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SID 5 Research Project Final Report

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NoteIn line with the Freedom of Information Act 2000, Defra aims to place the results of its completed research projects in the public domain wherever possible. The SID 5 (Research Project Final Report) is designed to capture the information on the results and outputs of Defra-funded research in a format that is easily publishable through the Defra website. A SID 5 must be completed for all projects.

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Project identification

1. Defra Project code AW0130

2. Project title

Welfare of finishing pigs under different management systems

3. Contractororganisation(s)

University of NewcastleSchool of Agriculture, Food & Rural DevelopmentKing George VI BuildingNewcastle upon TyneNE1 7RU

54. Total Defra project costs £ 205134

5. Project: start date................ 01 October 2001

end date................. 30 June 2005

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6. It is Defra’s intention to publish this form. Please confirm your agreement to do so...................................................................................YES NO (a) When preparing SID 5s contractors should bear in mind that Defra intends that they be made public. They

should be written in a clear and concise manner and represent a full account of the research project which someone not closely associated with the project can follow.Defra recognises that in a small minority of cases there may be information, such as intellectual property or commercially confidential data, used in or generated by the research project, which should not be disclosed. In these cases, such information should be detailed in a separate annex (not to be published) so that the SID 5 can be placed in the public domain. Where it is impossible to complete the Final Report without including references to any sensitive or confidential data, the information should be included and section (b) completed. NB: only in exceptional circumstances will Defra expect contractors to give a "No" answer.In all cases, reasons for withholding information must be fully in line with exemptions under the Environmental Information Regulations or the Freedom of Information Act 2000.

(b) If you have answered NO, please explain why the Final report should not be released into public domain

Executive Summary7. The executive summary must not exceed 2 sides in total of A4 and should be understandable to the

intelligent non-scientist. It should cover the main objectives, methods and findings of the research, together with any other significant events and options for new work.Background

Within the UK, there are ~2 million growing/ finishing pigs on farms at any given time, kept in a variety of different management systems. For the continued sustainability of the UK pig industry, it is essential that the biological and economic efficiency of production are maximised by adoption of appropriate housing and feeding regimes. However, this process must take due account of the welfare of the animals, both for ethical reasons and also to facilitate differentiation of UK pigmeat on welfare criteria. There is consequently a need for objective information on the welfare implications of commercial adoption of different management systems for finishing pigs on which to base policy decisions and advice to industry.

Methodology

To provide a commercial scale comparison of different finishing systems, with minimal confounding of other farm factors, a large multidisciplinary study of Pig Finishing Systems was established at the MLC Stotfold Unit. The animal health and welfare assessments carried out in this project were run in conjunction with separately funded, parallel studies on pig performance and environmental impact. The programme comprised a series of 4 experiments carried out consecutively over a 4 year period in two new experimental finishing houses: a fully-slatted building (FS) and a straw-bedded building with scraped dunging area (ST), of otherwise similar design. Each building contained four room of 4 pens, which were stocked with 32 pigs per pen Within each building different feeding treatments were compared in the main production studies (1024 pigs and 32 pens per study, from ~35 to 104 kg liveweight), and different environmental enrichment treatments were further compared as part of this welfare study.

Production trial 1 (PT1) – comparison of dry vs liquid feedingProduction trial 2 (PT2) – comparison of phase vs step feeding with liquid dietsProduction trial 3 (PT3) – comparison of fermented and non-fermented liquid dietsProduction trial 4 (PT4) – comparison of conventional and low (idealised) protein liquid diets

In each of these production trials, additional data were collected on a range of welfare parameters including health measures, serology and acute phase protein titres, skin lesions and hygiene, general, investigatory and feeding behaviour, and post mortem assessments of foot damage, osteochondrosis, lung, cardiac and gastric lesions. These data were used to address 5 scientific objectives, whose outcomes are summarised below.

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Objective 1. To quantify pig health and welfare when fed either dry or liquid diets, and the interaction with housing system

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. Main effects of the housing system are discussed under objective 2. Pigs fed dry diet had more respiratory health problems. Liquid fed pigs had poorer cleanliness scores than dry fed pigs, especially in straw-based housing. They spent more time resting, and showed less investigatory behaviour directed towards other pigs and pen components, although risk of tail biting was not reduced. Post-slaughter assessment showed reduced severity of gastric lesions with liquid feeding, but no other health or welfare differences. The results indicate that liquid feeding may offer some welfare benefits through improved satiety and gut health, but that pen hygiene requires attention.

Objective 2. To quantify pig health and welfare in slatted or straw based systems

Combined data from the 4 production studies were used to assess the magnitude and consistency of health and welfare differences between the slatted and straw based housing system. Lameness and tail biting were more prevalent health conditions in the fully-slatted system, whilst in the straw-based system pigs showed more respiratory and PMWS-type symptoms. Acute phase protein titres at slaughter were higher in pigs from the fully-slatted system. Skin lesion score did not differ between systems; however bursitis was more severe in pigs in the fully-slatted system. Pigs in the straw-based system had poorer hygiene scores, but the magnitude of this difference varied between studies depending on season. Pigs with straw were more active, spending a large proportion of time manipulating straw. In the absence of straw, pigs in the FS building spent more time in behaviour directed at other pigs and pen components. Post-slaughter assessments showed no system differences in lung lesions and cardiac scores, or osteochondrosis. Pigs with straw had more severe toe erosions on the foot , whilst pigs without straw had more severe sole and heel erosions. Gastric lesion scores were higher in the fully-slatted system. The results show both advantages and disadvantages to each of the housing systems for pig welfare.

Objective 3. To provide objective data on the feeding space requirements for pigs given liquid or dry feed

Feeding behaviour of pigs in Objective 1 was recorded over 24h periods at start, midpoint and end of the growth period. Although feeding behaviour patterns differed in the different housing, overall feeding time was not affected. Diet affected total time feeding, with pigs consuming dry diets feeding for longer, but there was no indication that shorter feeding time reflected restricted feeder access on the liquid treatment. The greater number of pigs queuing and lower proportion of feeding bouts ending voluntarily on liquid feeding probably related to the intermittent delivery of fresh feed throughout the day, but did not result in significant aggression. Overall, the lack of significant relationships between weight gain, lesion scores and feeding behaviour indicate that the feeder space allowance of 3.8 cm per pig up to 60 kg and 4.8 cm per pig up to 104 kg was adequate for pigs on ad libitum wet feeding.

Objective 4. To provide objective data on the role of environmental enrichment in pig welfare, performance and meat quality in relation to housing and feeding system

Two different forms of environmental enrichment were compared in each of three trials (PT2-4). In each case, the treatments were allocated to half of the pens within each room, to give a precise contemporary comparison fully balanced across feeding treatments within that experiment.

PT2: Rootable substrate v hanging toy Within the FS system, pigs spent more time in behaviour directed at a rootable substrate provided by a double-spaced hopper containing shreds of unmolassed sugar beet pulp (SBP), than at a hanging soft plastic ‘spider’ toy (Bite-Rite). Neither enrichment form gave occupation time (<2%) approaching that provided by straw bedding (16%).

PT3: Hanging v rootable toy of same materialWithin the FS system, pigs tended to spend more time in behaviour directed at a hanging hard plastic tube toy than at toys of the same material placed loose on the floor, but variation was high. Neither enrichment form gave occupation time (<2.5%) approaching that provided by straw bedding (19%).

PT4: Ratio of pigs to enrichment devices Within the FS system, there was no difference in the time pigs spent in behaviour directed at a hanging plastic ‘helicopter’ toy when proved with 1 or 4 toys per pen. Neither enrichment form gave occupation time (<2%) approaching that provided by straw bedding (21%).

Recent legislation has highlighted the urgency in identifying suitable enrichment that will meet the behavioural needs of the pig in unbedded systems. No such form of enrichment examined in this project

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provided anything close to the same level of occupation as seen with straw. There were no consistent effects of enrichment on pig performance. The reasons behind the difference in occupation time between straw manipulation and enrichment object interaction require further study, since such occupation is important in the prevention of other adverse behaviours, as indicated by the difference in tail biting prevalence between the straw based and fully slatted building.

