Health conditions of two genotypes of growing-finishing pig in three different housing systems: implications for welfare

Gastric ulcers in finishing pigs: the evaluation of selected non-dietary risk factors and impact on production performance

BACKGROUND

The complex aetiology of gastric lesions in pigs remains largely unknown and effective preventive measures and pharmaceutical treatment of the disease have not been developed yet. Regardless of the fact that the overwhelming majority of previous research works dealing with gastric ulceration in pigs focused on the role of the nutritional determinants, including chemical composition of feeds, cereal type, finely ground pelleted diets, and feed additives, conclusions presented therein remain highly ambiguous. Thus, the purpose of this study was to evaluate the impact of the disease on production performance, and investigate the influence of selected non-dietary risk factors on the prevalence of gastric alterations in finishing pigs reared under conditions of 11 modern farms located in Poland.

RESULTS

A total number of 26,043 finishing pigs was examined. 15,228 (58.47%) had gastric ulcers. Intact stomachs were detected in 6176 animals (23.71%). Parakeratosis and erosion were observed in 2551 (9.80%) and 2088 (8.02%), respectively. Among eight continuous variables two were found to be significantly associated with prevalence of the gastric ulcer: the growing number of animals in the herd, which was negatively correlated (P = 0.002; ρ = -0.37), and the growing average entry weight of animals transported to the finisher farm (P = 0.047; ρ = 0.24), which increased the risk of gastric ulcers prevalence. Among 12 nominal variables, problems with the quality of farm management (P = 0.041), and usage of straw as a bedding material (P = 0.002) were identified as determinants significantly associated with occurrence of the analysed health problem.

CONCLUSIONS

Among 20 non-nutritional variables analysed in our study only few factors were found to be associated with the prevalence of the disease. The impact of broadly understood management issues on gastric health in finishing pigs deserves further research.

Consequences of timing of organic enrichment provision on pig performance, health and stress resilience after weaning and regrouping

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We tested fodder beet and jute bags as novel enrichment for pigs in slatted systems.

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We investigated if enrichment mattered more when offered at weaner or finisher stage.

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Weaner enrichment improved ear lesions and performance at both stages.

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Enrichment provision throughout reduced finisher body lesions.

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Fodder beet and jute bags could be feasible enrichment for pigs in slatted systems.

Most pigs in slatted systems are provided with enrichment meeting only minimum legal requirements. We aimed to explore the effects of a novel enrichment treatment consisting of daily provided fodder beet and jute bags for pigs in slatted systems, and investigate the timing of enrichment provision on performance, health and stress resilience. We used 280 weaners allocated into standard (S, meeting only legal requirements consisting of a plastic toy and softwood) or enriched (E) treatment (n = 14 groups/treatment). At regrouping during the grower to finisher transition, pigs were either kept in the same treatment (EE, SS) or switched from enriched to standard (ES) and vice versa (SE); each treatment was replicated on five groups. Pigs were weighted at the start and end of weaner, and finisher stage, and feed intake was recorded. Occurrence of scouring, respiratory problems, locomotor disorders, tail, ear, and body lesions were recorded twice a week. Ten males per treatment were sampled for saliva on days 1, 2 and 4, either postweaning or after the housing switch. Saliva samples were analysed for cortisol, alpha-amylase, haptoglobin (Hp), and adenosine deaminase. Additionally, these pigs were sampled for hair at the start and end of weaner, and end of finisher stage to analyse for hair cortisol and cortisone. We found that E weaners consumed less feed (P = 0.04), had better FCR (feed conversion ratio, P = 0.03) and less ear lesions for two weeks postweaning (P = 0.04), and tended to have lower occurrence of scouring (P = 0.07) and higher salivary cortisol concentrations (P = 0.09) than S weaners. Effects of enrichment treatment during weaner stage on performance were carried through to finisher stage, with EE and ES pigs having better FCR (P = 0.0009) and higher BW (P = 0.0001) compared to SS and SE pigs. E treatment during finisher stage decreased feed intake (P = 0.04) and tended to decrease Hp levels (P = 0.07). There was a significant interaction between enrichment treatments during weaner and finisher stages on finisher body lesions: EE finishers had less lesions than SS, ES, and SE finishers (P = 0.04). There were no other significant differences caused either by enrichment treatment during weaner/finisher stage or their interaction. We conclude that the novel enrichment applied at weaner stage had positive effects on ear lesions and performance, which were carried through to finisher stage. Body lesions were affected by its application during both stages, with finishers receiving the enrichment treatment throughout (EE) having reduced body lesions than the rest of the finishers.

