all experiments complied with eu council directive 91/630/eec 
 , which lays down minimum standards for the protection of pigs , and eu 
 council directive 98/58/ec , which concerns the protection of animals kept for farming 
 purposes 
 .
. closely related f1 gilts ( large white    landrace ) were selected as replacement breeding 
 stock at birth on a commercial breeding company 's ( hermitage ai ) multiplier farm and 
 exposed to the same group housing and feeding regimens up to final selection at 22 weeks 
 of age . at this time , 158 gilts were selected on their backfat levels at the p2-site 
 ( 79  mm or 1014  mm , respectively ) and categorised as thin ( n 78 ) or fat 
 ( n 80 ) .
backfat depth was measured at the last rib and 65  mm from the 
 backbone of the gilt using an ultrasound scanner ( lean - meater , renco corporation ) on both 
 the left and right side and the mean was recorded . the difference in backfat between 
 groups
was nutritionally accentuated until service ( 32 weeks ) when the backfat depths of 
 thin and fat gilts were 12 ( sem 06 ) and 19 ( sem 06 )  mm , respectively . 
 between 22 and 30 weeks of age
, thin gilts were fed 18  kg / d dry sow diet ( 619  g / kg 
 lysine , 130  mj digestible energy ( de)/kg ) and the fat gilts were provided with ad 
 libitum access to a gilt developer diet ( 585  g / kg lysine , 143  mj
de / kg ) 
 ( table 1 ) . for 4 weeks before planned mating
, 
 gilts were provided with constant boar contact by introducing a boar into an adjoining 
 pen . at 2 weeks before service
, all gilts were provided with ad libitum 
 access to a lactation sow diet for the flushing effect ( table 1 ) .
a quantity of 9  ml of regumate equine ( altrenogest , 2.2 g / ml ; 
 intervet productions s.a . ) per gilt was added to the lactation sow diet daily for 6 d to 
 synchronise gilts to oestrus .
gilts were provided with 10 min boar contact twice daily to 
 aid oestrus detection once they came off the regumate .
gilts were artificially inseminated 
 at onset of standing oestrus and again 24  h later using semen pooled from eight closely 
 related hylean large white boars ( hermitage ai ) . immediately after service ,
gilts were 
 moved to individual gestation pens ( 24  m    06  m ; o'donovan engineering ) where they were 
 fed , once per d , the dry sow diet ( table 1 ) 
 until day 110 of gestation .
each gilt was fed 18  kg / d ( 234  mj de / d ) for the first 25  d 
 of gestation .
on day 25 of gestation , gilts from each body condition group ( fat or thin ) 
 were blocked according to weight and expected farrowing date and allocated at random to 
 one of three feeding levels : ( a ) restricted ( 18  kg / d ) , ( b ) control ( 25  kg / d ) or ( c ) high 
 feed level ( 35  kg / d ) , until day 90 of gestation . in total
there were six treatment 
 groups : thin restricted , thin control , thin high feed level , fat restricted , fat control 
 and fat high feed level .
after day 90 of gestation all gilts were fed 25  kg / d through to 
 day 110 .
110 gilts were moved to individual farrowing pens and liquid fed ( big 
 dutchman ) the lactation diet ( table 1 ) until 
 farrowing at an allocation of 203  kg / d ( 288  mj de / d ) .
gilts were accommodated in 
 farrowing rooms with ten gilts per room in national pig development company type farrowing 
 crates ( o'donovan engineering ) with hinged bottom bars .
after farrowing , gilts were scale 
 fed the lactation diet using a lactation feed curve increasing from 288  mj de / d at day 0 
 to 1127  mj de / d at day 28 post - farrowing .
room temperature was maintained at 20c except 
 at farrowing when the temperature was increased to 24c for 48  h. at farrowing litter 
 weight , total born , born alive , stillbirths and mummies were recorded as well as 
 individual piglet birth weights .
litter size was standardized at farrowing to approximately twelve pigs per litter by 
 cross - fostering within treatment groups within 24  h of birth .
the offspring were then kept 
 with the gilt and suckled by her for the first 28  d of their life .
in addition , a creep 
 feed ( 165  mj / de , lysine 16  % ; startrite 88 ; nutec ) was fed to all litters from day 12 
 postpartum to weaning at approximately day 28 postpartum .
