Evaluation of Tail Lesions of Finishing Pigs at the Slaughterhouse: Associations With Herd-Level Observations

Comparison between two scoring methods to assess tail damage of docked pig carcasses during postmortem inspection in Ireland

Background

Tail inspection in the abattoir is a tool to help determine the welfare status of pigs. However, methodologies vary widely. Moreover, meat inspection is moving from palpation and incision towards visual-only (VIS) examination. This study investigated whether a VIS examination was sufficient to detect tail damage compared to handling (HAND), which ensures examination of all aspects of the tail.

Method

The severity of tail skin damage (0 [undamaged] - 4 [partial/full loss of tail]) and presence/absence of bruises was scored using both methods after scalding/dehairing of 5498 pig carcasses.

Results

There was a good relationship between methods when evaluating tail skin damage (sensitivity, 82.48%; specificity, 99.98%; accuracy, 98.98%; correlation ρ = 0.84). The results were similar for the presence of bruises (sensitivity, 74.98%; specificity, 99.09%; accuracy, 89.94%; correlation ρ = 0.79). However, the percentage of tails classified as undamaged was higher using VIS (69.9%) than HAND (63.55%) examination. Conversely, VIS detected fewer mild lesions (score 1 - 13.64%; score 2 - 11.73%) than HAND (score 1 - 15.21%; score 2 - 15.53%). A higher percentage of bruises was detected using HAND than VIS (37.96% vs. 29.03%).

Conclusions

Visual evaluation is a valid alternative to handling evaluation of carcass tail damage and bruising.

Assessment of slaughterhouse-based measures as animal welfare indicators in fattening pigs

In recent years, there has been growing interest in the assessment of animal welfare in slaughterhouses. The aim of this study was to determine the effectiveness of slaughter-based measures as animal welfare indicators and evaluate the relationships between these indicators and the sociodemographic characteristics of livestock drivers and transport conditions for fattening pigs in a commercial slaughterhouse. A total of 1,161 heavy pigs (105.6 ± 14.15 kg), from 22 commercial farms, were evaluated. Pigs were assessed ante mortem, during lairaging, by evaluating the number, location, and color of skin lesions, tail length, and the presence or absence of biting lesions, lameness, cough, rectal or vaginal prolapse, and umbilical hernia. Pulmonary lesions, pleuritis, pericarditis, and liver lesions were also recorded postmortem. A descriptive analysis was performed on antemortem and postmortem indicators to estimate their prevalence, and the relationships among antemortem and postmortem indicators were analyzed using two multilevel mixed-effects models—a linear regression and a logistic regression analysis— with the farm of origin as a fixed effect. Cough was present in 18.9% (n = 219) of pigs, whereas the prevalence of tail biting lesions (4.6%, n = 53), rectal prolapse (0.1%, n = 11), and vaginal prolapse (0.1%, n = 11) was low. As regards lesion shape, linear lesions accounted for the majority of skin lesions (55.8%, n = 648), followed by comma-shaped (34.7%, n = 403), diffuse (6.9%, n = 80), and rectangular lesions (2.5%, n = 29). Only 25.2% (n = 512) of lesions were bright red. At postmortem, pulmonary lesions were noted in 34.2 ± 13.5 (mean ± SEM) pigs, and were more prevalent in the cranial (11.9 ± 4.9) and medium lobes (12.2 ± 5.2); the caudal (5.3 ± 2.7) and accessory lobes (1.6 ± 1.6) were less affected. The number of skin lesions was significantly associated with drivers’ age, job experience (years), and marital status (p ≤ 0.001). The presence or absence of tail lesions was strongly associated with the number of skin lesions, scoring of pulmonary lesions, and animal live weight (p ≤ 0.001). Antemortem and postmortem indicators at slaughterhouses with low annual slaughter volumes can provide key information for disease monitoring and animal welfare.