Understanding the relative risks of zoonosis emergence under contrasting approaches to meeting livestock product demand

It has been argued that intensive livestock farming increases the risk of pandemics of zoonotic origin because of long-distance livestock movements, high livestock densities, poor animal health and welfare, low disease resistance and low genetic diversity. However, data on many of these factors are limited, and analyses to date typically ignore how land use affects emerging infectious disease (EID) risks, and how these risks might vary across systems with different yields (production per unit area). Extensive, lower yielding practices typically involve larger livestock populations, poorer biosecurity, more workers and more area under farming, resulting in different, but not necessarily lower, EID risks than higher yielding systems producing the same amount of food. To move this discussion forward, we review the evidence for each of the factors that potentially link livestock production practices to EID risk. We explore how each factor might vary with yield and consider how overall risks might differ across a mix of production systems chosen to reflect in broad terms the current livestock sector at a global level and in hypothetical low- and high-yield systems matched by overall level of production. We identify significant knowledge gaps for all potential risk factors and argue these shortfalls in understanding mean we cannot currently determine whether lower or higher yielding systems would better limit the risk of future pandemics.

Behavior and Welfare of Undocked Heavy Pigs Raised in Buildings with Different Ventilation Systems

The present study aimed to evaluate animal welfare of pigs from the same farm, raised with two ventilation systems. The study involved 60 pens of fattening pigs, raised in two buildings: one naturally ventilated (NV) and the other mechanically ventilated (MV). Pigs were assessed on three observation days: at 40 kg (T1), 100 kg (T2), and 160 kg (T3) of live weight. Animal-based measures were used such as qualitative behavioral analysis (QBA), behavioral measures (BMs), and lesion and health measures (LHMs). Housing conditions (HCs) measured at each observation day were the number of pigs per pen, space allowance, temperature, light, and CO₂. The association study was performed using a general linear model and analysis of variance. Ventilation effect was analyzed by performing computational fluid dynamics. Results showed that overall pigs raised in the MV were in a more positive affective state. Despite that, with hot temperatures, the higher occurrence of pig soiling indicated heat stress in pigs and consequent welfare impairment. The higher frequency of pigs showing dog sitting behavior at T2 and T3 suggest welfare worsening in the last phases of fattening. The study concludes that ventilation system influences animal behavior and overall animal welfare, especially during the warmer season.

Risk factors for gastric ulceration in nursery pigs

Pars oesophageal gastric ulceration is a prevalent condition in swine production and often observed in finisher pigs at slaughter, with reported prevalence ranging from 32 % to 65 %. Although feeding practices in nursery and finisher pigs are similar, little is known about the prevalence and risk factors associated with this condition in nursery pigs. This prospective cohort study aimed to identify risk factors for gastric ulceration in nursery pigs. The objectives were: (1) to estimate the association of inherent pig characteristics (birth weight, sex, parity of sow, litter size, and pen fouling behavior) and management characteristics (antibiotic treatment during suckling and post weaning, piglet rotation during lactation, weaning age and weight) with pars oesophageal lesions; (2) to assess differences in gastric dry matter content, pH, and percentage of solid particles in the sediment in relation to pars oesophageal lesions. A total of 58 piglets tracked from birth to 20 days of age and 210 nursery pigs from birth to 10 weeks of age were euthanized and assessed for pars oesophageal gastric lesions. All nursery pigs were fed finely ground pelleted feed ad libitum. Based on a macroscopic assessment, the pigs' stomachs were categorized as either LPO "lesions in the Pars oesophagea" or NLPO "no lesions in the Pars oesophagea". We observed an overall prevalence of 26.2 % (CI 95 % 0.67 - 0.79) for LPO in nursery pigs at 10 weeks of age, while no lesion were observed in piglets at 20 days of age. A mixed multivariable logistic regression model showed that piglets with a birthweight ≤ 1.11 kg had a 2.11 times higher odds of LPO (CI 95 % 1.02-4.37, p = 0.04) than their heavier counterparts. There was a weak association of LPO in nursery pigs from pens with pen fouling with a 2.14 times higher odds (CI 95 % 0.97-4.72 p = 0.05). Nursery pigs with LPO presented an increased gastric content fluidity with a reduced (p ≤ 0.01) gastric dry matter content (18.7 %), solid phase (74.7 %), and pH (3.22) compared to NLPO nursery pigs (20.5 %, 85.09 %, 3.56, respectively). We have demonstrated that LPO are present in nursery pigs as early as 10 weeks of age. We observed that low birth weight is associated with higher odds for LPO in nursery pigs. These observations might help explain differences between individual pigs in terms of LPO development when groups are exposed to similar environments, management, and feeding conditions.