table 1.composition of experimental diets ( on an air dry basis ; g / kg)*gilt developer dietdry sow dietlactation dietwheat4239barley83298929350soyabean meal ( 50  % crude protein)7575160soyabean oil701040mineral and vitamins151515lysine hcl050520dl - methionine0007l - threonine0008di - calcium phosphate555limestone flour111112salt444phytase010101chemical compositiondm870871873crude protein153116158crude fat852639crude fibre323430ash393643lysine5856291digestible energy ( mj / kg)143130142*dry sow diet and lactation diet provided ( mg / kg completed diet ) : cu , 30  mg ; fe , 
 70  mg ; mn , 62  mg ; zn , 80  mg ; i , 06  mg ; se , 02  mg ; vitamin a as retinyl acetate , 
 3 mg ; vitamin d3 , as cholecalciferol , 25  g ; vitamin e as 
 dl--tocopheryl acetate , 100 mg ; vitamin k , 2  mg ; vitamin b12 , 
 15  g ; riboflavin , 5  mg ; nicotinic acid , 12  mg ; pantothenic acid , 10  mg ; choline 
 chloride , 500  mg ; biotin , 200  g ; folic acid , 5  mg ; thiamin , 2  mg ; pyridoxine , 
 3  mg. synthetic amino acids. sow diets contained 500 phytase units ( ftu ) per kg finished feed from natuphos 
 5000 ( basf). calculated from standard book values for ingredients .
composition of experimental diets ( on an air dry basis ; g / kg ) * dry sow diet and lactation diet provided ( mg / kg completed diet ) : cu , 30  mg ; fe , 
 70  mg ; mn , 62  mg ; zn , 80  mg ; i , 06  mg ; se , 02  mg ; vitamin a as retinyl acetate , 
 3 mg ; vitamin d3 , as cholecalciferol , 25  g ; vitamin e as 
 dl--tocopheryl acetate , 100 mg ; vitamin k , 2  mg ; vitamin b12 , 
 15  g ; riboflavin , 5  mg ; nicotinic acid , 12  mg ; pantothenic acid , 10  mg ; choline 
 chloride , 500  mg ; biotin , 200  g ; folic acid , 5  mg ; thiamin , 2  mg ; pyridoxine , 
 3  mg .  synthetic amino acids .
 sow diets contained 500 phytase units ( ftu ) per kg finished feed from natuphos 
 5000 ( basf ) .
 calculated from standard book values for ingredients . at weaning , gilts were moved to individual pens in the service area and provided with 
 ad libitum access to the lactation diet in pellet form until service . 
 the weaning to oestrus interval and feed intake during this period
gilts were returned to the dry sow accommodation and 
 provided with the dry sow diet in liquid form ( 30  mj de / d ( about 23  kg / d on a fresh 
 weight basis ) ) through to the subsequent farrowing .
gilts were weighed and backfat measurements were taken at about 22 weeks , at service 
 ( about 32 weeks ) on day 25 , 50 , 80 and 110 of gestation , at weaning and at the subsequent 
 oestrus .
feed allocation is presented on a meal equivalent fresh weight ( kg / d ) basis for 
 each period ( table 1 ) . to allow time for the gilts to adapt to their housing and their respective feeding 
 levels ,
a cotton swab ( salivette 
 plain ) was attached to a pair of surgical tongs and placed in the mouth of the gilt at 
 three time points during the day : 09.30 ( prior to feeding ) , 12.30 and 15.30 hours .
gilts were allowed to chew on the cotton swab for approximately 30  s , 
 or until saturated .
swabs were then returned to the container and centrifuged at 1000  g for 2  min at room temperature within 1 h of collection .
saliva samples were assayed for cortisol levels in 
 duplicate by a salivary cortisol eia kit ( salimetrics ) .
cortisol concentration was 
 quantified by interpolating absorbance readings from a standard curve generated in the 
 same assay . a colostrum sample ( about 5  ml )
colostrum samples were manually collected from teats at anterior , middle and posterior 
 locations of the udder , pooled and immediately frozen at 20c for subsequent analysis . 

colostrum samples were analysed in duplicate for igg levels using specific igg pig - elisa 
 kits ( bethyl laboratories inc . ) .
the igg levels were quantified according to the 
 manufacturer 's instructions by interpolating absorbance readings from standard curves 
 generated in the same assay .
milk samples ( about 15  ml ) were collected from gilts after their morning meal on day 21 
 of lactation which represents peak lactation 
 .
piglets were removed from the gilt in the morning in order to 
 facilitate refill of the mammary gland before sampling at noon .
milk samples were manually 
 collected from teats at anterior , middle and posterior locations of the udder , after a 
 1  ml ( 10  iu ) intramuscular injection of oxytocin ( eurovet animal health ) to induce milk 
 let down .
milk samples were thawed at 4c and preservatives were added to prolong shelf 
 life ( broad spectrum microtabs ii ; d&f control systems inc . ) .
milk 
 samples were diluted with distilled water prior to analysis to ensure that sample 
 composition fell within the validated calibration range for the infrared analyser .
samples 
 were heated to 40c and analysed in duplicate for percentage fat , protein and lactose 
 concentrations on an infrared analyser ( milkoscan ft 6000 ; foss electric ) .
protein 
 content was validated using the kjeldahl method ( result r 
 09396 ) according to iso 
 .
 gottlieb technique ( result 
 r 09313 ) according to james 
 . following extraction ,
30  mg of the respective milk fat were dissolved 
 in hexane and transesterfied at room temperature by the addition of 200  l of 
 2  m - methanolic koh .
after 5  min the reaction was terminated using 05  g of sodium 
 hydrogen sulphate monohydrate and the resulting fatty acid methyl esters ( fame ) were 
 analysed by glc ( 3400 ; varian ) as previously described by childs et 
 al . 
