Assessment of documentation provided on the use of rubber slats in the flooring of pig holdings 1

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1 EFSA Journal 2014;12(12):3959 SCIENTIFIC REPORT OF EFSA Assessment of documentation provided on the use of rubber slats in the flooring of pig holdings 1 European Food Safety Authority 2,3 European Food Safety Authority (EFSA), Parma, Italy ABSTRACT The Commission requested EFSA to assess three studies concerning the use of rubber slats in pig holdings regarding the statistical differences between the welfare outcomes for sows and gilts when comparing concrete slatted floors and floors with a rubber overlay. The appropriateness of the methods used was assessed with respect to objectives of the studies and minimisation of the risk of bias. Measures and methods of measurements applied in the studies were compared against animalbased and non-animal-based measures recommended in EFSA opinions. The risk factors and needs of different categories of pigs regarding flooring as outlined in EFSA opinions were compared. The validity of studies A and B is questionable because of the way the field experiments were performed and/or reported. Their results must be used with caution because of the risk of bias identified. The power of study B is possibly insufficient to detect any biologically relevant effects. Studies A and B only partially use welfare measures that are relevant for assessing the degree of compliance with the legal minimum requirements. The validity of study C is low because of some fundamental limitations in the methods used to perform the study and/or the way methods are described in the report. It does not provide relevant information regarding the degree of compliance of rubber floor with legal minimum requirements. Therefore, results of study C cannot be used to provide evidence of the effect of rubber floor on welfare of sows. The findings of the three studies cannot be extrapolated to other pig categories. Experimental studies should cover the entire range of legal minimum floor requirements in the outcomes assessment and be done under different thermal scenarios. Variability at different experimental unit levels (i.e. individual animal, pen and farm level) should be adequately addressed in order to provide representative results. European Food Safety Authority, 2014 KEY WORDS Sows, flooring, welfare, rubber, animal-based measures On request from the European Commission, Question No EFSA-Q , approved on 12 December Correspondence: ALPHA@efsa.europa.eu Acknowledgement: EFSA wishes to thank the EFSA Animal Health and Welfare Panel members: Sandra Edwards and Antonio Velarde for review of this scientific output, and EFSA staff: Andrea Gervelmeyer, Irene Alpigiani, Laura Ciccolallo and Laura Martino for the support provided to this scientific output. Suggested citation: EFSA (European Food Safety Authority), Assessment of documentation provided on the use of rubber slats in the flooring of pig holdings. EFSA Journal 2014;12(12):3959, 43 pp. doi: /j.efsa Available online: European Food Safety Authority, 2014

2 TABLE OF CONTENTS Abstract... 1 Background as provided by the European Commission... 3 Terms of reference as provided by the European Commission... 3 Assessment Introduction Data and methodologies Results Critical appraisal of the quality of the studies Critical appraisal of the quality of study A Appropriateness of study methodology for meeting the objective Bias due to incompliance to a priori defined methodology Selection bias Performance bias Detection bias Attrition bias Selective reporting bias Critical appraisal of the quality of study B Appropriateness of study methodology for meeting the objective Bias due to incompliance to a priori defined methodology Selection bias Performance bias Detection bias Attrition bias Selective reporting bias Critical appraisal of the quality of study C Suitability of welfare measures applied in the studies Suitability of welfare measures applied in study A Suitability of welfare measures applied in study B Suitability of welfare measures applied in study C Relevance of study findings for other pig categories Discussion Conclusions and recommendations References Appendix A. Critical appraisal tool for controlled trials in livestock Appendix B. Comfort around resting: Animal-based and Non-animal based measures cited in the EFSA opinions regarding floors in the swine species and assessment of the articles under evaluation. 29 Appendix C. Ease of movement: Animal-based and Non-animal based measures cited in the EFSA opinions regarding floors in the swine species and assessment of the articles under evaluation Appendix D. Thermal comfort: Animal-based and Non-animal based measures cited in the EFSA opinions regarding floors in the swine species and assessment of the articles under evaluation Appendix E. Absence of injuries: Animal-based and Non-animal based measures cited in the EFSA opinions regarding floors in the swine species and assessment of the articles under evaluation 38 Appendix F. Pigs categories and their needs (EFSA 2007 a, b) EFSA Journal 2014;12(12):3959 2

