Shackling of broilers: effects on stress responses and breast meat quality

Effects of Restraint Stress on Circulating Corticosterone and Met Enkephalin in Chickens: Induction of Shifts in Insulin Secretion and Carbohydrate Metabolism

This study examined the effects of acute restraint stress in the presence or absence of naltrexone on the circulating concentrations of insulin, glucose, Met-enkephalin and corticosterone in 14-week-old chickens [design: 2 sex × 2 stress/non-stress × 2 +/- naltrexone]. In chickens (five male and five females per treatment) subjected to restraint for 30 min, there were increases in the plasma concentrations of corticosterone and Met-enkephalin. The plasma concentrations of insulin and glucose were also increased in the chickens during restraint. Moreover, there were increases in the plasma concentrations of insulin and glucose in the chickens. The patterns of expression of the proenkephalin gene (PENK) in both the anterior pituitary gland and the adrenal gland were very similar to that of plasma Met-enkephalin. There were relationships between the plasma concentrations of corticosterone, Met-enkephalin, insulin and glucose after 30 min of restraint. The effects of naltrexone treatment on both untreated and stressed chickens were also examined, with naltrexone attenuating the stress-induced increases in the plasma concentrations of corticosterone, Met-enkephalin and glucose but not in those of insulin. The present study demonstrates that stress increases insulin secretion in chickens but also induces insulin resistance.

Behavior of broilers and impacts occurring to them during mechanical loading under field conditions

Mechanical loading has been used increasingly in recent years alongside the manual loading of broilers. The aim of this study was to analyze the influence of various factors on the behavior of broilers and the impacts occurring to broilers during loading with a loading machine in order to identify risk factors and thus improve animal welfare. During 32 loadings we assessed escape behavior, wing flapping, flip, bumping into an animal, and bumping against the machine or container by evaluation of video recordings. The parameters were analyzed for influences of rotation speed, container type (GP container vs. SmartStack container), husbandry system ("Indoor Plus" vs. "Outdoor Climate"), and season. In addition, the behavior and impact parameters were correlated with the loading-related injuries. The results showed that an increase in rotation and conveyor belt speed was associated with an elevated risk of all behaviors or impacts, except for a lower risk of escape behavior. The seasonal influence showed that the risk of wing flapping, bumping into an animal, and bumping against the machine or container was highest in fall. The comparison of the container types showed that the risk of escape behavior, wing flapping, and bumping into an animal was increased when loading with the SmartStack container, but the risk of bumping against the machine or container was reduced. For animals of the husbandry system "Outdoor Climate," the risk of bumping into an animal and bumping against the machine or container was reduced. In addition, we found an influence of the examined parameters on the loading-related injuries. Increased escape behavior reduced the risk of severe injuries (fractures, dislocations, epiphysiolyses). Wing flapping and bumping against the machine or container increased the risk of hematomas and abrasions. The risk of hematomas was increased if broilers bumped into conspecifics. In summary, our analysis revealed that the behavior and impacts on the animals during loading are influenced by each of the analyzed factors and that they in turn can affect loading-related injuries.

Meat quality of broiler chickens processed using electrical and controlled atmosphere stunning systems

Increased consumer concern for animal welfare has led some poultry producers to alter their stunning methods from electrical to controlled atmosphere stunning. The potential for different impacts on meat quality between commercially applied controlled atmosphere stunning (CAS) and electrical stunning (ES) using current US parameters needs further evaluation. Three trials were conducted in a commercial broiler processing facility that uses separate processing lines for ES and CAS. Blood glucose concentrations were measured from broilers stunned by either CAS or ES at: 1) lairage, 2) pre-stunning, and 3) post-stunning, using a glucose monitor. Occurrence of visible wing damage was evaluated post-defeathering and breast fillet meat quality was evaluated through measurement of pH, color, and drip loss at deboning and after 24 h. Data were analyzed using GLM or chi-square with a significance at P ≤ 0.05 and means were separated by Tukey's HSD. Blood glucose concentrations (mg/dL) from CAS and ES birds were not different at lairage (284, 272, P = 0.2646) or immediately prior to stunning (274, 283, P = 0.6425). Following stunning and neck cut, circulating blood glucose from birds stunned by CAS was higher than ES (418, 259, P < 0.0001). CAS carcasses had more visible wing damage than ES carcasses (3.6%, 2.2%, P < 0.0001). Breast fillet pH was lower, L* was higher, and a* was lower at debone for CAS fillets (5.81, 54.65, 1.96) compared to ES fillets (5.92, 53.15, 2.31, P < 0.0001, P = 0.0005, P = 0.0303). Drip loss did not differ between breast fillets from CAS or ES broilers (4.83, 4.84; P = 0.0859). The implications of increased blood glucose concentration post-CAS are unknown and require further evaluation. However, the increase in visible wing damage observed post-defeathering from CAS carcasses indicated a need for equipment parameter adjustments during the process from stunning through defeathering when using CAS for broiler stunning. Although differences were observed in breast fillet attributes at deboning, these differences would have minimal practical application and were no longer present at 24 h. Overall, use of CAS in a commercial facility resulted in differences in subsequent product quality when compared to ES.

Comparison of the Automatic and Manual Broiler Pre-Slaughter Chain Based on Trailer Microclimate during Transportation and Its Effect on m. pectoralis major

Simple Summary

Improper pre-slaughter catching, loading/unloading, handling, and transport may cause negative effects on the welfare and meat quality of poultry. During the catch process, noisy, rough, or aggressive techniques can cause birds to panic, which can lead to injuries and lower meat quality. Fractures, joint dislocations, and bruises can be common and cause bird suffering, mortality, carcass degradation, and economic loss. Proper pre-slaughter processes can ensure the safety of poultry and workers. One way to prevent these problems is to use automatic catching machines (harvesters/chicken cat), handling machines (shuttles), and air-conditioned trucks (trailers) to collect and handle poultry. Microclimate in trailers is another important factor influencing welfare. Internal overheating may cause high mortality of the animals during transport and reduced meat quality. The use of modern air-conditioned trailers results in improved welfare conditions, reduced mortality and the incidence of injuries and fractures, and increased meat quality.