 .
feed samples for analysis were collected before feeding at intervals throughout the 
 experiment and were pooled for analysis .
dm , crude ash , crude protein , crude fat and crude 
 fibre were analysed by the methods described previously 
 .
data were analysed using mixed models in sas ( sas institute , inc . ) . for gilt production 
 performance ,
the fixed effects were body condition ( thin or fat ) , feed level ( restricted , 
 control and high ) , block and the body condition    feed level interaction .
for the data describing body weight of 
 the gilt , the weight of the gilts at day 25 of gestation was included as a covariate . for 
 the milk and colostrum results , body condition , feed level and the interactions between 
 body condition and feed level
time was included as the repeated statement , and gilt ( feed level ) included as the 
 subject .
results were 
 considered statistically significant when p  <  005 and were 
 considered as trends when p    010 .
the ingredient composition and the nutrient content of the gilt diets are presented in 
 table 1 .
the final number of gilts included in the analysis for production parameters was 
 sixty - eight thin and seventy - two fat gilts , due to sixteen repeating and two deaths .
the 
 effect of maternal body condition and feed level during gestation on gilt weight , backfat 
 levels , lactation performance , length of pregnancy and subsequent reproductive performance 
 is presented in table 2 .
table 2.influence of the main effects , maternal body condition ( thin or fat ) and gestation 
 feed level ( restricted : 18  kg / d ; control : 25  kg / d ; or high feed level : 35  kg / d ) 
 on sow performance during gestation , during lactation and on subsequent reproductive 
 performance(adjusted mean values with their pooled standard errors)treatmentthinfat 
 sem 
 p*restrictedcontrolhigh feed 
 sem 
 p * 
 n 
 6872444848sow body weight ( kg)day 25 of gestation141715851610001149714991507204092day 50 of gestation1610176616300011605167617832070001day 80 of gestation1826198016400011759189020612080001day 110 of gestation1986213517600011919204322202200001farrowing weight1712184516500011622177519392000001weaning weight167617382010051616170118042510001sow backfat ( mm)day 25 of gestation1221890320001156155155041096day 50 of gestation13420103100011581651800400001day 80 of gestation14820203700011571701990470001day 110 of gestation14419003400011491651870430001weaning backfat11213803100011161221360390001daily lactation feed intake ( kg / d)498484012404354346946101540001lactation body weight change ( % ) 10359410400001 + 0073946581284001length of pregnancy ( d)11551155019098115511541156024086lactation length ( d)277277050081280277274050047weaning to oestrus ( d)*52560120025545553015050subsequent performancetotal pigs born / litter124124049097132120120062030total pigs born dead / litter0611024020070811020055 mean values within a row with unlike superscript letters were 
 significantly different ( p  < 
there was no significant body condition    feed level interaction for any of the 
 variables tested. estimated value : empty farrowing weight  =  ( sow weight at day 110    ( total 
 born    228 ) ) .
the value of 228  kg is an estimate of the increased weight in the 
 gravid uterus and in mammary tissue attributed to each pig in a 
 litter .
lactation body weight change ( % )  =  ( sow weaning 
 weight    ( sow weight at day 110    ( total born    228)))/(sow weight day 
 110    ( total born    228 ) )    100
. influence of the main effects , maternal body condition ( thin or fat ) and gestation 
 feed level ( restricted : 18  kg / d ; control : 25  kg / d ; or high feed level : 35  kg / d ) 
 on sow performance during gestation , during lactation and on subsequent reproductive 
 performance ( adjusted mean values with their pooled standard errors )   mean values within a row with unlike superscript letters were 
 significantly different ( p  <  005 ) ( tukey  kramer 
 adjusted ) .
* there was no significant body condition    feed level interaction for any of the 
 variables tested .
 estimated value : empty farrowing weight  =  ( sow weight at day 110    ( total 
 born    228 ) ) .
the value of 228  kg is an estimate of the increased weight in the 
 gravid uterus and in mammary tissue attributed to each pig in a 
 litter .
lactation body weight change ( % )  =  ( sow weaning 
 weight    ( sow weight at day 110    ( total born    228)))/(sow weight day 
 110    ( total born    228 ) )    100 .
the body weight of pre - selected thin and fat gilts was different from day 25 of gestation 
 onwards , with thin gilts being lighter throughout the trial 
 ( p  <  005 ) . at day 25 , body weights for restricted , control and 
 high feed level gilts were similar ( p  >  005 ) . from day 50 

onwards , however , feed level influenced body weight of the animals , with the restricted 
 fed gilts being lighter than control fed gilts , and control fed gilts being lighter than 
 high feed level gilts ( p  <  0001 ) .