3 BACKGROUND AS PROVIDED BY THE EUROPEAN COMMISSION Article 3(2) of Council Directive 2008/120/EC 4 on the protection of pigs contains specifications for the flooring surfaces, especially the size of gap openings in concrete slatted floors. Other provisions pertinent to the issue of floors are laid down in Annex I, Chapter I Paragraphs 3 and 5 and in Chapter II for the various categories of pigs. The Commission has received two requests concerning the use of rubber slats in pig holdings. One is from a Member State who refers to the outcomes of a study published in a peer reviewed article 5. The other request is from the industry that has provided three references, one of which is the same study referred to by the Member State 6. TERMS OF REFERENCE AS PROVIDED BY THE EUROPEAN COMMISSION The Commission requests EFSA, in the framework of Article 31 of Regulation (EC) No 178/2002 to review the different cases on the use of rubber slats/materials on the basis of the attached documentation and to conclude on the following: 1. Are there statistical differences between the welfare outcomes for sows and gilts when comparing concrete slatted floors and floors where there is a rubber overlay? 2. Are the conclusions scientifically valid for sows and gilts or are there uncertainties or weaknesses in one or more of the studies? 3. Can the results for sows and gilts be extrapolated to rearing pigs and piglets? The scientific assessment should include the criteria to assess the degree of compliance with the legal minimum requirements, i.e. overall quality of lying area, smooth non-slip floor to prevent injuries, suitable for size of pigs, allowing pigs to rest and get up normally and cleanliness. 4 Council Directive 2008/120/EC laying down minimum standards for the protection of pigs; OJ L47, , p. 5 5 Calderón Díaz JA, Fahey AG, KilBride AL, Green LE and Boyle LA, Longitudinal study of the effect of rubber slat mats on locomotory ability, body, limb and claw lesions, and dirtiness of group housed sows. Journal of Animal Science, 91, Calderón Díaz JA, Boyle LA, Effect of rubber slat mats on the behaviour and welfare of group housed pregnant sows. Applied Animal Behaviour Science, 151, Boyle LA and Calderón Díaz JA, Chapter 5 Effect of housing on rubber slat mats during pregnancy on the behaviour and welfare of sows in farrowing crates. In: Effect of Rubber Covered Slats on the Behaviour, Health and Welfare of Group Housed Sows. Final Report to EasyFix Rubber Products, June EFSA Journal 2014;12(12):3959 3

4 ASSESSMENT 1. INTRODUCTION The three studies submitted to EFSA present work administered by Teagasc s Walsh Fellowship Scheme through funding from Enterprise Ireland and EasyFix TM Ruber Products. The first study (Calderón Díaz et al., 2013) was carried out between October 2010 and February The objective of the study, as stated by the authors, was to compare the locomotory ability and claw, limb, and body lesion scores of 164 replacement gilts housed on concrete slatted floor (n=84) or rubber slat mats (n=80) over 2 parities. In this document the study is referred to as study A. In study A the control animals were housed during two gestation periods in pens with free access feeding stalls (each 1.51 m length by 0.75 m width by 1.23 m height) and a group area (2.40 m length by 2.94 m width) on conventional concrete slatted flooring (slat width 13 cm, gap width 2 cm, gap length 76 cm, and void area = 9.7%). The treatment sows were housed in pens of the same design during gestation, however, the slats in both the feeding stalls and the group area were covered with rubber slat mats (2.60 m length by 0.30 m width by 0.01 m height; void area = 6%). Observation of outcome measures took place during the gestation periods (Figure 1). The second study (Calderón Díaz and Boyle, 2014) was carried out between March 2011 and June The objective of the study, as stated by the authors, was to compare lameness, limb and body lesion scores of 64 sows housed on concrete slatted floor (n=32) or rubber slat mats (n=32) and to evaluate the effect of flooring type, lameness, body and limb lesion scores on postural and spatial behaviour of gestating sows. In this document the study is referred to as study B. In study B the control animals were housed during gestation in pens with free access feeding stalls (each 1.71 m L 0.65 m W 1.02 m H) and a group area (3.20 m L 2.68 m W) on concrete slatted flooring (slat width 14.5 cm, gap width 2 cm; void area = 8.2%). The treatment sows were housed during gestation in pens of the same design, in which the group area (3.20 m L 2.68 m W) was covered with rubber slat mats (1.60 m L 0.29 m W 0.01 m H; void area = 8.2%). Observation of outcome measures took place during the gestation period (Figure 1). The objective of the third, unpublished study (Boyle and Calderón Díaz, 2014), as stated by the authors, was to test whether reduced lameness and limb lesion scores expected to arise from housing on rubber flooring during pregnancy lead to better posture changing behaviour and lower limb lesion scores for sows in farrowing crates. The study is a continuation of study B in as far as it is an observation during the farrowing/lactation period of the same animals that were treated and observed during gestation in study B after they were moved to the farrowing crates. In this document the study is referred to as study C. In study C the animals were not exposed to any treatment at the time of observation but simply observed for their locomotory ability in the farrowing crates following the different gestation treatments of study B (Figure 1). Figures 2 and 3 provide an overview of the behavioural, animal- and resource-based measures used in the studies to measure the effect of rubber floor on welfare. The measurement methodology of the measures used was the same in all three studies (see Appendix B-E). EFSA Journal 2014;12(12):3959 4

5 Exposure to treatment Gestation 1 Study A Farrowing/ Lactation nd Gestation 2 Study B Gestation Study C Farrowing/ Lactation nd Observation nd Rubber mat position feeding stalls and group area feeding stalls and group area group area Figure 1: Overview of timing of exposure to rubber mats and of observation, and position of rubber mats in the studies assessed ( = exposure to treatment; = observation carried out; nd = not done) Spatial behaviour 1 Postural behaviour in group area Postural behaviour in feeding area Postural changes Lying down behaviour Postural behaviour Study A nd nd nd nd nd nd Study B x x x x nd nd Study C 2 na na na na x x Figure 2: Behavioural measures used in the studies assessed ( 1 group vs feeding area, 2 measures during farrowing; x=done; nd=not done; na=not applicable) Locomotory ability Claw lesions Limb lesions Body lesions Limb Body condition conformation score Manure on the body Flooring cleanliness Study A x x x x x x x x Study B x nd x x nd nd x x Study C 1 x nd x nd nd nd nd nd Figure 3: Animal- and resource-based measures used in the studies assessed ( 1 measures during farrowing; x=done; nd=not done; na=not applicable,) 2. DATA AND METHODOLOGIES The data reviewed in the assessment encompasses the data provided in the three papers submitted by the requestor. In order to assess if statistical differences exist between the welfare outcomes for sows and gilts when comparing concrete slatted floors and floors with a rubber overlay (ToR 1) and if the conclusions are scientifically valid for sows and gilts or if uncertainties or weaknesses in one or more of the studies exist (ToR 2), the quality of the studies was critically appraised using a Critical Appraisal Tool (CAT) designed by EFSA aiming at providing a standardised approach for assessing the internal validity of controlled trials for livestock (Appendix A). A list of items, that are considered relevant, is provided in the CAT. They are grouped according to two main methodological requirements: EFSA Journal 2014;12(12):3959 5