Review: Mitigating the risks posed by intensification in livestock production: the examples of antimicrobial resistance and zoonoses

Major shifts in how animals are bred, raised and slaughtered are involved in the intensification of livestock systems. Globally, these changes have produced major increases in access to protein-rich foods with high levels of micronutrients. Yet the intensification of livestock systems generates numerous externalities including environmental degradation, zoonotic disease transmission and the emergence of antimicrobial resistance (AMR) genes. Where the process of intensification is most advanced, the expertise, institutions and regulations required to manage these externalities have developed over time, often in response to hard lessons, crises and challenges to public health. By exploring the drivers of intensification, the foci of future intensification can be identified. Low- and middle-income (LMICs) countries are likely to experience significant intensification in livestock production in the near future; however, the lessons learned elsewhere are not being transferred rapidly enough to develop risk mitigation capacity in these settings. At present, fragmentary approaches to address these problems present an incomplete picture of livestock populations, antimicrobial use, and disease risks in LMIC settings. A worldwide improvement in evidence-based zoonotic disease and AMR management within intensifying livestock production systems demands better information on the burden of livestock-associated disease, antimicrobial use and resistance and resources allocated to mitigation.

Relationships between housing and management factors and clinical health events in elephants in North American zoos

Elephants experience a number of health issues that can contribute to their well-being and survival. In managed populations, housing conditions and management practices can influence individual health, so potential risk factors associated with morbidity or mortality should be identified to ensure the best possible standards of care. The goal of this study was to determine if the number of clinical events experienced could be a useful welfare indicator in zoo elephants, and to determine factors associated with key pathologies. We used an epidemiological approach to investigate how intrinsic (species, sex, age) and extrinsic (housing, management) factors were associated with both the total number of clinical events, and each of the four most prevalent pathology types (gastrointestinal issues, skin lesions, lameness, foot lesions), over a 12-month period. The study included 220 (127 African; 93 Asian) elephants housed at 61 facilities across North America. More than 1100 clinical events were identified. Species and sex differences were apparent in the types of pathology encountered, and unsurprisingly, the number of clinical events was positively correlated with age. Factors relating to housing (percent time with indoor/outdoor choice, space experience inside, number of unique environments an elephant was housed in, percent time on soft substrate) and management (enrichment diversity, spread of feeding opportunities) were also related to the number of clinical events. However, relationships were often counter to our initial hypotheses, highlighting caution in assuming cause and effect from correlational analyses such as these. Other welfare indicators such as serum and fecal glucocorticoids and serum prolactin were also associated with health status, being higher or more variable in individuals with a greater number of events. This approach provides insight into housing and management factors related to the health of these species in zoos, and in some cases, may reflect management changes that have already been made to mitigate existing or anticipated health concerns.

Effects of three husbandry systems on health, welfare and productivity of organic pigs

Organic pig husbandry systems in Europe are diverse - ranging from indoor systems with concrete outside run (IN) to outdoor systems all year round (OUT) and combinations of both on one farm (POUT). As this diversity has rarely been taken into account in research projects on organic pig production, the aim of this study was to assess and compare pig health, welfare and productivity in these three systems. Animal health and welfare were assessed using direct observation and records of 22 animal-based measures, comprising 17 health-, 3 productivity- and 2 behavioural measures. These were collected in pregnant sows, weaners and fattening pigs during direct observations and from records within a cross-sectional study on 74 farms (IN: n = 34, POUT: n = 28, OUT: n = 12) in eight countries. Overall, prevalence of several animal health and welfare issues was low (e.g. median 0% for pigs needing hospitalisation, shoulder lesions, ectoparasites; <5% for runts, tail lesions, conjunctivitis). Exceptions in particular systems were respiratory problems in weaners and fatteners (IN: 60.0%, 66.7%; POUT: 66.7%, 60.0%), weaning diarrhoea (IN: 25.0%), and short tails in fatteners (IN: 6.5%, POUT: 2.3%). Total suckling piglet losses (recorded over a period of 12 months per farm) were high in all three systems (IN: 21.3%; POUT: 21.6; OUT: 19.2%). OUT had lower prevalences of respiratory problems, diarrhoea and lameness of sows. POUT farms in most cases kept sows outdoors and weaners and fatteners similar to IN farms, which was reflected in the results regarding several health and welfare parameters. It can be concluded, that European organic pigs kept in all three types of husbandry system showed a low prevalence of health and welfare problems as assessed by our methodology, but respiratory health and diarrhoea should be improved in weaners and fatteners kept indoors and total piglet mortality in all systems. The results provide benchmarks for organic pig producers and organisations which can be used in strategies to promote health and welfare improvement. Furthermore, in future research, the identified health and welfare issues (e.g. suckling piglet mortality, weaning diarrhoea) should be addressed, specifically considering effects of husbandry systems.

