Once small always small? To what extent morphometric characteristics and postweaning starter regime affect pig lifetime growth performance

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1 Huting et l. Porine Helth Mngement (2018) 4:21 RESEARCH Open Aess One smll lwys smll? To wht extent morphometri hrteristis nd postwening strter regime ffet pig lifetime growth performne A. M. S. Huting 1*, P. Skks 1, I. Wellok 2, K. Almond 2 nd I. Kyrizkis 1 Astrt Bkground: The im of this study ws to determine the effet of piglet morphometri hrteristis nd strter regime on postntl growth. Some piglets orn light re le to grow fster thn others, nd identifying whih piglets re more t risk to remin light nd t whih stges of growth is essentil. A nutrient enrihed strter regime my llow lightweight pigs to improve their post-wening growth. A totl 1487 newly orn piglets from 137 litters originting from 8 onseutive frrowing thes were followed from irth (BiW) to wening (WW, d28) nd finishing (d99). At irth morphometri mesurements were tken, inluding ody mss index (BMI), ponderl index (PI) nd BiW:rnil irumferenes (BiW:CC). At wening pigs were rndomly lloted to one of two experimentl regimes: either nutrient enrihed regime with 20% higher essentil mino ids (EAA): energy rtio (HIGH) or stndrd regime (CTRL). Piglets were retrospetively lloted to 4 different weight lsses (C) using perentiles t irth, wening nd finishing, with C1 representing the lightest nd C4 the heviest lss. A series of novel sttistil models were used to determine whih ftors were le to predit performne. Results: For BiW C1 piglets, BMI (P = 0.003) nd BiW reltive to irth litter (P = 0.026) were positively ssoited with pre-wening performne, wheres BiW:CC (P =0.011)ndWW(P = 0.001) were positively ssoited with post-wening growth. Post-wening the est preditors of piglets wened light (WW C1) were PI (P = 0.037), BiW:CC(P < 0.001) nd WW (P < 0.001). Strter regime did not influene (P > 0.05) post-wening performne. Conlusion: Our results show tht not ll light pigs re the sme nd tht their performne is under the influene of ody shpe rther thn BiW. Therefore, pig produers should disriminte etween light pigs sed on irth hrteristis to improve the effetiveness of intervention strtegies t the different stges of growth. Irrespetive of weight lss piglets did not enefit from the EAA enrihed regime pplied. Keywords: Birth weight, Body mss index, Growth, Pigs, Ponderl index, Wening weight Bkground Slow growing pigs re more t risk to e delyed in ll-in-ll-out systems, resulting in remixing, inresing the potentil for disese trnsmission, ut most importntly ontriuting to onsiderle prodution losses (e.g. osts of feed, lour nd penlties t slughter) [1]. However, it hs een suggested tht some pigs orn light * Correspondene:.m.s.huting1@newstle..uk 1 Agriulture, Shool of Nturl nd Environmentl Sienes, Newstle University, Newstle Upon Tyne NE1 7RU, UK Full list of uthor informtion is ville t the end of the rtile my hve the potentil to ompenste during sukling [2] nd susequent growth stges [3 5]. It is therefore importnt to identify whih pigs re most likely to remin light throughout the prodution yle nd my require ttention. Birth- [1, 2] nd wening-weight [3 6] hve een identified s preditors for post-wening growth. Morphometri hrteristis t irth predit survivility [7, 8] nd my e utilised to identify piglets tht remin stunted throughout life [9], or potentilly enefit from intervention strtegies. However, the evidene out the effet of ody shpe t irth on The Author(s) Open Aess This rtile is distriuted under the terms of the Cretive Commons Attriution 4.0 Interntionl Liense ( whih permits unrestrited use, distriution, nd reprodution in ny medium, provided you give pproprite redit to the originl uthor(s) nd the soure, provide link to the Cretive Commons liense, nd indite if hnges were mde. The Cretive Commons Puli Domin Dedition wiver ( pplies to the dt mde ville in this rtile, unless otherwise stted.

