Behaviour of liquid-fed growing pigs provided with straw in various amounts and frequencies

Straw possesses many characteristics that make it attractive to pigs and can therefore be effective in preventing negative penmate-directed behaviours. However, straw is difficult to handle in current vacuum slurry systems under most commercial conditions and can therefore only be used in limited amounts. To occupy pigs effectively, straw must remain attractive to pigs throughout the whole day; hence, have a certain degree of novelty. We investigated the penmate-directed behaviour of liquid-fed growing pigs in a production herd, assigned to five experimental treatments: 1×25, 1×50, 1×100, 2×50 and 4×25 g of chopped straw/pig per day, with 20 replicates of each treatment (pen was regarded as experimental unit). Behaviour was observed at two different growth stages; ~40 and 80 kg live weight of the pigs. Activity and exploratory behaviour directed at penmates, straw, pen components and the slatted floor were registered continuously for 15 min of each hour during day time (0600 to 2200 h) by use of video observation of three focal pigs per pen. The pigs were active for about one-third of the day corresponding to ~5 h/day. Of the active time, an average of 7% (35 min) was spent on penmate-directed behaviour. The pigs were more active and increased their straw-directed behaviour when provided with 100 g straw/pig per day compared with 25 and 50 g (P<0.001). However, penmate-directed behaviour was not reduced with an increased amount of straw (P>0.05), and there was no effect on pigs’ behaviour when straw provision was increased per day (P>0.05). Pigs became less active and reduced their straw-directed activities when their weight increased from 40 to 80 kg live weight (P<0.001), but the amount of penmate-directed behaviour was similar (P>0.05). Further, the residual straw results indicated that perhaps a more frequent straw provision could help establish a more even level of fresh available straw during the day. However, the frequent straw provision did not occupy pigs more than one daily allocation did. In conclusion, there was no difference in penmate-directed behaviour of the pigs when given 25 or 50 g of straw/pig per day compared with 100 g of straw/pig per day, nor were there any difference when 100 g of straw/pig per day was provided more frequently.     

Effect of straw amount on feed intake and weight gain in growing pigs housed in pens with partly slatted floor

The provision of straw to pigs kept in conventional pens with concrete floor improves animal welfare, but the effects of straw on pigs’ performance are unclear. In two steps, we investigated the relationship between amount of straw provided to pigs and measures of performance in a set-up maintaining constant space allowance and controlled room temperature. From approximately 30- to 85-kg BW, pigs were housed in groups of 18 in pens (5.48 m × 2.48 m) with concrete floor (1/3 solid, 1/3 drained and 1/3 slatted). The pens were cleaned manually twice a week, and the designated amount of fresh uncut wheat straw was provided daily onto the solid part of the floor. In the first step, 48 pens were assigned to 10-, 500- or 1000-g straw per pig per day, while in the second step, 90 pens were assigned to 10-, 80-, 150-, 220-, 290-, 360-, 430- or 500-g straw per pig per day. Pigs were weighed at the start of the experimental period at approximately 30 kg and again at approximately 85-kg BW. The average daily gain increased 8.1 g (SEM 17) for every extra 100-g straw added daily (P < 0.001) resulting in 40 g higher average daily gain with 500 compared to 10-g straw per pig per day. The feed conversion ratio was not affected by the amount of straw provided, as the feed intake tended to be higher with increasing amounts of straw. Thus, between 10 and 500 g, the more straw provided, the higher the daily weight gain. As the nutritional value of straw is considered minimal, this result is likely due to improved gut health from the increasing amounts of straw ingested and increased feed intake due to increased stimulation of exploratory behaviour with increasing amounts of straw available, or a combination of these. The observed tendency for a higher feed intake supports this suggestion, but studies are needed to establish the impact of these two contributing factors.     

Gaseous emissions during the fattening of pigs kept either on fully slatted floors or on straw flow