6 appropriateness of the methods used with respect to the objectives of the studies; minimisation of the risk of bias. The items belonging to the first category are mainly based on the previous work done by EFSA on critical appraisal tools for Randomized Controlled Trials (not published) and the REFLECT statement (O Connor et al., 2010) and related Explanation and Elaboration document (Sargeant et al., 2010), proving guidelines for reporting controlled trials for livestock. The REFLECT approach has been adapted here to take into consideration the need to move the focus from the reporting to the appraisal exercise. The second category relies on the definition and characterization of the risk of bias provided in the Cochrane Handbook for Systematic Reviews of Interventions Version (Higgins and Green, 2011). According to Cochrane s approach, the bias is classified into the following categories: selection bias; performance bias; detection bias; attrition bias; selective reporting bias. A further category was added to cover the issue of compliance with pre-defined methodologies/protocol: Bias due to non-compliance with respect to a priori defined methodologies (Protocol, if any). It is recognised that quality of reporting is a pre-requisite in order to allow the assessment of the methodological quality of a study. This is reflected in the way experts judgements are defined (listed below separately for appropriateness and risk of bias): Definitively appropriate: there is direct evidence in the study that appropriateness requirements are met; Probably appropriate: there is indirect evidence in the study that appropriateness requirements are met; Probably not appropriate: there is either indirect evidence in the study that appropriateness requirements are not met or there is no evidence that appropriateness requirements are met; Definitively not appropriate: there is direct evidence in the study that appropriateness requirements are not met; Definitively low risk of bias: there is direct evidence in the study that risk of bias is low; Probably low risk of bias: there is indirect evidence in the study that risk of bias is low or; Probably high risk of bias: there is either indirect evidence in the study that risk of bias is high or there is no evidence of low risk of bias; Definitively high risk of bias: there is direct evidence in the study that risk of bias is high. The items are not weighted, so the issue of the relative importance of each item is not addressed. A narrative summary of them is provided by the assessors based on their judgement. To further address ToR 2, it was reviewed if the welfare measures applied in the studies were relevant for assessing the degree of compliance with the legal minimum requirements outlined in Annex I, Chapter I Paragraphs 3 and 5 and in Chapter II for the various categories of pigs of Council Directive 2008/120/EC, i.e. overall quality of lying area, smooth non-slip floor to prevent injuries, suitable for size of pigs, allowing pigs to rest and get up normally and cleanliness. It was also assessed if these measures were correctly applied. This was done by consulting the EFSA scientific opinions on the use of animal-based measures to assess welfare in pigs (EFSA, 2012), on animal health and welfare in fattening pigs in relation to housing and husbandry (EFSA, 2007a), on animal health and welfare aspects of different housing and husbandry systems for adult breeding boars, pregnant, farrowing sows and unweaned piglets (EFSA, 2007b) and on the welfare of weaners and rearing pigs: effects of different space allowances and floor types (EFSA, 2005). Animal-based and non-animal-based EFSA Journal 2014;12(12):3959 6

7 measures relevant for flooring and the descriptions of the method to obtain the measurements recommended in these documents were collated as references against which the measures and methods of measurements applied in the studies were compared (see Appendix B-E). Potential outcomes of the assessment were defined a priori as: 1 measure appropriate to assess the welfare criterion AND method of measurement appropriate 2 measure appropriate to assess the welfare criterion AND method of measurement not appropriate 3 measure not appropriate to assess the welfare criterion For ToR 3, to assess if the results for sows and gilts can be extrapolated to rearing pigs and piglets, the risk factors/hazards and needs regarding flooring of different categories of pigs as outlined in EFSA opinions (EFSA, 2007 a and b) were compared (see Appendix F). EFSA Journal 2014;12(12):3959 7