thin gilts had lower backfat 
 levels than fat gilts at day 25 and throughout the trial 
 ( p  <  0001 ) . at day 25 of gestation , backfat depths were similar 
 for restricted , control and high feed level gilts ( p  >  005 ) . from 
 day 50
onwards , however , feed level influenced the backfat depth 
 ( p  <  0001 ) .
restricted gilts had a higher average daily feed intake during lactation than control and 
 high feed level animals ( p  <  0001 ) .
there was no difference in 
 daily feed intake for thin and fat gilts ( p  >  005 ) . during 
 lactation ,
fat gilts lost more weight than thin gilts ( p  <  0001 ) . 

gilts restricted during gestation did not lose weight during lactation , while control and 
 high feed level gilts did ( p  <  001 )
. body condition or feed level 
 did not influence the length of pregnancy ( p  >  005 ) or lactation 
 length ( p  >  005 ) .
there was a tendency towards a body condition    feed level interaction for the weaning to 
 oestrus interval .
fat control gilts tended to have a longer weaning to oestrus interval 
 than thin control gilts ( 591 v. 505  d ; sem 0212  d ; 
 p  =  006 ) .
thin gilts had a shorter weaning to oestrus interval than fat 
 gilts ( p  <  005 ) .
there was no effect of the feed level or body 
 condition during the first gestation on the number of pigs born alive ( p 
 > 005 ) or born dead ( p  >  005 ) at the second parity .
the main effects of maternal body condition and feed level during gestation on piglet 
 growth up to weaning ( day 28 ) are presented in table 
 3 .
restricted gilts had higher numbers of piglets born alive than gilts on the 
 control feed level with both groups having similar values to that of high gilts 
 ( p  <  005 ) .
restricted gilts gave birth to lighter piglets than 
 gilts on the high feed level with both groups having similar values to that of control 
 gilts ( p  <  005 ) .
the mean weaning weight of the piglets was 
 influenced by the body condition of the gilt , with piglets from the fat gilts being 
 heavier than piglets from thin gilts ( p  <  005 ) .
piglets from fat 
 gilts also had higher average daily gain from birth to weaning than piglets from thin 
 gilts ( p  <  005 ) .
table 3.influence of the main effects , maternal body condition ( thin or fat ) and gestation 
 feed level ( restricted : 18  kg / d ; control : 25  kg / d ; or high feed level : 35 
kg / d ) 
 on litter size , piglet performance at birth and weaning(adjusted mean values with their pooled standard errors)treatmentthinfat 
 sem 
 p*restrictedcontrolhigh feed 
 sem 
 p * 
 n 
 6872444848litter sizelitter birth weight ( kg)165173049025171165170062072total number born121127038064130119123048020number born alive / litter114119038089124111114049004number born dead / litter07608001300590640800900165051number of pre - weaning deaths per litter17919802290521872141640287043total number weaned / litter101990220171049799027021piglet body weightmean piglet birth weight ( kg)14714900280671411501530036005cv of birth weight ( % ) 1836194407050231905188718780884099mean weaning weight ( kg)70374301400047217257220174091cv of weaning weight ( % ) 1709181508210331623181518491029023adg ( g / d)20242143421005209020952066528091cv of adg2040204510780981849209721821276015adg , average daily gain .
mean values within a row with unlike superscript letters were 
 significantly different ( p  < 
005 ) ( tukey  kramer 
 adjusted ) * there was no body condition    feed level interaction for any of the variables 
 tested. litter size was standardised at farrowing to approximately twelve pigs within 
 treatment groups. within - litter cv values .
influence of the main effects , maternal body condition ( thin or fat ) and gestation 
 feed level ( restricted : 18  kg / d ; control : 25  kg / d ; or high feed level : 35  kg / d ) 
 on litter size , piglet performance at birth and weaning ( adjusted mean values with their pooled standard errors ) adg , average daily gain .  
mean values within a row with unlike superscript letters were 
 significantly different ( p  <  005 ) ( tukey  kramer 
 adjusted ) * there was no body condition    feed level interaction for any of the variables 
 tested .
 litter size was standardised at farrowing to approximately twelve pigs within 
 treatment groups .  within - litter cv values .
there was a time effect , with salivary cortisol 
 concentrations being highest in the morning prior to feeding ( fig .
salivary cortisol concentrations were 986 , 504 and 
 533  nmol / l ( sem 0419  nmol / l ; p  <  0001 ) at 09.30 , 12.30 
 and 15.30 hours , respectively .