Effect of incorporating fungal-media residue in bedding on domestic-pig growth performance and welfare in winter

Bedding materials significantly affect the health and growth performance of domestic pigs. The residue media from mushroom cultivation has potential as pig bedding because of its nutrient content for microbes and low cost. However, its components and granularity are heterogeneous. The present study investigated the effect of beddings containing fungal-residue media on the growth performance, stress response, thermoregulatory behaviour and general welfare of domestic pigs. During winter, 96 pigs were tested in a 2 × 4 factorial experiment involving fungal-residue media from production of Flammulina velutipes or Pleurotus eryngii, each added at rates of 0%, 15%, 45% or 60% of bedding that otherwise consisted of sawdust, rice husks, corn flour and Bacillus subtilis. After 98 days, growth factors and biomarkers of stress were analysed, and the condition of the bedding materials was examined. Fungal residues from either source, as 45% of bedding material, were associated with higher growth performance, lower stress, less huddling and higher immunity of pigs. Beddings with 45% fungal-media residues were also warmer, with lower levels of odorous chemicals, and higher numbers of beneficial microbes. No significant difference was observed between the two residue sources. Higher (60%) or lower (15%) concentrations of residue in beddings caused minor or insignificant improvements. In summary, bedding consisting of 45% fungal-residue media can improve the growth performance and welfare of domestic pigs during winter and is safe to promote.

Research trends in outdoor pig production - A review

Since the industrialization of swine production in the late 1900s, swine farms in the United States, as well as in Europe, have largely become consolidated. Pig farms became larger in size but fewer in number, with 91% of market pigs being produced by large operations with 5,000 or more pigs on-site in the US, and only 3% of the total utilized agricultural land representing organic farming. Such change in the market made it difficult for small farmers to stay competitive, forcing them to find alternative ways to reduce the cost of production and increase profit using the outdoor production system. In contrast to the indoor confinement system, outdoor production system uses pasture-based units and/or deep-bedded hoop structures that promote animal welfare and environmental sustainability with a lower capital investment. In accord with the growing concern for animal and environmental welfare and food safety by the consumers, small farmers practicing an outdoor production system are seeing increased opportunities for marketing their products in the pork niche market. Unlike the general belief that the reproductive and growth performance measures of the outdoor sows and piglets are poorer in comparison with the animals reared indoors, studies showed that there was no significant difference in the performance measures, and some traits were even better in outdoor animals. Improved reproductive and production traits can increase the sustainability of outdoor farming. Present study reviewed the recent studies comparing the performance measures, meat quality and health of indoor and outdoor animals, as well as the efforts to improve the outdoor production system through changes in management such as hut types and breed of animals.

Lesions found at routine meat inspection on finishing pigs are associated with production system

Pigs raised under free-range conditions are expected to experience a higher level of animal welfare than conventionally raised pigs. However, free-range conditions may challenge prevention and treatment of diseases. In order to identify disease problems associated with raising conditions, this study compared slaughter lesions in pigs from conventional indoor, conventional free-range and organic free-range production systems. The study used data from 1,096,756 pigs slaughtered at one Danish abattoir from 1 January 2013 to 31 December 2015. Associations between production system and lesions at slaughter were tested in statistical models taking year, season and herd of origin into account. Both conventional free-range and organic free-range production systems were associated with increased population averaged odd ratios (OR_PA) for several lesions compared with conventional indoor systems. Pigs raised in conventional free-range and organic free-range production systems had higher odds for white liver-spots (OR_PA, 5-7), tail lesions (OR_PA, 3-4), arthritis (OR_PA, 3), skin lesions (OR_PA, 3), bone fractures (OR_PA, 2), septicaemia (OR_PA, 1.1-1.5) and abscesses (OR_PA, 1.1-1.3) at slaughter. Pairwise comparisons of the two free-range production systems did not reveal statistically significant differences (P>0.05). In all three production systems, airway infection was the most prevalent disease complex. In contrast to previous studies, this study did not find any association between airway infection and type of production (P>0.05). Three lesions (leg swellings (OR_PA, 0.4-0.5), hernia (OR_PA, 0.7-0.8) and hoof abscess (OR_PA, 0.7-0.9)) had lower ORs in conventional free-range and organic free-range production compared with conventional indoor production. There was a marked herd effect (intraclass correlation coefficients 21-35%) on the occurrence of white liver-spots, tail lesions, skin lesions and airway infections. These results suggest possibilities for herd-level management interventions of the problems studied.

