Comparing methods for catching and crating broiler chicken flocks: A trade-off between animal welfare, ergonomics and economics

Abstract

Catching, carrying, and loading of broilers before transport to the slaughterhouse causes stress. In this study three catching methods (two manual (inverted, upright) and one mechanical) were compared using a cost-benefit analysis of animal welfare, ergonomics and economic analysis. Depopulation of approximately 5,000 broilers per catching method per flock (upright vs. inverted vs. mechanical: n=3; upright vs. inverted: n=9; inverted vs. mechanical: n=3 flocks) was analyzed on 15 commercial farms. Economic considerations (person-hours per 1,000 chickens), ergonomics (catcher survey, ergonomic assessment of simulated catching), and animal welfare on-farm (wing flapping frequency, catcher-bird interaction) and at the slaughterhouse (catch damage and DOA prevalence) were considered. Wing flapping frequency was lower (2.0 ± 0.1 vs. 5.4 ± 0.1, P < 0.001), and catcher-bird interaction was better (3.7 ± 0.2 vs. 4.4 ± 0.2, P < 0.01) for upright catching compared to inverted catching based on a 7-point Likert scale. Prevalence of catch damage was lower for upright versus mechanical catching (15.5 ± 1.3% vs. 17.7 ± 1.4%, P = 0.046). More person-hours per 1,000 broilers were required for upright versus inverted (1.6 ± 0.1 h vs. 1.0 ± 0.1 h) and mechanical catching (0.6 ± 0.3 h) (P < 0.001). Upright catching was 1.5 and 1.2 times more expensive than inverted and mechanical catching based on 20,000 broilers. Compared to inverted catching, fair compensation would increase by €0.012 (upright) and €0.006 (mechanical) per kg of live weight. An ergonomics expert rated manual catching as very demanding, but catchers (n = 16) disliked upright catching (more labor-intensive). This study revealed animal welfare benefits of upright versus inverted (less wing flapping, better catcher-bird interaction) and mechanical catching (less catch damage), whereas mechanical catching provided the best labor conditions. Widespread application of upright catching would require testing of entire flocks and collaboration with the poultry sector to determine fair compensation, improve labor conditions and identify strategies to minimize catch and load duration.

Introduction

The phase before broiler chickens are transported to the slaughterhouse is critical for bird welfare and farmer income. How the chickens are caught and crated (“depopulated”) from the poultry house and subsequently loaded onto transportation vehicles can result in stress, injury and death of broilers. Different depopulation methods can influence both farm economics and animal welfare (Dulal, 2017; Cockram et al., 2020). Inverted catching is the most common method applied worldwide. The chickens are caught by one or both legs, carried upside down and placed in crates within transport containers that are subsequently loaded onto trucks (Nielsen et al., 2022). Importantly, catching chickens by the legs does not conform to Regulation 1/2005 in the EU. Upright catching, where one or two birds are caught and carried upright with the hands supporting the breast and covering the wings, has therefore been proposed as an alternative manual depopulation method (Eilers et al., 2009; Kittelsen et al., 2018). Mechanical catching has also been introduced in response to animal welfare concerns. This approach is mainly popular in regions (e.g., Finland) where laborers are expensive and hard to find, as manual depopulation is tiring, often leads to back pain, and is performed under poor labor conditions (Lacy and Czarick, 1998; Nijdam et al., 2004; de Lima et al., 2019). Whether one or more depopulation methods — mechanical, upright, and inverted — is encouraged or discouraged may depend greatly on the balance between potentially conflicting concerns such as animal welfare, the working conditions of the catchers (ergonomics), and farmer income (economics).

Inverted catching has been criticized from an animal welfare perspective (Nielsen et al., 2022). The noted differences in animal welfare consequences depend, however, on whether the birds are caught and carried by one leg or both legs. Catching chickens by both legs has been shown to take longer, and the chickens flap their wings more compared to one-leg catching (Langkabel et al., 2015). However, catching by one leg can increase the risk of hip dislocation and can also lead to more frequent and severe hemorrhaging in the thigh (Wilson and Brunson, 1968; Langkabel et al., 2015; Dutra et al., 2021). For these reasons, catching broiler chickens by both legs while supporting the body has been recommended (Belplume; Nielsen et al., 2022; Committee and House, 2023). However, according to surveyed Flemish broiler chicken farmers, broilers are usually caught by one leg instead of two legs (Delanglez et al., 2024a). In either case, inverted catching exerts intestinal pressure on the respiratory system and heart and can result in respiratory distress, wing flapping, struggling, stress, and a higher incidence of wing fractures (Hoorweg et al., 2024). Catching and holding the birds in an upright position has therefore been argued as preferable from an animal welfare perspective (Nielsen et al., 2022). Mechanical catching, in contrast, limits the direct contact between humans and animals (Scott and Moran, 1993; Lacy and Czarick, 1998). There are two types of mechanical catching: forced and unforced catching. In forced catching, the chickens are grasped and collected by rotating mechanisms equipped with soft, rubber-like components. Unforced catching is more gentle and uses a conveyor-belt type system to transport them upright and without physical force (Nijdam et al., 2005; Wolff et al., 2019). The different mechanical systems do not ultimately result in any major differences in the incidence of leg, breast, and wing injuries, according to (Nijdam et al., 2005). Forced mechanical catching, however, led to a faster return to normal heart rate and a shorter duration of tonic immobility (indicating less fear) than inverted catching (Duncan et al., 1986). The risk of injuring chickens with mechanical compared to manual catching remains unclear. Some studies indicate fewer injuries for mechanical catching compared to inverted catching (Knierim and Gocke, 2003; Nijdam et al., 2005; Hassan and Lashin, 2017), while others such as Ekstrand (1998), Musilová et al. (2013), Mönch et al. (2020), and Hoorweg et al. (2024) report more injuries for mechanical compared to inverted catching. Furthermore, the level of experience of the catching team in operating the catching machine is believed to affect both the risk of injuries and the severity of handling stress in mechanically caught birds (Nielsen et al., 2022). Many studies have reported that the prevalence of dead-on-arrivals at slaughterhouses (DOAs) is higher for mechanical compared with manual catching (Nijdam et al., 2005; Chauvin et al., 2011; Mönch et al., 2020).

Catcher well-being is also an important concern when comparing depopulation methods. Catching broiler chickens is generally carried out in a dusty, dirty, and dark environment, all of which negatively impact catcher well-being. The repetitive movements of catching can result in fatigue, pain and injury (Punnett and Wegman, 2004; van Rijn et al., 2010; Mora et al., 2016). Repetitive tasks, heavy lifting, insufficient recovery time, and rapid work pace can also lead to upper-body musculoskeletal injuries that in turn can negatively affect the handling of broiler chickens (Alencar et al., 2010; de Lima et al., 2019) and result in broiler mortality and trauma, such as hemorrhages, bruises and fractures (Nijdam et al., 2004; Caffrey et al., 2017). Improved work conditions can influence the catchers’ productivity and result in a reduction of stress and injuries of the broiler chickens, which can lead to fewer carcass rejections and problems with meat quality, thus minimizing economic losses (Queiroz et al., 2015; Dulal, 2017). Some studies have reported that catchers find upright catching more tiring than inverted catching because it takes longer to depopulate a flock (Leandro et al., 2001; Kittelsen et al., 2018; Delanglez et al., 2024b).