thin gilts tended to have higher mean cortisol levels than 
 fat gilts ( 734 v. 615 
nmol / l ; p  <  0001 ) ) than those for gilts fed 
 the high feed level ( 500  nmol / l ) and tended to be higher ( sem 0611  nmol / l ; 
 p  <  010 ) than those for gilts fed the control feed level 
 ( 673 
, control fed gilts tended to have higher 
 ( p  =  010 ) salivary cortisol concentrations than gilts fed the high feed 
 level . correlations between the average birth weight and maternal morning cortisol levels 
 were calculated .
there was a weak negative correlation ( 02651 ; 
 p  <  002 ) between maternal morning cortisol levels and the average 
 birth weight of the piglets .
however , when maternal body condition or feed level was 
 analysed together with morning cortisol their correlations with average birth weight were : 
 thin , 00548 ( p  >  005 ) ; fat , 04771 
 ( p  >  0003 ) ; restricted , 03755 
 ( p  >  005 ) ; control , 01177 ( p  >  005 ) ; 
 and high feed level , 03625 ( p  =  010 ) . fig .
1.effect of maternal body condition ( thin or fat ) and gestation feed level 
 ( restricted , 18 kg / d ; control , 25 kg / d ; or high feed level , 35 kg / d ) on saliva 
 cortisol levels at three different time points ( 09.30 , 12.30 and 15.30 hours ) . 

values are adjusted means , with their pooled standard errors represented by vertical 
 bars .
 , thin restricted ; , thin control ; , 
 thin high feed level ;  , fat restricted ; , fat control ; 
 , fat high feed level . 
 table 4.effect of maternal body condition ( thin or fat ) and gestation feed level 
 ( restricted : 18  kg / d ; control : 25  kg / d ; or high feed level : 35 
kg / d ) on saliva 
 cortisol levels at day 80 of pregnancy , and igg levels in colostrum at parturition 
 and day 21 milk composition(adjusted mean values with their pooled standard errors)thinfatp*treatment18  kg25  kg35  kg18  kg25  kg35  kg 
 sem 
 body conditionfeed level 
 n 
 212324232524cortisol ( nmol / l)927703579778644421091200810001 

n 
 91414121513milk composition day 21protein ( % ) 56585660566101304750881fat ( % ) 75615877819103100030760lactose ( % ) 61596160605700704870613 * there was no significant body condition    feed level interaction for cortisol , 
 colostrum or milk composition .
effect of maternal body condition ( thin or fat ) and gestation feed level 
 ( restricted , 18 kg / d ; control , 25 kg / d ; or high feed level , 35 kg / d ) on saliva 
 cortisol levels at three different time points ( 09.30 , 12.30 and 15.30 hours ) . 

values are adjusted means , with their pooled standard errors represented by vertical 
 bars .
 , thin restricted ; , thin control ; , 
 thin high feed level ;  , fat restricted ; , fat control ; 
 , fat high feed level .
effect of maternal body condition ( thin or fat ) and gestation feed level 
 ( restricted : 18  kg / d ; control : 25  kg / d ; or high feed level :
35  kg / d ) on saliva 
 cortisol levels at day 80 of pregnancy , and igg levels in colostrum at parturition 
 and day 21 milk composition ( adjusted mean values with their pooled standard errors ) * there was no significant body condition    feed level interaction for cortisol , 
 colostrum or milk composition .
the result of colostrum analysis at parturition for igg levels is shown in table 4 .
there were no differences between the 
 colostrum igg levels of thin ( 1107  mg / ml ) and fat ( 1362  mg / ml ) gilts ( sem 
 1523  mg / ml ; p  >  005 ) .
in addition , feed level did not influence 
 colostrum igg levels for restricted ( 1388  mg / ml ) , control ( 1115  mg / ml ) and high 
 ( 1198  mg / ml ) feed level gilts ( sem 1351  mg / ml ; 

the effects of maternal body condition and gestation feed level on milk composition at 
 day 21 postpartum are presented in table 4 .
fat 
 gilts had a higher milk fat percentage compared with thin gilts ( 83 v. 
 65  % fat ; sem 042  % ; p  <  0001 ) . milk fat levels were 
 not influenced by the level of feeding during gestation , being 76 , 71 , and 75  % 
 ( sem 055  % ; p  >  005 ) for restricted , control and high 
 feed level , respectively .
gestation feeding level or body condition had no effect on 
 protein and lactose levels in the milk .
thin gilts had higher levels of total saturated fat ( 3934  g/100  g of fame ) in their milk 
 than fat gilts ( 3691  g/100  g of fame ; sem 0736  g/100  g of fame ; 
 p  <  001 ) ( table 5 ) .
fat 
 gilts had higher levels of unsaturated fat in their milk ( 6201  g/100  g of fame ) than thin 
 gilts ( 5972  g/100  g of fame ; sem 0715  g/100  g of fame ; 
 p  <  005 ) .
the unsaturated : saturated fat ratio was 155:1 and 
 173:1 ( sem 0056 ; p  <  005 ) for thin and fat gilts , 
 respectively .