8 3. RESULTS 3.1. Critical appraisal of the quality of the studies Critical appraisal of the quality of study A Appropriateness of study methodology for meeting the objective The study has some limitations in terms of design, due to the mixing of experimental units for the second gestation group of the experiment (i.e. it is not clear if all sows exposed to rubber/control floor in the first gestation group of the experiment were also exposed to the same treatment of rubber/control floor in the second gestation group). The choice of the variables introduced in each statistical model is insufficiently documented and the related reporting is limited. This makes it difficult to understand the extent to which the effect estimates of the rubber mat treatment are biased (free from confounding). Some measures of effect are quite large, but their precision is rather low as shown by large confidence intervals. This means that data are compatible with quite smaller effects. Dichotomisation of the scores of the different measurements for the analysis was not planned a priori. This could have introduced a bias. The method of calculation used to compute medians is unclear (i.e. whether medians were calculated within or across treatments). Overall, it is concluded that a definitely high risk of bias is present for the second phase of the experiment (gestation 2) and that a probably high risk of bias is present for the first phase of the experiment (gestation 1) Bias due to incompliance to a priori defined methodology It is considered that the risk of bias is probably high because of the lack of evidence of a priori choices which affects mainly the statistical analysis Selection bias The study does not contain any information regarding random generation of the sequence for treatment allocation and its concealment, i.e. the mechanism used to implement the random allocation sequence, describing any steps taken to conceal the sequence until interventions were assigned (Consort, 2010). Sows included in the second gestation phase were a mixture of experimental animals from treatment or control groups in the first gestation period, unfamiliar experimental sows and nonexperimental animals (more than 50%), resulting in likely unbalanced comparison groups. There is a probably low risk of selection bias for the first gestation group and a probably high risk of selection bias for the second gestation group Performance bias Apart from the flooring in the group area, the animals assigned to the treatment/control groups were exposed to the same environmental conditions. Therefore, a probably low risk of performance bias is present Detection bias It is not clear whether outcome assessors were blinded to the treatment in the cases where this would have been possible (e.g. locomotory ability, claw, limb and body lesions). However, the methodologies used for measuring the outcomes are clearly defined and highly standardised. Therefore, overall there is a probably low risk of detection bias Attrition bias Twenty-four sows were culled during the experimental period (12 sows (7.3 %) from each treatment; 11 due to leg problems (10 controls, 1 treated), 6 due to reproductive failure (1 control, 5 treated), 7 due to other reasons (1 control, 6 treated)). This probably has affected the final outcome. Therefore, it is considered that there is a probably high risk of attrition bias. EFSA Journal 2014;12(12):3959 8

9 Selective reporting bias Rubber floor and pig welfare A definitely high risk of selective reporting bias is noted, since measures of outcomes at artificial insemination were not reported and the effect estimates adjusted for covariates that have subsequently not been included in the final multivariable models were not shown Critical appraisal of the quality of study B Appropriateness of study methodology for meeting the objective The experiment is not considered to be powerful enough to detect small differences between the two treatment groups because of the small sample size (8 experimental units per treatment/control). The choice of the variables introduced in each statistical model is insufficiently documented and the related reporting is limited. Overall it is concluded that the study is probably not appropriate to meet the objective Bias due to incompliance to a priori defined methodology A probably high risk of bias is present in the study because of the lack of a protocol, affecting mainly the statistical analysis Selection bias Neither random generation of the sequence for treatment allocation nor any allocation concealment are mentioned. The treatment and control groups were balanced per lameness on day 1, previous housing system and body weight. Overall, there is a probably low risk of selection bias because, despite the lack of randomization, the two groups seem to be balanced according to important factors Performance bias Apart from the flooring in the group area, the animals assigned to the treatment/control groups were exposed to the same environmental conditions. Therefore, a probably low risk of performance bias is present Detection bias It is not clear whether outcome assessors were blinded to the treatment in the cases where this would have been possible (e.g. locomotory ability, limb and body lesions). However, the methodologies used for measuring the outcomes are clearly defined and highly standardised. Therefore, overall there is a probably low risk of detection bias Attrition bias Only four animals were culled or died during the study period. This is considered a probably low risk of attrition bias Selective reporting bias A definitely high risk of selective reporting bias is noted, since only statistically significant results have been reported Critical appraisal of the quality of study C It is stated by the authors that study C tests a past exposure (during gestation). However, the study cannot be used for confirmatory purposes (i.e. to accept or reject a hypothesis) on its own since animals were not exposed to any treatment during study C, but simply observed for their locomotory ability and postural behaviour during the farrowing/lactation period after having been housed in pens EFSA Journal 2014;12(12):3959 9

10 with rubber mats or concrete floor in the gestation period (in study B) preceding the observations carried out in study C. Controlling the outcome measures for initial lameness on transfer to farrowing, the results of the study could be interpreted as the extent to which clinical lameness (which might have been a result of the flooring in gestation), mediated the effects on subsequent lying behaviour and lesions. However the study does not investigate sufficiently the extent to which the behaviour in the farrowing crates can be explained by the differences in locomotory ability at the moment of transfer. The methodology used for the statistical analysis of the data is poorly described in the report and makes it difficult to appraise the validity of the study. It is not clear from the report for instance which statistical model was used, which factors were controlled for or which groups of animals were compared. Therefore results from study C were considered to not provide evidence on the effect of rubber floor on welfare of sows Suitability of welfare measures applied in the studies The minimum legal requirements listed in Council Directive 2008/120/EC were matched to the welfare criteria relevant for flooring: comfort around resting, ease of movement, thermal comfort and absence of injuries. Comfort around resting is considered to be related to the minimum legal requirements rest normally, lying area physically comfortable, smooth floor, floors suitable for the size and weight of the pigs, rigid, even and stable surface, if no litter is provided, lying area adequately drained and clean. Ease of movement is considered to be related to the minimum legal requirements get up normally, floors not slippery, floors suitable for the size and weight of the pigs, rigid, even and stable surface, if no litter is provided. Thermal comfort is considered to be related to the minimum legal requirement lying area thermally comfortable. Absence of injuries is considered to be related to the minimum legal requirements floors designed, constructed and maintained as not to cause injury or suffering to pigs, floors suitable for the size and weight of the pigs, rigid, even and stable surface, if no litter is provided. The relation of the minimum legal requirements for floors listed in Council Directive 2008/120/EC, the welfare criteria and the welfare measures suggested by EFSA (EFSA, 2012) to assess them is shown in Figure 4. EFSA Journal 2014;12(12):

