the behaviour and welfare of sows and piglets in … · the behaviour and welfare of sows and...

The behaviour and welfare of sows and piglets in farrowing cratesor lactation pens

C. Singh1, M. Verdon1†, G. M. Cronin2 and P. H. Hemsworth1

1Animal Welfare Science Centre, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, 3010 VIC, Australia; 2Faculty of VeterinaryScience, The University of Sydney, Camden, 2570 NSW, Australia

(Received 7 July 2016; Accepted 1 November 2016; First published online 5 December 2016)

Temporary confinement during parturition and early postpartum may provide an intermediary step preceding loose housing that offersimprovement in sow and piglet welfare. Three experiments were conducted to investigate the implications of replacing farrowing crates(FCs) with an alternative housing system from 3 days postpartum until weaning. In each experiment sows farrowed in FCs and wererandomly allocated at day 3 of lactation to either a FC or a pen with increased floor space (lactation pen (LP)) until weaning. Inexperiment 1, piglet growth and sow and piglet skin injuries were recorded for 32 sows and 128 focal piglets in these litters. Behaviouraround nursing and piglet behavioural time budgets were also recorded for 24 of these litters (96 focal piglets for time budgets). Inexperiment 2, measures of skin injury and behavioural time budgets were conducted on 28 sows and 112 focal piglets. The behaviouralresponse of sows to piglet vocalisation (maternal responsiveness test (MRT)) was also assessed. In experiment 3, piglet mortality from day3 of lactation until weaning was recorded in 672 litters over 12 months. While housing did not affect piglet weight gain in experiment 1,or piglet skin injuries in experiments 1 or 2, sows in both experiments sustained more injuries in LP than FC (experiment 1, 2.9 v. 1.4;experiment 2, 2.5 v. 0.8 lesions/sow; P< 0.05). Sow–piglet interactions were more frequent in LP than FC at days 11 and 18 postpartumin both experiment 1 (day 11, 1.4% v. 1.2%; day 18, 1.7% v. 1.0% of observations; P = 0.05) and 2 (day 11, 1.0% v. 0.3%; and at day18 were 1.0% v. 0.6% of observations; P< 0.01), and LP sows were more responsive in the MRT in experiment 2 (2 v. 0 median numberof tests in which sows react, P< 0.01). In experiment 1 piglets played more (0.7% v. 0.3% of observations, P = 0.05) and manipulatedothers less (0.3% v. 0.7% of observations, P = 0.04) in LP, but more piglets missed nursing bouts (0.2 v. 0.1 piglets/bout, P< 0.01)compared with FC. There was no effect of housing on piglet mortality from day 3 of lactation until weaning in experiment 3 (0.63 and0.64 deaths/litter for LP and FC, respectively, P> 0.05). Thus, housing sows and litters in LP from day 3 of lactation minimises pigletmortality while improving maternal behaviour in sows and social behaviour in piglets.

Keywords: animal welfare, lactation housing, loose-housed sows, behaviour, piglet mortality

Implications

The present research suggests that increased floor space andgreater opportunity for interaction between sows and pigletsfrom days 3 to 25 of lactation results in improved maternalbehaviour in sows and improved social behaviour in piglets,without increasing piglet mortality in this period. Therefore,temporary confinement early postpartum may provide anintermediary step preceding loose-sow housing, that offersoverall improvement in both sow and piglet welfare.

Introduction

Growing societal concern for the welfare of confined farmanimals (e.g. Vanhonacker et al., 2009) has seen farrowingcrates (FCs) criticised on the basis that they restrict sow

movement and natural behaviour. Loose housing of sowsand their litters in pens may be a viable alternative to FCs.While loose-housed sow lactation systems are thought toimprove sow welfare by increasing the opportunity for sowsto move around, there is also evidence of improved maternalbehaviour in these systems (e.g. Cronin et al., 1996), whichmay in turn benefit the piglets in terms of social development(Oostindjer et al., 2011b).Providing sows with increased space during lactation,

however, can lead to a greater risk of piglet crushing(reviewed by Morrison et al., 2011). The majority of pre-weaning piglet mortalities occur within the first 2 to 3 dayspostpartum and are mainly caused by crushing, although thisis closely tied to nutritional status and thermal environment(Johnson and Marchant-Forde, 2009). Brief confinement ofsows around parturition and in early lactation, when pigletmortality risk is greatest, is effective in limiting neonatal† E-mail: [email protected]

Animal (2017), 11:7, pp 1210–1221 © The Animal Consortium 2016doi:10.1017/S1751731116002573

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mailto:[email protected]

mortality to rates similar to those achieved with continuousconfinement in conventional FCs (Moustsen et al., 2013;Hales et al., 2015). Thus temporary confinement early post-partum may be a valuable intermediary step preceding loose-sow housing.Play is a rewarding activity and is thus considered to be a

behavioural indicator of a positive affective state in animals(e.g. see review by Held and Špinka, 2011). Aggression, on theother hand, can lead to fighting-induced injuries and pain, aswell as fear, and so is considered a behavioural indicator of anegative affective state in recipient animals (Hemsworth et al.,2015). Harmful manipulative behaviours in piglets may also bea behavioural indicator of a negative affective state in both thepiglet displaying the behaviour, as it may be redirectedbehaviour arising from frustration, as well as the recipient,because of possible consequences for injuries and pain.Research is warranted to examine the relationships betweensow lactation housing and the prevalence of these behavioursbecause of the implications for piglet welfare.This research was conducted as a series of three

experiments. These experiments examined the effects oftemporary confinement early postpartum, followed by loose-sow housing, on pig welfare and behaviour. It was hypo-thesised that pigs transferred to lactation pens (LPs) at day 3postpartum will have improved welfare, as indicated bysow and piglet behaviour and injuries as well as pigletmortalities, in comparison with those housed in FCsthroughout lactation.