Objective 5. To synthesise recommendations for commercially applicable finishing pig systems which optimise pig health and welfare

The results of the work did not show that any housing or feeding system produced a clear health and welfare advantage across all parameters measured. Instead, it highlighted the different areas of risk to welfare in each system and, consequently, the aspects of design or management which should receive most attention within that system. This information has been disseminated to policy makers, pig producers and their allied industries and the scientific community in presentations to industry and scientific meetings, and in technical reports and scientific papers.

Project Report to Defra8. As a guide this report should be no longer than 20 sides of A4. This report is to provide Defra with

details of the outputs of the research project for internal purposes; to meet the terms of the contract; and to allow Defra to publish details of the outputs to meet Environmental Information Regulation or Freedom of Information obligations. This short report to Defra does not preclude contractors from also seeking to publish a full, formal scientific report/paper in an appropriate scientific or other journal/publication. Indeed, Defra actively encourages such publications as part of the contract terms. The report to Defra should include: the scientific objectives as set out in the contract; the extent to which the objectives set out in the contract have been met; details of methods used and the results obtained, including statistical analysis (if appropriate); a discussion of the results and their reliability; the main implications of the findings; possible future work; and any action resulting from the research (e.g. IP, Knowledge Transfer).

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1. Scientific Objectives of the project

1. To quantify pig health and welfare when fed either dry or liquid diets, and the interaction with housing system2. To quantify pig health and welfare in slatted or straw based systems3. To provide objective data on the feeding space requirements for pigs given liquid or dry feed4. To provide objective data on the role of environmental enrichment in pig welfare, performance and meat

quality in relation to housing and feeding system5. To synthesise recommendations for commercially applicable finishing pig systems which optimise pig health

and welfare

2. Background and rationale

Within the UK, there are currently about 2 million growing/ finishing pigs on farms at any given time, kept in a variety of different management systems. For the continued sustainability of the UK pig industry, it is essential that the biological and economic efficiency of production are maximised by adoption of appropriate housing and feeding regimes. However, this process must take due account of the welfare of the animals, both for ethical reasons and also to facilitate the current developments in differentiation of UK pigmeat on welfare criteria. There is consequently a need for objective information on the welfare implications of commercial adoption of different management systems for finishing pigs on which to base policy decisions and advice to industry.

Much of the current discussion relates to the need for provision of appropriate environmental enrichment for finishing pigs. EU Council Directive 2001/93/EU states that “ pigs must have permanent access to a sufficient quantity of material to enable proper investigation and manipulation activities, such as straw, hay, wood, sawdust, mushroom compost, peat or a mixture of such….”. This requirement has a firm scientific basis, as the prevention of motivated behaviour in barren housing environments has been implicated in the development of adverse behaviours. It extended the previous pig welfare directive within the EU that highlighted the importance of environmental enrichment for pigs, and suggested that access to straw was one of the most appropriate ways to meet this need: “…all pigs…shall have access to straw or other material or object suitable to satisfy those [behavioural] needs” (Directive 91/630/EEC). Straw is known to offer advantages for animal welfare due to its use as a recreational stimulus, a nutritional stimulus and as bedding. However, a recent review of housing systems in current use within the EU shows that 91% of pig producers in the EU are still using fully- or part-slatted finishing pig housing systems, which have no access to straw for either bedding or occupation. This situation reflects the limited availability of straw in many areas, and the higher variable costs and labour demands generally associated with straw-bedded systems. The provision of straw is not universally adopted as it is not compatible with fully- or part-slatted flooring and liquid manure handling systems. There are also concerns that housing pigs on straw may have detrimental consequences for hygiene, risk of infectious and zoonotic diseases and environmental emissions.

Recent years have seen an increase in adoption of computerised liquid feeding systems for finishing pigs. These offer advantages in ability to use a wider range of by-product materials, thus reducing cost of production, and to automate the control of feeding regimes. There may be additional benefits of increased feed intake, reduced feed wastage, and lower levels of dust impacting on respiratory health in comparison with conventional hopper feeding of dry meal or pelletted diets. However, there are also associated risks of poorer pen hygiene, malfermentation of the diet, increased gastric torsion and greater competition at feeding. There have been relatively few studies of the extent to which such potential benefits and problems are expressed in practical systems.

In comparing production systems, different approaches can be used. These often involve either small-scale comparisons of experimental pens which do not always mirror commercial practice, or large scale epidemiological studies of different farms. It is difficult to obtain objective comparisons at a commercial scale in which potential confounding farm effects are minimised. To provide such a comparison, a large multidisciplinary study of Pig Finishing Systems (co-funded by DEFRA and MLC) was established at the MLC Stotfold Unit. The animal health and welfare assessments carried out in this project were therefore run in conjunction with parallel studies on pig nutrition and performance, nutrient excretion and pollution, microbiology and product safety, and meat organoleptic assessment

3. General Experimental Design and Methods

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The overall programme was built around a structured series of experiments carried out consecutively over a 4 year period in two new experimental finishing houses constructed at MLC Stotfold. A fully-slatted (FS) and a straw-based (ST) building, were purpose built on the same site to an otherwise similar design (full details can be found in MLC, 2004a). Each house consisted of four rooms containing four pens. The ST pens measured 5.8m x 3.7m, including the scrape-through passage, which was cleaned out daily whilst pigs were shut in the lying area. After cleaning out, fresh barley straw was added to the pens at the rate of ~0.5 kg straw per pig per day. FS pens measured 5.5m x 3.7m and had flooring of concrete slats with 83mm width and 18mm gap. Each building has the capability to feed pigs in each pen on either a dry or liquid feeding system. The ventilation and environment in both housing systems was automatically controlled (Euromatic DOL34H, Skov, Denmark) to set maximum and minimum ventilation, relative humidity and temperature against occupancy day. Each room had two windows, allowing natural daylight, and artificial light was mainly used during husbandry tasks, weighing and behaviour observations.

Pigs of standard commercial (Large White x Landrace) x Large White genotype were delivered at regular intervals from an outside source and selected to enter the buildings in alternating weekly or fortnightly matched groups, with nutritional treatments applied concurrently in each of the two buildings. Pigs were delivered in batches of ~130 animals. After a period of 4-5 days acclimatisation, each pig was ear tagged for individual identification and then weighed. The batch was divided into four equal groups of 32 pigs in order of weight. Each group was randomly allocated to one of four pens within a single room. They were housed in pen groups of 32 with a mean weight of 30-35 kg at entry. Numbers per pen were reduced at week six (mid-point) to 25 in the FS system and 20 in the ST system, in accordance with normal commercial stocking densities for these housing types. Pigs were slaughtered at approximately 104kg liveweight.

The overall experimental programme implemented by the MLC was as follows:Production trial 1 (PT1) – comparison of dry vs liquid feeding, with 8 replicate pens of pigs allocated to each treatment in each housing type.Production trial 2 (PT2) – comparison of phase vs step feeding with liquid diets, with 8 replicate pens of pigs allocated to each treatment in each housing type.Production trial 3 (PT3) – comparison of fermented and non-fermented liquid diets, with 8 replicate pens of pigs allocated to each treatment in each housing type.Production trial 4 (PT4) – comparison of control and low (idealised) liquid diets, with 8 replicate pens of pigs allocated to each treatment in each housing type.

These production trials were managed by MLC and involved collaboration organisations to incorporate measurements of growth rate and efficiency of feed use, carcass and meat quality, gut microbiology, air quality, and waste output and composition. The current project superimposed additional measurements on this basal programme, to give four consecutive contemporary comparisons of health and welfare in straw based or slatted housing, together with factorial investigation of one other relevant comparison (feeding form or environmental enrichment treatment) blocked within-house in each experiment.

The measurements made within each study to assess health and welfare were designed in relation to the ‘Five Freedoms’. Some measures, for example health monitoring, were made on all pigs in the experiment, whilst others were made on a subset of pigs within the pen. At entry, three males and three females in each pen group were selected to serve as ‘focal’ animals according to the following criteria: two pigs (one of each sex) at approximately median weight for the group, two within the upper quartile weight band and two within the lower quartile weight band. These animals received an additional ear tag for ease of identification.