there was no effect of feed level during gestation on saturated or 
 unsaturated fat concentration in milk .
there was no effect of maternal body condition or 
 feed level during gestation on the composition of n-3 and 
 n-6 pufa .
feed level during gestation significantly affected the 
 concentration of c10 : 0 , c12 : 0 , c14 : 0 , c14 : 1c9 , c16 : 
 1c9 , c18 : 0 , c18 : 1c9 and c20 : 2 and tended to 
 influence c6 : 0 and c15 : 0 concentrations .
body condition significantly affected the 
 concentration of c10 : 0 , c12 : 0 , c14 : 0 , c14 : 1c9 , c15 : 0 , c16 : 0 , 
 c16 : 1c9 , c17 : 1c7 , c18 : 0 , c18 : 
 1c9 and c20 : 3n-6 and tended to affect the 
 concentrations of c10 : 1 , c14 : 1t9 , c9 , 
 t11 conjugated linoleic acid and c20 : 0 ( see table 5 ) .
table 5.effect of maternal body condition ( thin or fat ) and gestation feed level 
 ( restricted : 18  kg / d ; control : 25  kg / d ; or high feed level : 35 
kg / d ) on fatty 
 acid composition of milk at day 21 of lactation(adjusted mean values with their pooled standard errors)thinfatptreatment18 
kg25  kg35  kg18  kg25  kg35  kg 
 sem 
 body conditionfeed level 

n 
 91414121513fatty acid composition ( g/100  g of fame ) of milk 
 day 21*c4 : 0011006005005008002004104270395c10 : 0018015014017012010002000350005c12 : 0026022022025018017002300100006c14 : 0341304313319269242021600040014c14 : 1 c9032022023023017018003300050018c15 : 00100010200920097008000710009500140099c16 : 0324031123142313629472708146100180113c16 : 1 c91197944936947837784101800230052c17 : 0020024023021023021001803880144c17 : 1 c7031034031029031024003000500187c17 : 1 c10033035047043035028010405840886c18 : 0306391382357402449029500450006c18 : 1 total25428630027930333918500200015c18 : 2 t9 , t12 
 n-6163179173173167180009708880656c18 : 2n-616416115816817516509001590637c18 : 3n-6006009007008008012002402810571c18 : 3n-3162155155165171162009101310784c9 , t11 cla005006005007007007000900770680c20 : 2019027027021026038004502000010c20 : 3n-6021030027032033038004400090286c20 : 4n-6038051039045047050004802290181c22 : 5n-3013015015013016015001906270366c22 : 6n-30011003700210026002400280007505510185c24 : 0006005005006008005002107330609total unsaturated591960115985600061926409143300170154total saturated398538963922390237023469147500140146total n-3181183178190197187010601410697total n-6187018801827194020091925095801200669ratio unsaturated : saturated152158156158171189011300220192ratio n-6:n-3103510351028102410261033019307080992fame , fatty acid methyl esters ; cla , conjugated linoleic acid . mean values within a row with unlike superscript letters were 
 significantly different ( p  <  005 ) ( tukey  kramer 
 adjusted ) . *
only fatty acids of > 005  g/100  g of fame are shown ( c6 : 0 , c8 : 0 , c9 
 : 0 , c10 : 1 , c14 : 1 t9 , iso c16 : 0 , c16 : 1 
 t9 , c20 : 0 , c20 : 1 , c20 : 3n-3 , c20 : 
 5n-3 , c21 : 5 , c24 : 0 have been excluded for values 
 > 005  g/100  g of fame). there was a body condition    feed level interaction for c20 : 
 3n-3 ( p  =  005 ) and a trend on c6 : 0 
 ( p  =  006 ) , c9 : 0 ( p  =  009 ) and c22 : 
 6n-6 ( p  =  009 ) .
effect of maternal body condition ( thin or fat ) and gestation feed level 
 ( restricted : 18  kg / d ; control : 25  kg / d ; or high feed level : 35 
kg / d ) on fatty 
 acid composition of milk at day 21 of lactation ( adjusted mean values with their pooled standard errors ) fame , fatty acid methyl esters ; cla , conjugated linoleic acid .  
mean values within a row with unlike superscript letters were 
 significantly different ( p  <  005 ) ( tukey  kramer 
 adjusted ) .