Material and methods

All animal procedures were conducted with prior ethicalapproval from the University of Melbourne animal ethicscommittee under requirement of the Victorian Prevention ofCruelty to Animals Act 1986 in accordance with the NationalHealth and Medical Research Council/CommonwealthScientific and Industrial Research Organisation/AustralianAnimal Commission Australian code of practice for the careand use of animals for scientific purposes.

Animals and experimental designIn three experiments, this research examined the effects ofreplacing conventional FCs with LPs at 3 days postpartumuntil weaning on sow and piglet welfare and behaviour.

Experiments 1 and 2 examined behaviour, injuries andgrowth, whereas experiment 3 examined piglet mortalityduring the experimental period. Each experiment was con-ducted using Landrace× Large-White breed pigs and werelocated in the same sow farrowing and lactation unit at acommercial piggery in South West Victoria, Australia. Theaverage mean daily ambient temperature for spring, sum-mer, autumn and winter in the year when the experimentswere conducted were 21.1°C, 26.5°C, 21.3°C and 14.7°C,respectively. Details relating to the animals utilised in eachexperiment are summarised in Table 1. For all experiments,sows and their litters were randomly allocated to two treat-ments. Both the control (FC) and the experimental (LP) sowsfarrowed in standard commercial farrowing accommodationwhere they remained until an average of 3 days (range 2 to5 days) postpartum (referred to as day 3). At day 3, FCanimals were transferred from crated farrowing accom-modation to crated lactation accommodation that waslocated in a different shed. Also at day 3, LP animals weretransferred from crated farrowing accommodation to loose-sow pens in the lactation shed. The animals were studiedfrom day 3 of lactation until weaning, which occurred at anaverage of 24 days (range 19 to 26 days) postpartum.

Housing and management of animalsSows were moved from group gestation housing to FCs7 days before expected parturition. At day 3 of lactation,each sow and litter unit was randomly allocated to either theFC or LP treatment group and transferred to the respectivehousing treatments (referred to as day 3). In experiments 1and 2 litter sizes were equalised to 10 to 11 piglets/litter,using the production system’s standard cross-fosteringprocedure, prior to treatment allocation. Sows and pigletsremained in their treatment pens until piglets were weaned.It was standard practice at this piggery to house about aquarter of the lactating sows and their piglets in LP at day 3of lactation, and stockpeople were equally familiar withmanaging sows and piglets under both housing systems.There was very minimal cross-fostering outside of the first3 days of lactation, and if it did occur it remained withintreatment. In experiment 1, sows from FC and LP treatmentswere housed in the same lactation shed. However, inexperiments 2 and 3 FC sows were housed in a differentlactation shed to LP sows, although these sheds were adja-cent to each other and managed by the same stockpeople.

Table 1 Summary of animals details1

Animal numbers Sow parity

Time replication Sows Piglets Mean Range

Experiment 1 4 32 (8/replicate) 343 3.9 1 to 10Experiment 2 1 28 112

(4/litter)4.1 2 to 7

Experiment 3 Production records 672 sows (and their litters) 4.1 1 to 10

1Experiment 1 conducted over 5 months. Experiment 2 conducted over 2 months. Experiment 3 used litter size and mortality data over a12-month period.

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In all three experiments, the finger design (four prongs) FCsused were typical of conventional systems. The internal sowcrate dimensions were 2.0× 0.6m, within a total area mea-suring 2.0× 1.5m. The LP used in experiment 1 (1.8× 2.5m)provided a floor space of 4.5m2 and had sloping anti-crush barsand a heated creep with solid flooring (~1.23× 0.45m)(Figure 1). Following experiment 1, the design of the LP weremodified by the farm management, such that in experiments 2and 3 the pens were slightly smaller in floor space (1.7× 2.4m,total area of 4.08m2), although the creep dimensions werecomparable (Figure 1). In addition, the anti-crush guards inexperiments 2 and 3 extended further from the wall and at acurved angle in comparison with experiment 1 and a metalstructural support for the creep area was moved from near thecorner of the creep to the centre of the creep wall. In all threeexperiments the LP flooring was plastic and allowed drainage.No bedding was provided. Both FC and LP were fitted with abuilt-in trough for feed delivery and water was supplied adlibitum for sows and piglets. During lactation sows weremanually fed 4.0 kg of standard commercial lactation pelleteddiet (13.7MJ/kg dry matter, and 17.85% protein) in the morn-ing, with a top up offered in the afternoon as required. Creepfeed was offered to piglets from 12 days of age until weaning.

Data collectionBehaviour. In experiment 1, nursing behaviour was observedfor 24 sows and their litters and behavioural time budgetswere observed for 96 piglets (4 focal piglets/litter for24 litters). In experiment 2, behavioural time budgets wereobserved for 112 piglets (4 focal piglets/litter for 28 litters)and the behavioural response of sows to an audio recording

of an unfamiliar piglet squealing (maternal responsivenesstest (MRT)) were recorded for 28 sows.Four focal piglets per litter were selected immediately

after transfer to lactation housing treatments. Focal pigletswere balanced for sex and obvious runts (piglets displayingsigns of illness/injury or weighing<1.2 kg) were excluded. Toallow for individual identification, different symbols weremarked on the back of focal piglets using black stock-marker.The same focal piglets were observed throughout lactationand piglets were remarked before each recording day.Nursing behaviour was continuously recorded from 0700

to 1700 h using overhead video cameras (Signet CCD minicolour camera, model QV-3694; Techbrands, Guangdong,China) that were connected to a digital video recorder(TECHview 16 Channel stand-alone DVR, model QV-3039;Techbrands). These cameras did not have night vision. Thebehavioural time budgets of focal piglets in experiment 1were recorded using a handheld camcorder (Panasoniccamcorder, model NV-DS60; Panasonic Corporation, Osaka,Japan). Pens/crates were video recorded for 30 s at a timeover four 1 h periods (commencing at 0800, 0900, 1020 and1130 h), continuously rotating between litters in a standar-dised sequence. The behavioural time budgets of focalpiglets in experiment 2 was continuously recorded from 1100to 1300 using overhead video cameras, the same as thoseused to record nursing behaviour (described above).Recording times were determined by production schedules.The response of sows to the MRT was continuously recordedusing GoPro cameras (GoPro model Hero3 white edition;GoPro Inc., San Mateo, CA, USA). Details of behaviouralobservations are outlined below.