11 smooth floor lying area adequately drained and clean rest normally floors suitable for the size and weight of the pigs get up normally floors suitable for the size and weight of the pigs floors suitable for the size and weight of the pigs rigid, even and stable surface rigid, even and stable surface rigid, even and stable surface lying area physically comfortable floors not slippery lying area thermally comfortable floor does not cause injury or suffering to pigs Comfort around resting Ease of movement Thermal comfort Absence of injuries Shoulder lesions Slipping / Falling Lying posture Locomotion score Swollen bursae Claw / Foot lesions Lying location Skin lesions Manure on the body Panting Teat damage Floor cleanliness Claw / Foot lesions Lying location Lying posture Figure 4: Minimum legal requirements for floors listed in Council Directive 2008/120/EC, their related welfare criteria and the welfare measures suggested by EFSA to assess them For most of the welfare criteria the EFSA scientific opinions listed more than one welfare measure as relevant (Figure 4). For Comfort around Resting the welfare measure considered to be most specific and required for this assessment are: Shoulder lesions OR Swollen bursae AND Manure on the body OR Floor cleanliness AND Lying location AND Lying posture. For Ease of movement both Slipping/Falling and Claw /Foot lesions are considered to be required for the assessment. For Thermal Comfort all welfare measures listed in the EFSA opinion (EFSA, 2012) ( Lying posture AND Lying location AND Panting ) are considered to be required for the assessment. For Absence of injuries in this assessment the welfare measures Locomotion score AND Claw /Foot lesions AND Skin lesions, which include shoulder, limb, body and tail lesions, are considered to be required for the assessment. Teat damage provides both an indication of the suitability of the stocking density (ratio of animal number to space) and on the floor suitability. It is therefore not considered to be a required measure for this assessment Suitability of welfare measures applied in study A Of the relevant and specific measures related to Comfort around resting shoulder lesions and manure on the body/floor cleanliness were measured, the lying location and the lying posture were not evaluated. Of the relevant and specific measures related to Ease of movement only claw lesions were assessed. In addition, the authors assessed locomotory ability and limb lesions which provide specific information regarding ease of movement. However, it was not assessed if animals slipped or fell which is considered relevant for the assessment given that slipperiness of the floor has an impact especially on larger animals such as sows. EFSA Journal 2014;12(12):

12 Regarding Thermal comfort, none of the required measures deemed to be specific for the assessment of the effect of floor on this criterion were evaluated. In the context of this study where both feeding and group area were covered with rubber slats an assessment of the effect this has on thermal comfort of the sows by measuring e.g. lying posture or postural changes or postural time budgets, i.e. the time spent in a given position, would have been necessary. Of the relevant and specific measures related to Absence of injuries all were evaluated. In addition the authors assessed also limb lesions, which is a specific and useful measure. All measurements are considered to have been carried out in an appropriate manner. In conclusion, study A only partially uses welfare measures that are relevant for assessing the degree of compliance with the legal minimum requirements. Particularly non-slippery floor and thermal comfort have not been addressed appropriately Suitability of welfare measures applied in study B For the Comfort around resting criterion all the measures were assessed appropriately. Several behavioural measures such as postural behaviour in group and feeding areas and postural changes were assessed in addition, which can be considered useful and specific information for the assessment regarding comfort around resting. Regarding Ease of movement none of the required measures for the effect of flooring on this criterion were evaluated. Instead, the authors evaluated locomotory ability, limb lesions and behavioural measures such as postural behaviour in group and feeding areas and postural changes which can be considered useful measures of ease of movement. However, it was not assessed if animals slipped or fell which is considered relevant for the assessment given that slipperiness of the floor has an impact especially on larger animals such as sows. Regarding Thermal comfort only the behavioural measures of spatial behaviour and postural changes were assessed. While panting is seen in pregnant sows in extreme climates, postural time budgets would have provided an indication of the thermal comfort of the sows under the study conditions. Therefore it is considered that conclusive evidence has not been demonstrated for this criterion. For the criterion Absence of injuries the authors assessed the measure limb lesions instead of foot lesions and also assessed postural changes in addition to locomotion score and skin lesions on the shoulder. All measurements are considered to have been carried out in an appropriate manner. In conclusion, study B only partially uses welfare measures that are relevant for assessing the degree of compliance with the legal minimum requirements. Particularly non-slippery floor and thermal comfort have not been addressed appropriately. It is further suggested to also include the assessment of claw lesions in the assessment of the criterion absence of injuries Suitability of welfare measures applied in study C Study C is an observational study that was carried out during farrowing/lactation. Therefore a limited set of animal-based measures were assessed since sows were housed in farrowing crates (Figure 2, 3), focussing on Absence of injuries. In addition to measures listed in the EFSA opinions, behavioural measures such as postural behaviour and lying down behaviour were assessed. In conclusion, study C does not provide relevant information regarding the degree of compliance of the rubber floor with the legal minimum requirements. EFSA Journal 2014;12(12):