2 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 2 of 14 susequent performne is sre nd lks life time performne pproh. One strtegy tht hs een shown to e effetive in improving the performne of lightweight pigs re high speifition strter regimes [10, 11]; pigs wened light hve poor strt, ut under the influene of n improved nutritionl regime my e le to improve their performne. However, the regimes studied previously [10, 11] hve ltered the ingredient omposition onsiderly, mking it impossile to identify whih speifi nutrients resoure(s) would e most enefiil. Slow growing pigs re suggested to hve lower feed intke nd lower serum onentrtions of essentil mino ids (EAA) [5] ompred to their fst growing silings. The low feed intke of lightweight pigs [12, 13] nd possily higher protein turnover in reltion to their size [14], suggest tht lightweight pigs my exhiit improved performne when fed nutrient enrihed diets tht re high in EAA [15]. The ojetives of this study were: 1) to ssess the influene of morphometri hrteristis t irth on performne to finisher stge nd whether these n differentite etween pigs tht re le to exhiit n improved performne pre- nd post-wening; nd 2) whether nutrient enrihed strter regime ould ontriute to n improved post-wening performne of piglets wened light. Methods The experiment ws onduted t Cokle Prk Frm (Newstle University, Morpeth, Northumerlnd, United Kingdom). All nimls were mintined in ordne to the reommendtions for the welfre of livestok following UK legisltions (Defr nd Red Trtor UK frm ssurne sheme) nd the experiment ws pproved y the Animl Welfre nd Ethil Review Body (AWERB projet ID no. 419) of Newstle University. All newly orn piglets (n = 1487) of the 137 sows tht frrowed during 8 onseutive frrowing thes were followed to finisher stge (~ 14 weeks of ge nd 45 kg BW). Pre-wening mngement Following 3-week yle, sows of different prity were moved on Mondy to the frrowing unit; those tht hd not frrowed y Thursdy, were indued (23.9% of the sows) with Prostglndin nlogue (Plnte; Intervet UK, Wlton, United Kingdom). All sows were Lrge White x Lndre, inseminted with Hylen or semen (Hermitge Seorough, Ltd., Devon United Kingdom). They were fed home-milled mel twie dy (08:00 nd 15:00 h) nd wter ws ville d liitum throughout lttion. The temperture in the frrowing unit ws mintined t 21 C (20.7 C, rnge 18.2 to 26.9 C). AHDB Pork guidelines for ross fostering [16] were followed, to help piglets orn light redue ompetition nd fit piglet mouths to the tet size of the sow. Cross fostering ws pplied within the first 3 dys post-prtum to improve litter uniformity nd to equlize litter size mthing the numer of piglets with the numer of funtionl tets nd milking ility of the sow (litter size rnge 10 to 15). During the first two dys of life piglets were loked into the reep re (one dy; 08:00 h), whilst the sow ws eting, to minimize rushing. An infrred het lmp ws loted in the overed reep re nd wood shvings were provided s edding. Piglets hd unlimited ess to wter nipple drinker. Within the first 12 h fter irth piglets hd their teeth lipped. At ~ 3 dys of ge, piglets were til doked nd reeived n intrmusulr iron injetion. All piglets hd ess to reep feed from 10 dys of ge whih ws fed in smll quntities ( hndful) on the floor of the overed reep re. The reep ws n equl mixture (50:50) of diet 1 of the stndrd (CTRL) nd nutrient enrihed (HIGH) strter regimes (see setion Post-wening strter regime ). Post-wening mngement Piglets were wened t pproximtely 28 dys of ge (d 27.7, SD = 1.07) nd were vinted for M. hyopneumonie (M + PAC; Intervet UK, Wlton, United Kingdom) nd porine irovirus type 2 (Inglev Myoflex; Boehringer Ingelheim, Ingelheim, Germny). They were rndomly mixed to form groups of pproximtely 20 similr sized pigs/pen (rnge 9 to 24 pigs/pen), whilst lning for gender, nd moved to fully sltted nursery ommodtion. The numer of pigs per pen ws dependent on the numer of pigs ville per th, ensuring similr stoking density etween pens nd thes onsistent with UK legisltions. The nursery ommodtion onsisted of 6 seprte environmentl rooms, with pproximtely 3 rooms per th. Pen size, where pproprite, ws