***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The limited space in farrowing crate imposes many challenges , such as prolonged farrowing duration and high piglet stillbirth rate . Although the features of farrowing pens compensate for the drawbacks of farrowing crates , they are associated with high piglet crushing mortality caused by the greater space afforded to sows and their rolling-over behaviour . Therefore , a freedom farrowing pen was design ed to overcome the drawbacks of both farrowing crates and farrowing pens . The main features of the freedom farrowing pen are its left anti-crushing bar and detachable right anti-crushing bar on the sides of the sow lying area . It also has a 10 cm-high anti-crushing bar in the non-lying area . Eighteen healthy , multiparous Yorkshire sows ( 3 - 7 parity ) were averaged and r and omly assigned to farrowing crates , farrowing pens , and freedom farrowing pens to compare the effects of the farrowing systems on sow behaviour and performance . Results showed that the farrowing duration and the mean piglet birth intervals were longer for the sows in farrowing crates than for those in farrowing pens and freedom farrowing pens ( P<0.05 ) , but there was no difference between the sows in farrowing pens and those in freedom farrowing pens ( P>0.05 ) . The piglet stillbirth rate was higher for the sows in farrowing crates than for those in farrowing pens and freedom farrowing pens ( P<0.001 ) . Crushing mortality was higher among piglets in farrowing pens ( P<0.001 ) , but there was no difference between piglets in freedom farrowing pens and those in farrowing crates ( P>0.05 ) . The freedom farrowing pen and the farrowing pen allowed sows to turn around and move freely , but because of the different structures of their anti-crushing bars , the increase in sow movement did not cause higher piglet crushing mortality ( P>0.05 ) . Sows in freedom farrowing pens were found to be more protective of their piglets Alternatives to farrowing crates with continuous confinement of the sow are urgently needed because the animal welfare is negatively impacted . Given the increase of herd sizes , practical experience with loose-housing is needed to force the implementation of these systems in the field . Next to aspects of labour efficiency , detrimental piglet mortality rates that may occur during the first days postpartum ( pp ) is a major criticism . Therefore , loose-housing after a crating period limited to the first days pp might be a feasible alternative to improve welfare under intensive production conditions . The aim was to investigate the effect of crating sows during lactation for different periods on their behaviour and integument alterations and on piglets ' performance .  Gilts from a commercial herd were observed from 5 to 26 days pp and housed in farrowing crates ( 1.85 × 2.50 m ) that could be altered between confinement crates and loose-housing pens . Animals were divided into three groups , that were either crated continuously from birth until weaning ( Group A , n=55 ) , until 14 days pp ( Group B ; n=54 ) or 7 days pp ( Group C , n=59 ) . The behaviour of six r and omly selected gilts per group was video recorded from 5 to 26 days pp and analysed by time sampling technique . Lesions on the legs , shoulder and lumbar vertebra were scored on days 7 , 14 and 25 pp . Piglets were weighed weekly , causes of losses recorded and weight losses of gilts measured . Not different between groups ( P>0.05 ) , animals spent 72 to 76 % lying laterally , 14 to 17 % lying in abdominal or semi-abdominal position , 9 to 10 % st and ing and 1 to 3 % sitting . B-sows were lying longer in week 3 and 4 of lactation compared to A- and C-sows ( P0.05 ) , whereas almost 90 % of the losses occurred in the first week pp . In conclusion , loose-housing of lactating gilts after a reduced postnatal crating period of 7 days affected neither the activity level of the gilts and lesions on the integument nor pre-weaning mortality . Therefore , it is recommended to allow sows to move around to some extent during the later lactation period In the 24-h period prior to parturition , sows are active and motivated to perform nest-building behavior . The aim of this study was to investigate whether prepartum activity ( nesting and postural changes ) could predict maternal behavior 24 h postpartum , piglet mortality , and BW gain 24 h postpartum in farrowing pens and crates . Sows were r and omly moved either to a farrowing pen ( = 20 ) or a farrowing crate ( = 18 ) . Prepartum nest-building behavior ( PRE-nesting ) and prepartum postural changes ( prepartum postural changes ) were analyzed 24 h before the birth of the first piglet ( BFP ) and were divided into twelve 2-h intervals . Latency of the first suckling from the litter was observed after the birth of the last piglet . Udder accesses and piglet suckling were noted at 5-min intervals , using 1/0 sampling , during the first 24 h after BFP were counted . Piglet trapping , crushing , and total live-born mortality were measured