In a free and competitive market, a comparison of depopulation methods must also examine related economic aspects (DOAs, carcass rejections, professional or non-professional catching team, depreciation, maintenance, and transportation of the catching machine). Upright catching is more expensive than inverted catching because it takes longer for a catcher to catch and crate a given number of chickens (Leandro et al., 2001; Kittelsen et al., 2018; Delanglez et al., 2024b). To the best of our knowledge the price differential for broiler chickens has not been reported in scientific literature. Labor costs are lower (up to 60%) for machine vs. manual catching (Thornton, 1994). It has been estimated that the catching machine replaces four catchers, resulting in a team of four catchers instead of eight, depending on the size of the broiler house (Duncan et al., 1986; Gerritzen et al., 2022). Hassan and Lashin (2017) reported a decrease in production cost of -€1.02 per ton broilers for mechanical catching (CIEMME Super Apollo L.) compared to inverted catching.

While some studies have compared inverted versus upright catching and inverted versus mechanical catching of broiler chickens, studies comparing all three methods (inverted, upright, and mechanical catching) are severely limited. Most studies focus on animal welfare and neglect differences in labor conditions (specifically ergonomics) or economic differences. In contrast, in the present study animal welfare, catcher ergonomics and financial considerations between all three depopulation methods (inverted, upright, and mechanical catching) were compared. Three objectives were identified: 1) to compare upright (U), inverted (I), and unforced mechanical (M) catching of broiler chickens on commercial farms for parameters related to animal welfare, efficiency, costs, and the perceptions of the catchers; 2) to simulate and video-record the upright and inverted catching of broilers in an experimental setting, followed by an expert ergonomic assessment of the physical strain of both methods; and 3) to conduct a comprehensive cost-benefit analysis of the three catching methods based on on-farm and slaughterhouse observations as well as simulated scenarios.

Materials and methods

Field study on commercial farms

The study was conducted on 15 broiler chicken flocks at different commercial farms in the region of Flanders (Belgium) between September 2022 and April 2024. As part of the study design, the farmer, catching team, transport company, and slaughterhouse all agreed that in addition to the originally planned method of depopulation (i.e. the ‘default’ method), one or two ‘additional’ methods would be employed. For inverted and mechanical depopulation, the catching teams were instructed to proceed as they normally would, with no additional guidance other than when to switch to the next depopulation method. If the alternative method included upright manual catching, the catching team was first given a brief demonstration and instruction using a graphical poster (Fig. 1) because the catching teams had no or very little prior experience with upright catching. The common method of inverted catching was to grasp one leg per broiler chicken and carry three broiler chickens upside down in each hand; for mechanical catching the unforced approach (Apollo Generation 2 harvester, CMC Industries, Italy) was used.

Fig. 1.

Poster including guidelines for catching broiler chickens upright.

In total, three flocks were depopulated using the inverted (default) and mechanical method, nine flocks were depopulated using the inverted (default) and upright method, and three flocks were depopulated using all three methods, with approximately 5,000 broiler chickens per catching method (Table 1). The average slaughter age was 41.7 + 1.2 days. All birds were the same breed (Ross 308). Two local professional catching companies were involved in the study and received financial compensation from the research project for the upright depopulation of broilers with at least 5,000 broilers (n = 5,200 to 7,040; Table 1). The original aim was to randomize the order of application of the different depopulation methods; however, this was not always possible due to logistical constraints and objections from the catching teams (Table 1). Two types of transport systems were used, namely unrestrained plastic drawers (n = 6 flocks) (Kettlewell & Turner, 1985) or Stork ATLAS (Advanced Technology Live bird Arrival System) (Marel®) containers (n = 9 flocks) (Table 1). For mechanical catching, only the Stork ATLAS container was used as this type of container is most commonly used for mechanical catching in Belgium.

Table 1.

General information about the participating broiler chicken farms: the number (#) of broiler chickens per stable, the number (#) of broiler chickens caught inverted (I), upright (U), and mechanical (M), the order of the catching method, the number (#) of individual scored broiler chickens for inverted and upright catching on-farm, the transport system used (Stork Atlas (S) or Unrestrained plastic drawers (P)), and the number (#) of scored broiler chickens for inverted, upright and mechanical catching in the slaughterhouse in Flanders, Belgium (A, B, C, and D).

Farm	# broilers/stable	# broilers I	# broilers U	# broilers M	Order	# scored broilers (on-farm)	Transport system	# scored broiler (slaughterhouse)
1	16,988	5480	5480	6028	I-M-U	I: 75|U: 155	S	I: 3668|U: 3713| M:4050 (A)
2	32,000	5016	3648	/	U-I	I: 94| U: 90	P	I: 3300|U: 3850 (B)
3	33,000	5472	5472	/	U-I	I: 94|U: 218	P	I & U: 3300 (B)
4	32,000	5016	3648	/	I-U	I: 87|U: 118	P	I: 3850|U: 3300 (B)
5	33,000	5400	5400	/	U-I	I: 46|U: 85	P	I: 4110|U: 4007 (C)
6	33,000	5400	5400	/	I-U	I: 46|U: 89	P	I & U: 4110 (C)
7	13,740	6600	6600	/	U-I	I: 57|U: 71	S	I & U: 4050 (A)
8	20,535	6600	6600	6600	I-M-U	I 40|U: 67	S	I & M & U: 4050 (A)
9	30,000	6840	5700	/	I-U	I: 81|U: 115	S	I: 4082|U: 4050 (A)
10	20,500	5200	5200	5200	U-I-M	I: 69|U: 126	S	I: 3542 & M: 4110|U: 3921 (A)
11	38,000	5200	5200	/	U-I	I: 43|U: 56	S	I & U: 4410 (A)
12	39,000	7040	7040	/	U-I	I: 43|U: 77	P	I & U: 3180 (D)
13	20,535	7080	/	6933	M-I	/	S	I: 5528|M: 5669 (A)
14	15,000	6720	/	6720	M-I	/	S	I & M: 4795 (A)
15	16,000	6240	/	6240	M-I	/	S	I & M: 4795 (A)

Monitoring and measurement by the research team took place both at the farm during depopulation (see Animal Welfare On-farm During Depopulation, below) and at the slaughterhouse (see Animal Welfare of Depopulation Methods at the Slaughterhouse, below) that received the flocks. To the extent possible, the number of birds monitored per method was similar per flock (Table 1). Arrangements (researchers marking the containers with a specific color per catching method and grouping the containers per color on the truck and in the slaughterhouse) were made with the transporter and the slaughterhouse to identify the catching method of each depopulated flock, enabling data collection per depopulation method.