The aim of this study was to compare the environmental impact of the straw-flow system for fattening pigs with the slatted-floor system by measuring pollutant gas emissions such as ammonia (NH3), nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2), manure nitrogen (N) content and emissions of water vapour (H2O). Three successive batches of 32 pigs were fattened. For each batch, pigs were allotted to two groups raised in separated rooms fitted either with a concrete totally slatted-floor system (0.75 m2 per pig) or with a straw-flow system (0.79 m2 per pig). With this last system, pigs were kept on a sloped floor, straw being provided daily at the top of the pen. Throughout the fattening period, about 34.4 kg of straw were supplied per pig. The straw, mixed with dung, travelled down the slope by pig motion and went out of the pen to a scraped passage. The solid fraction was scraped every day, stored in a heap in the room and removed every month, 1 week before each period of gaseous emission measurement. The liquid fraction was automatically pumped from the scraped passage into a hermetic tank, which was emptied at the end of each fattening period. Rooms were ventilated mechanically in order to maintain a constant ambient temperature. Once a month, the emissions of NH3, N2O, CH4, CO2 and H2O were measured hourly for 6 consecutive days via infrared photoacoustic detection. Mean daily emissions per pig fattened on the slatted floor or on the sloped floor were, respectively, 4.98 and 13.31 g NH3, 0.67 and 0.68 g N2O, 15.2 and 8.88 g CH4, 548 g and 406 g CO2 equivalents, 1.61 and 1.77 kg CO2 and 2.33 and 2.95 kg H2O. Except for N2O emissions, all the differences were statistically significant (P < 0.001). From the slatted-floor system, the amount of slurry removed per fattening period was on average 256 kg per pig. From the straw-flow system, solid manure amounted on average to 209 kg per pig and liquid manure to 53 kg per pig. The total N-content of the manure was 2.23 kg N per pig with the straw-flow system (solid and liquid manure) v. 3.26 kg N per pig for slurry from the slatted-floor system. This reduction of 30% observed with the sloped floor was mainly explained by the higher level of NH3-N emissions.     

Behaviour of 3-week weaned pigs in Straw-Flow(R), deep straw and flatdeck housing systems

The behaviour of 3-week weaned pigs in different housing systems was examined as part of an assessment of the suitability of the Straw-Flow(R) system for pigs of this age. Three replicate pens of 20 pigs were weaned at 6.4 kg liveweight into each of: (a) deep-straw; (b) Straw-Flow(R); (c) large flatdeck; (d) small flatdeck. A kenneled lying area was provided in (a) and (b). The floor in (c) and (d) was expanded metal. Stocking densities were 0.23 m(2)/pig in (a), (b) and (c), and 0.17 m(2)/pig in (d). After 4-5 weeks (at 19.6 kg liveweight), 16 pigs from each pen were moved into Straw-Flow(R) grower pens (0.68 m(2)/pig) and observed until slaughter at 90.6 kg. Pigs in systems incorporating straw showed behaviour patterns associated with increased welfare (greater straw-directed behaviour and less pig-directed and pen-directed behaviour) relative to those in barren pens. Behavioural differences between (a) and (b) related to differences in available straw; there were few differences between (c) and (d). Pigs from (c) and (d) showed increased rooting relative to those from (a) after transfer to the grower pens, but other behavioural differences between weaner treatments did not persist. It is concluded that the Straw-Flow(R) system can provide suitable accommodation for weaned pigs.     

Which is the most preventive measure against tail damage in finisher pigs: tail docking,straw provision or lowered stocking density?

One challenge of intensive pig production is tail damage caused by tail biting, and farmers often decrease the prevalence of tail damage through tail docking. However, tail docking is not an optimal preventive measure against tail damage and thus, it would be preferable to replace it. The aim of the current study was to investigate the relative effect of three possible preventive measures against tail damage. The study included 112 pens with 1624 finisher pigs divided between four batches. Pens were randomly assigned to one level of each of three treatments: (1) tail-docked (n=60 pens) v. undocked (n=52 pens), (2) 150 g of straw provided per pig per day on the solid floor (n=56 pens) v. no straw provided (n=56 pens), (3) stocking density of 1.21 m²/pig (11 pig/pen; n=56 pens) v. 0.73 m²/pig (18 pigs/pen; n=56 pens). Tail damage was recorded three times per week throughout the finisher period by scoring the tail of each individual pig. A pen was recorded as a tail damage pen and no longer included in the study if at least one pig in a pen had a bleeding tail wound; thus, only the first incidence of tail damage on pen level was recorded. Data were analysed by a Cox regression for survival analysis assuming proportional hazards. Results are presented as hazards, and a higher hazard means that a pen has a higher risk of tail damage and of it happening earlier in the finisher period. Pens with undocked pigs had a 4.32-fold higher hazard of tail damage compared with pens with docked pigs (P<0.001). Pens with no straw provided had a 2.22-fold higher hazard of tail damage compared with pens with straw provided (P<0.01). No interactions was seen between the treatments, but the effect of tail docking was higher than the effect of straw provision (P<0.001). Stocking density did not have a significant effect on the hazard of tail damage (hazard rate ratios (HRR)=1.67; P=0.064). However, a combination of straw provision and lowered stocking density showed a similar hazard of tail damage as seen with only tail docking (HRR=1.58; P=0.39). In conclusion, tail docking and straw provision were preventive measures against tail damage, and tail docking reduced the risk more than straw provision. A combination of other preventive measures is necessary to reduce the risk of tail damage in undocked pigs to the same level as in docked pigs.     