The capacity of inspection on farm and at the abattoir to predict post-mortem outcomes in slaughter pigs: A study at animal level

The aim of this study was to investigate associations between ear, tail, and skin lesions, hernias, bursitis, and rectal prolapses at the abattoir and meat inspection outcomes in slaughter pigs, including carcass condemnations and trimmings, carcass weight, and carcass quality. This was an observational study whereby pigs were managed according to routine practices in a single abattoir. Data were collected from 1816 pigs. The relationship between animal-based welfare and post-mortem outcomes was analyzed using generalized mixed models (Proc Glimmix). Our findings showed that tail lesions were associated with entire carcass condemnations and trimmings (P < 0.001), a reduction in carcass weight (P < 0.05), and a potential to impair carcass quality by reducing muscle pH (P < 0.05), especially in carcasses from male pigs (P < 0.05). Additionally, hernias were associated with viscera condemnation (P < 0.05) and a reduction in carcass weight (P  < 0.05). Therefore, our findings confirm that ante-mortem inspection could be useful to predict post-mortem outcomes in the same pigs, especially in cases of tail lesions and hernia, which might trigger attention of the veterinary inspector in charge of the post-mortem inspection.

The capacity of ante-mortem inspection of pigs at the abattoir to predict post-mortem findings and associated financial implications: A study at batch level

This study aimed to investigate the associations between severe ear, tail, and skin lesions, hernias, bursitis, and rectal prolapses and meat inspection finding in slaughter pigs, including carcass weight and financial implications associated with carcass condemnations at batch level. Data were collected from 13,296 pigs from 116 batches from a single abattoir. Spearman's correlation coefficients were calculated to analyze the degree of association between the prevalence of welfare issues and condemnation findings. The association between batch-level results of carcass weight, batch size, and the prevalence of welfare issues was analyzed using generalized linear mixed models. The prevalence of tail lesions was significantly associated with both entire (r = 0.224; p = 0.0432) and partial (r = 0.276; p = 0.0120) carcass condemnation. Batches with pigs affected by more than one welfare issue were 9.9 kg lighter than those without welfare issues (p < 0.05), which was equivalent to a potential loss of €11.28 per pig. Our findings indicate that ante-mortem inspection could be useful to predict post-mortem findings at batch level and that welfare issues in pigs represent a financial loss to producers, as they are paid on a per kg basis and have tight margins.

Identifying Early Indicators of Tail Biting in Pigs by Variable Selection Using Partial Least Squares Regression

This study examined relevant variables for predicting the prevalence of pigs with a tail lesion in rearing (REA) and fattening (FAT). Tail lesions were recorded at two scoring days a week in six pens in both REA (10 batches, 840 scoring days) and FAT (5 batches, 624 scoring days). To select the variables that best explain the variation within the prevalence of pigs with a tail lesion, partial least squares regression models were used with the variable importance in projection (VIP) and regression coefficients (β) as selection criteria. In REA, five factors were extracted explaining 60.6% of the dependent variable's variance, whereas in FAT five extracted factors explained 62.4% of the dependent variable's variance. According to VIP and β, seven variables were selected in REA and six in FAT with the tail posture being the most important variable. In addition, skin lesions, treatment index in the suckling phase, water consumption (mean), activity time (mean; CV) and exhaust air rate (CV) were selected in REA. In FAT, additional musculoskeletal system issues, activity time (mean; CV) and exhaust air rate (mean; CV) were selected according to VIP and β. The selected variables indicate which variables should be collected in the stable to e.g., predict tail biting.

Individual behavioral correlates of tail biting in pre-finishing piglets

Introduction

Tail biting is a widespread problem in pig production systems and has a negative impact on both animal welfare and farm income. This explorative study aims to validate how tail biting is related to general behaviors at the individual level and explore whether these behaviors are related to a particular type of tail biting: two-stage, sudden-forceful, obsessive, or epidemic.

Methods

This research was conducted in a standard commercial setting where 89 tail-docked pre-finishing piglets divided into 8 groups were observed 4 days per week from 5 to 8 weeks of age. Each piglet was observed for a total of 160 min using continuous focal sampling. Ten individual behaviors were recorded based on the general behaviors expected to be linked to giving tail biting (PCA1), receiving tail biting (PCA2), and tail biting damage (PCA3). These PCAs were assembled and related to tail biting given, tail biting received, and tail biting lesions.