Nursing behaviour. From video records, nursing frequencyand duration as well as piglet behaviour during nursing(interactions with the sow, missing nursing, displacements atthe udder) were continuously observed by one person ondays 4, 11 and 18 of lactation. Table 2 provides a descriptionof behaviours recorded around nursing.

Piglet behavioural time budgets. Piglet behavioural timebudgets were obtained from video records at days 4, 11 and18 of lactation. In experiment 1, the behaviour of focal pig-lets in each of the 30 s video scans (total of 60 scans per pen/crate per day) was observed. In experiment 2, the behaviourof focal piglets was observed using instantaneous pointsampling at 30-s intervals (240 sample points/day). A singleperson conducted observations of piglet activity, investiga-tory and social behaviours, as described in Table 3.

Maternal responsiveness test. On the morning of days 12 and19 of experiment 2, the behavioural response of sows to anaudio recording of an unfamiliar piglet squealing wasassessed. This test involved broadcasting a pre-recordedsound of a piglet squealing from a portable stereo unit(80 decibels at a distance of 1m, Digitech mini sound levelmeter, model QM-1589; Techbrands) and observing theresponse of the sows. The sound level of 80 decibels is

Figure 1 Layout of lactation pen. Dimensions: experiment 1: length =250 cm, width = 180 cm; experiments 2 and 3: length = 240 cm, width170 cm. *In experiments 2 and 3 anti-crush guards extend further from thewall and were curved compared with experiment 1. #Creep dimensionscomparable in all experiments (length = 123 cm, width 45 cm).

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equivalent to that measured at 2m from the squeal of a livepiglet (Hutson et al., 1993). This test was adapted from thatused by Cronin et al. (1996). However, so that each sowwould be exposed to the same stimulus, this research used asound recording of a piglet that was unfamiliar to all sows.Previous research has shown that sows are more attentivetowards piglets when a piglet squeal recording is playedat 80 decibels than when no squeal is played (Hutsonet al., 1993).To conduct the MRT, the experimenter quietly entered the

shed 5min after sows received their first feed delivery forthe day (~08:00 h). After waiting 3 s at the shed entrance,the experimenter slowly walked down the aisle pausing for3 s in front of each crate/pen (<1m distance betweenobserver and sow) and applying the stimulus from a portablestereo unit hanging around their neck (i.e. stimulus appliedfor 3 s). The behavioural response of each sow to thestimulus was recorded. These observations were conductedsix times in succession (i.e. 6 tests/sow) on each testing day(days 12 and 19), which took ~2min (each shed) to complete.To assess the effectiveness of the stimulus applied in the presentstudy, on day 11 the experimenter followed the exact sameprotocol as that described above, only without applying thepiglet vocalisation stimulus (control test).The sow behaviours recorded in the control test and the

MRT included head up (number of tests, out of the six tests, in

which then sow lifted her head from feeding), grunt occurrence(the number of tests, out of the six tests, in which the sowgrunted in the direction of the observer or her own piglets) andgrunt frequency (the total number of grunts from the sow in thedirection of the observer or her own piglets, over the six tests).

Skin injuries. In experiments 1 and 2, the number of skinlesions on each sow and focal piglet were counted. Inexperiment 1 this was done at days 11 and 18 of lactation,whereas in experiment 2 this was done at days 4, 11 and 18.The same assessment described by Karlen et al. (2007) wasused to assess skin injuries for sows and piglets, howeveronly fresh lesions were recorded (i.e. any skin injury thatappeared red or inflamed indicating it had been obtainedrecently).

Piglet growth. Each focal piglet in experiment 1 was weighedat day 3 and again at weaning. These data were used tocalculate the average growth of focal piglets per litter fromday 3 until weaning (g/day).

Piglet mortality. In experiment 3, the production records of672 sows that farrowed in the 12 months from December2013 were obtained. It is standard practice on the farmwhere this research was conducted for computer records onthe number of piglets at transfer to the lactation treatment

Table 2 Description of sow and piglet behaviours observed around nursing

Nursing bout A bout of nursing where at least 75% of the litter gather at udder and massaging and/or nursing continued forat least 1.5 min

Start of nursing bout 75% of piglets gather at udder and begin massagingEnd of nursing bout 75% of piglets have stopped massaging (became still or moved away from the udder) or sow terminates

massage/nursing by changing postureSow–piglet interaction Sow is sniffing, grunting or nuzzling the piglets head, or vice versa, and contact is maintained for at least 1 s. Interactions

were recorded from 2min before nursing bout commenced until 2min after suckling bout concludedPiglets that missed nursing bout Piglets absent from the udder (not suckling/massaging or attempting to) for a majority of nursing bout durationDisplacement at udder A piglet is displaced from the udder (becomes detached from the teat and has to walk outside or over the cluster

of piglets to occupy a different/new teat order position) during a nursing bout, before milk-let down (pigletsstill with extended bodies for approximately 30s). Does not include piglets that leave the udder and which donot return immediately and resume suckling/massage

Table 3 Description of the behaviour observed in studying the time budget of behaviour of the piglets (adapted from Oostindjer et al., 2011a)

ActivityLying/inactive Lying or sitting, not engaged in activityWalking/standing Standing or walking but not otherwise engaged in activity (includes urinating and defecating)Suckling/udder massage Either mouth on teat or nose contact to udder with vertical head movements