Animal Welfare On-farm During Depopulation A trained team of researchers conducted on-farm observations and measurements on marked batches of birds that had been depopulated using different methods (Table 1). For each catching method, the entire process of catching and crating the experimental group was scored for noise, chicken behavior, and crating efficiency (scale from 1 to 7, with 1 being the best score and 7 the worst, as described in Delanglez et al., 2024). Additionally, the number of broiler body parts entrapped per container was recorded, along with the time taken to fill the containers.

Specifically for inverted and upright catching, individual broiler chickens (Table 1) were randomly tracked from catching to crating to evaluate (manually counted via the filled-in scoring system described in Delanglez et al. (2024)): 1) the wing flapping frequency (scale from 1 to 7, with 1 the best score and 7 the worst during the time the catcher held the bird), 2) catcher-bird interaction (scale from 1 to 7, with 1 the best score and 7 the worst), 3) whether the catching method was applied incorrectly with a specific description, and 4) whether the broiler slipped out of the catcher's hand.

Animal Welfare of Depopulation Methods at the Slaughterhouse For the animal welfare measurements in the slaughterhouse, the same groups of chickens for inverted, upright, and mechanical catching (Table 1) were observed in four slaughterhouses in Flanders (nine flocks in slaughterhouse A with CO₂ stunning, three flocks in slaughterhouse B with CO₂ stunning, two flocks in slaughterhouse C with electrical stunning, and one flock in slaughterhouse D with electrical stunning). The average transportation time to the slaughterhouse was 74 ± 22 minutes (range 36 – 120 min). DOAs were collected at the slaughterhouse per catching method. Necropsies on all DOA broilers were performed by a certified pathologist (blinded to the catching method) to evaluate whether the cause of death was related to the catching, crating, and loading process or if it was attributed to an underlying pathology that may imply that the animal was unfit for transport. In the evisceration zone, three observers counted the number of bruises and fractures. Observers 1, 2 and 3 focused on the wings, legs, and wing tip and breast, respectively. Only fresh bruises (≥ 1 cm, with red discoloration, without yellow or green discoloration) and fresh fractures (with or without protruding bone, accompanied by redness/blueness; a bruise combined with a fracture was only counted as a fracture) were taken into account to exclude injuries sustained before the catching, crating, and loading process. Postmortem fractures as a result of handling in the slaughterhouse (e.g. plucking machine) were excluded. These were recognized by the absence of bleeding or bruising. Multiple injuries of the same type (bruises or fractures) per body part (legs, breast, wings, and wing tips) were counted as one injury.

The assessments were conducted during six scoring sessions per experimental group per flock. Each scoring session lasted for 3 minutes followed by a 30 sec pause. The average line speed was 204 broiler chickens per minute (range 177 – 228 broiler chickens per minute). The number of broiler chickens scored is shown in Table 1.

The prevalence of different types of injuries per body part was calculated using the following formula (Jacobs et al., 2017):

$$Prevalance=\frac{\text{Number}\text{of}\text{animals}\text{with}\text{at}\text{least}1\text{injury}\text{on}\mathrm{a}\text{specific}\text{body}\text{part}}{\text{Line}\text{speed}*\text{Number}\text{of}\text{observed}\text{minutes}}*100$$

Economic Analysis The costs of different catching methods, i.e., labor costs, costs of loader (forklift), truck loading costs, and the duration of catching 1,000 broiler chickens (person-hours) based on the number of caught broilers per catching method and per flock (number of broilers per container multiplied by the number of containers), the number of catchers, and how long it took to catch and crate all batches (start of catching the first chicken until placing the last chicken in the container) were calculated using the following formulas:

$$Totalpersonhours\left(h\right)=Numberofcatchers*totaldurationofthecatchingmethod\left(h\right)$$

$$Totalpersonhoursper1000broilers=\frac{\text{Total}\text{person}-\text{hours}\left(\mathrm{h}\right)}{\text{Number}\text{of}\text{broilers}\text{caught}\text{per}\text{catching}\text{method}\text{per}\text{flock}}*1000$$

Total labor cost per 1000 broilers (€) = Total person-hours for 1000 broilers (h) * standard price (€/h)

To calculate the costs for the forklift and loading the truck, the following formulas were applied:

$$Totaldurationfor1000broilers\left(h\right)=\frac{Totaldurationofthecatchingmethod\left(h\right)}{\text{Number}\text{of}\text{broilers}\text{caught}\text{per}\text{catching}\text{method}\text{per}\text{flock}}*1000$$

Total forklift cost per 1000 broilers (€) = Total duration for 1000 broilers (h) * standard price (€/h)

Standard prices applicable in the Belgian poultry sector at the time of the study were used to calculate the costs of upright and inverted catching (e.g. labor: €40/h/person, forklift: €70/h, and loading of the truck: €80/h). For mechanical catching, various costs were outlined, including a price per chicken (€0.045, with labor costs included), loading of the truck: €80/h, transport costs for the catching machine (€370), and cleaning and lubricating the machine (2.5 h * €40 = €100). The total cost for catching, crating, and loading was calculated for upright catching: labor cost + cost of loader + truck loading costs; inverted catching: labor cost + cost of loader + truck loading costs; and mechanical catching: price per chicken + truck loading costs + transport costs of the catching machine (€370 as fixed cost) + cleaning and lubricating the catching machine (€100 as fixed cost). Ultimately, the additional cost per kg live weight was determined, based on an average poultry flock caught at the prices valid during the study period.

Statistical analysis

For the statistical analysis of the measurements on-farm and in the slaughterhouse, a linear mixed model was used with the catching method as a fixed effect and the farm as a random effect. A batch of animals within a farm with the same catching method was the experimental unit. Averages at the level of experimental unit were calculated for on-farm measurements (duration of catching 1000 chickens, duration of filling the container, evaluation of the catching process, wing flapping frequency, catcher-bird interaction, incorrect application of the method, chicken slips out of the catcher's hands) and averages in the slaughterhouse (bruises on wings, wingtip, breast, and legs, and fractures of wings and legs, DOAs, overall catch damage= the average percentage of chickens with at least one type of catch damage). P-values for the differences between catching methods were based on a type III ANOVA analysis of the model parameters. P-value < 0.05 was assessed as significant. In case of a significant difference between the catching methods, a post hoc pairwise comparison was done with a Tukey correction to correct the P-values for multiple testing. The data was assumed to be normally distributed based on a graphical assessment using a histogram and QQ plot of the residuals and a residual versus fitted plot. All statistical analyses were performed using R version 4.2.1.