13 3.3. Relevance of study findings for other pig categories Rubber floor and pig welfare Testing and approving of animal housing installations is not mandatory within the EU countries. Floor properties are determined by technical tests and other physical, chemical and technical descriptions (EFSA, 2005). However, for a complete assessment animal-based welfare outputs regarding behaviour, health and performance should be evaluated (EFSA, 2012). For this assessment, the risk factors/hazards and needs regarding flooring of boars, dry sows, pregnant sows, farrowing sows, piglets and fattening pigs as outlined in EFSA opinions (EFSA, 2007 a and b) were compared (see Appendix F). Overall, the risk factors can be summarised in two types: poor flooring condition and poor thermal conditions. No major differences exist between the different pig categories regarding their flooring needs, which are to rest and sleep, exercise, to thermoregulate and to avoid pain (lameness). However, floor properties affect different categories of pigs in a different way. Floor type is considered to influence the thermoregulatory activity of pigs (EFSA, 2005). Because of their small size thermal properties of the flooring are important for piglets. Dry sows are susceptible to hypothermia in cold conditions due to the limited amount of feed administered in this phase. On the other hand, finishing pigs are affected by the need to disperse excess body heat. The softness of the floor is of greater importance for larger size animals (sows, finishing pigs, boars) compared to smaller size animals (piglets, weaners) since the contact pressure on the lying area of the larger size animals is greater compared to piglets or weaners (EFSA, 2005). Floor softness is important for pregnant sows and their lying comfort, since they spend most of the time resting and lying (Tuyttens et al., 2008, Elmore et al., 2010). In relation to softness, finishing pigs may have needs similar to sows, however with decreasing body condition and increasing weight pressure, the softness needs of sows become greater than those of finishing pigs. EFSA (2007a) recommended that the flooring for piglets should have small void areas and low abrasiveness (EFSA, 2007a). Abrasiveness of the floor is supposed to cause lesions in the animals (Savary et al., 2009) and was associated with carpal joint and claw lesions in piglets (Mouttotou et al., 1999). For sows on the other hand, the flooring characteristics should provide a good foothold and sufficient abrasiveness (EFSA, 2007a). Slipperiness of the floor is linked to abrasiveness and cleanliness of the floor and has an impact especially on large size animals. The appropriate relation of solid versus gap areas depends on the pig s foot dimensions, thus different dimensions of the slatted flooring need to be considered for piglets as opposed to fattening pigs, sows and boars in order to avoid lesions. Social behaviour is affected when mixing pigs from different groups, e.g. of different litters of piglets at weaning or of sows moving into group housing for gestation; hence housing conditions and particularly flooring properties should be adequate to support the animals in these critical phases, in order not to impede their welfare (EFSA, 2005). Cleanliness of the flooring affects the coefficient of friction, increasing the likelihood for the bigger size animals to slip and fall (EFSA, 2005). In conclusion, the findings of the studies cannot be extrapolated to other categories of pigs Discussion Effective temperature influences pigs thermoregulatory behaviour: when temperature increases, in order to disperse heat, pigs prefer to lie laterally increasing the contact with the floor, especially if the surface is soft and comfortable (Tuyttens, 2008; Savary et al., 2009; Elmore et al., 2010). Temperature and thermal comfort of gilts and sows was not investigated in study A; in study B the authors discuss the influence of temperature on thermoregulatory behaviour of sows, but as the temperature range was EFSA Journal 2014;12(12):

14 within the sows thermoneutral zone, it was assumed that the temperature did not affect the behaviour of the sows. The properties of the floor also have an impact on the animals thermal comfort. Rubber mats floor provides insulation which could influence thermoregulatory behaviour of pigs (especially of large size categories) living in warm areas. When the room temperature rises above the thermoneutral zones, sows have been shown to prefer lying on concrete floors rather than on mats (Tuyttens et al., 2008). For this reason the findings of study B cannot be generalised to other geographical areas and room temperatures. The required duration of an assessment depends on the animal-based measures assessed. Some welfare measures (e.g. slipping, ease of posture changing, lying postures indicative of comfort) can be evaluated in one-day assessments. Other effects may take longer to become apparent, especially as materials start to wear (e.g. development of lesions, lameness, bursitis from prolonged pressure over bony protuberances). In the case of pregnant sows, the suitability of the flooring may change with the stage of pregnancy (newly weaned sows show greater activity and riding behaviour where slipping is greater risk, late pregnant sows become very heavy and need more time for posture changes). Characteristics of the animal category and breed also need to be considered when assessing the potential presence of bias. In the case of sows, the risk of shoulder lesions from hard flooring may vary between breeds; there is a genetic component of this condition which probably relates to the anatomy and conformation of the limb. It is also likely that effects of age (weight) and body condition on ease of posture changing (slipping) and risk of lesions exist. The number of parities per sow has to be considered since it is related to size and weight as well as their behaviour. A detailed description of both control and intervention flooring is needed since great variability exists both for rubber slats and concrete slatted flooring. In the EFSA opinion on the welfare of pigs in relation to floor, technical testing methods were provided (EFSA, 2005). The floor properties are mainly characterised by thermal comfort, softness, friction, abrasiveness and contact pressure (Scott, 1985; Nilsson, 1988). In addition the type of material, thickness, solid/void dimensions, state of repair and durability should be reported when assessing flooring (EFSA, 2005). The interaction between claw and surface as contact pressure distribution (static and dynamic) may be used as a measure of animal welfare (EFSA, 2005; Webb and Nilsson, 1983). The outcome of comparative studies on flooring depends on the quality of the control floor which sets the baseline and on farm management factors that can also affect the baseline. For this reason, it is not appropriate to generalise from a single farm study and it is essential to fully describe the quality of the control floor since great variability exists. CONCLUSIONS AND RECOMMENDATIONS CONCLUSIONS Conclusions regarding the presence of statistical differences between the welfare outcomes for sows and gilts when comparing concrete slatted floors and floors with a rubber overlay (ToR 1) and regarding the scientific validity of the conclusions for sows and gilts and uncertainties or weaknesses in one or more of the studies (ToR 2) Study A has some limitations in terms of design, a probably high risk of selection bias is present for the second phase of the experiment as well as a definitely high risk of reporting bias. It only partially uses welfare measures that are relevant for assessing the degree of compliance with the legal minimum requirements. Particularly non-slippery floor and thermal comfort have not been addressed appropriately. Overall, the validity of study A is questionable because of the above-listed flaws in the way the field experiment was performed and/or reported. The results of this study must be used with caution because of the risk of bias identified, especially those from the second phase of the experiment. EFSA Journal 2014;12(12):