EMA and EFSA Joint Scientific Opinion on measures to reduce the need to use antimicrobial agents in animal husbandry in the European Union, and the resulting impacts on food safety (RONAFA)

EFSA and EMA have jointly reviewed measures taken in the EU to reduce the need for and use of antimicrobials in food-producing animals, and the resultant impacts on antimicrobial resistance (AMR). Reduction strategies have been implemented successfully in some Member States. Such strategies include national reduction targets, benchmarking of antimicrobial use, controls on prescribing and restrictions on use of specific critically important antimicrobials, together with improvements to animal husbandry and disease prevention and control measures. Due to the multiplicity of factors contributing to AMR, the impact of any single measure is difficult to quantify, although there is evidence of an association between reduction in antimicrobial use and reduced AMR. To minimise antimicrobial use, a multifaceted integrated approach should be implemented, adapted to local circumstances. Recommended options (non-prioritised) include: development of national strategies; harmonised systems for monitoring antimicrobial use and AMR development; establishing national targets for antimicrobial use reduction; use of on-farm health plans; increasing the responsibility of veterinarians for antimicrobial prescribing; training, education and raising public awareness; increasing the availability of rapid and reliable diagnostics; improving husbandry and management procedures for disease prevention and control; rethinking livestock production systems to reduce inherent disease risk. A limited number of studies provide robust evidence of alternatives to antimicrobials that positively influence health parameters. Possible alternatives include probiotics and prebiotics, competitive exclusion, bacteriophages, immunomodulators, organic acids and teat sealants. Development of a legislative framework that permits the use of specific products as alternatives should be considered. Further research to evaluate the potential of alternative farming systems on reducing AMR is also recommended. Animals suffering from bacterial infections should only be treated with antimicrobials based on veterinary diagnosis and prescription. Options should be reviewed to phase out most preventive use of antimicrobials and to reduce and refine metaphylaxis by applying recognised alternative measures.

Understanding the culture of antimicrobial prescribing in agriculture: a qualitative study of UK pig veterinary surgeons

OBJECTIVES

The use of antimicrobials in food-producing animals has been linked with the emergence of antimicrobial resistance in bacterial populations, with consequences for animal and public health. This study explored the underpinning drivers, motivators and reasoning behind prescribing decisions made by veterinary surgeons working in the UK pig industry.

METHODS

A qualitative interview study was conducted with 21 veterinary surgeons purposively selected from all UK pig veterinary surgeons. Thematic analysis was used to analyse transcripts.

RESULTS

Ensuring optimum pig health and welfare was described as a driver for antimicrobial use by many veterinary surgeons and was considered a professional and moral obligation. Veterinary surgeons also exhibited a strong sense of social responsibility over the need to ensure that antimicrobial use was responsible. A close relationship between management practices, health and economics was evident, with improvements in management commonly identified as being potential routes to reduce antimicrobial usage; however, these were not always considered economically viable. The relationship with clients was identified as being a source of professional stress for practitioners due to pressure from farmers requesting antimicrobial prescriptions, and concern over poor compliance of antimicrobial administration by some farmers.

CONCLUSIONS

The drivers behind prescribing decisions by veterinary surgeons were complex and diverse. A combination of education, improving communication between veterinary surgeons and farmers, and changes in regulations, in farm management and in consumer/retailer demands may all be needed to ensure that antimicrobial prescribing is optimal and to achieve significant reductions in use.