Influence of a raised slatted area in front of the nest on leg health,mating behaviour and floor eggs in broiler breeders

European farms for broiler breeders often have raised slatted areas in front of the nests, but in other regions of the world no raised slatted areas are provided. This study aimed to investigate the effects of a raised slatted area on leg health, mating behaviour and floor laying behaviour. Ten groups of 33 broiler breeder hens and three males were housed in two pen types: with or without a raised slatted area in front of the nests. Each pen had one plastic and one wooden nest. Between 25 and 31 weeks of age, ten marked hens per pen were weighed and assessed weekly on foot pad dermatitis, hock burn and wounds. At the end of week 31, animals were euthanized and bone strength of the tibia and humerus of these individuals was assessed. At 24, 27 and 30 weeks of age, mating behaviour was observed for an hour per pen, noting both numbers of successful and unsuccessful copulations. The number of eggs laid in the nests and on the floor was recorded daily between 20 and 31 weeks of age. Foot pad dermatitis scores were affected by age, but not by pen type. Generally, there were only minor issues with foot pad dermatitis (scores < 11 on a 0–100 scale), probably due to the young age of the hens. Body weight was not affected by pen type, while the prevalence of hock burns was too low to analyse and no difference in bone strength was found for the tibia and the humerus. Overall, mating behaviour was less frequent in pens with raised slats than in pens without raised slats (29 ± 2 vs 35 ± 3 times/h) and more frequent at 27 weeks of age than at 24 and 30 weeks of age (38 ± 1 vs 31 ± 4 and 27 ± 2 times/h). The pens with raised slats had a lower percentage of floor eggs than pens without raised slats (11.2 ± 0.4 vs 19.3 ± 0.5%). The wooden nest was preferred over the plastic nest as on average 63% of the eggs were laid in the wooden nest. This study shows that providing raised slats decreases mating behaviour and percentage of floor eggs, although its effects on leg health remain inconclusive.     

More tail lesions among undocked than tail docked pigs in a conventional herd

The vast majority of piglets reared in the European Union (EU) and worldwide is tail docked to reduce the risk of being tail bitten, even though EU animal welfare legislation bans routine tail docking. Many conventional herds experience low levels of tail biting among tail docked pigs, however it is not known, what the prevalence would have been had the pigs not been tail docked. The aim of this study was to compare the prevalence of tail lesions between docked and undocked pigs in a conventional piggery in Denmark with very low prevalence of tail biting among tail docked pigs. The study included 1922 DanAvl Duroc×(Landrace×Large White) female and castrated male pigs (962 docked and 960 undocked). Docked and undocked pigs were housed under the same conditions in the same room but in separate pens with 20 (±0.03) pigs/pen. Pigs had ad libitum access to commercial diets in a feed dispenser. Manipulable material in the form of chopped straw was provided daily on the floor (~10 g/pig per day), and each pen had two vertically placed soft wood boards. From weaning to slaughter, tail wounds (injury severity and freshness) were scored every 2^nd week. No clinical signs of injured tails were observed within the tail docked group, whereas 23.0% of the undocked pigs got a tail lesion. On average, 4.0% of the pigs with undocked tails had a tail lesion on tail inspection days. More pens with tail lesions were observed among pigs weighing 30 to 60 kg (34.3%; P<0.05) than in pens with pigs weighing 7 to 30 kg (13.0%) and 60 to 90 kg (12.8%). Removal of pigs to a hospital pen was more likely in undocked pens (P<0.05, 47.7% undocked pens and 22.9% docked pens). Finally, abattoir meat inspection data revealed more tail biting remarks in undocked pigs (P<0.001). In conclusion, this study suggests that housing pigs with intact tails in conventional herds with very low prevalence of tail biting among tail docked pigs, will increase the prevalence of pigs with tail lesions considerably, and pig producers will need more hospital pens. Abattoir data indicate that tail biting remarks from meat inspection data severely underestimate on-farm prevalence of tail lesions.     

Longitudinal gait development and variability of growing pigs reared on three different floor types