djusted reting minimum of 4 to mximum of 8 pens per room. All pigs hd d liitum ess to wter vi nipple drinkers. The initil room temperture in the nursery ommodtion ws set t 26 C (24.6 C, rnge 20.7 to 27.2 C) nd redued y pproximtely 0.2 C eh dy to minimum of 22 C (23.4 C, rnge 21.5 to 26.7 C). When moved to the on-site grower ommodtion (d 61, SD = 1.17), pigs were fed the sme home-milled mel nd remined in the sme post-wening group. Groups of < 12 pigs were mixed to rete groups of ~ 20 pigs/ pen. At pproximtely weeks of ge (d 96.9, SD = 6.63) pigs were moved gin to fully sltted finisher uilding nd were fed ommeril finisher pelleted diet. Experimentl proedures Pre-wening proedures Piglets were weighed to the nerest 1 g within 12 h post-prtum (BiW, kg), nd individully identified (ID)

3 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 3 of 14 y er tgging (Dentg, Toptgs, Kelso, UK). Morphometri mesurements were tken from eh individul piglet, inluding rown to rump length (CRL, m), snout to ers length (hed length HL, m), dominl irumferenes (AC, m) nd rnil irumferenes (CC, m). Adominl irumferenes, ws tken t the nterior side of the umilius ord. Crown rump length (m) ws used to lulte the ponderl index (PI; BiW, kg/crl, m 3 ) nd ody mss index (BMI; BiW, kg/crl, m 2 )[9]. Additionl vriles were reted s n inditor of hed size in reltion to ody weight: 1) irth weight: rnil irumferenes (BiW:CC, kg/m) [9] nd 2) snout to ers length: irth weight (HL:BiW, m/kg) [17]. At the point of til doking litter omposition (foster litter), inluding sow nd piglet ID, ws reorded. The generl helth of piglets ws exmined on dily sis nd deths, inluding use of deth where possile, were reorded. Piglet er tgs were repled y lrger er tgs (Suretg flg, Dlton tgs, Newrk Nottinghmshire, UK) nd piglets were individully weighed t wening (WW, d 27.7, SD = 1.07). Post-wening strter regime At wening, piglets were rndomly lloted to either nutrient enrihed (HIGH) or ontrol (CTRL) 3-stge strter regime (Primry Diets, ABAgri, Ripon, North Yorkshire, UK). Diet 1 nd 2 of the HIGH regime (Tle 1) weresupplemented with dditionl syntheti EAA L-lysine, DL-methionine, L-threonine, L-tryptophn nd L-vline, in order to hieve 20% higher EAA: energy rtio when ompred to the CTRL diet, while mintining the sme NE nd ensuring the pproprite rtios to lysine were mintined; the CTRL regime met NRC reommendtions [18]. By 7 weeks of ge (d 48.0, SD = 0.887) ll pigs hd finished the first 2 strter diets. Diet 3 of oth the HIGH nd CTRL regimes were identil. For either regime, diet 1 ws fed until 2 kg of feed were onsumed nd diet 2 until 3 kg of feed were onsumed per pig. Diet 3 ws fed d liitum up to 9 weeks of ge when pigs were moved to the grower ommodtion. A totl of 70 nursery pens of nimls were prt of the experiment; 36 pens (n = 679) were fed the CTRL nd 34 pens (n = 683) were fed the HIGH strter regime. Post-wening proedures Until movement to the grower fility (d 61.5, SD = 1.17), pigs were weighed one week. At the sme time the mount of feed offered nd refused ws reorded to estimte weekly feed intke. Pigs tht lost weight during the first week post-wening were weighed individully nd dily during two suessive dys; those tht kept losing BW were removed from the experiment (see Sttistil Anlysis setion s to how this ws ddressed in the finl models). Two hundred nd six pigs (15.5%) were sold s growers (d 74.8, SD = 1.93). The reminder of the pigs (n = 1121) were individully weighed t finisher stge (d 98.8, SD = 0.937). Sttistil nlysis All sttistil models were performed with SAS version 9.4 (SAS inst. In. Cry, NC) using mixed models (PROC MIXED) unless stted otherwise. The residul vrine of the dt ws tested for normlity using the UNIVARIATE proedure. Severl ovrine strutures were tested, ut vrine omponents resulted in the lowest Akike Informtion Criterion (AIC) with n AIC differene of > 4 onsidered sustntil [19]. Dt were expressed s lest squre mens (LSM), with pproximte stndrd errors of the differenes of mens (SED) unless stted otherwise. Sttistil signifine ws ssessed t the 5% level nd tendenies were set t 10%. Performne per pen The effet of strter regime