Effect of feed deprivation and lairage time on carcass and meat quality traits on pigs under minimal stressful conditions

Implications of Lairage and Environmental Enrichment on Behavioral Responses and Skin Lesions in Finishing Pigs in a Slaughterhouse

Different resources, such as environmental enrichment, are being evaluated in order to minimize animal stress and promote better conditions during the life cycle of animals, as consumers are increasingly concerned about animal welfare issues. Lairage represents an important stage in the swine production chain and is directly related to animal welfare. The aim of this study was to evaluate the effect of lairage time in the slaughterhouse and environmental enrichment on the level of skin lesions and behavioral responses in pigs. A total of 648 finishing pigs of both sexes were assessed before and after lairage at the slaughterhouse with a five-point scale (0 = none, to 4 = ≥16 superficial lesions or >10 deep lesions). After lairage (after slaughter), lesions were also classified according to their source (mounting, fighting, and handling). Pigs were distributed into two treatments groups during lairage: with environmental enrichment (EE) on the pen, with hanging metal chains, and with no enrichment (NE). Behavior was monitored during the first four hours of lairage. Proportional odds, mixed linear model for longitudinal data, and non-parametric Wilcoxon signed rank tests were used to analyze the relation between treatments, skin lesions, and behavior. The simple metal chains did not affect skin lesion score or pigs' behavior (p > 0.05), whereas lairage duration influenced standing (SA), sitting (S), lying (L), idleness (I), and drinking water (D) (p < 0.001). The main source of skin lesions was handling, which did not differ between treatments (EE and NE) (p > 0.05). It was observed that the severity of the lesions (highest scores of 3, 4, and 5) increased in the different anatomical regions of the pigs when compared before and after slaughter, with the exception of the frontal area, which was the same (p = 0.7547). Lairage time has a proportional relation with skin lesions, and hanging chains at the slaughterhouse pens was not enough to reduce the number of lesions and to change pig behavior.

Impact of Procedures and Human-Animal Interactions during Transport and Slaughter on Animal Welfare of Pigs: A Systematic Literature Review

Animal welfare is a high social and political priority and is enshrined in European and national legislation. This systematic literature review (funded by the German Ministry of Food and Agriculture; grant no. 2817806A18) was conducted to find animal and management-based indicators that could be influenced by changes in pig handling and management procedures on the day of slaughter and, therefore, will directly result in improved animal welfare. For this systematic literature review, following the PRISMA guidelines, we conducted a structured literature search using the databases PubMed^®, Web of Science^TM, and LIVIVO with set search terms and their combinations in German and English. Only peer-reviewed original articles from European countries from 2009 until 2022 that dealt with welfare during transport and/or slaughter of fattening pigs and offered potential measurable indicators on the basis of the animal or management, and either directly or indirectly recommended handling practices were included. We used the literature management system EndNote^TM, and after duplicate removal, a total of 1099 records were found for further analysis. After analysis and discussion in the review team, which consisted of three experts in total, 105 articles underwent full-text screening. Finally, 39 articles were included in the results for this systematic literature review. According to this systematic literature review, the following procedures have a positive impact on the animal welfare of pigs on the day of slaughter. Calm-rather than rough-handling of pigs was the most influential factor. This can be achieved by using animal-friendly driving aids. Loud noise should be avoided in general or reduced as far as possible. Transport time is not always influenceable, but shorter transport duration with stocking density as stated by the European regulations as a maximum will reduce stress in pigs. Our review showed that there are differing scientific results about lairage duration, although this should be set in relation to prior stress and transport time. Knowledge of good stunning parameters, such as gas concentration, exposure time to the gas, recommended amperage, and current flow duration is essential. If electrical stunning is performed, the correct attachment of electrodes is crucial. The control of stunning effectiveness is extremely important to avoid suffering and pain, with the proviso that it is assessed on the basis of multiple parameters. The corneal reflex, regular gasping, and the up-righting reflex could be assessed together. Certificates of competence and continuing educational programmes for the personnel form the basis of animal-friendly handling and a stressless slaughter routine. It can be assumed that the results of this systematic literature review reflect the state of current research of pig welfare during transport and slaughter in the European Union, even though it must be assumed that not all relevant points were covered by the review, which can be seen as a limitation at the same time because important non-European or older publications could not be included.