15 Study B is not considered to be powerful enough to detect small differences between the two treatment groups because of the small sample size. A definitely high risk of reporting bias is present. The study only partially uses welfare measures that are relevant for assessing the degree of compliance with the legal minimum requirements. Particularly non-slippery floor and thermal comfort have not been addressed appropriately. Overall, the validity of study B is questionable because of the above-listed flaws in the way the field experiment was performed and/or reported. The results of this study must be used with caution because of the risk of bias and the possibility that the study power is insufficient to detect any biologically relevant effects. Study C could provide a measure of the extent to which clinical lameness (which might have been a result of the flooring in gestation), mediated the effects on subsequent lying behaviour and lesions, if outcome measures were controlled for initial lameness on transfer to farrowing. However the study does not investigate sufficiently the extent to which the behaviour in the farrowing crates can be explained by the differences in locomotory ability at the moment of transfer (that could potentially be treatment related). The methodology used for the statistical analysis of the data is poorly described in the report and makes it difficult to appraise the validity of the study. The study only partially uses welfare measures that are relevant for assessing the degree of compliance with the legal minimum requirements. Overall, the validity of study C is poor because of some fundamental limitations in the methods used to perform the study and/or in the way these methods are described in the report. Therefore the results of the study cannot be used. The generalizability of the results of the three studies is questionable. There is no evidence that the results of each single study are representative of the overall population of farms and sows as well as the quality of the control floor. Indeed only one farm was included in each experiment and a single category of pigs. Further, it is unclear why the three studies were selected for assessment and whether any additional evidence is available in the scientific literature on the same topic. Therefore the uncertainty around the use of results of these studies is large. Conclusion regarding the ability to extrapolate the results for sows and gilts to rearing pigs and piglets (ToR 3) The findings of the studies cannot be extrapolated to other categories of pigs. RECOMMENDATIONS The environmental temperature and the humidity (temperature-humidity index) as well as the ventilation system should be considered when rubber flooring is provided to pigs. It is recommended to conduct experimental studies under three different thermal scenarios: at thermal comfort, under warm temperatures and under cold temperatures. When studying the effect of flooring material on the welfare of pigs, care should be taken to cover the entire range of legal minimum requirements in the outcomes assessed and reported. Studies on the effect of flooring on welfare should adequately address the variability at different experimental unit levels (i.e. individual animal, pen and farm level) in order to provide representative results. Therefore a study power analysis should be carried out to compute the appropriate sample size for the animals, pens and farms needed. Detailed descriptions of the quality of the control floor, which sets the baseline, and of the farm management factors, that can also affect the baseline, should be provided. EFSA Journal 2014;12(12):

