Review: Concrete outdoor runs for organic growing-finishing pigs - a legislative, ethological and environmental perspective.

Concrete Outdoor Runs (OUTRUNs) are a characteristic part of organic pig housing. They must allow species-specific behaviours such as rooting and elimination, as explicitly required by organic legislation of the European Union (EU). However, OUTRUN design often fails to fulfil behavioural needs, and excreta can cover large parts of the OUTRUN leading to poor pen hygiene and associated ammonia (NH3) emissions. This review integrates legislative, ethological and environmental requirements for OUTRUNs for organic growing-finishing pigs. While EU regulations specify some welfare-related standards for OUTRUNs (e.g. minimal space allowance), national and private standards interpret some aspects differently, e.g. the proportion of roofed and slatted floor area. Furthermore, reducing NH3 emissions is equally a challenge for organic systems, even though EU legislation does not explicitly refer to OUTRUNs. Depending on the actual use of the OUTRUN for elimination, higher space allowance compared to conventional production norms increases the potential for a large NH3-emitting surface. The design of pen features (e.g. roof, floor, enrichment) can encourage pigs to separate functional areas and consequently reduce the elimination area and associated NH3 emissions. While providing the main lying area indoors, resting outdoors should be possible for sub-groups during the day. A roof protects pigs and resources (e.g. bedding) from adverse weather, but the effect on pig welfare and NH3 emissions is site-specific. A floor design that ensures practicable manure removal and drainage is most important to reduce emissions. Providing opportunities for exploring and rooting in the OUTRUN has particular relevance for pigs' behavioural needs and can improve pen hygiene by reducing the elimination area. Cooling facilities are increasingly important to prevent heat stress and its detrimental effects on welfare and pen hygiene. Finally, practicability for farmers needs to be ensured for all resources provided in OUTRUNs, as good management is crucial. Research gaps emerge regarding the association between soiling and NH3 and the influence of certain pen features (shape, roof, feeder location, pen partitions and wet areas) on pig behaviour and soiling.

Does hut climate matter for piglet survival in organic production?

Piglet mortality in outdoor production systems varies across the year, and a reason for this variation could be fluctuations in hut climate, as ambient temperature might influence piglet survival, both directly and indirectly. Therefore, the aim of the current study was to investigate the impact of farrowing hut climate and year variation on stillbirth and liveborn mortality. A large-scale observational study was conducted at five commercial organic pig-producing herds in Denmark from June 2015 to August 2016. Both year variation (F 3,635=4.40, P=0.004) and farrowing hut temperature (F 2,511=6.46, P=0.002) affected the rate of stillbirths. The risk of stillborn piglets was lowest in winter and during this season larger changes in hut temperature between day 1 prepartum and the day of farrowing increased the risk of stillbirths (F 1,99=6.39, P=0.013). In addition, during the warm part of the year stillbirth rate increased at temperatures ⩾27°C. Year variation also affected liveborn mortality (F 3,561=3.86, P=0.009) with a lower rate of liveborn deaths in spring. However, the hut climate did not influence liveborn deaths. Consequently, other factors than hut climate may explain the influence of year variation on liveborn mortality. These could be light differences causing seasonality in reproduction and lactation.

Changes in activity and object manipulation before tail damage in finisher pigs as an early detector of tail biting.

Tail damage within the production of finisher pigs is an animal welfare problem. Recent research suggests that removal of known risk factors may not be enough to eliminate tail biting, especially in undocked pigs, thus a different strategy is worth investigating. This could be early detection of tail biting, using behavioural changes observed before tail damage. If these early stages of tail biting can be detected before tail damage occurs, then tail damage could be prevented by early interventions. The first step in developing such a strategy is to identify the types of behaviour changes that emerge during early stages of tail biting. Thus, the aim of the current study was to investigate whether pen level activity and object manipulation evolved differently during the last 7 days before the scoring of tail damage (day 0) for pens scored with tail damage (tail damage pens) and pens not scored with tail damage (matched control pens). The study included video recordings for twenty-four tail damage pens and thirty-two matched control pens. Activity level and object manipulation were observed the last 7 days before day 0 during the morning (0600 to 0800 h), afternoon (1600 to 1800 h) and evening (2200 to 2400 h, only activity level). Both activity level and object manipulation were analysed using generalised linear mixed effects models with a binomial distribution for activity level and a negative binomial distribution for object manipulation. The probability of being active was higher in tail damage pens compared to control pens during the afternoon the last 5 days before day 0 (P<0.001). This was seen due to a decrease in activity level in the control pens, which makes it difficult to identify future tail damage pens from this difference. Object manipulation was lower in tail damage pens compared to the control pens on all 7 days before day 0, but only in pens with undocked pigs (P<0.01). Thus, it is still unknown when this difference in object manipulation initiated. It was concluded that both activity level and object manipulation seemed related to ongoing tail biting and should be investigated through more detailed observations and for a longer time to establish the normal behaviour pattern for a particular pen. Thus, it is suggested that future research focusses on developing automatic monitoring methods for pen level activity and object manipulation and applies algorithms that establish and detect deviations from the normal behaviour pattern of the pen before tail damage.

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.

The effect of varying duration of water restriction on drinking behaviour, welfare and production of lactating sows.