Ergonomic analysis

Ergonomics of the Catchers based on Their Opinion On-Farm After completing the catching process, the catchers were asked to complete a written survey on their opinions regarding upright versus inverted catching based on animal and catcher welfare. The survey was presented in Dutch, English, or Polish. Catchers were first asked about physical pain, i.e., whether they had much more/more/similar/less/much less pain in the neck, shoulders, upper back, arms, lower back, and knees when catching upright (non-default) compared to inverted (default) catching. In addition, they were asked to indicate whether upright catching (as compared to inverted catching) was strongly more tiring/more tiring/equally/less tiring/strongly less tiring, and whether the broiler chickens were more restless/restless/equally/calmer/much calmer. Finally, they were asked to score their perceived learning curve for upright catching as very rigid/rigid/equally/smooth/very smooth. In total, 16 of 125 catchers (12.8%) completed the survey.

Ergonomic Assessment of Experimentally Simulated Inverted and Upright Catching The ergonomics of the two manual depopulation methods (inverted and upright) were investigated in an experimental setting.

In the experimental setting (Fig. 2), three test persons (not habitual catchers) were observed while they caught and loaded broilers (weight of each broiler 2.6 kg) using the upright and inverted method. The experimental setting was a test stable with floor housing. Movements of the test persons were recorded using six cameras (front view: camera 1, side view left: cameras 2 and 3, side view right: cameras 4 and 5, and top view for asymmetry: camera 6). All movements were performed in the dark to mimic a realistic setting. Visible markers were placed on the lateral side of the body of the test persons to calculate joint angles, specifically at the malleolus lateralis (ankle), lateral epicondyle of the femur (knee), trochanter major (hip), acromion (shoulder), lateral epicondyle humerus (elbow), and ulna styloid process (wrist) (Fig. 2). Per simulated catching event each test person caught six broiler chickens from the floor using with the inverted method or two broiler chickens using the upright method; this was repeated three times. Catching was performed for three levels of crate heights (Level 1: 53 cm, Level 2: 84 cm, Level 3: 115 cm). Each catcher performed nine actions per catching method (3x catching at 3x crate heights).

Fig. 2.

Position of markers (white spots) on the test person's body to identify the different body parts for analysis.

The certified ergonomist (VG) used several methods to assess physical strain based on the video recordings: the NIOSH method (National Institute of Occupational Safety and Health) (Ashley, 2015), the ART tool (Assessment of Repetitive Tasks) (HSE – ART tool), and the MAC tool (Manual handling assessment charts) (HSE – MAC tool). See Delanglez et al. (2024b) for a detailed description of these methods.

The NIOSH method uses the revised lifting equation (RLE) to determine the recommended weight limit (RWL), using the following formula:

$$Recommendedweightlimit\left(\text{RWL}\right)=23kgxHMxVMxDMxAMxCMxFM$$

with HM: Horizontal multiplier, VM: Vertical multiplier, DM: Distance multiplier, AM: Asymmetric multiplier, FM: Frequency multiplier, and CM: Coupling multiplier (Waters et al., 1993). The ratio of the weight lifted during a lifting movement to the RWL is called the lifting index (LI). The target is LI < 1; LI > 1.5 the movement requires re-evaluation because the movement is potentially dangerous (Waters et al., 1993; Arjmand et al., 2015; Fox et al., 2019).

The ART tool applies to repetitive work and is used for risk analysis (expression of the risk of upper limb overload).

The categories used by the ART tool are:

• -GREEN: Low risk level
• -AMBER: Medium risk level - examine task closely
• -RED: High risk level – prompt action required

The ergonomist examined the recorded videos of the test persons based on the following categories: arm movements (score 0-6), repetition (score 0-6), force on hand (score 0-8), head/neck posture (score 0-2), back posture (score 0-2), arm posture (score 0-2), hand/finger grip (score 0-2), breaks (score 0-8), work pace (score 0-2), other factors (score 0-2), duration (less than 2 hours: *0.5, 2 hours to less than 4 hours: *0.75, 4 hours to 8 hours: *1, more than 8 hours: *1.5) (HSE – ART tool, 2024a). A score was assigned for each category using the above color codes. From this, a total score (sum of different scores) was obtained: a score between 0 - 11 is low risk, 12 - 21 is medium risk, and >22 is high risk.

The MAC tool evaluates the risks of injury due to lifting and carrying.

The categories applied by the MAC tool are:

• -GREEN: Low-risk level - although the risk is low, the exposure levels for vulnerable groups such as pregnant women, disabled people, recently injured, young or inexperienced workers should be considered
• -AMBER: Medium risk - task should be examined carefully
• -RED: High-risk level - prompt action is required, as this may expose a significant portion of the workforce to the risk of injury
• -PURPLE: Unacceptable risk - such actions may pose a serious risk of injury and must be corrected as soon as possible

The ergonomist examined the recorded videos of the test persons based on the following aspects: a load weight/frequency (score 0-10), hand distance from the lower back (score 0-6), vertical lift zones (score 0-3), torso twisting and sideways bending (score 0-2), postural constraints (score 0-3), the grip on the load (score 0-2), floor surface (score 0-2) and environmental factors (score 0-2) (HSE - MAC tool, 2024b). A score was assigned to each aspect using the color codes above. From this, a total score (sum of different scores) was obtained: 0 – 11 represents a low risk, 12 - 21 a medium risk, and >22 a high risk.

Cost-benefit analysis

Costs and benefits were compared between inverted, upright, and mechanical catching based on three main aspects: 1) Animal welfare: wing flapping frequency (I and U), catcher-bird interaction (I and U), evaluation of the catching process for noisiness, chicken behavior, and efficiency, and animal injuries (bruises and fractures), 2) Labor conditions: opinion of the catchers and an expert ergonomist's comparison of the physical strain between I and U, and 3) Economics: time required to catch 1,000 chickens (in person-hours), time needed to fill the container, cost of the use of the forklift, cost of loading the truck. Total costs were calculated per method for catching 20,000 broiler chickens and per kg live weight.