16 REFERENCES Boyle LA and Calderón Díaz JA, Chapter 5 Effect of housing on rubber slat mats during pregnancy on the behaviour and welfare of sows in farrowing crates. In: Effect of Rubber Covered Slats on the Behaviour, Health and Welfare of Group Housed Sows. Final Report to EasyFix Rubber Products, June Calderón Díaz JA, Fahey AG, KilBride AL, Green LE and Boyle LA, Longitudinal study of the effect of rubber slat mats on locomotory ability, body, limb and claw lesions, and dirtiness of group housed sows. Journal of Animal Science, 91, Calderón Díaz JA, Boyle LA, Effect of rubber slat mats on the behaviour and welfare of group housed pregnant sows. Applied Animal Behaviour Science, 151, Schulz KF, Altman DG, Moher D, CONSORT Group, CONSORT 2010 Statement: Updated Guidelines for Reporting Parallel Group Randomised Trials. PLoS Med 7(3): e doi: /journal.pmed Elmore MRP, Garner JP, Johnson AK, Richert BT, Pajor EA, A flooring comparison: The impact of rubber mats on the health, behavior, and welfare of group-housed sows at breeding. Applied Animal Behaviour Science, 123, Higgins JPT and Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version [updated March 2011]. The Cochrane Collaboration, Available online: EFSA (European Food Safety Authority), Opinion of the Panel on Animal Health and Welfare on a request from the Commission related to welfare of weaners and rearing pigs: effects of different space allowances and floor types. The EFSA Journal 2005, 268, EFSA (European Food Safety Authority), 2007a. Scientific Opinion of the Panel on Animal Health and Welfare on a request from the Commission on Animal health and welfare in fattening pigs in relation to housing and husbandry. The EFSA Journal 2007, 564, EFSA (European Food Safety Authority), 2007b. Scientific Opinion of the Panel on Animal Health and Welfare on a request from the Commission on Animal health and welfare aspects of different housing and husbandry systems for adult breeding boars, pregnant, farrowing sows and unweaned piglets. The EFSA Journal 2007, 572, EFSA Panel on Animal Health and Welfare (AHAW), Scientific Opinion on the use of animalbased measures to assess welfare in pigs. EFSA Journal 2012;10(1): pp. doi: /j.efsa Mouttotou N, Hatchell FM and Green LE, Foot lesions in finishing pigs and their associations with the type of floor. Veterinary Record, 144, O Connor AM, Sargeant JM, Gardner IA,, Dickson JS, Torrence ME, Dewey CE, Dohoo IR, Evans RB, Gray JT, Greiner M, Keefe G, Lefebvre SL, Morley PS, Ramirez A, Sischo W, Smith DR, Snedeker K, Sofos J, Ward MP, Wills R and consensus meeting participants, The REFLECT statement: Methods and processes of creating Reporting Guidelines For Randomized Controlled Trials for livestock and food safety. Preventive Veterinary Medicine, 93, Sargeant JM, O'Connor AM, Gardner IA, Dickson JS, Torrence ME, Dohoo IR, Lefebvre SL, Morley PS, Ramirez A and Snedeker K, The REFLECT Statement: Reporting Guidelines for Randomized Controlled Trials in Livestock and Food Safety: Explanation and Elaboration. Journal of Food Protection,73, Savary P, Gygax L, Wechsler B and Hauser R, Effect of a synthetic plate in the lying area on lying behaviour, degree of fouling and skin lesions at the leg joints of finishing pigs. Applied Animal Behaviour Science 118, EFSA Journal 2014;12(12):

17 Tuyttens FAM, Wouters F, Struelens E, Sonck B, Duchateau L, Synthetic lying mats may improve lying comfort of gestating sows. Applied Animal Behaviour Science, 114, EFSA Journal 2014;12(12):

18 Appendix A. Critical appraisal tool for controlled trials in livestock STUDY A STUDY B STUDY C APPROPRIATENESS OF STUDY METHODOLOGY for MEETING THE OBJECTIVE classified as: Definitively appropriate Probably appropriate Probably not appropriate Definitively not appropriate [Does the methodology used to design and perform the study allow answering to the study research question?] - Is the study performed at the appropriate time? (e.g. consider here the effect of seasonality) The objectives of this study were 1) to compare the locomotory ability and claw, limb, and body lesion scores of replacement gilts housed on concrete slatted floor or rubber slat mats over 2 parities and 2) to investigate the relationship between lameness and claw and limb lesions. The study has some limitations in terms of design, due to the mixture of experimental units in the second round (second parity sow groups). The choice of the variables introduced in each model is insufficiently documented and related reporting is limited. This makes it difficult to understand the extent to which the effect estimates of the rubber mat treatment are unbiased (free from confounding). Some measure of effect are quite large but precision is quite low (large confidence intervals), meaning data are compatible with quite smaller effects. Dichotomisation of the scores was not planned a priori. This also could have introduced a bias. Method of calculation used to compute medians is unclear (whether within or across treatments). From October 2010 to February 2012; sows went on trial between October 2010 and March 2011 or between October 2010 and May 2011 according to intervention (concrete vs. rubber). The objectives of this study were (1) to compare lameness, limb and body lesion scores of sows housed on concrete slatted floor or rubber slat mats, and (2) to evaluate the effect of flooring type, lameness, body and limb lesion scores on postural and spatial behaviour of gestating sows The experiment is not expected to be powerful enough to detect small differences between the two treatment groups because of small sample size (8 exp units per treatment). The choice of the variables introduced in each model is insufficiently documented and related reporting limited. Choice of a mixed model for time spent variable is not justified (apparently no random effects were considered or they are not specified). Dichotomisation of the scores was not planned a priori. This also could have introduced a bias. Method of calculation used to compute medians is unclear (whether within or across treatments). From March 2011 to June 2012 Aim of this study was to evaluate the effect of rubber or concrete flooring for group housed gestating sows on welfare and behaviour in farrowing crates The study has not an experimental setting (i.e. no exposure factors). It cannot be used for confirmatory purposes on its own (i.e. to accept or reject a hypothesis). Some of the animals had already locomotory issues at the time of the start of the study and controlling for their locomotory ability at the beginning of study C (i.e. analysis performed conditionally to the different degrees of locomotory ability) was not carried out. Therefore the observation of the locomotory ability at the end of the study cannot be considered an outcome of the previous exposure. The setting of the study does not allow to answer the research question. Not reported EFSA Journal 2014;12(12):