Birds housed with 30 cm elevated platforms had worse gait compared to those housed with straw bales and at the lower stocking density of 34 kg/m2 (P = 0.004 and P = 0.001). Broilers from the control group also had worse gait compared to those housed at 34 kg/m2 stocking density. In addition, birds housed with access to a 30 cm elevated platform had healthier footpads compared to birds housed with access to straw bales (P = 0.0001) and with increased distance between feed and water (P = 0.011). Furthermore, birds housed with straw bales had worse footpad condition compared to birds with access to a 5 cm elevated platform (P = 0.002). There were no observed treatment effects on scratches, plumage cleanliness, leg deformities and body weight (P > 0.05). Based on the welfare indicators used in the present study, decreased stocking density has the potential of improving animal welfare, whereas the effects of elevated platforms need to be further studied before a final conclusion can be drawn, as footpad health was positively affected, but walking ability was impaired.

Associations between carcass weight uniformity and production measures on farm and at slaughter in commercial broiler flocks

In poultry flocks, flock weight uniformity is often defined as the percent individuals within 10% of the mean body weight (BW) and the variability of this uniformity can be expressed as the CV of BW. Flock weight uniformity is a standardized and objective measured, and could potentially be used as a welfare indicator; however, little is known about the relationship between flock uniformity and other production measures on-farm or at slaughter. The aim of this study was to investigate the associations between carcass weight uniformity (CV of BW) and production measures on-farm and at slaughter in Norwegian commercial broiler flocks. A total of 45 randomly selected mixed-sex Ross 308 broiler flocks were visited prior to slaughter at 28 to 30 D of age (average slaughter age 30.6 D). All flocks were raised under similar farm management systems. The Welfare Quality protocol for broilers was used to assess different animal welfare indicators in each flock. All production data from the slaughterhouse were collected for each flock, including carcass weight uniformity (%), mortality (%), growth rate (g), feed conversion ratio (FCR), and rejected birds (%) in different rejection categories. Univariable and multivariable linear regression models were used to investigate the associations between flock weight uniformity and production and welfare measures. The results showed that flock uniformity varied from 11% to 18% between flocks within the same hybrid, similar management standards, and similar slaughter age (day 29 to 32). Poorer uniformity (i.e., high CV) was associated with increased first week mortality (P < 0.004, r = 1.48, increased total mortality (P < 0.013, r = 0.01), increased FCR (i.e., less efficient growth) (P < 0.024, r = 0.06), reduced growth rate (P < 0.0012, r = −0.01), and a reduced rejection rate at slaughter (P < 0.006, r = −0.01). The results show that flock uniformity varies across broiler flocks, and is associated with several production measures.

Lameness and its relationship with health and production measures in broiler chickens

The aim of this study was to explore lameness and the associations between lameness and health/production measures of animal welfare in commercial broiler production, using the Welfare Quality® protocol for broilers. A total of 50 flocks were included in the sample and farm visits were conducted for lameness scoring at a mean age of 28.9 days. The percentage of animals (n=7500) in the six different gait score (GS) categories were GS0: 2.53%, GS1: 44.19%, GS2: 33.84%, GS3: 16.32%, GS4: 2.36% and GS5: 0.53%. Production and other welfare data were collected for each flock after slaughter. Higher gait scores were associated with increased hock burn score (P<0.02), increased footpad dermatitis score (P<0.01), reduced bird cleanliness score (P<0.01) and peat litter (P<0.01). Although not statistically significant, there was a tendency for increased flock gait score being associated with wet litter (P=0.07). In addition, condemnations at postmortem inspection were associated with increasing gait scores (P<0.05), indicating that at least a portion of the lameness cases display pathological changes on the carcasses. In conclusion, 19%of the birds showed moderate-to-severe lameness, which was associated with several production or health and welfare observations including feather cleanliness and condemnations as unfit for human consumption at slaughter. Although stocking density and growth rate are already known key factors for lameness, associations of lameness with hock burns, footpad dermatitis and cleanliness of the birds suggest that a suboptimal physical environment (e.g. litter- and air quality) may be detrimental to leg health. Further studies are needed to explore these associations in more detail.