Investigatory behavioursInvestigating pen/floor/sow body Sniffing, touching, biting, rooting, pawing or rubbing any part of the pen, floor or sow’s body other than headInvestigating food/water Sniffing, touching, pawing, eating or drinking food or water

Social behavioursNosing other piglet Touching or sniffing any part of the head or nose of another pigletManipulative behaviour Nibbling, sucking, chewing or rubbing with nose any part of the body of another pigletAggression Ramming, pushing or biting another pigletMounting Standing on the back of another piglet with front legsPlay Shaking head, pivoting, jumping, or running with bouncy or jerky movementsInteracting with sow Sniffing, grunting or nuzzling sow’s head


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(day 3) as well as the date and death of piglets (but not thereason) throughout lactation to be kept. Thus, these recordsenabled the collation of data on the number of piglets attransfer to FC or LP treatments (day 3) and the number ofpiglet mortalities from day 3 until weaning.

Statistical analysisAll analyses were conducted using SPSS statistical package(SPSS 22.0; SPSS Inc., Chicago, IL, USA). The durationof nursing bouts, number of piglets that missed nursingbouts and number of piglet displacements at the udder(experiment 1) did not conform to a normal distribution(quantile–quantile plots and histograms) and were squareroot transformed before analysis. The proportion of nursingbouts terminated by the sow (experiment 1) and all pigletbehavioural time budgets (experiments 1 and 2) wereanalysed as relative frequencies and consequently werearcine-square root transformed before analysis. In experi-ments 1 and 2, mounting behaviour was rarely recorded(experiment 1 – mean = 0.05 (range = 0.00 to 0.18),experiment 2 – mean = 0.13 (range = 0.00 to 1.11), % oftotal observations, per focal piglet per litter) and will not befurther discussed.Piglet measurements were calculated for each of the four

focal piglets studied and then averaged for each litter. Inexperiment 1, behaviour and skin injuries were analysedusing GLM models. Repeated observations on the same sow/litter were taken into account by including a repeated effectof day within sow/litter. The model included day, FC or LPhousing treatment, and their interaction as fixed effects,while time replicate was included in the model as a randomeffect and sow parity as a covariate. In experiment 2, beha-viour and skin lesions were analysed using a general linearmodel with repeated measures function. This model includedday, housing treatment, and their interaction as fixed effectsand sow parity as a covariate. Least significant differenceswere assessed at each day separately when significanttreatment× day interactive effect was found. A univariateANOVA was used to examine treatment effects on pigletweight gain (experiment 1) with replicate included in themodel as a random variable. Mann–Whitney U tests wereused to (1) compare the behaviour of sows in the control testto that when the stimulus was applied, and (2) test fortreatment differences in the MRT at days 12 and 19(experiment 2). Spearman’s rank correlations were used toexamine the relationship between sow behaviour in thecontrol test at day 11 and that in the MRT at days 12 and 19.Data on piglet mortality (number of piglets that died per

litter from transfer (day 3 of lactation) to weaning) werediscrete. A GLM with an underlying Poisson distribution wasfitted to this variable. This function transforms data to alinear regression with a logarithmic function. Treatment, sowparity and week of farrowing along with corresponding twoand three-way interaction terms were included in the model,while number of piglets at transfer was included as acovariate. If an interaction term was not significant(P> 0.05), it was removed from the model. For simplicity,

sow parities six to 10 were grouped into a single category ofsows greater than or equal to parity 6 (parity 6 n = 58, parity7 n = 77, parity 8 n = 38, parity 9 n = 11, parity 10 n = 1;sows⩾ parity 6, n = 185, 27.5% of total sows). A total of 12sows farrowed twice in the recorded period (1.79%). Forthese sows, each farrowing was recorded and analysed asseparate data.

Results

Experiment 1Nursing behaviour. The effects of housing treatment onnursing behaviour at days 4, 11 and 18 of lactation arepresented in Figure 2. There was no effect of housing on thefrequency (P = 0.15; Figure 2A) or duration (P = 0.31;Figure 2B) of nursing bouts, or on the inter-nursing interval(P = 0.12; Figure 2C). The percentage of sow-terminatednursing bouts tended to be higher in FC treatment (P = 0.06;Figure 2D). There were differences due to day (litter age) onall of these variables with the frequency (F2,22 = 10.9P< 0.01) and duration (F2,22 = 23.2 P< 0.01) of nursingbouts declining over time, while the inter-nursing interval(F2,22 = 9.54 P< 0.01) and proportion of sow terminatedbouts (F2,22 = 5.28 P< 0.01) increased (Figure 2). Therewere treatment× day interaction effects on the frequency ofsow–piglet interactions around nursing (F2,22 = 5.95P< 0.01), the number of piglets missing nursing bouts(F2,22 = 4.08 P< 0.05) and displacements at the udder(F2,22 = 3.11 P< 0.05). At days 11 and 18, FC sows inter-acted less frequently with the piglets than LP sows, althoughpiglets in FC missed fewer nursing bouts on these days(Figure 2E and F). Farrowing crate piglets were displaced lessfrequently than LP piglets at day 11, but there was no dif-ference in piglet displacements at the udder at days 4 or 18(Figure 2G).

Piglet behavioural time budgets. Probability values andmeans for the main and interactive effects of housing andday on piglet behaviour in experiment 1 are presented inTable 4. Housing significantly affected the frequency ofmanipulative behaviours (F1,22 = 4.81 P< 0.05), whichwas higher in FC than LP, but both the frequency ofpiglet interactions with the sow (F1,20 = 4.27 P = 0.05) andplay behaviour (F1,22 = 4.49 P = 0.05) were higher inLP than FC. Litter age significantly affected many pigletbehaviours. Time spent lying (F2,22 = 24.1 P< 0.01) andsuckling (F2,22 = 3.50 P = 0.05) declined from day 4 to 18,whereas investigatory behaviours (investigating the pen(F2,22 = 18.5 P< 0.01) and investigating/eating food(F2,22 = 40.8 P< 0.01), as well as some social behaviours(aggression (F2,22 = 106 P< 0.01), manipulative behaviour(F2,22 = 13.7 P< 0.01) and play (F2,22 = 7.89 P = 0.01)increased over the same period.