Results

Animal welfare on-farm and at the slaughterhouse of depopulation methods

On-farm observations during depopulation included animal welfare parameters that could be compared between all three catching methods (inverted vs. upright vs. mechanical, Table 2) and parameters specific to the comparison of the two manual catching methods (I vs. U, Table 3). When comparing all three methods (Table 2), the inverted method was given the worst score for the level of noise but a non-significant score (trend) for bird behaviors indicative of resistance and stress. Furthermore, three entrapments were recorded for both inverted catching (one wing, two head) and upright catching (one wing, two head), whereas no entrapments occurred during mechanical catching (no statistical analysis possible because not enough observations). Detailed observations of individual birds during manual depopulation (not possible for the mechanical method) confirmed that the inverted method scored significantly worse than the upright method in terms of animal welfare, specifically in relation to wing flapping (5.39 ± 0.13 vs. 2.02 ± 0.13, P<0.001) and the catcher-bird interaction (4.43 ± 0.17 vs. 3.70 ± 0.17, P<0.01) (Table 3). These detailed observations also revealed that incorrect performance (i.e., not as instructed) occurred significantly more often for the upright method than the inverted method (22.43 ± 12.3% vs. 0.41 ± 0.60%, P<0.001) (Table 3). The most common deviation from the instructions was that the hands were not around the wings (16.7%), followed by holding birds by the wrong body part significantly more than in inverted catching (0% vs. 6.08%, P=0.002). This did not result in a significantly higher prevalence of catch damage (16.6% vs. 15.5%, P = 0.11) or DOAs (0.25% vs. 0.14%, P = 0.18) recorded at the slaughterhouse for inverted vs upright catching (Table 4). The prevalence of catch damage was significantly higher for the mechanical vs. the upright method (17.7% vs. 15.5%, respectively, P = 0.046). The descriptive analysis of necropsies performed on the DOAs of all the flocks revealed that 48% inverted, 32% upright, and 50% mechanically caught broiler chickens had no traumatic lesions but had underlying disease (polyserositis, chronic heart failure with abdominal dropsy, vascular disorders) (Table 4). Traumatic lesions with an underlying disease were observed in 19 inverted (26%), 19 upright (40%), and six mechanically (38%) caught birds. Birds with an underlying disease may be weak and are thus potentially not fit for transport. This may increase their mortality risk during catching, loading and transport. In addition, 19 inverted (26%), 13 upright (28%), and two mechanically (13%) caught DOA broiler chickens showed traumatic lesions without an underlying disease.

Table 2.

Summary of the on-farm assessments after inverted, upright, and mechanical catching of broiler chickens at 15 farms, expressed as mean ± SE, with NA = Not Applicable.

	Inverted	Upright	Mechanical	P-value
Duration of catching 1000 chickens (person-hours performed) (h)	1.01 ± 0.07a	1.64 ± 0.07b	0.56 ± 0.09c	<0.001
Duration filling container (min)	3.06 ± 0.24a	5.97 ± 0.26b	1.56 ± 0.33c	<0.001
Evaluation catching process (1-7) •Noisiness •Chicken behavior •Efficiency	4.70 ± 0.28a 4.60 ± 0.30 3.40 ± 0.21a	3.84 ± 0.30b 3.99 ± 0.32 4.04 ± 0.24a	3.99 ± 0.43ab 3.71 ± 0.48 2.10 ± 0.39b	0.02 0.08 0.002
# entrapments of body parts	3	3	0	NA

Significant P-values (P < 0.05) are indicated in bold and P-values between 0.05 and 0.10 are underlined.

Table 3.

Summary of the on-farm assessment after inverted and upright catching of broiler chickens at 15 farms, expressed as mean ± SE.

	Inverted	Upright	P-value
Wing flapping frequency (1-7)	5.39 ± 0.13	2.02 ± 0.13	<0.001
Catcher-bird interaction (1-7)	4.43 ± 0.17	3.70 ± 0.17	<0.01
Incorrect application method (%) •> 3 chickens per hand •Held by wrong body part •Hands not around the wings •Breast is not supported •Holding 1 chicken correctly & 1 chicken incorrectly	0.41 ± 0.60 0.29 ± 0.11 0 NA NA NA	22.43 ± 12.3 NA 6.08 ± 5.39 16.70 ± 1.50 0 3.59 ± 3.94	<0.001 0.002
Chicken slips out of the catcher's hand (%)	1.00 ± 1.40	0.32 ± 0.60	0.15

Significant P-values (P < 0.05) are indicated in bold.

Table 4.

Summary of the assessments in the slaughterhouse after inverted, upright, and mechanical catching of broiler chickens at 15 farms (except for the necropsies of the DOAs on 12 farms), expressed as mean ± SE, with NA = Not Applicable.

	Inverted	Upright	Mechanical	P-value
Overall catch damage (%)	16.6 ± 1.2ab	15.5 ± 1.3a	17.7 ± 1.4b	0.046
Catch damage (%): Bruise, wing Fracture, wing Bruise, wingtip Bruise, breast Bruise, leg Fracture, leg	6.53 ± 0.70 0.53 ± 0.11 4.45 ± 0.57 2.89 ± 0.71 3.05 ± 0.36 0.03 ± 0.01	5.70 ± 0.73 0.55 ± 0.11 4.39 ± 0.57 2.83 ± 0.72 2.77 ± 0.36 0.03 ± 0.01	7.38 ± 0.88 0.69 ± 0.13 4.53 ± 0.84 3.17 ± 0.80 2.97 ± 0.38 0.01 ± 0.02	0.12 0.31 0.98 0.82 0.14 0.70
DOAs (%)	0.25 ± 0.06	0.14 ± 0.07	0.20 ± 0.09	0.18
Necropsies DOAs (# chickens) No traumatic lesions, underlying disease Traumatic lesions, underlying disease Traumatic lesions, no underlying disease	73 35 19 19	47 15 19 13	16 8 6 2	NA NA NA NA

Significant P-values (P < 0.05) are indicated in bold.

Economic analysis

For 1,000 chickens, upright catching required an additional 0.63 and 1.08 person-hours in comparison to inverted and mechanical catching, respectively. For filling the containers with the same number of chickens, upright catching required an additional 2.91 and 4.41 extra minutes in comparison to inverted and mechanical catching, respectively (Table 2). Again per 1,000 chickens, inverted catching required 0.45 additional person-hours for catching and 1.5 extra minutes for filling the containers in comparison to mechanical catching. This was also reflected in the subjective efficiency scores given by the researchers, where mechanical catching was scored significantly better versus inverted and upright catching (2.10 ± 0.39 vs. 3.40 ± 0.21 vs. 4.04 ± 0.24, respectively). Efficiency scores for the inverted method were always located between the mechanical (most efficient) and upright (least efficient) methods (Table 2). The average labor costs for upright catching of 1,000 chickens were 1.5 times higher than for inverted catching (€67.2 vs. €43.4) (Table 5). Similarly, the cost of forklift use (i.e. cost of loading, see above) was 1.4 times higher for upright catching compared to inverted catching (€12.5 vs. €8.7). Additionally, the cost of loading the truck was 1.4 times higher for upright catching compared to inverted and mechanical catching (€14.3 vs. €10 vs. €10), with no difference in truck loading costs between inverted and mechanical catching (Table 5). As a result, the total additional cost for upright catching compared to inverted and mechanical catching of a flock of 20,000 broiler chickens is €638 and €310, respectively. Expressed per kg live weight, the additional cost was €0.012 and €0.006 for the upright and mechanical methods compared to inverted catching. However, as flock sizes increase, the cost of mechanical catching drops below that of inverted catching: when depopulating a flock of 70,000 chickens mechanical catching is less expensive than inverted catching (€4320 vs. €4347).