Access to drinking water is essential for animal welfare, but it is unclear if temporary water restriction during the night represents a welfare problem. The aim of the present study was to investigate the effect of various durations of nightly restriction of water on thirst in loose housed lactating sows from day 10 to 28 of lactation. A total of 48 sows were deprived of water for either 0 h (n=12; control), 3 h (n=12; 0500 to 0800 h), 6 h (n=12; 0200 to 0800 h) or 12 h (n=12; 2000 to 0800 h). Control sows consumed 22% of their water intake during the night (2000 to 0800 h), whereas water consumption during this time was reduced to 13%, 7% and 0% in sows restricted for 3, 6 and 12 h. With increased duration of nightly water restriction a reduced latency to drink (26.8, 18.0, 5.3 and 6.7 min for 0, 3, 6 and 12 h sows; P<0.001) and an increased water intake during the 1st hour after water became accessible (2.1, 3.4, 4.7 and 5.6 l for 0, 3, 6 and 12 h sows; P<0.001) was seen. During the last 30 min before water became accessible more sows deprived of water investigated (0%, 50%, 75%,and 50% of 0, 3, 6 and 12 h sows; P<0.01) or forcefully manipulated (0%, 17%, 50% and 33% of 0, 3, 6 and 12 h sows; P<0.05) the water trough, suggesting frustration and a negative experience of thirst. When all signs of imminent water access were provided, but access was delayed by 25 min, a tendency for more of the sows deprived of water for 6 and 12 h to interact forcefully with the water trough was seen (22%, 18%, 42% and 67% of 0, 3, 6 and 12 h sows; P=0.09). Duration of water restriction did not affect water consumption on a 24-h basis, nursing behaviour or performance. In conclusion, behavioural indicators of thirst increased with increasing duration of nightly water restriction in lactating sows.

Effect of radiant heat at the birth site in farrowing crates on hypothermia and behaviour in neonatal piglets.

It has been documented that floor heating of the farrowing area in loose housed sows improves survival of piglets significantly. However, today, the majority of farrowing pens are designed with crating of sows and slatted floor at the birth site. The aim of this study was to investigate whether providing radiant heat at the birth site to new-born piglets in pens with crated sows reduced hypothermia, time to first milk intake and growth of the piglets during the 1(st) week. Second parity Danish Landrace×Yorkshire sows (n=36) were randomly divided into two groups: Control (CG) and heat (HG). In the area behind the sow (zone 1), two radiant heat panels were mounted above the slatted floor in the HG. The farrowings were attended, and the heaters were turned on at birth of first piglet and turned off 12 h after. Birth time, time to leave zone 1, time to first contact with udder and time to first suckling were registered by direct observation. The piglet's rectal temperature (RT) was measured 15, 30, 60, 120, 180, 240 min after birth and 12, 14 and 24 h after birth of first piglet. Piglets were weighed at birth, 24 and 48 h and 7 days after birth. Data were analysed in a mixed model in SAS. The drop in RT was lower in HG compared with CG (P=0.002), and the RT in HG remained higher than in CG from 30 to 240 min after birth (P<0.05), whereas no difference was found at 12 h after birth of first piglet (P=0.92). Piglets in HG stayed longer in zone 1 than those in CG (P=0.01), whereas time to reach udder (P=0.35) and to first suckling (P=0.56) did not differ. No difference in weight gain was found between piglets in HG and CG at 24 h (P=0.23), 48 h (P=0.28) and 7 days after birth (P=0.44). Birth weight had a positive effect on RT (P<0.001) and reduced time to leave zone 1 (P<0.01), reach udder (P<0.001) and time to first suckling (P<0.001). The results showed that radiant heating behind the sows reduced hypothermia in new-born piglets and indicate that providing heat during the first half hour after birth is important.

Growing pigs' drinking behaviour: number of visits, duration, water intake and diurnal variation.

Individual drinking patterns are a potential tool for disease monitoring in pigs. However, to date, individual pig drinking behaviour has not been described, and effects of external factors have not been examined. The aim of this study was to perform detailed quantification of drinking behaviour of growing pigs and to examine effects of period of day and effects of competition for access to the drinking nipple on the drinking behaviour, amount of water used and water wastage. In all, 52 cross-bred castrated male pigs (live weight 20.5±1.7 kg; mean±s.d.) maintained as either 3 (N3) or 10 (N10) pigs per pen and water nipple (four groups/treatment) were used. All pigs were fitted with a transponder ear tag. A radio frequency identification reader recorded and time stamped visits at the nipple. In each pen, water flow was logged every second. The drinking behaviour was recorded for 4 consecutive days and analysed using a linear mixed model. Overall, the pigs spent 594 s at the nipple during 24 h distributed among 44 visits. During this period, 5 l of water were used, of which >30% was wasted. Social competition did not affect the drinking behaviour over 24 h, except for the proportion of interrupted visits where pigs, kept with recommended nipple availability (N10), showed an increased proportion of interrupted drinking bouts compared with pigs kept at very low level of competition (N3) (0.18±0.01 v. 0.11±0.01; P<0.01). However, splitting data into 8-h periods (P1, P2, P3) starting from 0600 h revealed differences between treatments, showing that in N3, water use per visit was lower in P1 than P2 and P3 (110±10 v. 126±7 and 132±7 ml; P<0.05), whereas in N10, the water used per visit was higher during P3 than during the other periods (P1: 107±14 ml, P2: 112±10 ml v. P3: 151±10 ml; P<0.001). A similar pattern was found for visit duration. In N3, fewer nipple visits were observed in P2 than P1 (15.6±1.2 v. 22.0±1.2; P<0.001), whereas no difference was found between P1 and P2 in N10. The results demonstrate that growing pigs at the two levels of competition maintained a comparable level of 24 h water intake by changing behavioural variables involved in drinking. This dynamic characteristic of drinking behaviour means that if individual drinking patterns are to be used as disease monitoring tools, it is important to consider effects of external factors and include data on period level to allow rapid detection of behavioural changes.