Biomechanical investigation into locomotor pathology in commercial pigs is lacking despite this being a major concern for the industry. Different floor types are used in modern, intensive pig production systems at different stages of the pigs’ production cycle. The general perception holds that slatted and/or hard solid concrete surfaces are inferior to soft straw-covered floors regarding healthy musculoskeletal development. Previous studies have compared pigs housed on different floor types using clinical, subjective assessment of leg weakness and lameness. However, reliability studies generally report a low repeatability of clinical lameness scoring. The objective of this study was to quantitatively assess the long-term effect of pen floors, reflected in the biomechanical gait characteristics and associated welfare of the pigs. A cohort of 24 pigs housed on one of three different floor types was followed from 37 to 90 kg average liveweight, with gait analysis (motion capture) starting at 63 kg. The three floor types were fully slatted concrete, partly slatted concrete and deep straw-bedded surfaces, all located within the same building. Pigs underwent five repeated camera-based motion captures, 7 to 10 days apart, during which 3D coordinate data of reflective skin markers attached to leg anatomical landmarks were collected. Pigs walked on the same solid concrete walkway during captures. One-way ANOVA and repeated measures ANOVA were used to analyse the gait data. Results revealed changes over time in the spatiotemporal gait pattern which were similar in magnitude and direction for the pigs from different floor types. Significant increases in elbow joint flexion with age were observed in all pigs (P⩽0.050; +6°). There were few differences between floor groups, except for the step-to-stride ratio in the hind legs being more irregular in pigs housed on partly slatted floors (P=0.012; 3.6 times higher s.d.) compared with those on 5 to 10 cm straw-bedding in all pen areas. As the level of clinical problems was generally low in this cohort, it may be that floors elicit problems only when there is a primary predisposing factor increasing weakness in susceptible tissues.     

Influence of different types of environmental enrichment on the behaviour of finishing pigs in two different housing systems: 3. Hanging toy versus rootable toy of the same material

This study aimed to assess the effects of (1) environmental enrichment with either straw bedding or a plastic toy and (2) the way in which the plastic toy was presented on the behaviour of finishing pigs in two different housing systems. One thousand and twenty four (Large White × Landrace) × Large White pigs were housed contemporarily in either a straw-based (ST) or fully slatted (FS) building from 35 kg to slaughter at 104 kg. In each building, half of the pens received additional environmental enrichment in the form of a hanging plastic toy. The remaining pens in the ST house were enriched only by the straw bedding. In the FS house, the remaining pens were provided with a rootable toy of the same plastic material presented on the floor of the pen. There was no significant effect of housing system on the level of manipulation of the hanging toy. Within the FS system, the level of manipulation of the hanging toy tended to be higher than that of the plastic toy presented on the floor (P = 0.052). Neither form of additional environmental enrichment provided a comparable level of occupation to that of straw bedding. In the absence of straw, more investigatory behaviours were directed towards both pen-mates (P < 0.001) and pen components (P < 0.001). Further study is required to identify functional forms of environmental enrichment in slatted systems to occupy pigs and prevent them from performing adverse behaviours.     

Effect of pen design on tail biting and tail-directed behaviour of finishing pigs with intact tails

Tail biting is a welfare and economical concern in modern pig production. One common preventive measure used throughout the world is tail docking, which is generally considered one of the most effective methods for limiting tail biting. However, tail docking is a painful mutilation and systematic tail docking is not allowed in the EU. Therefore, the aim was to compare pig behaviour and the prevalence of tail biting in finishing pigs with intact tails housed in two different pen designs under Danish commercial conditions. PEN1 was a traditional Danish pen and PEN2 was inspired by Swedish finisher pen design and had a larger proportion of solid floor area (PEN1: 1/3 and PEN2: 2/3), reduced group size (PEN1: 15 and PEN2: 12), increased space allowance per head (PEN1: 0.7 m² and PEN2: 0.89 m²) and straw allocated on the floor (PEN2) whereas straw was provided in a straw rack in PEN1. Tail damage observations were carried out daily by the stockperson and every 2 weeks one trained research technician assessed tail damages according to a tail scoring system. Tail lesions were observed in 51% of PEN1 and in 11% of PEN2 (P < 0.001). PEN1 had higher prevalence of tail damages than PEN2 (23% v. 5%, P < 0.001). Behavioural observations were carried out by the use of video recordings. Pigs in PEN2 tended to spend more time on tail-directed behaviour than pigs in PEN1 (P = 0.07), whereas pigs in PEN1 tended to spend more time on ear-directed behaviour (P = 0.08). Pigs in PEN2 spent more time on straw-directed behaviour compared to pigs in PEN1 (P < 0.001). Pen design did not affect time spent on other penmate-directed behaviour. In addition, the level of welfare between the two pen designs was compared using the Welfare Quality® protocol. PEN2 received an overall score of ‘excellent’ while PEN1 scored ‘enhanced’. PEN2 scored higher on all principles besides ‘good health’, where PEN1 scored better on lameness and wounds. The main measurements accounting for the differences were water supply, huddling, tail biting, social behaviour and fear of humans. In conclusion, the combination of increased space allowance, increased area of solid flooring, straw allocated onto the floor and reduced group size (PEN2) resulted in fewer tail damaged pigs and a better overall welfare assessment, despite a tendency for more tail-directed behaviour.     