Table 5.

The average costs, extra cost, and ratio of labor, forklift, loading the truck, the total cost of catching 1000, 20,000, and one broiler chicken(s), and the price per kg live weight for inverted (I), upright (U), and mechanical (M) catching.

	I (€)	U (€)	M (€)	Extra cost U vs. I (€)	Extra cost U vs. M (€)	Extra cost I vs. M (€)	Ratio U/I	Ratio U/M	Ratio I/M
Labor	43.4	67.2	NA*	23.8	NA	NA	1.5	NA	NA
Forklift	8.7	12.5	NA*	3.8	NA	NA	1.4	NA	NA
Loading truck	10	14.3	10	4.3	4.3	0	1.4	1.4	1
Total cost 1000 broilers⁎⁎	62.1	94	525	31.9	NA	NA	1.5	NA	NA
Total cost 20,000 broilers	1242	1880	1570	638	310	-328	1.5	1.2	0.8
Total cost 70,000 broilers	4347	6580	4320	2233	2260	27	1.5	1.5	1.0
Total cost one broiler⁎⁎⁎	0.062	0.094	0.078	0.032	0.016	0.016	1.5	1.2	0.8
Price per kg live weight⁎⁎⁎⁎	0.022	0.034	0.028	0.012	0.006	-0.006	1.5	1.2	0.8

^⁎The costs for labor and the forklift are included in the price per chicken (€0.045)

^⁎⁎Included costs are price per chicken (€0.045) (labor and forklift costs are integrated), loading of the truck: €80/h, transport costs of the catching machine (€370) (fixed cost), and cleaning and lubricating the machine (2.5 h * €40 = €100) (fixed cost)

^⁎⁎⁎Based on the cost of 20,000 broilers

^⁎⁎⁎⁎Weight broiler chicken (2.8 kg)

Ergonomic analysis

Ergonomics of the Catchers Based on On-Farm Survey Analysis of the catchers’ survey revealed that the catchers considered upright catching to be more tiring in comparison to inverted catching; both methods resulted in equal pain in different body parts (neck: 56%, shoulders: 56%, and arms: 56%) and upright catching caused much more/more pain in several body parts (upper back: 44% vs. 25%, lower back: 50% vs. 31%, and knees: 38% vs. 25%) (Fig. 3). Many catchers found that upright catching is hard (53%) to very hard (27%) to learn compared to inverted catching (Fig. 3). The opinion of the catchers about the behavior of the birds when using the upright versus inverted method was approximately equal between methods.

Fig. 3.

Catcher survey results regarding upright and inverted catching in terms of pain experienced during catching in their different body parts (%), fatigue levels (%), their experience of chicken behavior (%), their own performance (learning curve) (%) with red indicating the worst score and green the best. Indication of pain in the different body parts (n = 16 respondents) where red: much more pain (i.e. during upright vs. inverted catching), orange: more pain, grey: equal, light green: less pain, and dark green: much less pain. Fatigue (n = 16 respondents) with red: much more tiring, orange: more tiring, grey: equally tiring, light green: less tiring, dark green: much less tiring; behavior of the broiler chickens (n = 16 respondents) with red: more restless, orange: restless, grey: equally calm, light green: calmer, dark green: much calmer; and the learning curve (n = 16 respondents) with red: very difficult, orange: difficult, grey: equally difficult, light green: smooth, dark green: very smooth.

Ergonomic Assessment of Experimentally Simulated Inverted and Upright Catching According to the NIOSH method, catchers of broiler chickens are allowed to lift a maximum of 1 kg under unfavorable conditions and 1.5 to 2 kg under favorable conditions. The favorability of conditions is determined by the asymmetry of the catcher's body relative to the animal and the height relative to the ground (i.e., catching by the legs is closer to the ground than catching the whole body of the chicken) when catching the broiler chickens. In 55.56% of the cases, the RWL was equal to 0, indicating that these movements may not be performed (Table 6). Furthermore, the lifting index (LI), which should always be LI < 1, was calculated for the other movements. The LI was only < 1 when catching one broiler chicken upright (Test person 1, Level 2: 0.71, Test person 1, Level 3: 0.76, Test person 2, Level 2: 0.70), as this indicates a very low risk when performing this movement (Table 6). Given the average weight of broiler chickens at depopulation (ca. 2.8 kg), the NIOSH method therefore recommends lifting a maximum of one broiler chicken at a time for both inverted and upright catching methods (Table 6). For the ART tool, all total scores were higher (indicating a higher risk of physical strain) for inverted than upright catching (Test person 1: 24 vs. 20; Test person 2: 24 vs. 20; Test person 3: 23 vs. 19; Total average score: 24 vs. 20) (Table 7). The ART tool color codes assigned by the expert ergonomist for the risk level of the different ergonomic aspects during inverted versus upright catching are presented in Table 7. Total scores exceeding 22 indicate a dangerous situation; total average scores for inverted and upright were 22 and 19, respectively. The differences between both catching methods can be attributed to the differences in the force exerted by the hand. All total scores were three points higher for inverted compared to upright catching (Test person 1: 22 vs. 19 & Test person 2: 22 vs. 19 & Test person 3: 22 vs. 19 & Total average score: 22 vs. 19), indicating a (slightly) lower ergonomic risk in upright catching (Table 8). This is due to lower scores for weight and frequency of load, as well as for torso rotation and sideways bending (Table 8). It should be noted, however, that for both inverted and upright catching, the distance between the hand and lower back, vertical lifting zones, posture restrictions, grip on the load, floor surface, and environmental factors all received the worst score possible. Furthermore, the ergonomist found mechanical catching to be less labor-intensive compared to inverted and upright catching.

Table 6.

Assessment of ergonomics of three test persons for catching of broiler chickens using inverted and upright method (NIOSH evaluation method), with Recommended Weight Limit (RWL) (kg) and parameters of Revised Lifting Equation (RLE, with WC = weight constant in kg, HM=Horizontal multiplier, VM= Vertical multiplier, DM=Distance multiplier, AM=Asymmetric multiplier, CM=Coupling multiplier and FM=Frequency multiplier), the number of lifted broilers, the lifted weight (LW), the lifting index (LI), and the risk according to the LI per test person and per crate level, with NA = Not applicable if RWL = 0.