* only fatty acids of > 005  g/100  g of fame are shown ( c6 : 0 , c8 : 0 , c9 
 : 0 , c10 : 1 , c14 : 1 t9 , iso c16 : 0 , c16 : 1 
 t9 , c20 : 0 , c20 : 1 , c20 : 3n-3 , c20 : 
 5n-3 , c21 : 5 , c24 : 0 have been excluded for values 
 > 005  g/100  g of fame ) .
 there was a body condition    feed level interaction for c20 : 
 3n-3 ( p  =  005 ) and a trend on c6 : 0 
 ( p  =  006 ) , c9 : 0 ( p  =  009 ) and c22 : 
 6n-6 ( p  =  009 ) .
the present study demonstrates that gestation feeding level affects the numbers of 
 offspring born alive per litter and offspring birth weight , while maternal body condition 
 affects weaning weight and growth of offspring .
this is , to our knowledge , the first study 
 combining feed level and body condition interactions during pregnancy to determine their 
 influences on postnatal piglet growth .
restricted gilts had higher levels of salivary cortisol than those provided with 
 high feed levels during gestation .
piglets from fat gilts had a higher average daily gain 
 between birth and weaning than piglets from thin gilts .
day 21 milk from lactating fat gilts 
 had a higher percentage of fat , less saturated fat and higher unsaturated fat than milk from 
 thin gilts .
we selected gilts at 22 weeks of age based on their backfat and for this reason 
 we can not rule out the possibility that the offspring in our study may have been genetically 
 predisposed , as opposed to programmed in utero , to the body condition 
 influences observed . on the other hand , closely related f1 gilts were selected to minimise 
 the genetic variation within the trial and indeed the backfat differences used for selection 
 purposes at 22 weeks were small .
piglets born to fat gilts had higher average daily gain between birth and weaning and 
 were heavier at weaning than piglets born to thin gilts .
this increased postnatal growth 
 rate may be attributable to ( a ) the higher milk fat percentage of the fat gilts , ( b ) the 
 difference in milk fat composition and/or ( c ) it could be due to other factors not 
 measured such as appetite , which can be affected by programming 
  or possibly the uptake of nutrients in the gastrointestinal tract .
a 
 high fat content in sow milk is desirable as it promotes weight gain and fat deposition in 
 piglets that functions as an insulation layer 
 .
although milk fat and fatty acid composition levels are largely 
 determined by the level and source of dietary fat used in the diet 
 , revell et al . 
  also observed that fat levels in the milk increased by 21  % for fat 
 sows ( 340  g of body fat / kg body weight ) compared with thin ( 280  g of body fat / kg body 
 weight ) sows .
interestingly , in our study the fat gilts on a high feed level during 
 gestation had the highest ratio ( 189:1 ) of unsaturated : saturated fat in their milk .
milk 
 tag come from two sources : biosynthesis of fatty acids within the mammary gland 
 ( de novo synthesis ) and uptake from the plasma by the mammary 
 gland 
 .
saturated fat contains mainly scfa that arise predominately from 
 de novo synthesis in the mammary gland , while longer - chain fatty acids 
 arise directly from blood lipids from dietary fatty acids 
 . as all gilts were given the same lactation diet and there was no 
 difference in lactation feed intake , the milk fat difference between thin and fat gilts 
 observed may have arisen from differences in rates of de novo synthesis . 

in addition , the thin restricted gilts had higher levels of fat in their milk than the 
 thin control and thin high feed level gilts , suggesting different pathways of energy 
 distribution for maintaining high fat levels in the milk in these groups .
it is probable 
 that for the thin gilts the main fat source for milk production came from the feed , 
 contrary to the fat gilts where the primary source could have been a mixture of endogenous 
 and exogenous sources . although the main limiting factor for intake in piglets is milk volume 
 , the differences found in piglet growth between thin and fat gilts 
 could also be influenced by the differences in milk fatty acid composition .
for example , 
 the amount of oleic acid ( c18 : 1cis9 ) was higher in the milk from fat 
 gilts and increased with gestation feeding level . in vitro cellular 
 models altering the conformation of a c18 : 1 double bond from cis to 
 trans ( oleic acid to elaidic acid ) decreases cholecystokinin secretion , 
 a satiety hormone involved in appetite regulation 
 .
oleic acid also provides a signal of nutrient abundance which 
 switches fuel sources from carbohydrates to lipids 
 .
this would indicate that offspring from fat gilts were receiving a 
 healthier milk composition , with regard to appetite regulation . of the 
 n-3 and n-6 pufa
, only c20 : 3n-6 , a 
 precursor for the synthesis of prostaglandins and other eicosanoids , was increased in the 
 milk of fat gilts .
an alteration in the balance of eicosanoid synthesis can cause chronic 
 inflammation , arterial hypertension , chd , atherosclerosis and diabetes 
 mellitus 

  later in life .
saturated fats c10 : 0 ( capric acid ) , c12 : 0 ( lauric 
 acid ) and c14 : 0 ( myristic acid ) increased in milk both from restricted fed gilts and 
 from thin gilts .
the importance of the lactation period has been demonstrated in rats 
 where postnatal factors overcame both genetic predisposition and prenatal factors in 
 determining the development of adiposity , insulin sensitivity and brain pathways that 
 mediate these functions 
 .
feeding regimens and body condition did not influence the 
 n-6 to n-3 pufa levels , indicating that supplementation 
 with different dietary fats would be required to change 
 n-6:n-3 ratios 

 .