3.1. Health and welfare measurements made in each experiment

3.1.1. Health recordsPigs were inspected twice daily for signs of ill health and welfare. A health record was kept that included any administration of drugs or other health related treatments and reasons for removing any animals from the experiment. All deaths and culls for health reasons were recorded and a post-mortem was conducted by a veterinary surgeon from the Acorn House Practice to assess the cause of death.

3.1.2. Acute Phase Proteins and serologyA blood sample was taken from six focal pigs per pen at the start, at the mid-point (~60 kg) and at slaughter (~104 kg) for determination of the serum concentrations of two Acute Phase Proteins (APP), C-reactive protein (CRP) and Haptoglobin (Hp). APP assays were conducted by the Glasgow Veterinary School. A subset of samples from each experiment were also sent for serology to determine the background level of health of pigs at entry and level of challenge experienced during the trial period.

3.1.3. Skin lesions and hygiene

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Skin lesions, including bruises, scratches and wounds, and adventitious bursitis of the hock were assessed weekly for focal pigs. Each animal was scored for the frequency of all skin lesions for seven body areas: face and ears, neck, shoulders, flank, rump, buttocks and tail. For each area, excluding the tail, lesions on the left and right hand sides of the body were recorded separately. The presence and severity of adventitious bursitis of the hock was visually assessed using subjective scores from 0 to 5, with 0 representing no swelling and 5 representing a large, eroded swelling (after Lyons et al., 1995). The hygiene status of focal pigs was scored on a weekly basis by visual assessment of the percentage of body surface which was clean as opposed to soiled.

3.1.4. BehaviourBehavioural time budgets were recorded by direct observation during three 2h-periods (09.00-11.00, 12.00-14.00, 15.00-17.00) in the week of entry, week before group reduction (mid-point) and week before slaughter. Six focal pigs per pen were individually identified using stock marker spray and their posture, behaviour and any substrate used were recorded by scan sampling at 10 minute intervals. 24h video recordings of feeding behaviour were made for each pen at the onset, mid point and end of the experiment and were analysed to show diurnal feeding patterns and the degree of competition for feed access in the different systems.

3.1.5. Post-slaughter measurementsPigs were transported a distance of 40 miles to the abattoir and slaughtered under commercial conditions. A range of measures were made on focal animals after slaughter.

3.1.5.1. Foot damageFoot damage of focal pigs was evaluated based on the method of Smith (1997). Both claws of the left hind foot were inspected for the presence of white line lesions, toe erosions, sole erosions and heel erosions. Subjective scores from 0 to 3 were given for the severity of each condition as follows: 0=no damage; 1=mild damage; 2=moderate damage; 3=severe damage.

3.1.5.2. Lung and cardiac lesionsThe degree of lung damage as a result of enzootic pneumonia was assessed for all pigs following a technique described by Goodwin and Whittlestone (1979). This involved scoring the consolidated area of all seven lobes of the lung to give a maximum score of 55. The heart of each pig was assessed for the presence of pericarditis and subjectively scored from 0 to 3 as follows: 0=no pericarditis; 1=mild pericarditis; 2=moderate pericarditis; 3=severe pericarditis.

3.1.5.3. Gastric ulcerationThe stomach of each focal pig was collected and assessed for signs of parakeratosis and ulceration in the pars-oesophageal region using a graded scoring system, where 0 indicated no abnormality and 5 indicated a large and bleeding ulcer (after Potkins and Lawrence, 1989).

3.1.5.4. OsteochondrosisIn studies one, three and four, the left fore-limb of two pairs (equal sexes) of focal pigs per pen was dissected to expose the distal end of the humerus. Lesions on the surface of front and rear aspect of the joint were scored according to a method described by Slevin et al (2001), where 0 represented no gross lesion and 4 represented extensive erosion, ulceration or absence of cartilage.

4. Results for individual objectives

Results are presented in relation to each project objective in turn, indicating the experiment(s) used to derive the data and any necessary further detail of methodologies.

4.1. Objective 1. To quantify pig health and welfare when fed either dry or liquid diets, and the interaction with housing system

4.1.1. Materials and MethodsA 2 x 2 factorial design was employed in PT1 to investigate the separate and/or interactive effects of housing system (fully-slatted and straw-based) and feeding system (automated liquid feeding and dry hopper feeding). The housing systems were as detailed in the general methods. Two feeding systems, either automated liquid feeding (L) or dry hopper feeding of a pelleted compound diet (D), were replicated between rooms within each housing system. Both dry and liquid diets were formulated to the same nutrient specification using similar ingredients. In both feeding systems a grower diet was offered from entry to approximately 60 kg (14.7 MJ DE/kg, 1.2% total lysine) and a finisher diet from 60 kg to slaughter (14.2 MJ DE/kg, 0.9% total lysine). Dry diets were commercially manufactured in 3 mm pellets and offered in ad libitum hoppers. Liquid diets were produced on site by milling cereals and mixing individual ingredients and were available ad libitum except for the period between 24.00-01.00, when the system was automatically paused to allow pigs to clear troughs of any accumulated

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residues. Liquid-feeding was computer controlled by feed demand at the troughs using sensors. Water was available ad libitum from four nipple drinkers per pen.

1024 pigs were received in eight equal batches of 128 over 11 weeks from April through to June 2002. Batches were allocated alternately between the housing systems until all rooms were filled. Three males and three females in each group were selected to serve as ‘focal’ animals according to the criteria: two pigs (one of each sex) at approximately median weight for the group, two within the upper quartile weight band and two within the lower quartile band. For all statistical analyses of data the pen was the experimental unit. Health data were not normally distributed and could not be normalised by log transformation; therefore the Kruskal-Wallis non-parametric test was used. The behaviour data were collated and the frequency at which each category of the ethogram occurred was expressed as a percentage of the total number of observations. Data were analysed using analysis of variance, with housing system and feeding system as main factors and their interaction. Tukey’s HSD was used for pair-wise comparison of the means of the treatments.

4.1.2. Results

4.1.2.1. Health recordsOverall mortality was low (0.9%) and did not differ significantly between the housing systems or feeding systems. A total of 47 pigs (4.6%) were removed from the study for health and welfare reasons, with more removed from the FS system than the ST system (P<0.05). Reasons for rejection are summarised in Table 1.1. Removals for lameness (P=0.09) and tail biting (P=0.06) were higher from the FS system than the ST system. More pigs were removed from the D diet as a result of respiratory conditions than from the L diet (P<0.01).

Table 1.1. Deaths and removals (no. of animals) by feeding system within housing system (from an initial allocation of 256 animals to each treatment combination)

Fully-Slatted Straw-basedLiquid Dry Liquid Dry

Deaths 2 1 4 2Removals

Respiratory 1 4 0 4Enteric 1 0 0 1

Lameness 7 2 1 1Tail bitten 5 8 0 1Thin/poor 0 1 0 2

Other 3 2 1 2Total 17 17 2 11

The number of veterinary treatment episodes (temporally separate courses of treatment to individual pigs) was greater in the ST system (P<0.01) as a consequence of respiratory (P<0.01) and enteric conditions (P<0.01), whereas the FS system received more treatments for tail biting (P=0.07) and lameness, although the difference was not statistically significant. Days spent on treatment followed a similar pattern; pigs in the ST system spent more total days on treatment (P<0.01), due to respiratory (P<0.01) and enteric conditions (P<0.01), whilst pigs in the FS system spent more days on treatment as a result of tail biting (P=0.07) and lameness (P=0.1). There were no significant effects of feeding system on the number of pig days spent on treatment.