Biosecurity and Lairage Time versus Pork Meat Quality Traits in a Farm-Abattoir Continuum

The modern pig production chain is increasingly focused on biosecurity, quality, and safety of meat and is associated with many challenges impacting world meat markets, such as animal disease outbreaks and sanitary restrictions, trade regulations and quality requirements. To overcome such challenges and assure more consistent pork meat quality (and safety), there is a need to develop an effective and reliable monitoring system in a farm-abattoir continuum that can be based on selected biomarkers. This study assessed interrelations of selected stress and inflammation biomarkers (acute phase proteins (APP)) between farm biosecurity score versus pork meat quality traits after two different lairage periods. Briefly, the maximum recorded levels of stress hormones (436.2 and 241.2 ng/mL, for cortisol and Chromogranin A (CgA), respectively) and APP (389.4 and 400.9 μg/mL, Pig Major Acute Proteins (MAP) and Haptoglobin (Hp), respectively) at four commercial farms were within the recommended threshold values. Cortisol and APP were negatively correlated to the internal and total biosecurity scores of farms. The increase of level of both sets of biomarkers was found at bleeding (after transportation and lairage period), but with lower values after long (18-20 h) versus short (1-3 h) lairage lay-over time. In general, negative correlation was confirmed between stress and inflammation biomarkers and carcass/meat quality traits. The farm total biosecurity level significantly affected chilling yield, meat temperature, and a* value. Pig-MAP emerged as a good biomarker with a promising potential for assessment and anticipation of broad aspects in the pork meat chain. It can be used for detection of failures in the pig production system and might be incorporated in certification programs for the pork meat industry.

A Study on the Preparation of Microbial and Nonstarch Polysaccharide Enzyme Synergistic Fermented Maize Cob Feed and Its Feeding Efficiency in Finishing Pigs

1000 g maize cob mixed material was synergistically fermented by adding 2.5% composite probiotics and 0.06-0.08% NSP (nonstarch polysaccharide) enzyme to prepare fermented feed, and its effectiveness as feed for fattening pigs was investigated. The results showed that the appearance, texture, and nutrient quality of maize cobs significantly improved after fermentation, the total number of bacteria was 4.5 × 1010 CFU/g, and the protein content was 7.1%. Compared to the control group, the pigs in the 6% fermented maize cob feed experimental group showed significantly increased daily feed intake, daily weight gain, and nutrient digestion rate (p < 0.05) and reduced feed conversion ratio (p < 0.05). Most indicators including slaughter performance and meat quality significantly improved. In addition, beneficial bacteria including Lactobacillus in the intestines of the finishing pigs significantly increased, and pathogenic bacteria including Escherichia coli in the intestines and feces were found to be significantly reduced (p < 0.05). The intestinal crypt depth, VH/CD ratio, and ileal mucosal immunity of the finishing pigs also significantly improved (p < 0.05). The cytokine content and gene expression of sIgA, IL-8, and TNF-α were found to be significantly increased (p < 0.05). It could be concluded that the addition of 6% fermented maize cob feed to the diets of finishing pigs could promote their growth, improve their production performance and slaughter performance meat quality, and enhance their intestinal microecological balance and immunity.

Welfare of pigs at slaughter

The killing of pigs for human consumption (slaughtering) can take place in a slaughterhouse or on farm. The processes of slaughtering that were assessed for welfare, from the arrival of pigs until their death, were grouped into three main phases: pre-stunning (including arrival, unloading from the truck, lairage, handling and moving of pigs); stunning (including restraint); and bleeding. Stunning methods were grouped into three categories: electrical, controlled atmosphere and mechanical. Twelve welfare consequences the pigs can be exposed to during slaughter were identified: heat stress, cold stress, fatigue, prolonged thirst, prolonged hunger, impeded movement, restriction of movements, resting problem, negative social behaviour, pain, fear and respiratory distress. Welfare consequences and relevant animal-based measures were described. In total, 30 welfare hazards that could occur during slaughter were identified and characterised, most of them related to stunning and bleeding. Staff were identified as the origin of 29 hazards, which were attributed to the lack of appropriate skill sets needed to perform tasks or to fatigue. Corrective and preventive measures for these hazards were assessed: measures to correct hazards were identified, and management was shown to have a crucial role in prevention. Outcome tables linking hazards, welfare consequences, animal-based measures, origins and preventive and corrective measures were developed for each process. Mitigation measures to minimise welfare consequences are proposed.

How do season, on-farm fasting interval and lairage period affect swine welfare, carcass and meat quality traits?