Skin injuries. The effects of housing on the number of skininjuries sustained by sows and piglets at days 11 and 18


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of experiment 1 are presented in Figure 3A and B. Skininjuries for sows were higher in LP than FC (F1,27 = 6.90,P = 0.01) but there was no effect of day on sow skin injuries(P> 0.05). Treatment had no effect on piglet skin injuries(P> 0.05), but skin injuries increased with time(F1,30 = 84.4, P< 0.01).

Piglet growth. There was no housing effect on piglet dailyweight gain from day 3 until weaning in experiment 1

(means (±SEM) were 240 (10.1) and 230 (12.3) g/day for FCand LP piglets in experiment 1, respectively; P = 0.64).

Experiment 2Piglet behavioural time budgets. Probability values andmeans for the main and interactive effects of housing andday on piglet behaviour in experiment 2 are presented inTable 5. There was an interaction effect of housing× day onpiglet interactions with the sow (F2,48 = 6.86, P< 0.01), but

Figure 2 Effects of farrowing crate (solid) and lactation pen (dashed) housing on piglet behaviour during nursing bouts observed between 0700 and1700 h at days 2, 11 and 18 of experiment 1. Behaviours observed were (A) the frequency, (B) duration, (C) inter-nursing interval and (D) proportionof sow terminated nursing bouts, (E) the frequency of sow–piglet interactions around nursing, and the numbers of piglets (F) missing nursing boutsand (G) displaced at the udder. Means (back-transformed means for B, D, F and G) per sow (for A, B, C, D and E) or per nursing bout per sow(for F and G) ±95% confidence interval are reported. a,bWithin a day, means with different superscripted letters differ (P≤ 0.05).


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for no other observed behaviours (P> 0.05; Table 5). Morepiglet interactions with the sow were observed in LP at days11 and 18. There were no main effects of housing for anyobserved behaviours (P> 0.05, Table 5). Most piglet beha-viours were affected by day (litter age), with the exception ofsuckling behaviour (P> 0.05) and time spent investigatingfood (P> 0.05). Lying behaviour declined from day 4 to18 (F2,48 = 6.15, P< 0.01), while time spent walking(F2,48 = 8.40, P< 0.01), investigating the pen (F2,48 =7.58, P< 0.01), nosing (F2,48 = 18.0, P< 0.01) or manip-ulating (F2,48 = 5.57, P< 0.01) other piglets and playing(F2,48 = 11.6, P< 0.01) increased over the same period.Aggressive behaviour increased over time, although peakingat day 11 (F2,48 = 7.02, P< 0.01; Table 5).

Maternal responsiveness test. Sows responded morefrequently to the researcher when the recording of the piglet

vocalisation was played at day 12 (‘head up’ Z = −2.20,P = 0.03; ‘grunt occurrence’ Z = −2.24, P = 0.03; ‘grunt fre-quency’ Z = −2.16, P = 0.03) and day 19 (‘head up’ Z =−2.57, P = 0.01; ‘grunt occurrence’ Z = −2.48, P = 0.01;‘grunt frequency’ Z = −2.56, P = 0.01) than to the researcherwhen no piglet vocalisation was played (control test). Sowbehaviour in the control test at day 11 was not related to that inthe MRT at day 12 (‘head up’ r = 0.14, P = 0.49; ‘grunt occur-rence’ r = 0.24, P = 0.23; ‘grunt frequency’ r = 0.21, P =0.28) or day 19 (‘head up’ r = 0.24, P = 0.22; ‘grunt occurrence’r = 0.25, P = 0.21; ‘grunt frequency’ r = 0.24, P = 0.23).However, sow behaviour in theMRT at day 12was related to thatin the MRT at day 19 (‘head up’ r = 0.73, P<0.01; ‘gruntoccurrence’ r = 0.48, P<0.01; ‘grunt frequency’ r = 0.53,P<0.01).Sows in the LP responded to the MRT by lifting their heads

at each application of stimulus more often than FC sows.

Table 4 Experiment 1: behaviour of piglets in farrowing crates (FC) or lactation pens (LP) from 0800 and 1230 h on days 4, 11and 18 postpartum1

Treatment P-value

Behaviour Day FC LP SEp Treatment Day Treatment× day

ActivityLying/inactive 4 62.5 63.0 0.13 0.11 <0.01 0.15

11 55.3 52.6 0.0818 56.9 51.3 0.11

Walking/standing 4 6.30 6.30 0.04 0.87 0.23 0.6511 7.40 6.80 0.0418 6.00 6.40 0.05

Suckling/udder massage 4 23.9 23.7 0.11 0.55 0.05 0.2511 23.4 26.4 0.0718 21.7 21.8 0.14

Investigatory behavioursPen/floor/sow body 4 3.20 3.30 0.05 0.47 <0.01 0.82

11 4.70 5.30 0.0518 5.70 6.50 0.04

Food/water 4 0.00 0.00 0.06 0.43 <0.01 0.2411 0.06 0.20 0.0818 1.70 1.80 0.18

Social behavioursNosing other piglet 4 1.70 1.60 0.07 0.14 0.07 0.59

11 2.20 2.80 0.0318 1.60 2.50 0.05

Manipulative behaviour 4 0.20 0.00 0.03 0.04 <0.01 0.6411 1.20 0.50 0.0518 0.80 0.50 0.06

Aggression 4 0.00 0.00 0.03 0.46 <0.01 0.3711 2.10 1.80 0.0618 2.60 3.90 0.08

Play 4 0.10 0.20 0.03 0.05 0.01 0.5211 0.40 0.90 0.0618 0.30 1.00 0.06

Interacting with sow 4 0.70 1.20 0.04 0.05 0.17 0.5911 1.20 1.40 0.0418 1.00 1.70 0.05

SEp = pooled standard error of the mean.1Data were arcsine-square root transformed before analysis. Back-transformed means (% of observations the behaviour was observed, per focalpiglet per litter) ± pooled SE are presented.a,bWithin a row, means with different superscripted letters differ (P≤ 0.05).