Table 1.2. Veterinary treatments for different health problems by feeding system within housing system Fully-Slatted Straw-based

Liquid Dry Liquid DryTreatment episodes

Respiratory 1 5 29 22Enteric 0 0 8 4

Lameness 19 3 6 9Tail bitten 7 0 0 0Thin/poor 0 0 1 1

Other 3 2 1 1Total 30 10 45 37

Pig days on treatmentRespiratory 5 21 145 110

Enteric 0 0 40 4Lameness 56 22 22 26Tail bitten 23 0 0 0Thin/poor 0 0 5 3

Other 9 5 3 3

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Total 93 48 215 146

4.1.2.2. Skin lesions and hygieneThere were no significant treatment effects on body damage (Table 1.3). The mean number of skin lesions per pig was similar across both housing systems and feeding systems. Pigs had previously been housed in both slatted and straw-based accommodation; consequently bursitis score at the start of the study was used as a covariate in the analysis of mean bursitis score. Despite this, there were no significant effects of housing system or feeding system on mean bursitis score. The proportion of clean skin was greater in pigs from the FS system than the ST system (P<0.001) and in D fed pigs compared with L fed pigs (P<0.001) (Table 1.3). An interaction was observed between housing system and feeding system, with L fed pigs having a lower proportion of clean skin relative to D fed pigs in straw-based housing (P<0.01).

Table 1.3. Body damage and hygiene by feeding system (F) within housing system (H) and their interaction (I)Fully-Slatted Straw-based S.E.M. P-value

Liquid Dry Liquid Dry H F ISkin lesions/pig 14 11 13 16 1.2Bursitis score (0-5) 1.1 1.0 1.0 1.1 0.1Hygiene score (% clean) 82 87 60 76 2.1 *** *** **

4.1.2.3. BehaviourBehavioural results are given in Table 1.4. There were significant differences between both housing system and feeding system in respect of levels of activity, as measured through standing, and levels of inactivity, as measured through ‘sleeping’ (lying down with eyes shut). Pigs in the ST system spent less time sleeping (P<0.001) and correspondingly more time standing (P<0.01) than pigs in the FS system. L fed pigs spent more time sleeping (P<0.01) and less time standing (P<0.05) than D fed pigs. There was a tendency for pigs in the ST system to spend more time eating than pigs in the FS (P<0.07); however this difference was not apparent between the feeding systems. As anticipated, D fed pigs spent more time drinking than L fed pigs (P<0.001).

Investigatory behaviours (nosing, chewing, rooting or biting any available substrate) were performed more by pigs in the ST system than pigs in the FS system (P<0.001) and more by D fed pigs than L fed pigs (P<0.05). Pigs in the ST system spent less time in behaviour directed at pen components than pigs in the FS system (P<0.05), although there was no significant difference between the housing systems in behaviour directed at pen-mates. D fed pigs spent more time in behaviour directed at both pen components (P<0.001) and pen-mates (P<0.01) than L fed pigs.

Table 1.4. Mean percentage of time spent performing various behaviours by pigs according to feeding system (F) within housing system (H) and their interaction (I)

Fully-Slatted Straw-based S.E.M.

P-value

Liquid Dry Liquid Dry H F IStanding 19.4 25.7 27.6 31.2 1.86 *** *‘Sleeping’ 65.0 56.4 52.3 48.6 2.10 *** **Eating 3.9 4.4 4.6 5.0 0.32Drinking 0.4 1.2 0.7 1.2 0.13 ***Investigating 15.2 21.9 27.6 30.9 1.93 *** *

Oral behaviour towards: Straw - - 14.3 14.0 0.95 Pen components 6.9 10.6 5.7 7.6 0.79 * *** Another Pig 7.0 10.0 7.9 8.8 0.67 **

4.1.2.4. Post-slaughter measurementsThere was no consistent difference in the overall level of foot damage between treatments; however the type of damage did differ significantly between the housing systems (Table 1.5). Pigs in the ST system had more severe toe erosions (P<0.001) whilst pigs in the FS system had more severe heel erosions (P<0.001). There were no significant effects of feeding system on foot damage.

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Table 1.5. Foot damage (0-3 scale) by feeding system (F) within housing system (H) and the interaction (I)Fully-Slatted Straw-based S.E.M

.P-value

Liquid Dry Liquid Dry H F IFoot damage: White line lesion 0.8 1.0 1.1 1.2 0.14 Toe erosion 0.5 0.4 1.2 1.1 0.14 *** Sole erosion 0.7 0.9 0.7 0.8 0.14 Heel erosion 1.0 1.3 0.3 0.3 0.19 ***

There were no significant differences between treatments with respect to lung or cardiac lesions (Table 1.6).There were no significant effects of treatment on the extent of osteochondrosis (Table 1.6).

Table 1.6. Lung and cardiac lesions and osteochondrosis by feeding system (F) within housing system (H) and their interaction (I)

Fully-Slatted Straw-based S.E.M.

P-value

Liquid Dry Liquid Dry H F ILung lesions (0-55 scale) 1.5 1.0 1.5 1.3 0.34Cardiac lesions (0-3 scale) 0.96 0.97 0.96 0.98 0.01Osteochondrosis (0-4 scale)

Front score 2.5 2.4 2.5 2.7 0.10Rear score 2.0 2.0 2.0 1.9 1.10

The frequencies of gastric lesions and the mean gastric lesion scores are shown in Table 1.7. Moderate parakeratosis was found in 19 cases (10.2%). Severe parakeratosis was observed in 20 cases (10.8%) and only in animals fed the D diet. There were significant effects of both housing system and feeding system on mean gastric lesion scores: mean lesion scores were higher in FS pigs than ST pigs (P<0.01) and higher in D pigs than L pigs (P<0.001).

Table 1.7. Frequencies of gastric lesions (% of pigs) and mean gastric lesion score by feeding system within housing system

Fully-Slatted Straw-basedLiquid Dry Liquid Dry

Lesional score:0 18.8 2.2 41.7 4.41 31.2 4.4 37.5 24.42 25.0 26.7 10.4 15.63 14.6 24.4 10.4 22.24 10.4 20.0 0 11.15 0 22.2 0 22.2

Mean lesional score# 1.7 b 3.2a 0.9c 2.8a

#S.E.M. = 0.19. Different superscripts in the same row are significantly different (P<0.001)

4.1.3. Discussion and Conclusions

The results highlight the relative advantages and disadvantages of each housing and feeding system for pig welfare. The straw-based system gave better behavioural occupation but poorer hygiene and respiratory health under summer conditions. Liquid feeding offered welfare benefits in behaviour and gastric ulceration but reduced hygiene. In the present study, liquid feeding resulted in reduced hygiene scores in both housing systems, but particularly in straw-based housing. Liquid feeding involves the ingestion of large volumes of water, which can result in increased water excretion. For this reason, the majority of current liquid feeding systems are associated with slatted housing to reduce the risk of soiled wet bedding. Lower hygiene scores in the ST system may also have been attributable to pigs wallowing under the hot summer conditions, when external temperatures frequently reached 340C. Activity levels, indicated by the reduced proportion of time spent sleeping, were greater for pigs in the ST system than in the FS system. Many previous studies have indicated that straw promotes activity, provides an outlet for exploratory behaviour and reduces undesirable behaviours, as was the case in this study (see also objective 2). Liquid feeding resulted in pigs spending more time sleeping and less time standing than dry feeding. This may have occurred because the ingestion of dilute liquid feed resulted in a greater gut fill and sense of satiety. The significant decrease in pig-directed behaviours with liquid feeding suggests that reduced investigative

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activity in the pen leads to fewer meetings between animals and therefore fewer interactions. It is possible that this might reduce the risk of outbeaks of tail biting behaviour, but such an effect was not seen in this study.

4.2. Objective 2. To quantify pig health and welfare in slatted or straw based systems

4.2.1. Materials and MethodsFour consecutive studies (PT1-4) were carried out over a three-year period, from April 2002 to December 2004, to investigate the effects of housing system (fully-slatted and straw-based) on the health and welfare of finishing pigs. The timing of the studies was such that they were representative of the different seasons of the year. In each study, 1024 externally sourced (Large White x Landrace) x Large White pigs were received in eight equal batches of 128. These were allocated alternately between the housing systems until all rooms were full. In addition to the housing comparison, each study involved a two treatment nutritional comparison of an aspect of liquid feeding, according to a factorial design. Each diet was offered ad libitum and the overall nutrient specification was similar for the different diets in each contemporary comparison. In Study 1, dry or liquid diets, formulated to the same nutrient specification using similar ingredients, were compared (see Objective 1). The remaining studies evaluated different aspects of liquid feeding technologies: phase feeding versus a single all-through diet in Study 2; controlled cereal fermentation versus a non-fermented diet in Study 3, and low crude protein (idealised with synthetic amino acids) versus a less idealised diet in Study 4 (for full details on the nutritional comparisons see MLC, 2004a-d). The different liquid feeding treatments, which were balanced across building in each study, had relatively few direct or interactive effects on health and welfare measures, and are not reported further .