on post-wening performne nd oeffiient of vrition (CV) within pen ws ssessed using PROC MIXED. The experimentl unit ws pen verge loked y room nested within frrowing th; weight sttement ws used to ount for differenes in the numer of pigs per pen. Gender ws dded to the preliminry model s ovrite. Asolute performne per ody weight lss Pigs were retrospetively ssigned to ody weight (BW) lsses sed on 25% perentiles [3] reting 4 groups t irth (BiW), wening (WW) nd finisher (FW). Clss 1 represented the lightest (ottom 25%) nd 4 the heviest (top 25%) pigs. Body weight lsses reted inluded ll pigs tht were live or remined on site t the strt of speifi stge of prodution (e.g. irth, wening nd finisher). Clsses were reted oth within th nd over the entire period, however lsses tht were reted within th resulted in the est model fit. The experimentl unit for ll mixed models ws piglet, loked y frrowing th. To ount for ny litter or pen effets piglets were loked y: (1) sow (irth or foster sow) nested within frrowing th for evluting pre-wening performne, nd (2) pen x room nested within frrowing th for evluting post-wening performne. In the post-wening mixed model min effets of interest were BW lss, strter regime nd their intertion. As lsses were reted retrospetively nd piglets were lloted to the different strter regimes on the sis of their WW nd not BiW, WW ws inserted in the model for BiW lss to ount for WW differenes t the strt of the tretment. In the preliminry models frrowing th, gender, totl numer of pigs orn, irth litter/ prity, foster litter/ prity, pre-wening litter size, ge nd post-wening group size were inserted s

4 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 4 of 14 ovrites where pproprite. As result of mortlity nd pig removls due to weight loss or sikness, pre-wening litter nd post-wening group size were orreted using the following formul over given period: Litter/Group size = [(totl time (h) piglets reside in the foster litter/ pen)/ 24 h]/ totl period in d An dditionl vrile pen vrition ws reted (pen vrition = verge BW lss within pen) sed on BiW or WW lss nd ws dded to ll post-wening nlysis. Additionl file 1: Tle S1 speifies the finl model Tle 1 Ingredient omposition on n s-fed sis nd hemil nlysis of the post wener feeds used. Pigs were rndomly lloted to either nutrient enrihed (HIGH) or stndrd (CTRL) strter regime. Diet 1 ws fed until 2 kg ws onsumed, nd diet 2 until 3 kg were onsumed per pig. Diet 3 ws fed d liitum 1 Diet Regime CTRL HIGH CTRL HIGH Ingredient g/kg Mironized rley Whet Mironized whet Mironized ots Fishmel Soy en mel Pig wener vitmin/ Tre element supplement 2 Dried skim milk powder Whey L-Lysine HCL DL-Methionine L-Threonine L-Tryptophn L-Vline Vitmin E Benzoi id Limestone flour Dilium phosphte Slt Binder (LignoBond DD) Sodium ironte Soy oil Anlysed omposition, % s fed CP Crude fier Moisture Ash Tle 1 Ingredient omposition on n s-fed sis nd hemil nlysis of the post wener feeds used. Pigs were rndomly lloted to either nutrient enrihed (HIGH) or stndrd (CTRL) strter regime. Diet 1 ws fed until 2 kg ws onsumed, nd diet 2 until 3 kg were onsumed per pig. Diet 3 ws fed d liitum 1 (Continued) Diet Regime CTRL HIGH CTRL HIGH Clulted omposition, % s fed or s speified DE, MJ/kg NE, MJ/kg Clium Phosphorus Ltose Lysine Methionine Methionine + Cysteine Threonine Tryptophn Arginine Histidine Isoleuine Leuine Vline Phenyllnine + Tyrosine Diets were supplied y Primry Diets, ABAgri, Ripon, North Yorkshire, United Kingdom 2 It provided per kilogrm of omplete diet 11,500 IU of vitmin A, 2000 IU of vitmin D 3, 100 IU of vitmin E, 4 mg of Vitmin K, 27.5 μg of vitmin B 12, 15 mg of pntotheni id, 25 mg of niotini id, 150 μg of iotin, 1.0 mg of foli id, 160 mg of Cu (CuSO 4 ), 1.0 mg of iodine (C (IO 3 ) 2 ), 150 mg of Fe (FeSO 4 ), 40 mg of Mn (MnO), 0.25 mg of Se (one morphogeneti protein), nd 110 mg Zn (ZnSO 4 ) 3 Borregrd LignoTeh, Srpsorg, Norwy 4 All mino ids re expressed on stndrdized ilel digestile (SID) sis desriptions fter removl of nonsignifint ovrites used for the different ojetives. A hi-squre test ws rried out to test whether the reson for removl nd pre- nd post-wening mortlity ws different mong pigs of different BW lsses nd whether this ws ffeted y strter regime nd/or gender. In ddition, hi-squre ws used to test whether the numer of pigs tht deresed, remined or inresed t lest one BW lss t wener or finisher [3, 20] ws different mong the different BW lsses. Cluster nlysis A prinipl omponent nlysis (PCA) ws performed using PROC FACTOR to determine whether there is distint group within BiW nd WW lss 1 piglets le for ompenstory growth during respetively the prend post-wening period. An dditionl vrile for irth