during the first 72 h after BFP . Piglet BW gain was estimated 24 h after BFP . Increased PRE-nesting observed 2 h before BFP were associated with fewer suckling intervals in crates but not in pens ( < 0.01 ) as well as an increase in postural changes during parturition ( < 0.001 ) in both housings . A link between housing and PRE-postural changes was evident . An increase in the number of PRE-postural changes 2 h prior to BFP was associated with lower incidences of udder access in crates but not in pens ( < 0.05 ) . A higher probability of piglet trapping was associated with increased PRE-nesting in the 2 to 4 h before BFP . No significant relationship between either PRE-nesting and postural changes and piglet BW gain and mortality was detected . Our results suggest that increased prepartum activity 2 h before parturition is associated with less suckling and less udder access in farrowing crates but not in farrowing pens . This suggests that the same sow behavior can have different consequences in pens vs. in crates . Future research should focus on nest-building activity , its relationship to endocrine indicators ( e.g. , oxytocin , cortisol ) before parturition , and its potential long-lasting effects on subsequent maternal behaviors and piglet production Free farrowing pens ( pens ) improve the welfare of sows but may increase sow activity and negatively influence piglet production .  The aim of this study was to assess the effect of pens and crates on  sow postural changes , piglet trapping , sow responses to piglet screams , piglet mortality , and piglet BW gain .  It was predicted that provision of greater space ( in pens ) would increase not only the frequency of sow postural changes and the probability of trappisng but also sow responses to the screams of piglets ; thus , the outcome would be no differences in fatal piglet crushing or overall mortality between the housing systems . Sows were r and omly moved to either a farrowing pen ( n = 20 ) or farrowing crate ( n = 18 ) . Sow behavior was recorded and analyzed for 72 h from the birth of the first piglet ( BFP ) . Sow postural changes included rolling from a ventral to lateral position and vice versa and going from st and ing to sitting , st and ing to lying , and sitting to lying . Occurrences of piglet trapping and sow responsiveness to real crushing situations were analyzed . Sow responsiveness was assessed in response to audio playbacks ( PB ) of piglet screams on d 3 postpartum ( 48 to 72 h after BFP ; PB crush calls ) and real piglet crushing during the first 72 h after BFP ( real crush calls ) . Piglet BW gain was estimated 24 h after BFP , piglet BW was recorded at weaning , and piglet crushing and piglet mortality were recorded during the 72 h after BFP . Data were analyzed using PROC MIXED and PROC GENMOD of SAS . Sows in pens showed more postural changes ( P = 0.04 ) and tended to have greater incidences of piglet trapping ( P = 0.07 ) than those in crates . Sow response to PB crush calls was greater in pens ( P = 0.04 ) but did not differ for real crush calls between pens and crates ( P = 0.62 ) . There was no effect on the probability of piglet crushing ( P = 0.38 ) and mortality ( P = 0.41 ) during the 72 h after BFP nor in piglet mortality at weaning ( P = 0.81 ) between pens and crates . Piglet BW gain at 24 h after BFP ( P = 0.01 ) and piglet BW at weaning ( P = 0.02 ) were greater in pens . Sows in pens showed more postural changes and tended to trap more piglets ; however , the response to real crush calls did not differ between the two housing systems . Despite this , there was no increase in piglet crushing or mortality in pens , which might be influenced by the better piglet body condition observed in pens , which in turn could influence their ability to avoid crushing by the sow 
    Output:
    
The relative risk of piglet mortality was 14 % higher in farrowing pens than farrowing crates , which indicated that non-confinement of sows compromises post-natal piglet survival .
Overall , the type of farrowing accommodation did not affect the number of stillborn piglets .
However , the rate of stillborn piglets was lower in farrowing pens that were not enriched when compared with farrowing crates , also with no enrichment .
There was no effect of housing type on the number of piglets born alive or the number of piglets weaned , although the sample size for the later was much smaller .
Producers should anticipate an increase in mortality when piglets are reared by sows that are unconfined in the pen design s that are currently available , which supports the wider belief that crates are successful for reducing pre-weaning piglet mortality .
Abstract There are conflicting reports regarding the effect of farrowing house accommodation on piglet performance .
There was no overall effect on piglets that were born alive or number weaned .
This was the first systematic review and meta- analysis conducted on the performance of farrowing accommodation and identified that farrowing pens do compromise post-natal piglet survival .