Husbandry Practices, Health, and Welfare Status of Organic Broilers in France

Simple Summary

Organic poultry production has grown rapidly in Europe for the past several years in the context of sustainable development within farming. The authors carried out a field study in France between 2014 and 2015 concerning 85 organic broiler flocks that showed a wide diversity of farming management systems from independent farmers set up for direct sales of poultry to farmers under contract with a company for product sales. Health and welfare characteristics did not significantly differ between these two farming systems, except slightly dirtier feathers and more footpad dermatitis on the independent farms, related to the poultry housing conditions in mobile houses. A mortality rate of 2.8% was found, with digestive problems mainly being observed. Better knowledge of husbandry practices, health, and the welfare status of organic poultry is of primary importance to improve the management of organic production and to help in characterizing farming sustainability.

Abstract

Organic poultry production has increased sharply with growing consumer demand in the context of sustainable development. A study was conducted in 85 organic broiler flocks between 2014 and 2015 to describe the husbandry practices and the health and welfare status of organic broilers in France, and to study farming diversity by comparing independent farms (Ind farms, n = 15) with direct sales to farms working with companies (Comp farms, n = 70). Each flock was visited at 3 and 11 weeks of age to collect data on farming conditions, health disorders, and mortality. Welfare notation of 30 broilers per flock and parasitic examination of 5 broilers per flock was also performed. Findings showed significantly different farming management between Ind farms and Comp farms, with smaller flocks on the Ind farms (476 broilers/house vs. 3062 broilers/house, p < 0.01) more frequently in mobile houses. The mean mortality rate was 2.8%, mainly involving digestive disorders. Helminths were detected in 58.8% of the flocks. On average, 21.9% and 5.8% of broilers in a flock had footpad dermatitis and dirty feathers, respectively. The health and welfare characteristics of organic broilers on Ind farms vs. Comp farms were not significantly different, except dirtier feathers and more footpad dermatitis on Ind farms (19.1% vs. 2.9%, p = 0.03 and 39.6% vs. 18.1%, p = 0.02, respectively), associated with poultry housing conditions in mobile houses (p < 0.01). This study provides greater insight into farming sustainability aspects related to the husbandry practices, and the health and welfare of organic broilers in France.

Welfare assessment of conventional and organic broilers in Denmark, with emphasis on leg health

The aim of this study was to survey and report the walking ability in broilers housed in both conventional and organic production systems in Denmark. To this end, the authors assessed the walking ability, by using the Bristol scale, in 31 conventional broiler flocks and in 29 organic broiler flocks distributed across Denmark. In addition, assessment of contact dermatitis, leg abnormalities, scratches and plumage cleanliness, as well as postmortem analysis of tibial dyschondroplasia, was performed in conventional broilers. The survey found a prevalence of 77.4 per cent of impaired walking ability (gait score (GS) >0) in conventional broilers and 38.1 per cent in organic broilers. The prevalence of severe lameness (GS >2) was 5.5 per cent and 2.5 per cent for conventional and organic broilers, respectively. The prevalence of tibial dyschondroplasia in conventional broilers was 4.7 per cent. The results on other welfare indicators are also presented for conventional broilers. The results from the present and previous surveys indicate that the prevalence of impaired walking ability in broiler chickens in the Danish conventional production system is high, but the severity has been steadily decreasing over the last 19 years. Furthermore, the results from the survey of organic broilers suggest that lameness is less prevalent and severe in this system relative to conventional production.

The relationship between measures of fear of humans and lameness in broiler chicken flocks

In the Welfare Quality® assessment protocol for broilers, the touch test is included to assess the human-animal relationship in the flock. The test is designed to measure the animals' fear of humans, assuming that broilers will withdraw from the observer if they are fearful. However, many broilers close to slaughter age have impaired walking ability, and the results from the touch test may thus be biased by lameness and poor leg health. As the touch test is currently being used in several countries to assess human-animal relationship in broilers, there is an urgent need to examine this potential relationship for a further validation of the test. In the present study, fear of humans was assessed in 50 randomly selected Norwegian broiler flocks, using the touch test as described in the Welfare Quality® protocol for ty broilers. Leg health was assessed by examining the gait of 150 random birds in each of the flocks, using a six-point gait score scale from 0 to 5. The coefficient for the relationship between touch test score and gait score was 0.034 (P<0.001), indicating that the animals express less fear as assessed by the touch test when the gait scores increase. This implies that the touch test may be confounded by impaired walking ability and therefore might be a suboptimal method of assessing fear of humans and human-animal relationship in broilers. In conclusion, the results from this study suggests that the touch test must be further validated in broilers and perhaps be replaced with a fear test that doesn't rely on walking ability.