In each study, the pen was the experimental unit for statistical analyses of all data. Most data were analysed using analysis of variance, with housing system and study number as main factors and their interaction. Tukey’s HSD was used for pair-wise comparisons. Behaviour data were collated and the frequency at which each category of the ethogram occurred was expressed as a percentage of the total number of observations. Health data were expressed as the proportion of pigs affected in each pen. These were not normally distributed and could not be normalised by transformation; therefore the Kruskal-Wallis non-parametric test was used.

4.2.2. Results

4.2.2.1. Health RecordsOverall mortality was low (1.2%) and did not differ between the systems. The total number of pigs removed from the trial pens for health and welfare conditions also did not differ between the housing systems, despite differences in removals for specific causes. Reasons for rejection are summarised in Table 2.1. Removals for lameness (P<0.05) and tail biting (P<0.001) were higher from the FS system, whilst removals for loss of body condition, generally associated with PMWS as diagnosed by a veterinarian, were higher from the ST system (P<0.05). The number of pigs removed from trial as a consequence of loss of condition, generally associated with PMWS symptoms, increased with each study (P<0.001).

Table 2.1. Number of pigs (from a starting number of 2048 in each housing system) that died or were removed from trial for welfare reasons by housing system

Fully-slatted Straw-basedDeaths 20 29Removals

Respiratory 6 13Enteric 1 1

Lameness 38 20Tail bitten 60 7

Loss of condition (PMWS) 24 66Other 23 29Total 152 136

The number of veterinary treatment episodes (temporally separate courses of treatment to individual pigs) was greater in the ST system than in the FS system (P<0.05) (Table 2.2). Veterinary treatments for respiratory conditions were greater in the ST system (P<0.001), whilst in the FS system there were more treatments for lameness (P<0.001). When considering both the incidence and duration of treatments, pigs in the ST system spent more days on treatment for respiratory conditions (P<0.01) and for loss of condition, generally associated with PMWS symptoms (P<0.01). Veterinary treatment episodes for respiratory (P<0.001) and enteric conditions (P<0.001) were highest in the first study, and then decreased with subsequent studies. Conversely, treatment episodes for loss of condition (PMWS) increased with each study (P<0.001).

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Veterinary treatments for tail biting were only administered to pigs on trial in PT1; in subsequent studies injured pigs were immediately removed from the experimental pens and subsequently treated in hospital pens. Once established, tail biting can spread quickly amongst pigs in a pen and many different animals may be injured by a single perpetrator; therefore it is appropriate to consider not just the number of affected animals, but also the number of affected pens. Tail bitten animals were observed in both housing systems and in each of the four studies, however more FS pens showed tail biting than ST pens (34.4 v 7.8%, P<0.01).

Table 2.2. Number of veterinary treatment episodes and pig days spent on treatment by housing systemFully-slatted Straw-based

Treatment episodesRespiratory 6 59

Enteric 2 14Lameness 141 71Tail bitten 7 0


Pig days on treatmentRespiratory 26 279

Enteric 6 50Lameness 430 198Tail bitten 23 0


4.2.2.2. Acute Phase Proteins and serologyLevels of CRP at entry increased with each study, suggesting deteriorating health status in the source population. Pigs in the FS system had higher levels of Hp than pigs in the ST system at both the mid-point (P=0.054) and at slaughter (P<0.001) (Table 2.3). There was a similar trend towards higher levels of CRP at slaughter (P=0.053) in pigs from the FS system compared with pigs from the ST system. In contrast serology of a sample of the focal pigs in each experiment indicated that the level of seroconversion for Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae and PRRS was greater in the ST system, whilst PCV2 was more variable.

Table 2.3. Concentrations of C-Reactive protein (µg/ml) and Haptoglobin (mg/ml) in serum of pigs in different housing systems (H) during four consecutive studies (S)

Housing System S.E.M P-valueFully-Slatted Straw-Based H S HxS

At entryC-Reactive protein 245.9 239.1 12.91 ***

Haptoglobin 0.99 0.91 0.04 ***At mid-point

C-Reactive protein 198.1 197.6 18.0 *Haptoglobin 1.28 1.10 0.06 0.054

At slaughterC-Reactive protein 162.3 128.4 12.23 0.053 **

Haptoglobin 0.66 0.47 0.03 ***

4.2.2.3. Skin lesions and hygieneSkin lesion score did not differ between the systems (Table 2.4). Bursitis scores were greater for pigs housed in the FS system than for those in the ST system (P<0.001). Pigs in the ST system were less clean than those in the FS system (P<0.001), but the magnitude of this difference varied between experiments depending on season (Table 2.4). The difference in hygiene score between the housing systems was most pronounced in studies 1 and 4, which both ran over hot summer periods.

Table 2.4. Body damage and hygiene score in different housing systems (H) during four consecutive studies (S)Housing System S.E.M P-value

Fully-Slatted Straw-Based H S HxSSkin lesions/pig 9.2 9.5 0.27 ***Bursitis score (0-5 scale) 1.0 0.7 0.03 *** ***Hygiene score (% clean) 79.8 72.1 0.80 *** *** ***

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4.2.2.4. BehaviourBehavioural results are given in Table 2.5. In both housing systems pigs spent a large amount of the observation period lying. However, pigs in the ST system spent significantly less time lying (P<0.05) and correspondingly more time standing (P<0.01) compared to those in the FS system. FS pigs spent more time sleeping (lying down with eyes shut) (P<0.001) and motionless but alert (P<0.001) than ST pigs. The amount of time spent eating and drinking did not differ between the housing systems.

Investigatory behaviours (nosing, chewing, rooting or biting any available substrate) were performed more by pigs in the ST system than by pigs in the FS system (P<0.001). Pigs in the ST system spent less time in behaviours directed at pen mates (P<0.001) and pen components (P<0.001) than pigs in the FS system. Pigs provided with straw bedding spent 17.6% of the observation period manipulating it.

Table 2.5. Mean percentage of time spent performing various behaviours in different housing systems (H) during four consecutive studies (S)

Housing System S.E.M P-value% Time Fully-Slatted Straw-Based H S HxSStanding 24.0 27.4 0.73 **Sitting 4.9 3.5 0.20 *** *** ***Lying on side 49.4 44.5 0.98 ** *** *Lying on belly 21.6 24.2 0.65 ** ***Total lying 70.9 68.7 0.76 * * *Sleeping 56.7 52.2 0.83 *** ***Motionless and alert 16.9 13.5 0.31 *** * *Eating 4.7 4.3 0.15 *Drinking 0.4 0.4 0.04 ***Investigating 19.9 28.0 0.66 ***Oral behaviour towards:Pig 7.8 6.2 0.24 *** *** ***Straw - 17.6 0.39Pen components 11.3 4.6 0.30 *** ***

4.2.2.6. Post-slaughter measurementsPost-slaughter measurements are given in Table 2.6. Post-slaughter assessment showed system differences in the type of foot damage; the FS system gave more severe sole (P<0.001) and heel erosions (P<0.001) but lower toe erosions (P<0.001) than the ST system. White line lesion scores did not differ between systems. Overall lung lesion scores were low and did not differ between the housing systems; however they did consistently increase over the course of the four studies. Pericarditis showed no system difference. Gastric ulceration scores were lower in pigs in the ST system than those in the FS system (P<0.001). There were no significant effects of housing system on the extent of osteochondrosis; however both front and rear scores did decrease over trials.