Abstract

This study aims to compare two broiler pre-slaughter chain methods: (i) the automatic pre-slaughter chain (APC) and (ii) manual pre-slaughter chain (MPC). The comparison is based on the evaluation of the trailer microclimate, number of injuries, and breast muscle (m. pectoralis major) quality. Transportation lasts 3.5 h, unloading 1 h. The selection of two hundred 39-day-old broilers (Ross 308 and Cobb 500 breeds) is random for each type of method. After slaughter, the pH value, electrical conductivity (EC), and color (lightness) of breast muscle tissues are determined at different post-mortem intervals. The MPC negatively affects the microclimate (p < 0.001), meat qualitative characteristics (p < 0.001), and places a greater strain on the body of chickens compared with APC. The average pH_15min value of MPC broiler breast muscle tissue, generally used as the main meat quality parameter, is 5.97 ± 0.12, in contrast to 6.36 ± 0.16 for APC. Higher pH_15min value of APC indicates better welfare and pre-slaughter handling. Values of EC and L* of breast tissues also confirms a difference between the methods of broiler handling (p < 0.001). No difference is found between the breed lines (p > 0.05).

Characterization of Carcass Color Differences Between Hens (Small Birds) and Meat-Type Male Pheasants (Large Birds)

The underlying changes in hen carcass color upon freezing were compared with the color of meat-type male pheasants upon freezing. Chemical and physical assessments of these two pheasant types (n=5) and the effects of different chilling methods on hen carcasses (n=10) were evaluated. The results showed that hen carcasses exhibited more red pigmentation (myoglobin, hemoglobin), as well as significantly higher pH values and redness, than the carcasses from meat-type pheasants. The moisture content was higher in hens than in meat-type pheasants, especially in the skin. The intermediate fiber (IIA) type was the only type found in the pectoralis major muscle, regardless of pheasant type. Chilling method significantly changed the color attributes of the hen carcass. Immersion chilling decreased skin redness (less pigmentation and Commission Internationale de l ́Eclairage [CIE] a*); the breast meat was less red than that from the chilling-in-a-bag condition. The skin had substantially higher levels of red pigmentation than the breast muscles, irrespective of the pheasant type and chilling method (P &lt; 0.05). Our findings suggest that the more intense red appearance may be related to a combination of greater residual hemoglobin levels and higher pH within the skin. The greater moisture content of the skin may have facilitated the development of greater transparency to the darker, more red breast muscle.

Carcass Characteristics, Proximate Composition, Fatty Acid Profile, and Oxidative Stability of Pectoralis major and Flexor cruris medialis Muscle of Broiler Chicken Subjected to with or without Level of Electrical Stunning, Slaughter, and Subsequent Bleeding

Simple Summary

The rapid growth in the global and Muslim population has increased the demand for ritually obtained meat, creating a scope of the global meat business. Pre- and post-slaughter practices are of concern in the global meat industries. Therefore, this study examined four types of slaughter, applied with or without a level of electrical stunning, halal neck cutting, and subsequent bleeding (LSHS, MSHS, and HSHS vs. NSHS). Treatments were as follows: (1) NSHS (without electrical stunning, halal neck cut, and subsequent bleeding was for 180 s), (2) LSHS (electrically stunned at 250 mA for 5 s, halal neck cut, and subsequent bleeding was for 180 s), (3) MSHS (electrically stunned at 500 mA for 10 s, halal neck cut, and subsequent bleeding was for 180 s), and (4) HSHS (electrically stunned at 1000 mA for 20 s, halal neck cut, and subsequent bleeding was for 180 s). Slaughtering practices were evaluated in broiler chickens to determine if they influence the carcass characteristics, livability, bleeding out, Pectoralis major and Flexorcruris medialis proximate composition, cholesterol content, fatty acid profile, post-mortem pH, microbial loads, and oxidative stability. With or without stunning, halal neck cutting and subsequent bleeding did not have a significant negative impact on the nutritional aspects, such as proximate composition, cholesterol content, and fatty acid profile, or post-mortem pH, microbial loads except for a variation in some carcass characteristics, livability, bleeding out, and oxidative stability during post-mortem. Since the pre-slaughter conscious state of the animal/bird and post-slaughter bleeding are ritual demands in this process, higher livability and higher bleed out was exhibited in NSHS and LSHS, and there was no large negative impact on nutritional aspects. Therefore, the meat industry can consider without stunning (NSHS) or short-time electrical stunning (LSHS) to capture the global meat market.

Abstract

With an emphasis on the global meat market and considering the ritual requirements and quality aspects, four types of slaughtering treatments were compared: (1) NSHS (without electrical stunning, halal neck cut, and subsequent bleeding for 180 s), (2) LSHS (electrically stunned at 250 mA for five seconds, halal neck cut, and subsequent bleeding for 180 s), (3) MSHS (electrically stunned at 500 mA for 10 s, halal neck cut, and subsequent bleeding for 180 s), and (4) HSHS (electrically stunned at 1000 mA for 20 s, halal neck cut, and subsequent bleeding for 180 s). Four hundred 36 day-old Ross 308 broiler chickens (body weights of 1.4 to 1.8 kg) were divided into four random groups of 100 birds each (ten replicated pens of ten birds). This study examined the livability, bleeding out, Pectoralis major and Flexor cruris medialis proximate composition, cholesterol content, fatty acid profile and post-mortem pH, microbial loads, and oxidative stability. The livability and bleeding out were higher in NSHS and LSHS than MSHS and HSHS (p < 0.05). The Pectoralis major and Flexor cruris medialis proximate composition, cholesterol content and fatty acid profile, post-mortem pH, and microbial loads were unaffected by the slaughter treatments (p > 0.05), but the oxidative stability of Pectoralis major differed during the eight-day post-mortem period (p < 0.05). The results suggest that for capturing the global meat market, the meat industry can consider NSHS and LSHS because the ritual requirements are fulfilled, and there is no negative impact on the nutritional aspects.