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The median number of tests in which FC and LP sows liftedtheir heads at day 12 were, respectively, 0 (range 0 to 1) and2 (range 0 to 5) (Z = − 3.67, P< 0.001), and at day 19 were,respectively, 0 (range 0 to 2) and 2 (range 0 to 5)(Z = − 3.61, P< 0.001). However, neither the frequency oftests in which sow grunted (day 12, Z = − 0.97, P = 0.51;day 19, Z = − 0.55, P = 0.73) nor the frequency of gruntsper test (day 12, Z = − 0.87, P = 0.54; day 19, Z = − 0.41,P = 0.80) was affected by housing. The median value forboth FC and LP sows in these two tests was 0.

Skin injuries. The effects of housing on the frequency of skininjuries sustained by sows and piglets at days 11 and 18 oflactation in experiment 2 are presented in Figure 3C and D.There were interaction effects of housing and day on skininjuries sustained by sows (F2,50 = 4.50, P< 0.05). Sows inFC and LP had similar skin injuries at days 4 and 18, but LPsows had more skin injuries at day 11. There was no maineffect of housing on skin injuries in piglets (P> 0.05), norwas there a treatment× day interaction (P> 0.05), butinjuries increased over time (F2,50 = 4.84, P< 0.05).

Experiment 3Piglet mortality. There was a tendency for there to be morepiglets per litter in the FC than in the LP at the beginningof treatment (means for the number of piglets at transferfor sows assigned to LP and to FC, respectively, were 10.2and 10.4 piglets, F1,659 = 3.61, P = 0.06), and sows inthe LP were of a higher parity than those in the FC (4.15 v.3.51, F1,669 = 25.2, P< 0.01). The number of pigletmortalities per litter from day 3 until weaning (mean (±SEM)number of piglet mortalities in LP and FC treatments,

respectively, were 0.63 (0.06) and 0.64 (0.07) per litter)was not affected by housing (P = 0.17), sow parity(P = 0.15) or week of farrowing (P = 0.29), nor were any ofthe interaction terms significant (P>0.05).

Discussion

The results of this research suggests that, following tem-porary confinement in a FC, loose-sow housing withincreased floor space from days 3 to 28 of lactation results inimproved maternal behaviour in sows and improved socialbehaviour in piglets, without increasing risks to piglet mor-tality in this period.

Maternal behaviourAs has been found by other studies (Cronin and Smith, 1992;Cronin et al., 1996), there were more interactions betweensows and piglets around nursing in the LP in experiment 1and during the time budget observations in LP in experi-ments 1 and 2. Piglets may have had greater accessibility tothe sow’s head in LP because of the larger floor space and norestriction imposed by the crate. On the other hand, loose-housed sows are better able to orient themselves towardspiglets, which may be more conducive to the developmentand display of maternal behaviour. Pigs communicate usinga combination of visual and olfactory cues as well as voca-lisations, and to some extent parental behaviour is manipu-lated by the offspring (Broom and Fraser, 2010). As such,differentiating between interactions initiated by piglets andthose initiated by the sow is obviously difficult. Nevertheless,how the interaction is initiated may be less important than

Figure 3 Effects of farrowing crate (solid) and lactation pen (striped/dashed) housing on skin lesions for (A) sows and (B) piglets at days 11 and 18 ofexperiment 1, and for (C) sows and (D) piglets at days 2, 11 and 18 of experiment 2. Back-transformed means (per sow or per focal piglet per litter) ±95%confidence interval are presented. a,bWithin a day, means with different superscripted letters differ (P≤ 0.05).


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the outcome of the interactions, in terms of the developmentof both maternal behaviour in the sow and social behaviourin the piglet (discussed later).In the present research, the frequency and duration of

nursing bouts declined over time, while the interval betweenbouts increased. These observations have previously beenreported in both domestic and wild-type sows (see Jensen,1988). Experiment 1 found no effects of lactation housing onthese variables, although nursing behaviour was onlyobserved during daylight hours. Pedersen (2015) conductedobservations in both day and night time periods, and foundthat sows that were loose housed during parturition and for3 days postpartum nursed more frequently and had a shorterinter-nursing interval than sows that were confined for thisperiod. However, there was no effect of housing on nursingduration. Experiment 1 also found that sows in FC tended to

terminate more nursing bouts than LP sows. Other researchsuggests that loose-housed sows terminate more nursingbouts than crated sows in the first 3 days of lactation(Pedersen, 2015) but the reverse is seen at mid to latelactation (Pedersen et al., 2011). Pedersen et al. (2011)proposed that reduced accessibility to the udder in FCincreases competition and fighting for teats and this disruptsthe sow. Indeed, more teat fights were reported in crates,and when teat fights occurred more piglets missed the milk-let down (Pedersen et al., 2011). Although the presentresearch did not record fighting at the udder, it found that inLP more piglets were displaced during nursing at day 11, andthere were more missed nursing bouts at days 11 and 18.In the study by Pedersen et al. (2011), loose-housed sows

were confined only during parturition, whereas in Pedersen(2015) they were not confined at all. By contrast, in the