Synthetic rubber surface as an alternative to concrete to improve welfare and performance of finishing beef cattle reared on fully slatted flooring

The aim of this study was to compare a fully slatted concrete floor (concrete slatted (CS)) with the same floor on which synthetic rubber slats were placed on the concrete slats (rubber slatted (RS)) as housing solution for finishing beef cattle. The present study involved five commercial beef cattle farms in which the floor of at least three pens was kept as fully slatted, and in an equal number of pens a rubber cover was placed on the floor, tightly matching the gap profile of the concrete slats to allow the drainage of manure. A total of 326 finishing beef bulls were used (153 on CS and 173 on RS), and regardless of the floor treatment animals were housed in groups of 6 to 12 bulls/pen with a space allowance of 3.1±0.2 m²/bull. Bulls had similar initial live weights (422.3 kg on CS and 425.0 kg on RS), but bulls on RS were heavier at the end of the finishing period with a higher average daily gain than bulls kept on CS (1.53 v. 1.46 kg/day; P<0.05). The proportion of bulls treated for locomotor problems was lower in RS pens compared with CS. Rubber covering prevented the occurrence of bursitis, but it increased the odds for hoof overgrowth at end of the finishing period. Hoof overgrowth detected in vivo in bulls on RS was confirmed at the slaughterhouse by the longer dorsal wall and diagonal lengths of the hoof as well as by a more acute toe angle. Compared with bulls on CS, bulls on RS showed less inactivity and resting time, increased social interactions, decreased abnormal lying down and unsuccessful attempts to lie down, as well as shortened the time for lying down. Bulls in RS pens were dirtier compared with those in CS pens, likely due to the draining gaps being reduced to 11.6±1.2% of the total pen surface compared with the 16.9±1.7% in CS pens. This study gave further evidence about the positive effects of the RS floor on growth performance and welfare of finishing beef cattle, although compromising cleanliness and hoof overgrowth.     

Effect of pens with an elevated platform on space utilization,skin lesions and growth performance in nursery pigs

Environmental enrichment, adequate space and the ability to separate a living area into suitable functional areas are key elements for pig welfare. In this study, a two-level pen for nursery pigs was explored with the aim of analysing the use of space and the impact on pig behaviour, health and performance. Therefore, per batch, three experimental groups in pens with elevated platforms (two-level pens) and one control group in a standard pen were formed after weaning at the age of 4 weeks. Thereafter, groups were studied for a period of 6 weeks. In a total of eight batches (n = 882 pigs), the occurrence of skin lesions was determined per individual using a lesion score, and in seven batches (n = 761 pigs) individual daily weight gain was analysed. In five batches (n = 450 pigs), the individual use of space and the behaviour of pigs were investigated by direct observation (4 h per day on 2 days in weeks 1, 3 and 6 of the housing period, respectively). Results revealed that 98.9% of pigs (n = 445) were observed on the elevated platform at least once. The probability that an individual pig used the platform was significantly higher than 0.95 (P < 0.0001, confidence interval = 0.977, 1). The use of the platform was not affected by sex (odds ratio (OR) = 1.013, P = 0.937). However, the probability of observing an individual on the elevated platform increased with increasing BW during the experimental period (OR = 1.043, P < 0.0001). The presence of a platform decreased the probability of seeing a pig fighting (P = 0.014) and increased the probability of observing locomotor behaviour as opposed to lying (P < 0.0001). In two-level pens, pigs sustained fewer skin injuries than in standard pens (day 41: OR = 0.731, P < 0.0001). Over 41 days of experiment, pigs in two-level pens had higher daily weight gains than animals in standard pens (416 versus 393 g/day, P = 0.006). We conclude that usable space for nursery pigs can be effectively extended by introducing elevated platforms into the pigs’ pen. Furthermore, pigs may benefit from two-level systems by establishing spaces for activity as well as for retreat from other pen mates, thereby reducing aggressive behaviour and social stress. The installation of two-level pens is therefore encouraged, if they are intended to provide more space than legally stipulated.     