Phenolic compounds as natural feed additives in poultry and swine diets: a review

Due to ban on using antibiotics in feed industry, awareness of using natural feed additives have led to a great demand. The interest of plants phenolic compounds as a potential natural antioxidant source has been considered in research community due to their predictable potential role as feed additives in poultry and swine production. However, the mode of action for their functional role and dosage recommendation in animal diets are still remain indistinct. Taking into account, the present review study highlights an outline about the mode of action of phenolic compound and their experimental uses in poultry and swine focusing on the growth performance, antioxidant function, immune function, antimicrobial role and overall health status, justified with the past findings till to date. Finally, the present review study concluded that supplementation of phenolic compounds as natural feed additives may have a role on the antioxidant, immunity, antimicrobial and overall production performance in poultry and swine.

Age and Staphylococcus aureus Inoculation Route Differentially Alter Metabolic Potential and Immune Cell Populations in Laying Hens

In 2018 and 2019, Staphylococcus aureus was isolated from multiple post-molt commercial laying hens with unusually high mortality. A challenge study was conducted to elucidate the role of S. aureus in this disease outbreak and the work herein represents the assessment of immunological responses in laying hens experimentally infected with S. aureus isolates from these cases. A total of 200 laying hens at 22 or 96 weeks of age (100/ age group) were assigned to 1 of 4 experimental inoculation groups (negative control, oral gavage, subcutaneous injection, or intravenous injection) after a 72 h acclimation period. Blood samples were taken prior to inoculation (baseline), 6 h post-inoculation (pi), 24 hpi, 3 dpi, and 7 dpi. Additional spleen samples to further assess systemic immunity were taken at baseline, 3 and 8 dpi. Metabolic phenotypes of peripheral blood mononuclear cells (PBMC) were isolated and assessed by Seahorse metabolic assay. Immune cell profiles in the spleen and PBMC were assessed by multicolor flow cytometry. At baseline, 96-week-old laying hens had 26.7% fewer PBMC-derived T cells compared to 22-week-old birds. Older hens had 28.9% increased helper T cell (T_H) populations and 60.5% reduced γδ T cells (P = 0.03 and < 0.0001) which may contribute to variable clinical responses between age groups; however, no age-related differences in metabolic potential were observed. Metabolic outcomes showed that birds remained stressed from transport and re-housing past a 72 h acclimation period and through 24 h- 3 days post-inoculation. Inoculation with S. aureus generally reduced oxidative and glycolytic potentials compared to the control, with the greatest reductions observed in birds inoculated by intravenous injection (P < 0.05). Overall CD3⁺ T cell populations showed significant reductions in the intravenous group compared to other inoculation routes from 24 hpi to 7 dpi (23.6–39.0%; P ≤ 0.0001). These results suggest that age-related baseline differences in T cell populations and changes to T cell subpopulations and other immune cells due to inoculation route may have an additive effect on S. aureus- induced reductions in metabolic potential; however, further research linking metabolic potential and immune cell profiles is needed.

Understanding the Determination of Meat Quality Using Biochemical Characteristics of the Muscle: Stress at Slaughter and Other Missing Keys

Despite increasingly detailed knowledge of the biochemical processes involved in the determination of meat quality traits, robust models, using biochemical characteristics of the muscle to predict future meat quality, lack. The neglecting of various aspects of the model paradigm may explain this. First, preslaughter stress has a major impact on meat quality and varies according to slaughter context and individuals. Yet, it is rarely taken into account in meat quality models. Second, phenotypic similarity does not imply similarity in the underlying biological causes, and several models may be needed to explain a given phenotype. Finally, the implications of the complexity of biological systems are discussed: a homeostatic equilibrium can be reached in countless ways, involving thousands of interacting processes and molecules at different levels of the organism, changing over time and differing between animals. Consequently, even a robust model may explain a significant part, but not all of the variability between individuals.

Effect of chestnut wood extract on performance, meat quality, antioxidant status, immune function, and cholesterol metabolism in broilers

Plant extracts have been proved as natural antioxidants resources as well as alternative feed additives in livestock and poultry species. Chestnut wood extract (CWE) as a source of hydrolysable tannic acid was used to evaluate the growth performance, nutrient retention, meat quality, antioxidant status, and immune function of broilers. A total of 168, day-old Arbor Acre male broilers (weight 46.59 ± 0.44 g) were randomly divided to 3 treatments, 7 replicate pens per treatment, 8 broilers per pen. The treatments contain a control diet, CON (corn-soybean meal basal diet); an antibiotic diet, CTC (basal diet + 75 mg/kg chlortetracycline); and chestnut wood extract diet, CWE (basal diet + 1,000 mg/kg chestnut tannins). At the finisher phase, final body weight was higher (P < 0.05) in CWE supplemented diet than in CON. Average daily body weight gain was higher (P < 0.05) and feed gain ratio was lower (P < 0.05) in broilers fed CWE than in those fed CON at the finisher phase. Crude protein digestibility was higher (P < 0.05) in broilers offered CWE than that in broilers fed CON and CTC diets. Breast muscle pH value at 24 h (pH24 h) was higher (P < 0.05) in broilers fed CWE than that in those fed CON and CTC diets. The bursa weight was higher (P < 0.05) in broilers offered CWE than that in those fed CON and CTC. Total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) values were higher (P < 0.05) in both breast muscle and thigh muscle of broilers offered CWE supplemented diet than those in broilers fed CON and CTC diets. Similarly, broilers offered with CWE diets showed higher (P < 0.05) T-AOC, GSH-PX, and SOD value in serum than those fed CON and CTC diets. Serum concentration of IgG was higher (P < 0.05) in broilers offered with CWE diets than that in those fed CON and CTC diets. Total cholesterol, low-density lipoprotein cholesterol, and urea-N concentration were lower (P < 0.05) in broilers offered CWE diet than those in broilers fed CON and CTC diets. It was recommended to supply CWE at the 1,000 mg/kg level for improving antioxidant status, cholesterol metabolism, and growth performance without affecting normal meat quality in broilers.