restricted gilts had the highest level of salivary cortisol , most likely due to 
 undernutrition and suboptimal gut fill being stressful to the pregnant animal .
high levels 
 of cortisol during pregnancy may lead to in utero growth restriction as 
 thin restricted gilts gave birth to piglets with the lowest birth weights .
undernutrition 
 per se can reduce birth weight in offspring due to the reduced nutrient 
 supply to the fetus as a consequence of suboptimal feeding of the mother .
for example , a 
 reduction to 30  % of ad libitum intake in pregnant rats resulted in 
 newborns with a 25  % reduced birth weight compared with the control 
 .
however , in addition there is also substantial evidence that maternal 
 glucocorticoid levels , such as cortisol , affect offspring birth weight and glucose 
 metabolism 
 .
monkeys subjected to a mild stressor in the form of noise and removal 
 from their cage during pregnancy gave birth to lower birth weight 
 offspring 
 .
furthermore , glucocorticoid administration during pregnancy reduces 
 birth weight by 9  % in human subjects 
 , and by 15  % in response to one dose of 05  mg / kg betamethasone in 
 sheep 
 . in addition , pregnant sows treated orally with hydrocortisone - acetate 
 gave birth to piglets with lower birth weight ( 15  kg ) compared with piglets born to 
 control sows ( 165  kg ) 
 . surprisingly , restricted gilts gave birth to the highest number of piglets born alive . 

this could be because of differences in placental attachment and blood flow due to 
 treatment .
. 
  showed that oral administration of hydrocortisone - acetate to sows 
 during pregnancy ( day 21 to 110 ) increased the number of piglets born alive .
they 
 hypothesised that this could be due to enhanced maturation of the organs of the piglets 
 born to cortisol - treated sows 
 .
mullan & williams 
  also found that total birth weights were lower for gilts restricted to 
 15  kg feed per d during pregnancy .
one suggested pathway is that low placental 
 11-hydroxy - steroid dehydrogenase type 2 activity correlates with lower birth weight 
 because of increased transplacental passage of active maternal 
 glucocorticoids 
 .
as cortisol is an inhibitor of the growth hormone  insulin - like growth 
 factor 1 axis 
 , this elevated level might suppress insulin - like growth factor 1 
 actions , causing growth retardation 
 .
our results suggest that even though restrictive feeding increased the number of piglets 
 born alive per litter , a fixed uterine capacity resulted in lighter individual piglets in 
 these larger litters . restricting feed intake during pregnancy did not increase the total 
 number of piglets born per litter , indicating that despite the lack of a significant 
 effect of feed level on the number of piglets born dead , a numerical reduction in the 
 number of piglets born dead was in part responsible for the increase in the number of 
 piglets born alive from restricted gilts . in conclusion
, few maternal body condition  gestation feed level interaction effects 
 were observed for offspring growth . during gestation , feed - restricted gilts had higher 
 cortisol levels and gave birth to lighter piglets .
weaning weights were heavier and average daily gain was 
 greater in piglets born to fat gilts .
furthermore , body condition of gilts and feed level 
 during gestation altered the milk fat percentage and profile , with thin gilts having 
 higher levels of saturated fat than fat gilts .
 the fetal and early postnatal environment can have a long - term influence on offspring 
 growth . using a pig model , we investigated the effects of maternal body condition ( thin or 
 fat ) and maternal gestation feeding level ( restricted , control or high ) on maternal 
 stress , milk composition , litter size , piglet birth weight and pre - weaning growth . a total 
 of sixty - eight thin ( backfat depth about 8  mm ) and seventy - two fat ( backfat depth about 
 12  mm ) 
 gilts were selected at about 22 weeks . 
 this backfat difference was then accentuated 
 nutritionally up to service at about 32 weeks . during gestation 
 , individual gilts from 
 within each group were randomly allocated to a gestation diet at the following feed 
 allowances : 18  kg / d ( restricted ) ; 25  kg / d ( control ) and 35  
 kg / d ( high ) until day 90 of 
 gestation . during gestation restricted gilts had higher levels of cortisol than high and 
 control fed animals . 
 piglets born to fat gilts had higher average daily gain during the 
 lactation period and higher weaning weights at day 28 than piglets born to thin gilts . 
 
 gilts on a high feed level had heavier piglets than those provided with restricted and 
 control allocations . 
 fat gilts had less saturated fat in their milk at day 21 of lactation 
 and higher unsaturated fat levels . 
 no differences were found in the 
 n-6:n-3 pufa ratio in the milk between thin and fat 
 gilts . in conclusion , 
 maternal body condition influenced the daily weight gain of 
 offspring up to weaning ( day 28 ) and milk fat composition . 
 furthermore , maternal feed 
 level during gestation alters maternal cortisol levels and milk fat composition . 
Materials and methods
Results
Discussion