		WC	HM	VM	DM	AM	CM	FM	RWL	# broilers	LW	LI	Risk
Inverted
Test person 1	Level 1	23	0	0.95	0.91	0.96	1	0.55	0	NA	NA	NA	NA
	Level 2	23	0	0.97	0.88	0.98	1	0.55	0	NA	NA	NA	NA
	Level 3	23	0	0.87	0.86	1	1	0.55	0	NA	NA	NA	NA
Test person 2	Level 1	23	0.65	0.96	0.91	0.98	1	0.55	7.02	5	13.00	1.85	Moderate
	Level 2	23	0.44	0.95	0.87	0.99	1	0.55	4.57	4	10.40	2.28	High
	Level 3	23	0.46	0.86	0.86	0.98	1	0.55	4.21	4	10.40	2.47	High
Test person 3	Level 1	23	0	0.95	0.91	0.97	1	0.55	0	NA	NA	NA	NA
	Level 2	23	0	0.96	0.88	0.99	1	0.55	0	NA	NA	NA	NA
	Level 3	23	0.46	0.87	0.86	0.98	1	0.55	4.28	4	10.40	2.43	High
Upright
Test person 1	Level 1	23	0	0.95	0.91	0.98	0.9	0.55	0	NA	NA	NA	NA
	Level 2	23	0.41	0.93	0.87	0.97	0.9	0.55	3.64	1	2.60	0.71	Very low
	Level 3	23	0.41	0.86	0.86	0.99	0.9	0.55	3.41	1	2.60	0.76	Very low
Test person 2	Level 1	23	0	0.94	0.93	0.93	0.9	0.55	0	NA	NA	NA	NA
	Level 2	23	0.41	0.94	0.88	0.95	0.9	0.55	3.70	1	2.60	0.70	Very low
	Level 3	23	0.42	0.84	0.86	0.95	0.9	0.55	3.24	2	5.20	1.60	Moderate
Test person 3	Level 1	23	0	0.95	0.92	0.93	0.9	0.55	0	NA	NA	NA	NA
	Level 2	23	0	0.96	0.88	0.98	0.9	0.55	0	NA	NA	NA	NA
	Level 3	23	0	0.87	0.86	0.98	0.9	0.55	0	NA	NA	NA	NA

LI ≤ 1.0: very low risk, no intervention required

1.0 < LI ≤ 1.5: low risk, avoid high lifting frequencies and extreme lifting weight

1.5 < LI ≤ 2.0: moderate risk, re-evaluation of lifting is required

2.0 < LI ≤ 3.0: high risk, adjustments of lifting movement are a priority

LI > 3.0: very high risk, immediate adjustment is necessary (Fox et al., 2019)

Table 7.

Assessment of ergonomics of three test persons for catching broiler chickens using inverted and upright method according to different categories (score) of the ART Tool (Arm movements, Repetition, Force on hand, Head/neck posture, Back posture, Arm posture, Wrist posture, Hand/finger grip, Breaks, Work pace, Other factors, and Duration), with GREEN: Low-risk level, AMBER: Medium risk level - examine task closely, and RED: High-risk level – prompt action required, and the linked explanation.

Table 8.

Assessment of ergonomics of three test persons for catching broiler chickens using the inverted and upright method according to different categories (score) of the MAC tool (A Load weight/frequency, Hand distance from the lower back, Vertical lift zones, Torso twisting and sideways bending, Postural constraints, Grip on the load, Floor surface, and Environmental factors) with GREEN: Low-risk level, AMBER: Medium risk, and RED: High-risk level, and the linked explanation.

Cost-benefit analysis

A summary of the main advantages and disadvantages between the three depopulation methods with regards to bird welfare, catcher ergonomics, and financial costs is presented in Table 9. This overview indicates that upright catching is more expensive but is better for some bird welfare indicators as compared to inverted catching. With regards to ergonomics, the results are not unambiguous as ergonomic analyses by the expert do not always agree with the catcher survey. A full comparison with the mechanical method is not possible as data on ergonomics and some animal welfare variables were not collected, except that mechanical catching can improve the catchers' ergonomics because the catchers operate a machine instead of physically catching the chickens. Based on the available data we conclude that by using mechanical methods, flocks can be depopulated faster and more efficiently and that the total financial cost of this method is intermediate between the inverted and upright method, unless flocks > 70,000 at which point the mechanical methods become more cost effective (Table 9).

Table 9.

Cost (C) and benefit (B) analysis of inverted, upright, and mechanical catching broiler chickens with the comparison between costs, ergonomics, and animal welfare, with NA = Not Applicable.

Averages		Inverted	Upright	Mechanical
Costs (€)	Cost catching 20,000 broilers	1242 (B)	1880 (C)	1570 (C)
	Cost per kg live weight	0.022 (B)	0.034 (C)	0.028 (C)
Ergonomics	Expert	– (C)	- (C)	+ (B)
	Catchers	+ (B)	- (C)	NA
Animal welfare	Wing flapping frequency (1-7)	5.39a (C)	2.02b (B)	NA
	Catcher-bird interaction (1-7)	4.43a (C)	3.70b (B)	NA
	Average catch damage (%)	16.6 ± 1.2ab (C)	15.5 ± 1.3a (B)	17.7 ± 1.4b (C)

Discussion

In this cost-benefit study inverted, upright, and mechanical catching were compared in terms of animal welfare, labor conditions with a focus on ergonomics, and economic costs. Inverted (more wing flapping, worse catcher-bird interaction) and mechanical (more catch damage) methods had more welfare issues compared to upright catching, while upright catching was less efficient and more costly.