Results

Tail biting did not lead to major damage on the piglets' tail at 8 weeks of age but was observed 420 times, where most of the individuals (72%) were categorized as "biters and victims." When relating PCA1 with tail biting given, piglets that gave more tail biting showed more "active exploration." When relating PCA2 with tail biting received, piglets receiving more tail biting were more "explored while active" and "attacked and explored." When relating PCA2 with tail biting lesions, piglets presenting lesions showed more "agonism." Surprisingly, tail biting lesions were not significantly related to PCA3. The relationship between explorative behaviors and tail biting indicates that the pre-damage stage of two-stage tail biting was the predominant tail biting type, while the damaging stage was likely incipient. The relationship between tail biting and aggression, as well as the minor tail lesions observed suggest that sudden-forceful tail biting was probably present even though it was rarely seen. Obsessive and epidemic tail biting were not observed.

Discussion

This study demonstrates that studying tail biting at the individual level helps to identify the type of tail biting present. This gives directions to farmers for applying appropriate measures to prevent the development of tail biting behavior in piglets.

Analysis of bovine postmortem condemnation data in France: Contributions from a comprehensive and standardised information system at the slaughterhouse

BACKGROUND

The condemnation of carcases and offal unfit for human consumption is a regulatory requirement at the slaughterhouse. Condemnation data, if comprehensive and standardised, can be a valuable source of information for risk-based inspection and decision making.

METHODS

The aim of this study was to analyse postmortem condemnation data that were recorded in all bovine slaughterhouses in mainland France from 1 January 2016 to 31 December 2020 in a comprehensive and standardised information system. The rates of and reasons for condemnation, as well as factors influencing rate variation, were investigated through descriptive analysis and multivariable logistic regression models.

RESULTS

The global, total and partial condemnation rates were 4.5%, 0.7% and 3.8% for adult cattle and 1.4%, 0.3% and 1.1% for calves, respectively. Reasons for condemnation varied with the animal category; for example, the three main reasons for total condemnation in adult cattle were serous infiltration of connective tissue (49% of condemned animals), congestive peritonitis (12.2%) and fibrinous peritonitis (10.9%), whereas the top three reasons for partial condemnation were unique abscess (21.9%), haemorrhagic infiltration (20.6%) and muscular sclerosis (17.4%). Condemnation rates were influenced by animal-related factors (sex, age, type of breed) and slaughterhouse-related factors (status, type, slaughter volume).

CONCLUSION

Our findings could usefully contribute to the continuous improvement of the harmonisation of inspection decisions and support the risk manager's strategy in the modernisation of official controls at the slaughterhouse.

The Evidence for a Causal Link Between Disease and Damaging Behavior in Pigs

Damaging behaviors (DB) such as tail and ear biting are prevalent in pig production and reduce welfare and performance. Anecdotal reports suggest that health challenges increase the risk of tail-biting. The prevalence of tail damage and health problems show high correlations across batches within and between farms. There are many common risk factors for tail-biting and health problems, notably respiratory, enteric and locomotory diseases. These include suboptimal thermal climate, hygiene, stocking density and feed quality. The prevalence of tail damage and health problems also show high correlations across batches within and between farms. However, limited evidence supports two likely causal mechanisms for a direct link between DB and health problems. The first is that generalized poor health (e.g., enzootic pneumonia) on farm poses an increased risk of pigs performing DB. Recent studies indicate a possible causal link between an experimental inflammation and an increase in DB, and suggest a link between cytokines and tail-biting. The negative effects of poor health on the ingestion and processing of nutrients means that immune-stimulated pigs may develop specific nutrient deficiencies, increasing DB. The second causal mechanism involves tail-biting causing poor health. Indirectly, pathogens enter the body via the tail lesion and once infected, systemic spread of infection may occur. This occurs mainly via the venous route targeting the lungs, and to a lesser extent via cerebrospinal fluid and the lymphatic system. In carcasses with tail lesions, there is an increase in lung lesions, abscessation, arthritis and osteomyelitis. There is also evidence for the direct spread of pathogens between biters and victims. In summary, the literature supports the association between poor health and DB, particularly tail-biting. However, there is insufficient evidence to confirm causality in either direction. Nevertheless, the limited evidence is compelling enough to suggest that improvements to management and housing to enhance pig health will reduce DB. In the same way, improvements to housing and management designed to address DB, are likely to result in benefits to pig health. While most of the available literature relates to tail-biting, we suggest that similar mechanisms are responsible for links between health and other DB.