Prevention and treatment of tail biting in weaned piglets

The aims of this study were to evaluate four preventive measures and two curative treatments of tail biting. The preventive measures were: chain, rubber hose, straw rack (5 g/pig/day) and the provision of straw on the floor twice daily by hand (2 × 10 g/pig/day). The two curative treatments, which were applied following the onset of tail biting in a pen were: straw twice daily (as in the fourth preventive measure) and the removal of the biter. In total, 960 undocked weaned piglets (10 piglets per pen) were observed during 5 weeks. Tail lesions (none, bite marks and wounds) were recorded daily. The incidence of pens with wounded pig tails was significantly lower when straw was provided twice daily (8% of pens) compared to the chain (58% of pens) and rubber hose (54% of pens) treatment, but did not differ significantly from the straw rack treatment (29% of pens). Tails with bite marks were significantly less common in pens with twice daily straw (16% of pens) compared to chain (88% of pens), rubber hose (79% of pens) and straw rack (75% of pens). No significant difference was found between the curative treatments. Both treatments showed a reduced incidence of red fresh blood on the tails at days 1–9 following curative treatment, compared to day 0. However, neither curative treatment eliminated tail biting entirely. In conclusion, this study indicates that tail biting is best prevented with a small amount of straw, provided twice daily, and to a lesser extent with a straw rack, compared to providing a chain or a rubber hose. Once tail biting has occurred, providing a small amount of straw twice daily and removing the biter appears to be equally effective.     

The effects of weight asymmetry and resource distribution on aggression in groups of unacquainted pigs

The relationship between weight asymmetry and aggression when mixing groups of unacquainted pigs in two different environments was investigated. Ten groups of 4 female (LandracexYorkshire), unacquainted pigs with a weight asymmetry of 3.1+/-0.2 kg (mean weight: 16.6+/-0.6 kg) between each pig, and another 10 groups with a weight asymmetry of 1.2+/-0.1 kg (mean weight: 14.1+/-0.1 kg), were mixed at the age of 7 weeks. Ten of the groups (five of each) were mixed in an experimental pen with a heterogeneous distribution of straw. The pen consisted of two main compartments with straw in one of them, and a passage area with concrete floor in between. The other 10 groups were mixed in the same pen, but with a homogenous distribution of straw (straw spread all over the pen).The results showed that fighting duration was significantly shorter in groups with large weight asymmetry than in groups with small weight asymmetry irrespective of the environment. The number of bites delivered during the fights in the heterogeneous environment was lower in groups with large weight asymmetry than in groups with small weight asymmetry. In the homogenous environment, however, there was no significant difference between groups with large and small weight asymmetries regarding the number of bites. The combination of a limited straw area and a small weight asymmetry resulted in the greatest number of bites. In groups with large weight asymmetry, the largest pig won around 50% of the fights, and 25% of the variation in the percentage of fights won was explained by the weight asymmetry.In groups with small weight asymmetry, less than 10% of the variation in the percentage of fights won could be explained by weight asymmetry. The two largest pigs delivered significantly more bites and spent significantly more time fighting than the smallest pig. The second largest pig received significantly more bites and body lesions than the smallest pig in the groups. Fights between the two largest pigs had a significantly longer duration than when other pigs were involved. The results were discussed in relation to sequential assessment theory and resource defence theory.     

The interaction of liveweight and the degree of competition on drinking behaviour in growing pigs at different group sizes

The pattern of drinking behaviour in pigs, and the influence of social factors such as competition on this behaviour, have been poorly documented. If competition for access to a limited resource is substantial, access to that resource may be allocated disproportionately to different members of a group. Priority may be based on a dominance hierarchy, or on physical characteristics, such as weight. The pattern of drinking behaviour was examined and the effect of pig liveweight on drinking behaviour under conditions likely to produce different levels of competition was investigated. Four replicates of a 2x2 factorial design of two group sizes (20 vs. 60) and two drinker:pig ratios (1:10 vs. 1:20) used a total of 640 growing pigs (start weight 36+/-5.0 kg). The drinking behaviour, skin lesion score and performance of nine focal pigs (three each of heavy (41.9 S.E.M. 0.57 kg), medium (35.7 S.E.M. 0.51 kg) and light weight (30.9 S.E.M. 0.63 kg)) per pen were recorded. For all focal pigs, the maximum time spent at the drinkers occurred between the 1800 and 1900 h and the minimum time between 0700 and 0800 h. The mean number of drinking bouts per pig per day was 30.9 S.E.M. 1.41, the median bout length was 21 s and the mean daily duration spent at the drinkers was 832 s. The frequency of visits to the drinkers, drinking bout duration and daily drinking time were affected by group size and drinker allocation, but not by weight or the interaction of treatments and weight. The diurnal spread of drinking was similar for each of the four treatment combinations and each weight category. Heavy pigs had the greatest number of lesions, and light weight pigs the least (13.2 vs. 8.8 S.E.D. 1.18, P<0.005), but this was not affected by the four treatment combinations. Lesion score correlated poorly with the parameters of drinking behaviour. The treatments, in isolation, or in interaction with weight, did not affect performance. No treatment encouraged sufficient competition to compromise the drinking behaviour, social behaviour or performance of the lightest animals in the pen.     