Table 2.6. Post-slaughter measures in different housing systems (H) during four consecutive studies (S)Housing System S.E.M P-value

Fully-Slatted Straw-Based H S HxSFoot Damage (0-3 scale)

White line lesion 0.7 0.7 0.04 ***Toe erosion 0.4 1.3 0.04 *** *

Sole erosion 1.1 0.6 0.05 *** *** ***Heel erosion 1.3 0.3 0.04 *** *** **

Lung score (0-55 scale) 2.3 2.3 0.15 ***Cardiac score (0-3scale) 0.3 0.3 0.01 ***Stomach lesion score(0-5 scale)

2.1 1.3 0.09 *** ***

Osteochondrosis(0-4 scale)

Front score 2.4 2.4 0.05 **Rear score 1.5 1.6 0.05 ***

4.2.3. Discussion and ConclusionsThe results show both advantages and disadvantages to each of the housing systems for pig welfare, which were relatively consistent in direction, although not always in magnitude, across the four studies. The straw-based system gave better behavioural occupation and a lower risk of lameness and tail biting, but poorer hygiene, PMWS susceptibility and respiratory/enteric health. The beneficial effects of straw can be attributed to its

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physical cushioning, thermal insulation and nutritional properties, and also to its role as a behavioural substrate; however not all these functions require the presence of full straw bedding. The results of this study highlight the weak points of each system which should be addressed in order to improve pig welfare.

4.3. Objective 3. To provide objective data on the feeding space requirements for pigs given liquid or dry feed

4.3.1. MethodsA comparison of the feeding behaviour of pigs in PT1 was made. Each building contained 8 pens of pigs on liquid feeding, and eight pens on dry feeding (see objective 1 for full housing details). The liquid feeding troughs were 120 cm wide, 30 cm deep and with a lip height of 22 cm. The hoppers for dry feed were 122 cm wide with a height of 104 cm. The depth of the hopper to the bottom was 46cm and to the top lip was 36 cm. 24h video recordings of feeding behaviour were made for each pen at the onset, mid point and end of the experiment and were analysed by two different methods to show diurnal feeding patterns and the degree of competition for feed access in the different systems. The first method involved scan sampling at 15 minute intervals to give a count of the number of pigs feeding and queuing (waiting with their head within 1m of the feeder). From these data, the mean proportion of pigs feeding and queuing in each pen was calculated for the whole 24-h period. The second method involved more detailed analysis of the diurnal feeding patterns of the focal pigs within each pen, which were uniquely spray marked so they could be recognised individually. The times of all feeding bouts for each focal pig were recorded as time of arrival and time of departure from the feeding trough. Termination of a feeding bout was defined as when either the pig moved more than 1 m away from the feeding area or was not seen eating for more than 15 seconds, following the methodology of Turner et al. (2002). The reason for the pig leaving was also categorised as either voluntary or non-voluntary depending on the interactions with other penmates. Non-voluntary finishing of feeding was defined as physical pushing out or biting directed toward the feeding pig.

Average length of feeding bout, total number of feeding bouts, total feeding time and proportion of feeds ending voluntarily were calculated for each of the focal pigs. To give representative group data, since pigs within a group could not be considered statistically independent, means for each pen of pigs were subject to analysis of variance, once the assumption of normality had been validated. The effects of housing and diet and the interaction between these were considered. The data relating to the proportion of feed bouts ending voluntarily were assessed using non-parametric tests. Kruskal-Wallis tests were used to assess the affect of treatment and building individually.

4.3.2. Results

Results from the scan sampling are shown in Table 3.1. Pigs offered the liquid diet spent less time feeding, particularly in slatted housing, but spent more time queuing. Pigs in straw based housing spent more time queuing, and this was most pronounced with liquid feed. However, the average numbrer of pigs queuing at any one time was relatively low, suggesting that the feeding space provided was adequate.

Table 3.1. Feeding behaviour of pigs in different housing systems (H) fed dry or liquid diet (D). (Pen means across the 3 observation periods, based on % of pigs recorded in 15 minute scan samples)

Fully-slatted Straw-based S.E.M P-valueDry Liquid Dry Liquid H D I

% Time:Feeding 3.2 2.6 3.0 2.9 0.11 NS ** *Queuing 0.1 0.5 0.2 1.1 0.06 *** *** ***

The effects of housing and diet on the more detailed feeding behaviour of focal pigs at the mid point of the experiment, immediately prior to reduction in number of pigs per pen, are shown in Table 3.2. The results obtained by this method show good agreement with those obtained by scan sampling. Food type had no significant effect on the mean number of feed bouts per pig per 24 hour. However, building type did have an effect (P< 0.05), with pigs in slatted housing having significantly more feed bouts/24h than pigs in straw housing. Both diet and building type had significant (P< 0.05) effects on the average feed bout lengths. Pigs fed dry diet and pigs in the straw building had significantly longer feed bout durations. Combining these two measures to give total feeding time per pig per 24h, showed no significant difference between building types. However, food type had an effect (P=0.07) effect, with pigs fed dry diets having greater total feeding times. The proportion of feeding bouts ending voluntarily was higher for pigs in the straw building (P< 0.05), and for pigs fed the dry compound diet (P<0.001).

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Table 3.2. The feeding behaviour of focal pigs based on continuous recording of all feeding boutsFully-slatted Straw-based S.E.M P-value

Dry Liquid Dry Liquid H D INo. feeding bouts/ 24 hours

11.5 14.0 9.8 10.2 0.91 **

Mean bout length (secs)

243.5 167.8 268.9 197.2 12.28 * ***

Total time feeding (min/24h)

42.7 37.6 41.9 33.8 3.42 0.07

Median proportion of bouts ending voluntarily

0.82 0.50 0.94 0.65 * ***

The diurnal group feeding patterns for the pigs were graphed and were similar for pigs fed either a liquid or a dry diet when housed in a slatted building. For both diets, the number of pigs feeding peaked at approximately 15:00 and then decreased to low levels during the night between the hours of 20:00 and 04:00. Overall, pigs in the straw based housing had a higher proportion of their feeding bouts during the night (31% v 26% of bouts).

4.3.3. Discussion and Conclusions Although feeding behaviour patterns were different in the different housing types, overall feeding time was not affected. Diet did affect total time spent feeding, with pigs consuming dry diets feeding for longer. However, it is known that the rate of feed ingestion is higher when diets are presented in liquid form, and performance records from this study show that the liquid pigs had better growth. There was therefore no indication that shorter feeding time reflected limited feeder access on this treatment. The greater number of pigs queuing and lower proportion of feeding bouts ending voluntarily on liquid feeding probably related to the intermittent delivery of fresh feed throughout the day on this system (15-19 occasions/24h when the level of food in the trough falls below the sensor and a fresh delivery is triggered, accompanied by an audible sound). However, this did not seem to result in significant aggression, since the number of skin lesions per pig was not increased with this feeding treatment. The lower number of feeding bouts, longer bout duration and higher proportion of bouts ending voluntarily in straw based housing may reflect the availability of other occupation for the animals, making them less focussed on feeding activity and less likely to be stimulated by social facilitation of this activity. Overall, the lack of significant relationships between weight gain and feeding activity, the lack of differences between systems in within-pen variation in liveweight gain and skin lesion scores indicate that the feeder space allowance of 3.8 cm per pig up to 60 kg and 4.8 cm per pig up to 104 kg was adequate for pigs on ad libitum wet feeding.

4.4. Objective 4. To provide objective data on the role of environmental enrichment in pig welfare, performance and meat quality in relation to housing and feeding system

Two different forms of environmental enrichment were compared in each of three trials (PT2-4). In each case, the treatments were allocated to half of the pens within each room, to give a precise contemporary comparison fully balanced across feeding treatments within that experiment. Behavioural time budgets were recorded for three 2h-periods (09.00-11.00, 12.00-14.00, 15.00-17.00) in the week of entry, week before group size reduction at approximately 60kg (mid-point) and week before slaughter. Focal pigs were individually identified using stock marker spray and observations were carried out by a single observer. Scan samples were taken at 10 minute intervals for each 2h-period according to a predetermined ethogram. This ethogram detailed the animal’s posture, behaviour and the substrate towards which the behaviour was directed.

Methods and Results are summarised for each comparison in turn, followed by combined discussion and conclusions.