Growth performance and carcass characteristics of two genotypes of growing-finishing pig in three different housing systems

A trial was conducted to compare the growth performance and carcass characteristics of 720 growing pigs housed in one of three different finishing systems: outdoor paddocks, straw yards and fully slatted pens. Two genotypes were used: ‘indoor’ (progeny of Large White ✕ Landrace sows mated to Large White boars) or ‘outdoor’ (progeny of part-Duroc or part-Meishan sows, mated to Large White boars). Groups of 20 pigs were reared from an average of 30 to 80 kg live weight and given ad libitum access to a commercial specification diet. The outdoor genotypes had significantly lower average daily gain than the indoor genotype (682, 673 and 719 g respectively for part-Duroc, part-Meishan and indoor-type pigs, P 0·01). Part-Meishan genotypes had significantly higher backfat levels than the indoor genotype (P 0·05), with an intermediate value for part-Duroc pigs (22·6, 21·1 and 21·8 mm respectively). Values for food conversion ratio were significantly higher for combined outdoor genotype groups when compared with the indoor genotype (2·76 v. jt>2·62, P 0·05). Average daily gains of pigs in straw yards and outdoor paddocks were significantly higher than for those in fully slatted pens (736 and 675 v. 627 g, P 0·01 respectively). Food conversion ratio was similar for pigs in outdoor paddocks and fully slatted pens, but significantly lower for those in straw yards (2·77 and 2·75 v. 2·55, P 0·01 respectively). Backfat depth (P1 + P3mm) was significantly greater for animals finished in straw yards compared to those in outdoor paddocks (22·2 v. 20·6 mm, P 0·05) and intermediate for those finished in fully slatted pens (21·5 mm). Interaction between finishing system and genotype did not occur to any major degree, hence it appears unnecessary to specify a particular genotype for a particular finishing system. It was concluded that pigs of the outdoor genotype had a lower growth performance compared with the indoor genotype. Finishing systems however may have been confounded by other factors so that no clear recommendations can be made as to the optimum finishing system.

Impact of the amount of straw provided to pigs kept in intensive production conditions on the occurrence and severity of gastric ulceration at slaughter

This study examined effects of the amount of straw offered on occurrence and severity of gastric lesions in pigs kept in pens (18 pigs, 0.7 m(2)/pig) with partly slatted flooring and 10, 500 or 1000 g straw/pig/day from 30 kg live weight. The pigs had ad libitum access to dry feed. Forty-five pigs were used, three from each of 15 pens. After euthanization, the dimension of the non-glandular region of the stomach was measured. Lesions were characterized and scored. Irrespective of straw provided, 67% of the pigs showed signs of gastric pathology. Pigs provided with 500 or 1000 g straw were pooled as 'permanent access'. The proportion of pigs with ulcerations was reduced by permanent access to straw (7 vs. 33%; P<0.05), suggesting that permanent access to straw may improve animal health, and be considered as one possible strategy to limit gastric ulceration in pigs.

Variance components of aggressive behavior in genetically highly connected Pietrain populations kept under two different housing conditions

Mixing of unfamiliar pigs is a standard management procedure in commercial pig production and is often associated with a period of intense and physically damaging aggression. Aggression is considered a problem for animal welfare and production. The objective of the present paper was to investigate the genetic background of aggressive behavior traits at mixing of unfamiliar gilts under 2 different housing conditions. Therefore, a total of 543 purebred Pietrain gilts, from 2 nucleus farms (farm A: n = 302; farm B: n = 241) of 1 breeding company, were tested at an average age of 214 d (SD 12.2 d) for aggressive behavior by 1 observer. Observations included the frequencies of aggressive attack and reciprocal fighting during mixing with unfamiliar gilts. On farm A 41% of the gilts were purebred Pietrains, whereas 59% were purebred Landrace or Duroc gilts. On the farm B 42% of the gilts were purebred Pietrains, and 58% purebred Large White gilts. The average size of the newly mixed groups of gilts was 28 animals on farm A and 18 animals on farm B. The Pietrain gilts from the 2 herds were genetically closely linked. They were the offspring of 96 sires, with 64% of these sires having tested progeny in both farms. There were clear differences in the housing of the animals between the 2 farms. The test pen on farm A had a solid concrete floor littered with wooden shavings and was equipped with a dry feeder. On farm B there was a partly slatted floor, and the gilts were fed by an electronic sow feeder. Mean space allowance was 2.6 m(2)/gilt on farm A and 3.9 m(2)/gilt on farm B. Although large interindividual differences existed, gilts from farm B performed numerically more aggressive attack (mean 1.12, SD 1.42 vs. mean 0.71, SD 1.20) and reciprocal fighting (mean 0.78, SD 0.98 vs. mean 0.44, SD 0.82) when compared with gilts from farm A. The heritabilities and additive genetic variances for behavioral traits were estimated with a linear animal model and were on a low level in farm A (h(2) = 0.11, SE = 0.07, and σ(2)a = 0.12 for aggressive attack and h(2) = 0.04, SE = 0.07, and σ(2)a = 0.02 for reciprocal fighting) and on a moderate level in farm B (h(2) = 0.29, SE = 0.13, and σ(2)a = 0.44 for aggressive attack and h(2) = 0.33, SE = 0.12, and σ(2)a = 0.27 for reciprocal fighting). For both aggressive attack and reciprocal fighting, genetic correlation of the same trait between farm A and farm B was 1.0. Therefore, aggressive behavior does not seem to be influenced by genotype × environment interactions. Under these circumstances aggressions in group housing can be reduced by genetic selection against aggressive behavior. Therewith, the welfare and health of sows will ultimately increase.