Effects of two stall flooring systems on the behaviour of tied dairy cows

Effects on dairy cow behaviour of a new type of flooring in tie-stalls, with the ability to drain faeces and urine, was studied in a controlled randomised trial in one Swedish university herd. Forty-two Swedish Red and White cows were kept tied in traditional long-stalls (2.20m). In 21 stalls (one stall row), the rearmost 0.74m of the solid stall floor had been replaced with nine rubber-coated 53mm wide slats, divided by 29mm slots. Stalls with rubber slats were equipped with 20mm ethyl-vinyl-acetate (EVA) mats in the front part and littered with 0.7kg of wood shavings daily, while stalls with a solid floor had standard rubber mats and received 3kg of chopped straw daily as bedding. Behaviour was compared between the two stall types, using video recordings of 12 matched pairs of cows for two complete 24h periods each. Statistical analysis was done using the Student's t-test for matched pairs or the sign test. Cows on the rubber slatted flooring lie down and rise normally and without any increased risk of slipping. They lay down more comfortably, i.e. spent on an average 23% less time preparing to lie down, and slipped less frequently during rising. There was some evidence of a preference for a solid floor when lying.     

Comparison of growth performance and agonistic interaction in weaned piglets of different weight classes from farrowing systems with group or single housing

The present study was designed to analyze the growth performance, behavioral patterns and intensity of injuries of weaned pigs (26 days) during a rearing period of 6 weeks. The farrowing system (group housing (GH) v. single housing (SH)) and the post-weaning regrouping weight class (light, medium, heavy) were considered as the main factors. A number of 120 GH-pigs and 120 SH-pigs were kept in three batches (20 pens, 12 pigs each). The GH- and SH-pigs were divided by weight into three groups: light (5 to ⩽7 kg), medium (>7 to ⩽9 kg) and heavy (>9 to ⩽12 kg), with two pigs of six different litters in each pen. The pigs were weighed individually at weaning (week 1) and during rearing (weeks 2, 3 and 7). The feed conversion ratio (FCR) was calculated between weeks 1 and 7. The duration and number of fights (NF) per pen and hour were determined by continuous sampling (40 h after weaning). Lesions of the integument were scored into four classes (none, minor, medium, severe) and recorded at weaning and 48 h afterwards. The farrowing system had no effect on the weights in week 1 (GH: 7.8 kg v. SH: 7.7 kg; week as linear, quadratic regression nested within housing systems) or in week 7 (GH: 29.4 kg v. SH: 28.6 kg). The body weights were influenced significantly by the weaning weight class (light: 11.7 kg (s.e.m.: 0.30), medium: 14.8 kg (s.e.m.: 0.22), heavy: 17.3 kg (s.e.m.: 0.26)). The FCR of the GH-pigs was 1.64 (s.e.m.: 0.03) and 1.58 (s.e.m.: 0.03) for SH-pigs. A reduced agonistic behavior of the GH-pigs was observed with 2.1 fights per pen and hour (s.e.m.: 0.07) v. the SH-pigs with 4.6 fights per pen and hour (s.e.m.: 0.05). The fight duration of the GH-pigs with 10.3 s per pen and hour (s.e.m.: 1.07) was significantly lower in comparison to the SH-pigs with 18.8 s per pen and hour (s.e.m.: 1.06). The SH-pigs had more new skin lesions at the shoulders than the GH-pigs 48 h after weaning (P < 0.05). In conclusion, early mixing of unacquainted litters during lactation had no influence on their growth performance during rearing but reduced agonistic behavior and lesion score difference during the first 2 days after weaning. No significant interaction between the farrowing system and weaning weight class was detected with regard to growth performance and NF.     

Tear staining in finisher pigs and its relation to age,growth, sex and potential pen level stressors

Tear staining (TS) in the pig has been related to different stressors and may be a useful tool for assessing animal welfare on farm. The aim of the current study was to investigate TS across the finisher period and its possible relation to age, growth, sex and experimentally induced stressors. The study included 80 finisher pens divided between three batches. Within each batch, the pens either included pigs with docked or undocked tails, had straw provided (150 g/pig/day) or not and had a low (1.21 m²/pig, 11 pigs) or high stocking density (0.73 m²/pig, 18 pigs). Tear staining (scores 1 to 4; from smaller to larger tear stain area, respectively) and tail damage were scored on each individual pig three times per week over the 9-week study period, and the individual maximum TS score within each week was chosen for further analysis. Data were analysed using logistic regression separately for each of the four possible TS score levels. The TS scores 1 and 2 decreased with weeks into the study period and were negatively related to the average daily gain (ADG) of the pigs, whereas the TS score 4 increased with weeks into the study period and was positively related to ADG. None of the TS scores differed between females and castrated males, and neither straw provision nor lowering the stocking density affected the TS scores. However, the TS score 1 decreased the last week before an event of tail damage (at least one pig in the pen with a bleeding tail wound), whereas the TS score 4 increased. The results of the current study advocates for a relation between TS and the factors such as age, growth and stress in the pig, while no relation was found between TS and the environmental factors straw provision and lowered stocking density. The relations to age and growth are important to take into consideration if using TS as a welfare assessment measure in the pig in the future.     