A. Rootable substrate v hanging toy (PT2)

Materials and MethodsTwo different environmental enrichment treatments were compared in each of two housing systems, giving a total of four treatments each replicated across 8 pens of pigs. In a straw-based building, pens with straw bedding as the only form of enrichment were compared with pens which had an additional hanging plastic toy. In an otherwise similar building with fully slatted flooring, the same plastic hanging toy was compared with a rootable particulate substrate provided in a hopper. The toy was the commercially available Bite-Rite (B-R) object (Ikadan System, Denmark). This consisted of a plastic cone with four protruding plastic chewing arms, and was suspended at pig level. The rootable substrate in the FS system was provided by a double-spaced hopper

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containing shreds of unmolassed sugar beet pulp (SBP), which was cleaned out and replenished as required. The mean daily use of SBP was 0.5 kg per pen.

The frequency at which each category of the ethogram occurred was expressed as a percentage of the total number of observations. The possible effect of time was tested using repeated measures ANOVA; however this revealed no interaction between environmental enrichment device and time. Consequently, behaviour data were averaged across the three observation times and analysed initially as a 4 treatment comparison by ANOVA. Paired t-tests were then carried out between specific valid comparisons, i.e. environmental enrichment comparison within the FS system only and B-R manipulation in each housing system.

ResultsResults for the mean percentage of time spent in different behaviours are given in Table 4.1. Pigs in the ST system spent 16.1% of the observation period in straw-directed behaviour. The level of straw manipulation was not affected by the provision of additional environmental enrichment in the form of the B-R object. Levels of B-R manipulation were low in both housing systems compared with levels of straw manipulation; however FS pigs spent significantly more time manipulating the B-R object than ST pigs (P<0.05), which was reflected in the level of chewing damage to the devices when measured at the end of the experimental period (FS=16.7 cm of chewing arm remaining v ST=22.2cm, P<0.001). Within the FS system, pigs spent more time in behaviour directed at the SBP than the B-R (P<0.05). There were no significant effects of housing system or type of enrichment on the level of behaviour directed at pen mates. Pigs in the FS system spent more time in behaviours directed at pen components than pigs in the ST system (P<0.001).

Table 4.1. Mean percentage of observations over three time periods that pigs spent engaged in behaviours directed at either straw or an available enrichment device, and in behaviours directed at pen-mates or pen components (B-R = hanging Bite-Rite, SBP= sugar beet pulp shreds in hopper). Building Straw-based Fully-slatted S.E.M. P-valueEnrichment Control + B-R + B-R + SBP% behaviour towards:

Straw 15.8 16.4 - - 1.3 NSEnrichment device - 0.5 1.1 1.9 0.2 ***

% behaviour towards:Other pig 7.4 6.4 7.4 8.0 0.7 NS

Pen components 4.9 4.8 10.5 10.6 0.7 ***

B. Hanging v rootable toy of same material (PT3)

Materials and methodsTwo different environmental enrichment treatments were again compared in each of two housing systems, giving a total of four treatments each replicated across 8 pens of pigs. In a straw-based building, pens with straw bedding as the only form of enrichment were compared with pens which had an additional hanging ‘toy’. In an otherwise similar building with fully slatted flooring, a comparison was made between the same hannging toy and toys of similar material presented free on the floor where they could be rooted around the pen. The hanging toy comprised 2 lengths (50cm) of rigid plastic piping of different diameters (50mm and 65mm) attached together by their centres on a chain and suspended at pig level. The toy presented on the floor comprised two 1.2m lengths of plastic rigid piping of 50mm diameter and two 1.2m lengths of plastic rigid piping of 65mm diameter.

The frequency at which each category of the ethogram occurred was expressed as a percentage of the total number of observations. Behaviour data were averaged across the three observation times and initially analysed as 4 treatments by ANOVA. Paired t-tests were then carried out between specific valid comparisons, i.e. enrichment form comparison within the FS system only and hanging toy manipulation in each housing system.

ResultsResults for the mean percentage of observations spent in different behaviours are given in Table 4.2. Pigs in the ST system spent 19.2% of the observations in straw-directed behaviour. The level of straw manipulation was not affected by the provision of additional environmental enrichment in the form of the hanging toy. Levels of toy manipulation were low in both housing systems compared with levels of straw manipulation, and did not differ in pairwise comparison of the same toy in different housing systems, although there was a tendency for the hanging toy to be manipulated more within the FS system (P=0.07). Behaviours directed at pen mates and pen components were both more frequent in FS than in ST housing (P<0.001), and were not affected by type of toy.

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Table 4.2. Mean percentage of observations over three time periods that pigs spent engaged in behaviours directed at either straw or an available enrichment device, and in behaviours directed at pen-mates or pen components.Building Straw-based Fully-slatted S.E.M. P-valueEnrichment Control +Hanging

toy+Hanging

toy+Floor

toy% behaviour towards:

Straw 19.8 18.7 - - 1.87 NSEnrichment device - 1.3 2.5 0.7 0.56 NS

% behaviour towards:Other pigs 4.1 5.1 8.3 8.9 0.73 ***Pen parts 3.5 3.6 14.2 13.9 1.04 ***

C. Ratio of pigs to enrichment devices (PT4)

Materials and Methods Two different environmental enrichment treatments were again compared in each of two housing systems, giving a total of four treatments each replicated across 8 pens of pigs. In a straw-based building, pens with straw bedding as the only form of enrichment were compared with pens which had an additional hanging ‘toy’. In an otherwise similar building with fully slatted flooring, the ratio of pigs to available enrichment was investigated by comparing pens with a single hanging toy and those with 4 of the same hanging toy. This ‘toy’ was a plasic “helicopter” toy constructed on-farm from two lengths of alkathane piping (diameter 18mm, length 80cm) suspended from their centre on a chain.

The frequency at which each category of the ethogram occurred was expressed as a percentage of the total number of observations. Behaviour data were averaged across the three observation times and initially analysed as 4 treatments by ANOVA. Paired t-tests were then carried out between specific valid comparisons, i.e. environmental enrichment number comparison within the FS system only and single hanging toy manipulation in each housing system.

ResultsResults for the mean percentage of observations spent in different behaviours are given in Table 4.3. Pigs in the ST system spent 21% of the observations in straw-directed behaviour. The level of straw manipulation was not affected by the provision of additional environmental enrichment in the form of the hanging toy. Levels of toy manipulation were low in both housing systems compared with levels of straw manipulation, and did not differ in pairwise comparison of the same toy in different housing systems, or the different numbers of the toy within the FS system. Behaviours directed at pen mates (P=0.06) and pen components (P<0.001) were both more frequent in FS than in ST housing, and were not affected by type of toy.

Table 3.3. Mean percentage of observations over three time periods that pigs spent engaged in behaviours directed at either straw or an available enrichment device, and in behaviours directed at pen-mates or pen componentsBuilding Straw-based Fully-slatted S.E.M

.P-value

Enrichment Control + 1 toy + 1 toy + 4 toys% behaviour towards:

Straw 21.55 20.53 - - 1.77 NSEnrichment device - 0.32a 0.87a,b 1.37b 0.20 **

% behaviour towards:Other pig 5.08 4.95 6.75 6.16 0.53 0.064

Pen components 3.19 3.28 12.70 11.09 0.77 ***

Overall ConclusionsRecent legislation has highlighted the urgency in identifying suitable enrichment that will meet the behavioural needs of the pig in unbedded systems. No such form of enrichment examined in this project provided anything close to the same level of occupation as seen with straw, although there were no consistent effects of enrichment on pig performance. Greatest occupation was provided in PT2 by a rootable, edible substrate (sugar beet pulp shreds), but the difference between this and a hanging toy was not great. Any difference appeared to more

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attributable to the particulate/edible nature of the substrate rather than its floor level location and rooting possibility, since these attributes per se did not improve object use in PT3. The reasons behind the difference in occupation time between straw manipulation and enrichment object interaction require further study, since such occupation is important in the prevention of other adverse behaviours, as indicated by the difference in tail biting prevalence between the straw based and fully slatted building.