Indirect genetic effects and housing conditions in relation to aggressive behaviour in pigs

Indirect Genetic Effects (IGEs), also known as associative effects, are the heritable effects that an individual has on the phenotype of its social partners. Selection for IGEs has been proposed as a method to reduce harmful behaviours, in particular aggression, in livestock and aquaculture. The mechanisms behind IGEs, however, have rarely been studied. The objective was therefore to assess aggression in pigs which were divergently selected for IGEs on growth (IGEg). In a one generation selection experiment, we studied 480 offspring of pigs (Sus scrofa) that were selected for relatively high or low IGEg and housed in homogeneous IGEg groups in either barren or enriched environments. Skin lesion scores, a proxy measure of aggression, and aggressive behaviours were recorded. The two distinct IGEg groups did not differ in number of skin lesions, or in amount of reciprocal fighting, both under stable social conditions and in confrontation with unfamiliar pigs in a 24 h regrouping test. Pigs selected for a positive effect on the growth of their group members, however, performed less non-reciprocal biting and showed considerably less aggression at reunion with familiar group members after they had been separated during a 24 h regrouping test. The enriched environment was associated with more skin lesions but less non-reciprocal biting under stable social conditions. Changes in aggression between pigs selected for IGEg were not influenced by G×E interactions with regard to the level of environmental enrichment. It is likely that selection on IGEg targets a behavioural strategy, rather than a single behavioural trait such as aggressiveness.

The welfare of growing pigs in five different production systems: assessment of feeding and housing

Ninety-one farms were visited over a 2-year period to assess the welfare of growing pigs in five different production systems found either in France or in Spain using the Welfare Quality® protocol. This study focused on animal-based measures as indicators of 'good feeding' and 'good housing'. Multiple Generalized Linear Mixed Models were performed for each measure to evaluate the differences between production systems and to detect possible causal factors. Pigs in the conventional system presented the lowest prevalence of poor body condition, whereas extensive Mallorcan Black pigs and extensive Iberian pigs were associated with a decreased prevalence of bursitis and pig dirtiness. The straw-bedded system presented a lower prevalence of bursitis, but poorer hygiene and more susceptibility of poor body condition than the conventional system. The age of the animals had a significant effect on the appearance of bursitis in the three intensive systems studied. The type of floor was a significant causal factor of bursitis and pig dirtiness in the conventional system and among intensive Iberian pigs. The feeding system was another causal factor of pig dirtiness on more than 50% of the body in the conventional system, whereas pig dirtiness on less than 50% of the body was influenced by the age of the animals. The prevalence of huddling animals in the conventional system was associated with the highest stocking densities and the lowest environmental temperatures. The results indicate that there were important differences between production systems based on animal-based indicators of the good feeding and housing principles. The recording of the age of the animals, type of floor, feeding system, stocking density and environmental temperature can be useful to predict the appearance of a given welfare measure of 'good housing' on a farm.

Behaviour and performance of pigs finished on deep bedding with wood shavings or rice husks in summer

Concern that excessive temperatures arising from substrate fermentation could have a deleterious effect on voluntary feed intake and weight gain, especially during the hottest times of the year, might be a barrier to the widespread adoption of deep-bedding systems for pig production in Brazil. The aim of this study was to compare the behaviour and performance of pigs reared on deep bedding with two different substrates, wood shavings and rice husks, or in barren, part-slatted, concrete-floored pens (n = 4 pens per treatment), from 60 days of age through to slaughter, during the summer months in Santa Catarina, southwest Brazil. Floor and pigs’ skin temperatures were 2.2 and 3.9% higher, respectively, in the pens with bedding than with concrete flooring; these differences resulted in modest, non-significant effects on performance and meat quality. Certain elements of the behaviour of pigs reared with bedding, such as increased play activity and substrate manipulation and less peer-directed behaviours, indicated improved welfare compared to pigs reared in concrete-floored pens. Performance and meat quality were similar in bedded pens with either wood shavings or rice husks. In both bedding substrates, the animals spent more time lying or standing on the beds than on the concrete platforms, where the feed and the water troughs were located, despite the higher temperature in the substrate compared to the concrete platform; suggesting that such temperature differences were not relevant for the thermal comfort of the animals. These results indicate that both substrates, abundant and readily available in the region, are suitable bedding materials for pigs.