Upright versus inverted catching

The on-farm measurements during depopulation revealed less wing flapping for upright compared to inverted catching. With the upright method, the hands of the catcher cover the wings, which calms the chickens (Kittelsen et al., 2018; de Lima et al., 2019; Nielsen et al., 2022). Furthermore, the catcher-bird interaction was scored better for upright than inverted catching. This did not result in a significant reduction in catching damage recorded at the slaughterhouse, however. Other studies have reported fewer wing fractures (Kittelsen et al., 2018) and fewer catch and loading injuries (Hoorweg et al., 2024) for upright compared to inverted catching. Some differences between upright and inverted catching may have been masked in the present field study due to observed incorrect application of the upright method (e.g., hands not around the wings or holding chickens by the wrong body part). The surveyed catchers also reported that the upright method was more tiring and painful for themselves than the inverted method and was difficult to apply correctly. In general, the attitude of the catchers towards upright catching was rather negative, in accordance with Kittelsen et al. (2018) and Delanglez et al. (2024). More experience with upright catching might lead to a more positive attitude and more accurate application of the method. It is important to note that only 16 out of the 125 catchers completed the survey. Some may have perceived upright catching negatively due to fears that this study could contribute to a legal ban on the standard practice of inverted catching. The negative attitude of the catchers and some other actors within the poultry industry towards upright catching is an important concern that should be acknowledged. It is interesting to note that the catchers’ subjective experience of upright catching is not supported by the expert ergonomist's evaluations of video recordings of both methods. The ergonomist concluded that both manual catching methods impose excessive physical strain, but the upright catching method scored slightly better. For example, according to NIOSH, the lift required for inverted catching is slightly higher because the catchers must stoop closer to the ground to grasp the chickens’ leg. This evaluation does not consider, however, that the catchers need to perform the lifting movement more often in upright vs. inverted catching because upright can only crate a maximum of two birds vs. ca. six. When using the same number of catchers per 1,000 birds, upright catching takes longer to complete. Upright catching was also assigned slightly better scores by the ART and MAC tools due to lower scores for weight and frequency of load, as well as for torso rotation and sideways bending. It should be noted that the expert evaluation of the simulated catching events has some limitations: for example, reliance on a single ergonomist, assessment of non-professional catchers, an artificial setting, and the evaluation of a limited number of non-calibrated movements. While both manual methods are labor-intensive, upright catching took longer than inverted catching, leading to the broiler chickens experiencing a longer period of stress and longer period of fasting, both of which can negatively affect animal welfare (Kittelsen et al., 2018). To reduce the duration of upright catching, either the number of catchers would need to be increased or the number of birds transported per unit would need to be decreased. Neither option would solve the financial drawback inherent to upright catching, namely that it is less labor-efficient as compared to inverted catching. In the present study, total cost of catching 20,000 broiler chickens was estimated to be 1.5 times higher for upright compared to inverted catching. A price premium of €0.012 per kg live weight is needed to compensate for this additional cost. Future research should assess the feasibility of upright catching for entire flocks, taking into account factors such as truck wait times, slaughter schedules, costs, and personnel requirements.

Mechanical versus manual catching

At slaughter, measurements revealed significantly more catch damage with mechanical catching as compared to upright catching, whereas the difference with inverted catching was not significant. Hoorweg et al. (2024) reported a similar difference in incidence of injuries with mechanical catching vs. upright catching. The literature that compares catch damage between mechanical versus inverted catching is not univocal: some studies report a higher risk with mechanical catching (Ekstrand, 1998; Mönch et al., 2020; Hoorweg et al., 2024) while others report a higher risk with inverted catching (Knierim and Gocke, 2003; Nijdam et al., 2005). In the present study, pathologist inspection of DOA birds at the slaughterhouse identified trauma without underlying illness in 26% and 27% of examined broiler chickens subjected to inverted and upright catching methods, respectively, as well as in 13% of mechanically caught broilers. This may indicate that the catching, loading and transport process was directly responsible for this premature mortality. These results fall at the intermediate of the range reported in other studies (Ritz et al., 2005; Whiting et al., 2007), which indicate that 10% to 45% of DOA chickens had trauma-related causes of death (hip dislocation, ruptured liver, and head trauma). In our study, the catching method did not significantly affect the number of DOAs. However, several other studies mentioned more DOAs for mechanical compared to inverted catching (Nijdam et al., 2005; Chauvin et al., 2011; Mönch et al., 2020).

The present study also shows that mechanical catching is more labor-efficient compared to upright and, to a lesser extent, inverted catching. Furthermore, mechanical catching can be performed by only four catchers in comparison to inverted or upright catching, which both require seven to ten catchers. Besides the physically strenuous nature of manual catching due to the repetitive task and upper-body musculoskeletal injuries (Mitchell and Kettlewell, 2004; Barbosa Filho, 2008; Vieira et al., 2009; Delanglez et al., 2024b), mechanical catching seems to be an attractive and labor-efficient alternative as it requires less activity by the catchers and decreases the amount of dust inhaled (Morris et al., 1991; Ramasamy et al., 2004). It should be noted, however, that our study did not include an ergonomic comparison of mechanical versus manual catching. Moreover, Stork ATLAS containers were always used for mechanical catching because they are easier to use (drawers are wider and deeper) compared to unrestrained plastic drawers. Using other types of containers for mechanical catching would likely reduce the efficiency and increase animal welfare concerns. Despite the high labor efficiency of mechanical catching, the total cost of catching 20,000 broiler chickens was 1.2 times higher for mechanical catching than inverted catching. A price premium of €0.006 per kg live weight is needed to compensate for this additional cost. For flocks of 20,000 birds in Belgium, mechanical costs were intermediate between upright and inverted catching, and the lowest of the three methods for flocks of 70,000 birds (60,000 birds is the average flock size in Belgium; Agentschap Landbouw en Zeevisserij, 2024). Because mechanical catching involves many fixed costs (e.g. transport costs of the catching machine, cleaning and lubricating of the machine) irrespective of flock size, it is financially more attractive for larger flocks. Hassan and Lashin (2017) and Lacy and Czarick (1998) also compared the costs of inverted and mechanical catching. They estimated labor costs for a 9-person catching crew at approximately $215,000/year (inverted catching, multiple catching events), and for three to four person crew, approximately $72,000/year (mechanical catching, multiple catching events), a difference of $143,000/year. Hassan and Lashin (2017) calculated that the reduction in labor cost alone would pay off a catching machine (assumed to cost €100,000) in less than 15 months. It should be noted, however, that financial considerations such as a comparison of worker's compensation claims and worker health care costs, costs associated with maintenance of the machine, cleaning and disinfection, and training of personnel are not included (Lacy and Czarick, 1998; Löhren, 2017). Limitations of mechanical catching include extra costs (purchase, transport, and cleaning), elevated biosecurity risk (difficult to clean the machine and which can result in a higher chance of contamination), and specific requirements for being able to access the stable (height and width) (Hassan and Lashin, 2017; Löhren, 2017).

Conclusions

This study showed that upright catching provides better animal welfare for some parameters compared to both inverted (less wing flapping, better catcher-bird interaction) and mechanical catching (less overall catch damage). However, upright catching is less labor-efficient (more person-hours), more costly with an additional cost of €0.012 (inverted) and €0.006 (mechanical) per kg of live weight based on catching 20,000 broilers, and negatively perceived by catchers (despite some minor ergonomic advantages according to an expert ergonomist assessment including less force on the hand, lower load weight, and reduced occurrence of either torso twisting or sideway bending of the body). While mechanical catching reduces labor strain because catchers don't need to catch the chickens themselves and it increases efficiency, it results in poorer animal welfare outcomes (more overall catch damage) as compared to upright catching and is not cost-effective for flocks smaller than 70,000 chickens as compared to inverted catching.

In the future, specifically for upright catching, the feasibility of catching entire flocks should be investigated, taking the following into account: catching procedures, truck wait times, slaughter schedules, and related costs for the industry (e.g., poultry farmers, catchers, transporters, slaughterhouses, retail, and consumers) and personnel conditions (e.g., the effect of long term workload for catchers). Industrial implementation of upright catching requires compensation for additional labor costs, addressing negative catcher attitudes and poor labor conditions, and streamlining the catching, crating, and loading process to shorten broiler exposure to stress and extended fasting time.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.