Effect of transportation and shackling on plasma concentrations of corticosterone and heterophil to lymphocyte ratios in market weight male turkeys in a commercial operation

There is limited information on the effects of stress and/or physiological manipulation on either plasma concentrations of corticosterone (CORT) and/or heterophil: lymphocyte (H : L) ratios in turkeys. The present studies examine the effects of catching/transportation/lairage in a holding shed and shackling on plasma concentrations of CORT and H : L ratios in male market weight turkeys. Plasma concentrations of CORT were increased after transportation and lairage but not further elevated by shackling, irrespective of its duration up to 240 s. In one study, there were increased H : L ratios following catching/placing birds into transportation cages/transportation/lairage. In one study, H : L ratios declined following shackling. It is concluded that while moving turkeys from the farm to immediately before the shackling line is stressful, shackling for up to 4 min was not perceived as more stressful in turkeys. There were also differences between farms/houses for both plasma concentrations of CORT and H : L ratios.

Effects of putative stressors and adrenocorticotropic hormone on plasma concentrations of corticosterone in market-weight male turkeys

There is limited information on the effects of stress and/or physiological manipulation on plasma concentrations of corticosterone (CORT) in turkeys. Under basal conditions, there was evidence for episodic release of CORT in turkeys. The present studies determine the effects of handling, herding, herding, the administration of Escherichia coli endotoxin, and challenge with turkey adrenocorticotropic hormone (ACTH) on plasma concentrations of CORT in market-weight male turkeys. Plasma concentrations of CORT were increased after challenge with turkey ACTH, handling together with saline injection or herding (moving birds from one pen to another). There were no effects on plasma concentrations of CORT of the following putative stressors: handling per se, endotoxin challenge, or of placing in an inverted position on simulated shackles.

Effects of preslaughter shackling on postmortem glycolysis, meat quality, changes of water distribution, and protein structures of broiler breast meat

The objective of this study was to investigate the effects of preslaughter shackling on stress, postmortem glycolysis, meat quality, water distribution, and protein structures of pectoralis majors. Before slaughter, Arbor Acres broilers (n = 105, 42 days old, 2.0 to 2.5 kg) were randomly categorized into 3 treatment groups: (I) control group without shackling (NS); (II) 2.5 min shackling (SS); (III) 4.5 min shackling (LS). Each treatment group consisted of 5 replicates with 7 broilers each. Results indicated that preslaughter shackling increased (P < 0.05) plasma corticosterone and adrenocorticotropic hormone concentrations in comparison with the control group. Antemortem shackling increased (P < 0.05) activity of glycogen phosphorylase and phosphofructokinase-1 (PFK-1) accompanying with rapid glycolysis and pH decline at early postmortem. LS treatment led to myosin denaturation, decreased (P < 0.05) α-helix content, and increased (P < 0.05) β-sheet structures proportion in the myofibrillar proteins. Furthermore, meat from LS treatment had higher (P < 0.05) lightness, redness, and poorer water-holding capacity. These results indicated that the longer shackling duration (4.5 min) increased stress and the rate of glycolysis, causing myosin denaturation and changes of the secondary structure in the myofibrillar proteins, which aggravated the deterioration of meat quality.

Killing for purposes other than slaughter: poultry

Poultry of different ages may have to be killed on‐farm for purposes other than slaughter (in which slaughtering is defined as being for human consumption) either individually or on a large scale (e.g. because unproductive, for disease control, etc.). The processes of on‐farm killing that were assessed are handling and stunning and/or killing methods (including restraint). The latter were grouped into four categories: electrical methods, modified atmosphere, mechanical methods and lethal injection. In total, 29 hazards were identified and characterised, most of these regard stunning and/or killing. Staff were identified as origin for 26 hazards and 24 hazards were attributed to lack of appropriate skill sets needed to perform tasks or due to fatigue. Specific hazards were identified for day‐old chicks killed via maceration. Corrective and preventive measures were assessed: measures to correct hazards were identified for 13 hazards, and management showed to have a crucial role in prevention. Eight welfare consequences, the birds can be exposed to during on‐farm killing, were identified: not dead, consciousness, heat stress, cold stress, pain, fear, distress and respiratory distress. Welfare consequences and relevant animal‐based measures were described. Outcome tables linking hazards, welfare consequences, animal‐based measures, origins, preventive and corrective measures were developed for each process. Mitigation measures to minimise welfare consequences were also proposed.

Genetical Genomics of Tonic Immobility in the Chicken

Identifying the molecular mechanisms of animal behaviour is an enduring goal for researchers. Gaining insight into these mechanisms enables us to gain a greater understanding of behaviour and their genetic control. In this paper, we perform Quantitative Trait Loci (QTL) mapping of tonic immobility behaviour in an advanced intercross line between wild and domestic chickens. Genes located within the QTL interval were further investigated using global expression QTL (eQTL) mapping from hypothalamus tissue, as well as causality analysis. This identified five candidate genes, with the genes PRDX4 and ACOT9 emerging as the best supported candidates. In addition, we also investigated the connection between tonic immobility, meat pH and struggling behaviour, as the two candidate genes PRDX4 and ACOT9 have previously been implicated in controlling muscle pH at slaughter. We did not find any phenotypic correlations between tonic immobility, struggling behaviour and muscle pH in a smaller additional cohort, despite these behaviours being repeatable within-test.

Effects of method and duration of restraint on stress hormones and meat quality in broiler chickens with different body weights

Objective

The study was designed to investigate the effects of restraint method, restraint duration, and body weight on stress-linked hormones (corticosterone, adrenaline, and noradrenaline), blood biochemical (namely glucose and lactate), and the meat quality in broiler chickens.

Methods

A total of 120 male broiler chickens (Cobb 500) were assigned to a 2×3×2 factorial arrangement in a completely randomized design using two restraint methods (shackle and cone), three durations of restraint (10, 30, and 60 s), and two categories of live body weight (1.8±0.1 kg as lightweight and 2.8±0.1 kg as heavyweight).