This study was carried out in order to determine the effects of different combinations of on-farm fasting intervals (8, 12, 16, 20 h) and 1.5 h of transport plus lairage periods (1, 3, 6 h) at different seasons (summer/winter) on blood stress parameters (cortisol and lactate), stomach content and weight, skin lesion and meat quality in a total of 960 pigs from eight farms. Blood lactate levels were greater in the summer (P < 0.001) and stomach content was affected (P < 0.05) by season, on-farm fasting interval (P < 0.001), lairage time (P < 0.0001). Stomach content weight reduces as the total feed withdrawal time increases up to on-farm fasting of 17 and 1 h of lairage. Stomach content can be influenced by feed and water in different ways according to treatments. Only 8 h of on-farm fasting is not enough to empty stomachs from feed content. However, an on-farm fasting period of 16 h or longer can also increase the occurrence of more water in the stomachs. Carcass lesions caused by fighting were greater (P ≤ 0.005) in the winter, mainly after 3 and 6 h of lairage (P ≤ 0.005). Loin and ham pH_u was lower (P ≤ 0.05) for pigs slaughtered after 6 h of lairage during the summer. The application of 12 h of on-farm fasting with 6 h of lairage seemed to be best combination to reduce stomach content weight (feed and water). In the winter, shorter lairage period can be used to reduce percentage of skin lesions and better pork quality traits in pigs.

Effect of lairage time, behaviour and gender on stress and meat quality parameters in pigs

The objective of this study was to determine the effects of lairage time (short vs. long), behavior (aggressive vs. non-aggressive) and gender (gilts, barrows and boars) on stress and meat quality parameters in pigs (n = 100). In the group with short lairage, aggressive behavior of gilts and boars was observed. At exsanguination, blood samples were collected and levels of blood lactate and plasma cortisol were determined. Post mortem pH value, temperature, drip loss, sensory and instrumental color and meat quality class were determined on the muscle Longissimus dorsi. Higher blood lactate concentration (P < 0.05) and skin blemish score (P <0.001), lower temperature (P < 0.05) and drip loss (P < 0.01), as well as darker, less red and yellow meat color (P < 0.001) were found after long lairage compared to short lairage. Gilts had higher plasma cortisol concentrations than barrows (P < 0.05), while barrows had lower skin blemish scores (P < 0.05) than gilts and boars after long lairage. The highest incidence of PSE (pale, soft and exudative) meat was observed in barrows (100.00%) and boars (91.67%) after short lairage, while the lowest incidence of PSE meat was found in barrows (28.89%) after long lairage. Aggressiveness affected meat temperature, as aggressive pigs had higher meat temperature (P < 0.05) than non-aggressive pigs.

Effects of preslaughter feed withdrawal time on finishing pig carcass, body weight gain, and food safety characteristics in a commercial environment

The effects of feed withdrawal time before slaughter on finishing pig carcass composition were evaluated in 2 studies. In Exp. 1, 728 pigs (BW = 128.9 ± 1.2 kg) were allotted to 1 of 4 treatments in a randomized design with number of pigs per pen and location within barn balanced across treatment. The 4 treatments were feed withdrawal times of 8, 24, 36, or 48 h and there were 12 replicate pens per treatment. Before feed withdrawal, pigs were fed a standard corn-soybean meal diet containing dried distillers grains with solubles (DDGS), bakery coproducts, and 5.0 mg/kg ractopamine HCl. Feed withdrawal time decreased (linear; P < 0.02) live weight, HCW, and backfat while increasing percentage yield (quadratic; P < 0.01) and fat-free lean index (FFLI; linear; P < 0.001). In Exp. 2, 843 pigs (BW = 125.4 ± 1.6 kg) were used to determine the impact of feed withdrawal on growth, carcass, blood lactate, and meat quality. There were 4 treatments: withholding feed for 8, 12, 24, or 36 h, with 10 replicates per treatment. Pigs were fed a common corn-soybean meal-based diet containing 20% DDGS and 5.0 mg/kg ractopamine HCl. Withholding feed decreased (linear; P < 0.001) live weight, ultimately resulting in decreased (P < 0.01) HCW. There were no differences in FFLI or backfat, but percentage yield (linear; P < 0.001) increased with longer withdrawal times. Carcass contaminations by stomach contents escaping from the oral cavity after shackling (leaking ingesta) or visible fecal contamination of the exterior of the carcass (runny bung) were also measured. Although withholding feed did not affect runny bung, it increased (linear; P < 0.001) the incidence of leaking ingesta, whereas blood lactate, visual color score, and purge loss were unaffected. Withholding feed increased 45-min pH (quadratic; P > 0.02) and ultimate pH (linear; P < 0.01) and increased (quadratic; P < 0.03) visual marbling score. Withholding feed decreased (linear; P < 0.001) feed intake, resulting in feed savings of up to 3 kg/pig. Although several heavyweight pigs were removed before trial commencement and the variable number of remaining pigs per pen may have influenced the response to feed withdrawal, the present data indicates that finishing pigs can experience between 24 and 36 h of feed withdrawal without negatively affecting carcass composition. However, the increased incidence of leaking ingesta beyond 12 h of feed withdrawal is concerning.