Table 5 Experiment 2: behaviour of piglets in farrowing crates (FC) or lactation pens (LP) from 1100 and 1300 h on days 4, 11and 18 postpartum1

Treatment P-value

Behaviour Day FC LP SEp Treatment Day Treatment× day

ActivityLying/inactive 4 72.3 66.3 0.17 0.26 <0.01 0.84

11 47.2 41.6 0.4618 54.5 52.0 0.46

Walking/standing 4 7.90 10.3 0.05 0.77 <0.01 0.4211 29.9 26.1 0.3518 34.0 37.0 0.40

Suckling/udder massage 4 18.8 21.8 0.21 0.81 0.10 0.5811 19.5 18.3 0.2118 10.1 10.0 0.12

Investigatory behavioursPen/floor/sow body 4 0.50 1.10 0.07 0.47 <0.01 0.81

11 4.40 4.70 0.0818 10.2 10.5 0.24

Food/water 4 0.00 0.00 0.00 0.43 0.33 0.8111 0.20 0.30 0.0418 0.50 0.80 0.10

Social behavioursNosing other piglet 4 0.20 0.10 0.02 0.98 <0.01 0.52

11 1.40 1.70 0.0318 2.20 2.30 0.04

Manipulative behaviour 4 0.20 0.20 0.03 0.70 <0.01 0.4911 0.70 1.10 0.0318 1.10 0.90 0.04

Aggression 4 0.00 0.10 0.02 0.10 <0.01 0.5611 2.40 2.70 0.0618 0.50 0.50 0.05

Play 4 0.00 0.10 0.01 0.28 <0.01 0.5611 0.40 0.50 0.0418 3.30 4.70 0.17

Interacting with sow 4 0.30 0.10 0.01 0.14 0.02 <0.0111 0.30a 1.00b 0.0318 0.60a 1.00b 0.03

SEp = pooled standard error of the mean.1Data were arcsine-square root transformed before analysis. Back-transformed means (% of observations the behaviour was observed, per focalpiglet per litter) ± pooled SE are presented.a,bWithin a row, means with different superscripted letters differ (P≤ 0.05).


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present research, sows were confined in FC from 7 days beforeparturition until day 3 of lactation. Confinement during par-turition and early lactation may disrupt the establishment ofnursing behaviour and maternal bonding. Indeed, otherresearch has shown that nursing behaviour establishes morequickly when sows farrow in pens with straw than in crates(Cronin and Smith, 1992), and that loose-housed sows formstronger social bonds with their piglets early in lactation(Pedersen, 2015). The importance of maternal behaviour in thedays immediately preceding parturition on subsequent sowbehaviour requires further research.In the present research, FC sows lifted their heads less

frequently in the MRT than sows in LP. Similar results werereported by Cronin et al. (1996), and Thodberg et al. (2002)found that sows in crates took longer to react as they movedto a lying position when an audio recording of a screamingpiglet was played. While the present study found no housingeffects on sow vocalisations in the MRT, other studies havefound that crated sows vocalise less towards their piglets ina MRT (Cronin et al., 1996) and a litter separation test(Thodberg et al., 2002). Both Cronin et al. (1996) andThodberg et al. (2002) tested sows at day 3 of lactation, aperiod where sows in the natural environment would bestaying in close proximity to their litters (Jensen, 1986 and1988), whereas the present research tested sows at days 12and 19 of lactation. Under natural conditions, piglets at thisage are typically integrated into the sounder and movingincreasingly greater distances from the sow (Jensen, 1986and 1988). This could correspond to reduced vigilance fromthe sow. Further, Hutson et al. (1993) found that sowattentiveness towards piglets increased with audio playbackvolume, but only influenced lying behaviour at a loud volume(>92 decibels). Thus, the MRT with a playback volume of 80decibels utilised by the present research may have beenmasked by the general noise levels in the shed and, conse-quently, reduced sow responsiveness.There are several points that need to be considered when

interpreting the results of the MRT. First, sows were testedwhile feeding, rather than during a ‘risky’ postural change,and the experimenter remained in sight. However, sows inthe present research were more responsive to an experi-menter standing at the front of the pen/crate playing arecording of a piglet vocalisation (i.e. MRT) than when nowas vocalisation played (i.e. control). Further, sow behaviourin the control test was not related to that in the MRT at eitherday 12 or 19 of lactation, but sow behaviour in the MRT atdays 12 and 19 was related. Thus, in addition to the presenttest being conducted at feeding and in the presence of theexperimenter, the playback of a piglet vocalisation per secontributed to the sow’s behavioural response in the MRT.Second, sows may habituate to the MRT over time (Heldet al., 2006), and, in the present study, sows were con-secutively tested in the same building. However, the medianand range for variables recorded in the MRT barely changedbetween days 12 and 19. The short length of the test (2 min)and time between testing days (7 days) may have minimisedhabituation. Third, the piglet vocalisations used in the MRT

were recorded when the animal was isolated and restrainedby the experimenter. It has been suggested that vocalisationsunder these conditions could differ from those observed in anactual piglet crush, and therefore affect the strength of thesow’s response in the MRT (Illmann et al., 2008). None-theless, in the present research each sow in both treatmentswere tested using the same methodology and effects ofhousing treatment on sow responsiveness were found.