4.5. Objective 5. To synthesise recommendations for commercially applicable finishing pig systems which optimise pig health and welfare

The results of the work did not show that any housing or feeding system produced a clear health and welfare advantage across all parameters measured. Instead, it highlighted the different areas of risk to welfare in each system and, consequently, the aspects of design or management which should receive most attention within that system. This information has been disseminated to policy makers, pig producers and their allied industries and the scientific community in the following knowledge transfer activities:

4.5.1. Technical Reports

MLC. (2004a). Finishing Pigs: Systems Research. Production Trial 1 Dry versus liquid feeding in two contrasting finishing systems (fully slatted versus straw based housing). pp. 59. Milton Keynes: Meat and Livestock Commission.MLC. (2004b). Finishing Pigs: Systems Research. Production Trial 2 Evaluation of phase feeding in two contrasting finishing systems (fully slatted versus straw based housing). pp. 36. Milton Keynes: Meat and Livestock Commission.MLC. (2005a). Finishing Pigs: Systems Research. Production Trial 3 Controlled fermentation of cereals in liquid diets fed to pigs in two contrasting finishing systems (fully slatted versus straw based housing). pp. 35. Milton Keynes: Meat and Livestock Commission.MLC. (2005b). Finishing Pigs: Systems Research. Production Trial 4 Reducing the protein content of liquid diets fed to pigs in two contrasting finishing systems (fully slatted versus straw based housing). pp. 45. Milton Keynes: Meat and Livestock Commission.

4.5.2. Presentations to Policy makers and Industry

Presentations of interim results were made to the Project Steering Group Meetings on 16/9/2002 and 12/12/2002, 20/3/2003, 19/6/2003 and 18/9/2003, 18/12/2003, 25/3/2004 and 23/9/2004, and 22/7/2005. Updates on results were given to Defra Veterinary Research Division at Stotfold on 20/5/2004 and at Newcastle on 9/3/2005. A presentation was made to the Review of ‘On-farm Pig Welfare’ organised by Defra Veterinary Research Division (10-11 July 2003).

Talks on the results from the experiments were given at Producer Study Days at the MLC Stotfold Unit on 29/1/03 and 9/4/03, and the Stotfold Pig Discussion Group on 15/12/2004. Talks including results from the work have been given by BPEX/MLC extension staff during Producer visits to the MLC Stotfold Unit, and included in presentations at a series of 6 NPA/BPEX Regional Meetings and 5 pig producer discussion group meetings in Autumn 2003, and 7 pig producer discussion group meetings in 2004.

4.5.3. Conference presentations

Scott K, Armstrong D, Chennells DJ, Eckersall PD, Gill BP, Hunt B, Taylor L, Edwards SA. 2004. ‘The welfare of finishing pigs under different housing and feeding systems: 1. liquid versus dry feeding in fully-slatted and straw-bedded housing’. Proceedings of the British Society of Animal Science, p43. [presented at the Annual Meeting of the British Society of Animal Science, York, April 2004]

Edwards SA, Scott K, Armstrong, D, Chennells DJ, Eckersall PD, Gill BP, Hunt B, Taylor L. 2004. Finishing pigs systems research: health and welfare. The Pig Journal, volume 53: 123-127. [presented at Pig Veterinary Society meeting, Leeds, November 2003].

Scott K, Taylor L, Gill BP, Edwards SA. 2005. Influence of different types of environmental enrichment on the behaviour of finishing pigs in two different housing systems. Proceedings of the British Society of Animal Science, p82. [presented at the joint meeting of the British Society of Animal Science and International society of Applied Ethology, York, April 2005]

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Scott K, Campbell F, Chennels D, Hunt B, Armstrong, D, Taylor L, Gill B, Edwards SA. 2005. Acute phase protein concentrations in finishing pigs under two different management systems. Proceedings 5 th International Colloquium on Animal Acute Phase Proteins, Dublin 14-15 March.

Edwards SA, Scott K, Chennells DJ, Campbell, F, Hunt B, Armstrong, D, Taylor L, Gill BP. 2005. Finishing pig systems: health and welfare in straw bedded or slatted housing. The Pig Journal, in press. [Presented at the Pig Veterinary Society Meeting, Leeds, May 2005]

Scott K, Chennells D, Hunt B, Armstrong, D, Taylor L. Gill BP, Edwards SA, 2005. Multidisciplinary welfare assessment of pig finishing systems. Proc 3rd International Workshop on the Assessment of Animal Welfare at Farm and Group Level, Vienna, September 22-24. [accepted for presentation]

The work carried out under this project has also been referred to in the following review presentations:Gill B P (2002) Pig finishing systems research: a multidisciplinary research programme co-ordinated by the MLC. Proceedings of the Society of Feed Technologists, November 2002.Edwards SA (2003) ‘Current developments in pig welfare’ presented at ‘The Appliance of Pig Science’, an Occasional Meeting of the British Society of Animal Science, Nottingham, September 2003. Thompson J (2003) ‘Nutritional precision and performance benefits: the potential of liquid feeding’ presented at ‘Practical Pig Nutrition’, a joint conference of the MLC and Society of Feed Technologists, Coventry, November 2003.Edwards SA, 2005. Experimental welfare assessment and on-farm application. Proc 3 rd International Workshop on the Assessment of Animal Welfare at Farm and Group Level, Vienna, September 22-24. [plenary presentation]

4.5.4. Scientific papers

Scott K, Chennells DJ, Armstrong D, Taylor L, Gill BP and Edwards SA. The welfare of finishing pigs under different housing and feeding systems: liquid versus dry feeding in fully-slatted and straw-based housing. Circulated draft awaiting Steering Group approval for submission to ‘Animal Welfare’

Scott K, Chennells DJ, Campbell F, Hunt B, Armstrong D, Taylor L, Gill BP and Edwards SA , The welfare of finishing pigs in two contrasting housing systems: fully-slatted versus straw-based accommodation. Circulated draft awaiting Steering Group approval for submission to ‘Livestock Production Science’

Scott K, Taylor L, Gill BP and Edwards SA. Influence of different types of environmental enrichment on the behaviour of finishing pigs in two different housing systems: 1. hanging toy v. rootable substrate. Circulated draft awaiting Steering Group approval for submission to ‘Applied Animal Behaviour Science’

Scott K, Taylor L, Gill BP and Edwards SA. Influence of different types of environmental enrichment on the behaviour of finishing pigs in two different housing systems: 2. ratio of pigs to enrichment. Circulated draft awaiting Steering Group approval for submission to ‘Applied Animal Behaviour Science’

Scott K, Watson H, Taylor L, Gill BP and Edwards SA. Feeding behaviour of pigs offered ad libitum dry or liquid diets in fully slatted or straw based housing. In preparation..Scott K, Campbell F, Chennells DJ, Hunt B, Armstrong D, Taylor L, Gill BP and Edwards SA. Inter-relationships between health status, growth and acute phase proteins in finishing pigs. In preparation.

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References to published material9. This section should be used to record links (hypertext links where possible) or references to other

published material generated by, or relating to this project.

Scott K, Armstrong D, Chennells DJ, Eckersall PD, Gill BP, Hunt B, Taylor L, Edwards SA. 2004. ‘The welfare of finishing pigs under different housing and feeding systems: 1. liquid versus dry feeding in fully-slatted and straw-bedded housing’. Proceedings of the British Society of Animal Science, p43.

Edwards SA, Scott K, Armstrong, D, Chennells DJ, Eckersall PD, Gill BP, Hunt B, Taylor L. 2004. Finishing pigs systems research: health and welfare. The Pig Journal, volume 53: 123-127.

Scott K, Taylor L, Gill BP, Edwards SA. 2005. Influence of different types of environmental enrichment on the behaviour of finishing pigs in two different housing systems. Proceedings of the British Society of Animal Science, p82.

Scott K, Campbell F, Chennels D, Hunt B, Armstrong, D, Taylor L, Gill B, Edwards SA. 2005. Acute phase protein concentrations in finishing pigs under two different management systems. Proceedings 5th

International Colloquium on Animal Acute Phase Proteins, Dublin 14-15 March.

Edwards SA, Scott K, Chennells DJ, Campbell, F, Hunt B, Armstrong, D, Taylor L, Gill BP. 2005. Finishing pig systems: health and welfare in straw bedded or slatted housing. The Pig Journal, in press.

Scott K, Chennells D, Hunt B, Armstrong, D, Taylor L. Gill BP, Edwards SA, 2005. Multidisciplinary welfare assessment of pig finishing systems. Proc 3rd International Workshop on the Assessment of Animal Welfare at Farm and Group Level, Vienna, September 22-24. In press.

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