A cross-sectional study of the prevalence and associated risk factors for bursitis in weaner, grower and finisher pigs from 93 commercial farms in England

A cross-sectional study of 93 farms in England was carried out to estimate the prevalence and associated risk factors for bursitis. A total of 6250 pigs aged 6-22 weeks were examined for presence and severity of bursitis. Details of pen construction, pen quality and farm management were recorded including floor type, presence of bedding, condition of the floor and floor materials. The prevalence of bursitis was 41.2% and increased with each week of age (OR 1.1). Two-level logistic regression models were developed with the outcome as the proportion of pigs affected with bursitis in a pen. Pigs kept on soil floors with straw bedding were used as the reference level. In comparison with these soil floors, bursitis increased on concrete floors where the bedding was deep throughout (OR 4.6), deep in part (OR 3.7), and sparse throughout (OR 9.0), part slatted floors (OR 8.0), and fully slatted floors (OR 18.8). Slip or skid marks in the dunging area (OR 1.5), pigs observed slipping during the examination of the pen (OR 1.3) and wet floors (OR 3.6) were also associated with an increased risk of bursitis. The results indicate that bursitis is a common condition of growing pigs and that the associated risk factors for bursitis were a lack of bedding in the lying area, presence of voids and pen conditions which increased the likelihood of injury.

A cross-sectional study of the prevalence and associated risk factors for capped hock and the associations with bursitis in weaner, grower and finisher pigs from 93 commercial farms in England

The prevalence of capped hock in 5601 post-weaning pigs from 93 pig farms in England was 17.2%. The prevalence increased with age. Once adjusted for age, the lowest prevalence of capped hock was observed in pigs kept on soil floors (usually covered with deep straw bedding). There was no significant increase in the risk of capped hock in pigs kept on solid concrete floors with deep straw bedding. However, pigs kept on solid concrete with some, or the entire pen, sparsely bedded and pigs kept on partially or fully slatted floors had an approximately threefold increased risk of capped hock. This did not vary significantly between these four floor types. This was in contrast to the associated risks for bursitis in the same pigs, where as the floor went from highly resilient (straw and solid floors) to hard and perforated (fully slatted) the risk of bursitis increased in a similar way to a dose response. No other variables that were measured were associated with a change in risk for capped hock, while observation of pigs slipping or slip marks and wet, dirty and worn pens were also associated risks for bursitis. These results indicate that capped hock and bursitis are both affected by exposure to floors, but in different ways. The prevalence of capped hock was associated only with floor hardness, with deep straw protecting the pigs, while bursitis was associated with both changes in bedding depth (hardness), floor material (soil versus concrete) and floor construction (solid versus slatted floors) and in factors associated with locomotion (slipping and slip marks). These results indicate that the aetiology of capped hock and bursitis might differ.

The welfare of finishing pigs under different housing and feeding systems: liquid versus dry feeding in fully-slatted and straw-based housing

This study assessed the health and welfare implications of feeding pigs a dry or liquid diet when housed in either fully-slatted or straw-based accommodation. Between April and October 2002, 1024 (Large White × Landrace) × Large White pigs, housed in pens of 32, were fed ad libitum from 34 kg to slaughter at 104 kg liveweight. Data were collected on a range of welfare parameters. Feeding system affected only respiratory health losses. Lameness and tail-biting tended to be more prevalent health conditions in the fully-slatted system, while in the straw-based system pigs showed significantly more enteric and respiratory disease. There were no significant treatment effects on skin lesions or bursitis of the hock. Liquid fed pigs had poorer hygiene scores than dry fed pigs, especially in straw-based housing. Liquid feeding reduced activity level and investigatory behaviours directed towards other pigs. Pigs with straw spent a large proportion of their time manipulating it. Pigs without straw were less active and spent more time manipulating the pen hardware. In post-slaughter assessments, there were no systems differences in lung lesions or osteochondrosis, but other measures differed between housing or feeding systems; pigs with straw had more severe toe erosions on the foot, while pigs without straw had more severe heel erosions. Gastric lesions were more pronounced with dry feeding and in the fully-slatted system. The results highlight the relative health and welfare advantages and disadvantages of these systems for finishing pigs.