Piglet behaviourAlthough there were no effects of housing on general pigletactivity (lying, walking, suckling) in the present research,piglets spent significantly more time playing in LP in experi-ment 1. It is generally accepted that play is an indicator ofpositive affective state (see review Held and Špinka, 2011),and, in young pigs, play is considered a suitable and sensitiveindicator of welfare (Newberry et al., 1988; Brown et al.,2015). The increased space in LP may have made it physicallyeasier for play behaviour to be expressed. Alternatively, asfound by Chaloupková et al. (2007), enrichment of the pre-weaning environment, through the provision of increasedspace and environmental and social stimulation, may haveimproved overall piglet welfare and therefore the piglet’smotivation to engage in play. While play increased inexperiment 1, manipulative behaviour was reduced in LP.Manipulative behaviour may be a re-directed behaviour thatis indicative of a lack of environmental enrichment or over-crowding (Dybkjær, 1992). Oostindjer et al. (2011b) foundreduced manipulative behaviour and increased play beha-viour in piglets raised in a lactation environment enrichedwith space and straw, although sow confinement per se hadno effect.In contrast to experiment 1, experiment 2 did not find

effects of lactation housing on play or manipulative beha-viour. It is not immediately clear why the results differedbetween the two experiments. The design of LP (e.g. lessspace in experiment 2) and differences in the behaviouralsampling methodology (60 sample points over 4 h inexperiment 1 v. 240 sample points over 2 h in experiment 2)may have contributed. Social factors, such as individualvariation and group dynamics, may also affect the prevalenceof positive and negative social behaviours (Sih, 2013). Brownet al. (2015) found variability in play behaviour duringlactation both between and within litters of piglets, althoughlitter was a much stronger source of variation. Nonetheless,the results from experiment 1, considered with those repor-ted by others (Chaloupková et al., 2007; Oostindjer et al.,2011b), indicate that play may be increased and manipu-lative behaviour may be decreased with the provision ofincreased space during the lactation period.Similar to the finding of Oostindjer et al. (2011b), there

was no treatment effect on nasal contact with other pigletsor aggression in the present research. The benefits ofimproved welfare during lactation may well persist beyondweaning (e.g. Chaloupková et al., 2007; Oostindjer et al.,2011b; Martin et al., 2015). However, Verdon et al. (2016)found that piglets reared in an enriched single litter, loose


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sow pen were just as aggressive in the 2 h post-mixing atweaning as those reared in FC. The long-term effects of sowlactation housing on piglet social behaviour will benefit frommore research. Neither the present research, nor thatconducted by Oostindjer et al. (2011b) found effects of sowhousing on piglet investigative or feeding-related beha-viours. Piglets learn to eat solid food by observing the sow(Oostindjer et al., 2011a), but the feeding system in LP in thepresent research did not allow piglets to actively observe thesow eating.

Skin injuriesIn the present research, sows in LP sustained more skininjuries than those in FC. There are several possible expla-nations for this result. First, in comparison with FC sows, LPsows had more freedom to move about and perform posturalchanges (e.g. Bøe et al., 2011; Pedersen, 2015). Some pos-tural changes, such as descending from standing to lying orrolling, may also qualitatively differ between the two housingsystems. Consequently, sows in LP in the present study mayhave undergone a period of adjustment, during which theyhad to learn how to change posture in the new environment.Second, previous research suggests that skin lesions andlying-down behaviour is associated with flooring, particularlyif no substrate is provided (reviewed by Baxter et al., 2011).Anecdotally, the plastic flooring used in the LP in the presentstudy may be slippery when wet. This could have contributedto difficulties sows may have had in changing posture ormoving about the pen, and consequently may have con-tributed to increased injuries. Further, although piglet pro-tection features are a necessity in loose-housed sow lactationsystems, sows prefer to use solid sloped or vertical walls overfarrowing rails as a support while lying (see Baxter et al.,2011). Thus, the piglet protection rails used in LP in thepresent research may have been uncomfortable to leanagainst or caused injury to the sows. Third, increased inter-action with piglets in the LP would likely contribute toincreased scratches. There were no effects of treatment onpiglet skin injuries in this research, which were possiblyobtained from fighting among pen mates. However, roughplay and collisions with the pen fittings and walls as well asrubbing on hard surfaces during suckling (Baxter et al., 2011)may also result in injuries.

Piglet growth and mortalityThere was no treatment effect on piglet growth rate in thepresent research. This research used focal piglets, balancedfor sex and size, to obtain weight gain data and thereforehousing effects on the extreme (i.e. very small or very large)piglets may not have been apparent. However, these resultsare comparable with those reported by others (Condouset al., 2016; Verdon et al., 2016).There is a significant body of research indicating that

liveborn piglet mortality increases when sows are loosehoused around farrowing, primarily due to an increase in theincidence of crushing (e.g. Cronin et al., 2000; Moustsenet al., 2013; Hales et al., 2014; Condous et al., 2016). In the

present research, loose housed sows were temporarily con-fined during farrowing and for 3 days postpartum whileothers remained in crates throughout lactation, and no dif-ference in piglet mortality was found. These results arecomparable with other research that has examined tempor-ary confinement of gilts (Lambertz et al., 2015) and sows(Hales et al., 2015; Condous et al., 2016) around paruritionand up until 3 to 7 days postpartum. However, this researchcontrasts that of Chidgey et al. (2015) who found higherpiglet mortality when sows were loose housed from 4 dayspostpartum until weaning, although the authors noted thatmortality rates were low, compared to the industry average.Thus, piglet mortality in LP appears to be, at the very least,similar to that when sows are confined in FC, as long asloose-housed sows are temporarily confined for 3 to 4 daysfollowing parturition.

Conclusion

Following temporary confinement in a FC, this research hasfound that loose-sow housing, with increased floor spaceand greater opportunity for interaction between sows andpiglets from days 3 to 28 of lactation, may result in improvedmaternal behaviour in sows and improved social behaviourin piglets, without increasing piglet mortality in this period.While these results suggest an improvement in piglet welfarein the loose pens from day 3 of lactation, further and moreextensive observations on piglet behaviour, both pre- andpost-weaning, and maternal behaviour are required.

AcknowledgementsThis research was funded by the Australian Pork CooperativeResearch Centre (project 1C–113). The authors would like tothank staff from the AWSC that contributed to this project, andin particular Tracie Storey. The authors also thank the ownersand staff of the participating piggery for their collaboration onthis research.

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