Results

Irrespective of the duration of restraint and body weight, the coned chickens were found to have lower plasma corticosterone (p<0.01), lactate (p<0.001), lower meat drip loss (p<0.01), cooking loss (p<0.05), and higher blood loss (p<0.05) compared with their shackled counterparts. The duration of restraint had significant effects on the meat initial pH (p<0.05), ultimate pH (p<0.05), and yellowness (p<0.01). The lightweight broilers exhibited higher (p< 0.001) blood loss and lower (p<0.05) cooking loss compared to the heavyweight broilers, regardless of the restraint method used and the duration of restraint. However, the interaction between the restraint method, duration of restraint, and body weight contributed to differences in pre-slaughter stress and meat quality. Therefore, the interaction between the restraint method and the duration of restraint affected the meat shear force, lightness (L*) and redness (a*).

Conclusion

The duration of restraint and body weight undoubtedly affect stress responses and meat quality of broiler chickens. Regardless of the duration of restraint and body weight, the cone restraint resulted in notably lower stress, lower meat water loss, and higher blood loss compared to shackling. Overall, the findings of this study showed that restraint method, duration of restraint, and body weight may affect the stress response and meat quality parameters in broilers and should be considered independently or interactively in future studies.

Effect of pre-slaughter shackling and wing flapping on plasma parameters, postmortem metabolism, AMPK, and meat quality of broilers

The objective of this study was to determine the effects of shackling and wing flapping on stress, postmortem metabolism, AMP-activated protein kinase (AMPK), and quality of broiler pectoralis major. Before slaughter, a total of 80 Arbor Acres broilers was randomly categorized into 2 replicate pens (40 broilers per pen) and each pen randomly divided into 2 groups (shackling, T; control, C). Corticosterone, creatine kinase, and lactate dehydrogenase were determined on blood plasma parameters. Pectoralis major were removed after evisceration and used for determination of energy metabolism, meat quality, and AMPK phosphorylation. In this study, shackling and wing flapping increased (P < 0.05) plasma corticosterone level, creatine kinase activity, and lactate dehydrogenase activity. Shackling and wing flapping increased (P < 0.05) AMPKα(Thr172) and acetyl-CoA carboxylase (ACC) phosphorylation, followed by rapid glycolysis and accumulation of lactic acid, and leading to a fast pH decline in the initial postmortem meat. Shackling and wing flapping have an adverse effect on final meat quality, which increased (P < 0.05) muscle lightness, drip loss, and cooking loss. The results indicate that antemortem shackling and wing flapping increased stress and AMPKα(Thr172) phosphorylation, which may accelerate glycolysis and lead to a low water-holding capacity of broiler meat.

Preliminary Study on Physicochemical and Biochemical Stress Markers at Poultry Slaughterhouse

Pre-slaughter stress can result in variations in the glycogen storage and metabolic changes of muscle, responsible for quality poultry meat. Aim of this study was to investigate, as pre-slaughter stress markers and quality meat, physicochemical (pH), biochemical (muscle glycogen content), and chemical (super oxides free radicals) parameters. The carcass quality, as incidence of individual carcass defects, was also evaluated. Twenty broilers were processed with two different electrical stunning: high (250 Hz; 640 mA; 60V) (Lot C or control) and low (150 Hz; 360 mA; 60 V) (Lot A) frequency and intensity, using sinusoidal alternating current. As preliminary results, the use of low frequency and intensity induced faster pH decline post mortem and adequate acidification of pH at 3 hours (6.49 Lot C; 6.37 Lot A), better muscle glycogen reserve (0.770 μL/50 mL Lot C; 1.497 μL/50mL Lot A), and lightly more rapid muscle oxidation (IDF: 0.109 Lot C; 0.122 Lot A), (FOX: 0.131 MeqO₂/kg Lot C; 0.140 MeqO₂/kg Lot A). The incidence of individual carcass defects sufficient to cause downgrading or rejection, both in Lot C and Lot A, was generally low. In a multidisciplinary approach, to assess animal welfare and quality poultry meat, additional and feasible parameters should be implemented. Monitoring of pH, muscle glycogen reserve and superoxide free radical production measurements might be markers easier to use, routinely, in practice at abattoir. Further studies are needed to evaluate the usefulness of these parameters.

Study on the effects of electrical stunning parameters for broilers on biochemical and histological markers of stress and meat quality

This study was designed to investigate physicochemical (pH, peroxides) and histological parameters (glycogen reserve, muscle damages), as pre-slaughter stress markers and quality meat evaluators. Ross commercial broilers was processed, either without stunning (NS Lot), or by combining two current levels of 200 mA, 67 V (HV Lot), and 200 mA, 53 V (MV Lot); with two frequencies of 1000 Hz and 800 Hz, using sinusoidal alternating current. The use of high frequency (800 and 1000 Hz) induced the fastest pH decline, already at 3 h postmortem, in Pectoralis major and Quadriceps femoris of MV and HV Lot carcasses (P < 0.05). Moreover HV carcasses showed a lesser production of superoxide free radicals than the NS Lot and MV Lot carcasses (P < 0.05). Changes in the glycogen reserve and the histological muscle damages did not show significant differences in the analysed Lots. The incidence of individual carcass defects, sufficient to cause downgrading or rejection was generally low in each Lot. To assess animal welfare and quality poultry meat the pH monitoring and measurement of superoxide radical production, as additional and feasible parameters, might be markers easier to use in practice at abattoir.

A note on protein expression changes in chicken breast muscle in response to time in transit before slaughtering

Aims of the research were to devise a proteome map of the chicken Pectoralis superficialis muscle, as resolved by two-dimensional gel electrophoresis, and to characterize protein expression changes in the soluble protein fraction in commercial conditions due to age and to time in transit before slaughtering. Broilers were reared under commercial conditions until they reached a mean 1.8 kg and 36 d, or 2.6 kg and 46 d of age. Transport to the slaughterhouse took 90 or 220 minutes. Transport-induced stress was assessed from blood metabolites and leukocyte cell counts, revealing significant changes in albumin, glucose and triglyceride concentrations, in heterophils and leukocyte counts for chickens in transit for longer, and in glucose depending mainly on age. The sarcoplasmic protein fractions were extracted from a total of 39 breast muscle samples, collected 15 min post mortem, for analysis by two-dimensional electrophoresis.