Influence of pig rearing system on animal performance and manure composition

A total of 200 crossbred pigs (castrated males and females) were used in five replicates to evaluate the influence of rearing conditions for fattening pigs on growth performance, manure production and gaseous emissions. Approximately at 36 kg body weight (BW), littermates were allocated to either a conventional (fully slatted floor, 0.65 m2/pig, considered as control, CON) or an alternative (sawdust bedding, 1.3 m2/pig, with free access to an outdoor area 1.1 m2/pig, OUT) system, until slaughter at approximately 115 kg BW. Pigs had free access to standard growing and finishing diets. Manure was stored as slurry below the slatted floor in the CON system and as litter, for the inside area, or slurry and liquid, for the outside area, in the OUT system. The amount and composition of manure were determined at the end of each replicate. Ammonia emission from the rooms was measured continuously. Dust and odour concentrations were measured in replicates 1 and 2, and CH4, N2O and CO2 emissions were measured in replicate 3. Compared with the CON, the OUT pigs exhibited a faster growth rate (+8%, P < 0.001) due to their greater feed intake (+0.21 kg/day, P < 0.01), resulting in a heavier BW (+7.3 kg, P < 0.001) and a lower lean meat content (-1.6% points, P < 0.001) at slaughter. The total amount of manure produced per pig was similar in both systems (380 kg/pig), but because of the contribution of sawdust, dry matter (DM) content was higher (P < 0.001) and concentrations in N, P, K, Cu and Zn in DM were lower (P < 0.001) in manure from the OUT than from the CON system. In the OUT system, most of the manure DM (70%) was collected indoor, corresponding mostly to the contribution of the sawdust, and most of the manure water (70%) was collected outdoor. Pigs excreted indoor about 60% and 40% of urine and faeces, respectively. Ammonia emission from the room was lower for the OUT system, whereas total NH3 emissions, including the outdoor area, tended to be higher (12.0 and 14.1 g/day N-NH3 per pig for CON and OUT, respectively). Nitrous oxide emission was higher (1.6 and 4.6 g/day N-N2O per pig for CON and OUT, respectively) and methane emission was lower (12.1 and 5.9 g/day per pig for CON and OUT, respectively), for the OUT compared with the CON system.     

An investigation into the effectiveness of compressed straw blocks in reducing abnormal behaviour in growing pigs

The provision of manipulable material to pigs is a legal requirement to ensure their good welfare. Loose straw is edible, chewable, investigable and manipulable, and has been proven to be effective in reducing abnormal behaviour. However, it is incompatible with slatted systems and therefore not a viable option for many intensive units. Thus, there is a need to identify enrichment materials that are as effective as loose straw and compatible with slatted floors. This study investigated the viability of using compressed straw blocks on a commercial farm in terms of cost and effectiveness in reducing biting relative to plastic hanging toys. A total of 880 slaughter pigs were used, among which half (n = 440, 8 groups) were provided with commercial pig toys (TOY) and the other half (n = 440, 8 groups) were provided compressed straw blocks (STRAW BLOCK). Animals were separated according to sex to investigate whether there was a higher propensity to tail and ear bite depending on sex. Pigs were monitored from weaning to slaughter, with tails being examined post scalding and any condemnations recorded at the abattoir. Throughout their life, the tails and ears of all pigs were examined individually, and behavioural observations of each pig group were conducted fortnightly. Salivary cortisol was also obtained from a subsample of pigs from each group every fortnight to monitor stress levels. The highest straw usage was recorded in the second weaner stage (39 to 67 days after weaning). Enrichment type or sex had no effect on tail lesion scores or cold carcass weight recorded at the abattoir. There was also no effect of enrichment type or sex on body, tail, or ear lesion scores during either the weaner (0 to 39 days after weaning) or finisher stage (67 to145 days after weaning). Female pigs showed more biting behaviour than males, and female pigs that were provided STRAW BLOCK performed better than those provided TOY. In both the weaner and finisher accommodation, more instances of interaction were recorded with TOY pens as enrichment than with STRAW BLOCK, but the interaction duration was not recorded. There was no effect of sex on either stage. More instances of aggression were observed with the TOY than with STRAW BLOCK in the weaner stage (P < 0.05). Enrichment type or sex had no effect on cortisol levels. Thus, relative to plastic hanging toys, compressed straw blocks provided in this manner did not benefit pig welfare.