Image and statistical analyses enabled us to study the qualitative and quantitative differences between the samples. Twelve up- or down-regulated protein spots were detected (P < 0.05): 8 related to the age effect, 2 to time in transit, and 2 to the interaction between the two. Age and time in transit influenced the avian proteome regulating the biological processes linked to the cellular housekeeping functions, related mainly to metabolism, cell division and control of apoptosis. Principal component analysis clustering was used to assess differences between birds. Age difference discriminated between the chickens analyzed better than time in transit, which seemed to have less general impact on the proteome fraction considered here.

Isolating and identifying the proteins whose expression changes in response to transport duration and age shed some light on the biological mechanisms underlying growth and stress-related metabolism in chickens. Our results, combined with a further characterization of the chicken proteome associated with commercial chicken slaughtering management, will hopefully inspire alternative strategies and policies, and action to reduce the impact of stress related to time in transit.

Blood corticosterone levels in growing geese around feather gathering

Feather production is realised by gathering feathers from geese right as they start their natural moulting. The adequate gathering time coincides with the time of moulting. There is still scarce information as to whether or not gathering causes distress and pain to geese. A series of experiments was carried out by our research group to determine the effect of gathering on plasma corticosterone level in growing geese. In the present experiment, the reactions of five groups (two gathered and three not gathered groups) of 9-week-old Babat Hungarian Upgraded geese were compared regarding gathering. Blood samples were taken right before, during and 5 min, 1 and 3 h after gathering into heparinised tubes from all groups. The plasma concentration of corticosterone was determined by radioimmunoassay (RIA). The results show that the plasma concentration of corticosterone is high in the first sample of all groups but is significantly lower at subsequent blood samplings compared to the first samples, especially in gathered geese. Compared to the first sampling, we observed higher corticosterone levels in samples collected 1 and 3 h after gathering. This was true only for groups which were not gathered, especially for the group which was not given any antistress material. From these results it can be concluded that the handling of geese causes an elevation in plasma corticosterone level and that feather gathering does not result in a higher corticosterone level than the handling or catching of the bird. Therefore, it can be concluded that feather gathering - especially when it is done adequately in time - does not cause more distress than the handling or catching of the bird.

Time course changes in selected biochemical indices of broilers in response to pretransport handling

Two experiments were conducted to assess the stress response of broilers to catching and pretransport handling followed by different periods of crating. The short-term changes in selected biochemical indices were monitored at 1-min intervals within 10 min of crating after the catching and handling of broilers (experiment 1). These indices were further monitored at 15-min intervals for 2 h of crating after the catching and handling of broilers (experiment 2). Increased (P < 0.001) corticosterone concentrations were observed immediately after the broilers were caught, handled, and placed in crates. They continued to increase until 7 min after crating and then slowly decreased, but even at 120 min after handling, corticosterone concentrations were higher (P < 0.001) in crated broilers than in control broilers. In addition, lactate concentrations increased (P < 0.001) immediately in comparison with those of broilers with no additional handling except for catching and blood sampling, but 15 min later, the lactate concentrations had decreased to the precrating level. Lactate dehydrogenase concentrations increased (P = 0.042) 30 min after crating and continued to increase for the rest of the monitored period. A decreased level of cholesterol (P = 0.017) and increased concentration of uric acid (P = 0.041) were found 1 min after crating. The decrease in cholesterol was visible up to 9 min after crating; it then returned to its original value except for the period from 75 to 90 min after crating, when a decrease (P < 0.05) was again detected. Higher (P < 0.01) concentrations of uric acid were found continuously from 4 to 75 min after crating. Glucose concentrations were increased (P = 0.017) 2 min after crating, but the stress-induced increase was not consistent over the course of the next few minutes after crating. Glucose concentrations were not different from those of control broilers from 10 to 120 min after crating, although they showed a decreasing pattern. A decrease (P = 0.031) in triglyceride concentrations was detected 75 min after crating.

Functional genomics of the muscle response to restraint and transport in chickens

In the present study, we used global approaches (proteomics, transcriptomics, and metabolomics) to assess the molecular basis of the muscle response to stress in chickens. A restraint test, combined with transport for 2 h (RT test) was chosen as the potentially stressful situation. Chickens (6 wk old) were either nontreated (control chickens) or submitted to the RT test (treated chickens). The RT test induced a 6-fold increase in corticosterone concentrations, suggesting hypothalamic-pituitary-adrenal axis activation. The RT test decreased the relative abundance of several hexose phosphates [glucose-1-P (G1P), glucose-6-P (G6P), fructose-6-P (F6P), and mannose-6-P (M6P)] in thigh muscle. In addition, 55 transcripts, among which 39 corresponded to unique annotated genes, were significantly up- (12 genes) or downregulated (27 genes) by treatment. Similarly, 45 proteic spots, among which 29 corresponded to unique annotated proteins, were overexpressed (11 proteins), underexpressed (14 proteins), or only expressed in treated chickens. Integrative analysis of differentially expressed genes and proteins showed that most transcripts and proteins belong to 2 networks whose genes were mainly related with cytoskeleton structure or carbohydrate metabolism. Whereas the decrease in energetic metabolites suggested an activation of glycogenolysis and glycolysis in response to the RT test, the reduced expression of genes and proteins involved in these pathways suggested the opposite. We hypothesized that the prolonged RT test resulted in a repression of glycogenolysis and glycolysis in thigh muscle of chickens. The down-expression of genes and proteins involved in the formation of fiber stress after the RT test suggests a reinforcement of myofibrils in response to stress.

Changes in muscle cell cation regulation and meat quality traits are associated with genetic selection for high body weight and meat yield in broiler chickens

Between-breed genetic variation for muscle and meat quality traits was determined at eight weeks of age in 34 lines of purebred commercial broiler and layer lines and traditional breeds (categories) of chickens. Between-breed genetic variation for plasma ion concentrations and element concentration in muscle dry matter and ash were determined. Plasma from broilers had higher concentrations of Na⁺, K⁺, Mg⁺⁺, total and free Ca⁺⁺ and lower free:total Ca⁺⁺ than plasma from layer and traditional lines. Muscle from broilers contained more Na and higher concentrations of K, Mg and Ca per mg of ash but not of dry matter compared with layer and traditional lines. In comparison with layer and traditional lines, broiler genotypes were over three times heavier, their plasma creatine kinase activity (CK), a marker of muscle tissue damage, was higher, their breast muscle colour was lighter (L*) and less red (a*) and yellow (b*) in appearance, the initial and final pH of their muscles were lower, the pH change was higher and their breast muscle was more tender. Thus, genetic selection for broiler traits has markedly altered cation regulation in muscle cells and may be associated with changes in muscle cell function and the development of pathology and meat quality problems.

The Effect of Feed Withdrawal and Crating Density in Transit on Metabolism and Meat Quality of Broilers at Slaughter Weight

Commercial broilers are exposed to a number of stressors prior to slaughter, including feed deprivation, crating density (high vs. low), and transportation. Hence, the individual and additive or overruling effects of these stressors on welfare and energy metabolism were examined. Live weight gain, rectal temperature, physiological responses, and meat quality of broilers were determined. The fasting of broilers before being transported resulted in a decrease of triglycerides, uric acid, and triiodothyronine concentrations, indicating a negative energy balance. Feed withdrawal was also associated with a reduction in body weight, and highest body weight losses were observed after being fasted for 13 h. For some parameters there was a combined effect of feed withdrawal and crating density, whereas for others the crating density overruled the effect of previous feed withdrawal: broilers that had no access to feed before being transported had higher thyroxine and lower lactate concentrations (only at high crating density) compared with their fed counterparts before the transport process, indicating the combined effect of both actions. The distinction due to the feeding pattern could no longer be observed for the plasma uric acid, nonesterified fatty acids, triglycerides, and triiodothyronine concentrations because it was overruled by the transport effect, especially if broilers were transported at high crating density. Plasma corticosterone concentrations increased as a consequence of the procedure of transportation and peaked if broilers were crated at high density. In our study, no significant effect of preslaughter stressors on meat quality, plasma creatine kinase activity, or lipid peroxidation levels were noticed. It can be concluded that transportation at high stocking densities should be avoided to reduce economic losses and stress to broilers. Plasma hormone as well as metabolites, rectal temperature, and heat shock protein 70 mRNA all indicated the high stress level of broilers. Furthermore, this effect often overruled the feed withdrawal and transport effect, indicating the importance of crating density.

Stress in Broilers Resulting from Shackling

The aim of this study was to assess stress response of broilers to different periods of shackling. Stress effects of shackling were monitored in a group of male Ross 308 broilers (total number: 400) aged 42 d. Three shackling treatments were used in our experiment: shackling of broilers for 30 s (group T30), 60 s (group T60), and 120 s (group T120). Corticosterone plasma concentration was elevated in T60 broilers (P<0.05) and in T120 birds (P<0.01); glucose plasma concentration was increased (P<0.05) in both T60 and T120 broilers when compared with nonshackled control. Lactate concentrations increased in T30 birds (P<0.05) and in both T60 and T120 birds (P<0.01). Furthermore, T120 broilers exhibited an increase (P<0.01) in heterophil counts and heterophil:lymphocyte ratio. Duration of tonic immobility was increased (P<0.05) in T60 and T120 broilers. Number of attempts to induce tonic immobility decreased (P<0.01) in all test groups (T30, T60, T120). Duration of shackling period was positively correlated (P<0.001) with corticosterone, glucose and lactate level, tonic immobility duration, and heterophil:lymphocyte ratio. The number of inductions was negatively correlated (P<0.001) with duration of the shackling period. According to the results of our study, the act of shackling is a considerable traumatic procedure for broilers, and its stress effect is markedly dependent on duration of shackling period that the broiler chickens experience. It follows from our study that the optimal shackling period should be less than 60 s.

Effects of Diet and Stress Mimicked by Corticosterone Administration on Early Postmortem Muscle Metabolism of Broiler Chickens

Three experiments were conducted to evaluate the effects of preslaughter physiological states mimicked by long- or short-term administration of corticosterone (CORT) and dietary energy sources on muscle glycogen contents and meat quality of broiler chickens. In experiment 1, the broilers were fed a high lipid diet (LD) or a normal diet (ND) that differed in carbohydrate (3.8%) and lipid (2.5%) contents from 21 d of age. From 28 d of age onwards, 50% of the chickens in each dietary treatment were subjected to CORT treatment (30 mg/kg of diet). At 7 and 11 d after CORT supplementation, musculus pectoralis major was sampled before and immediately after slaughter and analyzed for glycogen, pH, and R-value. In experiment 2, broilers, fed with the LD or ND diet from 21 d of age were subjected to 1 single s.c. injection of CORT (4 mg/kg of BW) for 3 h to mimicked acute stress at 46 d of age. In experiment 3, broiler chickens were supplied with water supplemented with glucose (30 g/L) for 1 wk before slaughter and were then subjected to the same CORT treatment as experiment 2. Blood and muscle samples were respectively obtained before and immediately after slaughter and analyzed for plasma glucose, urate and lactic acid, and muscle variables. Plasma concentrations of glucose and urate were significantly increased by acute CORT administration, whereas the lactic acid was not changed. Neither dietary energy source nor water glucose supplementation had any influence on the plasma variables. Dietary energy source or water glucose supplementation could not alter glycogen stores in musculus pectoralis major. Breast muscle glycogen stores were increased by stress mimicked by long-term CORT administration rather than by acute treatment. Preslaughter stress reactions had no relation to the depletion of breast muscle glycogen during the initial postmortem period. The initial breast muscle pH was significantly decreased by long-term CORT administration. The result suggests that short-term upregulation of circulating CORT is not involved in the elevated drip loss induced by preslaughter stress.

Behavioural and physiological responses of three chicken breeds to pre-slaughter shackling and acute heat stress

1. The aim of this study was to compare the behavioural and physiological responses to hanging and acute heat stress in three different chicken breeds. Chicks were obtained from a slow-growing French 'Label Rouge' line (SGL), a fast-growing standard line (FGL) and a heavy line (HL). The SGL, FGL and HL birds were slaughtered at their respective market ages of 12, 6 and 6 weeks, in an attempt to achieve similar body weights. Before stunning, birds were either shackled by their legs on the moving line for 2 min (shackling stress: SH) or placed in a room at 35 degrees C and 60% of humidity for 3.5 h and then shackled for 2 min (acute heat stress plus shackling: H + SH) or subjected to minimal stress by shackling for 10 s before stunning (control group: C). 2. Bird physiological responses to the three pre-slaughter treatments were estimated by measuring blood corticosterone, glycaemia, creatine kinase activity, acid-base status and electrolyte concentration as well as lactate content and glycolytic potential in the breast (Pectoralis major) and thigh (Ilio tibialis) muscles. Behavioural responses to shackling stress were evaluated by measuring wing flapping duration, straightening up attempts and vocalisations. 3. Blood corticosterone was higher in SH and H+SH groups than in the C group, regardless of genotype. The struggling activity on the shackle line differed among chicken breeds. It was more intense and occurred more rapidly after hanging in the SGL birds than in both other breeds. Furthermore, SGL struggling activity was not affected by hanging duration while it increased with hanging duration in FGL and HL birds. 4. Wing flapping duration was negatively correlated with blood pH, bicarbonate concentration and positively correlated with breast muscle lactate content, indicating that struggling stimulated antemortem glycolysis activity in breast muscle. Acute heat stress affected blood Ca2+ and Na+ concentration and increased glycaemia and glycolytic potential of thigh muscle. 5. Both acute heat stress and shackling before slaughter were experienced as stressful events by all types of birds.

Comparison of bruises and mortality, stress parameters, and meat quality in manually and mechanically caught broilers

A field trial was conducted to compare manual catching of broilers with a mechanical catching method. Both methods were compared with respect to the incidence of bruises and dead on arrival, stress parameters, and meat quality. Also the dynamics of corticosterone, glucose, and lactate were investigated on the day broilers were killed. The broilers originated from 8 commercial broiler farms; visits were made on the day of catching during spring and autumn of 2001. Broilers of one house were caught manually, and those of the second house were caught mechanically. Plasma samples were taken before catching started, 30 min after the start of catching, 30 min before the end of catching, and at exsanguination of broilers from the first- and last-loaded transport vehicles. Postmortem measurements of pH, temperature, and water-holding capacity were made. Mechanical catching was associated with higher DOA percentages than manual catching in spring, although the difference was not significant in autumn. Catching method did not influence the percentage of bruises or meat quality. Moreover, corticosterone levels indicated that both methods induced the same amount of stress. The dynamics of corticosterone, glucose, and lactate levels showed a similar pattern. Plasma levels increased at the start of catching, and they further increased during transport, shackling, and stunning. However during catching itself, no large changes were observed. Our findings indicated that attempts to reduce stress in broilers during the last day of life could better be focused on factors other than catching.

Variation of chicken technological meat quality in relation to genotype and preslaughter stress conditions

The present study was aimed at estimating the genetic variability between lines of breast and thigh meat quality (pH decline, color, drip loss, and curing-cooking yield) by comparing a slow-growing French label-type line (SGL) and a fast-growing standard line (FGL) of chickens exposed to different preslaughter stress conditions. The birds were slaughtered under optimal conditions or after exposure to 2 h of transport or acute-heat stress (2 h at 35 degrees C). Relationships between meat quality and stress sensitivity were investigated by measuring struggle during shackling and tonic immobility (TI) duration, 1 wk before slaughter, as an indicator of the basal level of fear of the birds. Although most of the meat quality indicators varied between the 2 lines, differences were muscle dependent. In concordance with a lower ultimate pH, curing-cooking yield of thigh meat was decreased for the FGL birds. In contrast, these birds had a higher curing-cooking yield and a lower drip loss of breast meat resulting from a less rapid pH decline in this muscle compared with SGL birds. Thigh meat characteristics were influenced by both preslaughter stresses, but no significant effects were detected for breast meat. The main effect of heat stress in thigh meat was a decrease of the ultimate pH and led to paler color and lower curing-cooking yield; opposite effects were obtained for transport. Breast meat was much more sensitive to physical activity of birds on the shackle line. Longer durations of wing flapping on the shackle line gave more rapid initial pH decline. Whatever the line, no relationship between TI duration and meat quality characteristics or activity was observed. The present study suggested that SGL birds could be at disadvantage due to more struggle during shackling and accelerated postmortem glycolysis, which is detrimental to the quality of breast meat.

Effects of feed deprivation and transport on preslaughter blood metabolites, early postmortem muscle metabolites, and meat quality

In practice, poultry have their feed with drawn several hours before being collected and put on transport to the slaughter plant. With the exhaustion of their internal energy stores, the chickens may lack energy to cope with the conditions to which they are subjected. Meat quality is affected by the energy stored in the muscle at time of slaughter and its rate of decrease postmortem. Of 320 broiler chickens, half were subjected to 5 h feed deprivation whereas the others had access to feed until transport. In both groups, half the chickens were transported for 1.5 h, and the rest were transported within 5 min to the on-site slaughter facility. Twenty chickens were equipped with an ultrafiltration-collection device for monitoring glucose and lactate profiles. After slaughter, liver pH was measured. Stimulation of muscle metabolism was minimized by avoiding plucking. Breast muscle samples were taken at 0, 1, 2, 4, and 6 h and analyzed for pH and metabolite concentrations, and meat quality was measured at 96 h. Although liver glycogen was depleted in feed-deprived chickens, feed deprivation and transport for short periods were not found to affect blood glucose or lactate levels nor glycogen levels in the muscle at slaughter. Muscle carbohydrate metabolism was found to come to a complete halt after 6 h, which was not caused by exhaustion of the glycogen store but by the muscle's ability to generate adenosine triphosphate (ATP) after 4 h. At this time, rigor mortis had set in and deboning could be done without risk of cold shortening.