5 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 5 of 14 weight in reltion to irth litter verge were lulted using the following formul [4, 8]: Reltive irth weight (Reltive BiW): [Birth weight piglet/ men irth weight irth litter] For BiW lss 1 piglets 10 vriles were onsidered, inluding irth weight, reltive BiW nd the vrious morphometri hrteristis (AC, CC, CRL, BMI, PI, HL, BiW: CC nd HL: BiW). The ove vriles plus pre-wening ADG nd WW were onsidered for WW lss 1 piglets. Prinipl omponents with n Eigenvlue greter thn 1 were retined in the model nd were used in the luster nlysis (PROC CLUSTER) using the Wrd method to minimise within-luster vrine. The numer of lusters were determined on the sis of fit sttistis (e.g. Cui Clustering Criteri, Pseudo F nd t 2 sttistis; [21]) nd the dendrogrm. The effet of the lusters on the different vriles tht were onsidered in the PCA nd its effet on pre- nd post-wening performne were nlysed using mixed models djusting the degrees of freedom to unequl vrine with denomintor degrees-of-freedom (DDF) Stterthwite nd studentized mximum modulus (SMM) enling multiple omprison. Proility for ompenstory growth Two different logisti regressions (PROC LOGISTIC) were onduted to identify whether piglets from different BW lsses differ in their ility to hnge lss in lter life, nd whether this ws under the influene of strter regime nd the vrious morphometri hrteristis. The first logisti regression tested whether piglets of BiW lss 1 to 4 hd different proility to end up in WW lss 1 to 4. A similr model ws onduted etween BiW FW nd WW - FW. The effets of interest ws BW lss (BiW or WW lss), strter regime nd their intertion. In the seond logisti regression, pre-wening ADG nd vrious morphometri hrteristis were dded to determine whether pig ility to hnge BW lss deresed or inresed (log odds ± SE) with one unit inrese in the preditor vrile. For oth regressions, the response vrile of interest (e.g. WW nd FW lss) hd more thn two levels nd ws therefore formtted to enle the estimtion of piglet proility to end up in one of the intermedite BW lsses (lss 2 or 3), with zero representing everything other thn the BW lss of interest. The referene vlue ws set to the finl BW lss of interest using the DE- SCENDING option to ensure the likelihood to end up in the highest BW lss ws tested. Multivrite nlysis All potentil preditor vriles were fitted in univrite mixed model to test their effet on pre- nd post-wening performne. Only preditor vriles tht were signifint (P < 0.05) in the univrite model were tken forwrd in the multivrite nlysis. Multivrite models were uilt following forwrd nd kwrd stepwise proedure only leving ftors in tht hd proility elow 0.05 nd using the AIC riteri to determine whih model fitted est. Different models were uilt for vriles tht were highly orrelted (r > 0.70) to ensure the vrine infltion ftor (PROC REG) remined low (< 2). Results An overview of pre-nd post-wening frm hrteristis n e found in Additionl file 2: Tle S2. Gender signifintly ffeted irth (P = 0.006) nd wening weight (P = 0.043), with mles eing wened hevier (respetively 1.47 kg, SD = nd 7.26 kg, 2.20) thn femles (respetively 1.46 kg, SD = nd 7.09 kg, SD = 2.08). Certin morphometri hrteristis, inluding AC, CC, PI, nd BMI, were lso signifintly (t most P < 0.05) lower for femles thn mle piglets. However, the rtio of hed size to BW (i.e. BiW:CC) tended (P = 0.094) to e higher in femles thn in mle piglets. Wek positive orreltions were found etween BiW nd WW (r =0.497, P < 0.001) nd BiW nd pre-wening ADG (r =0.326, P < 0.001), wheres high orreltion ws found etween WW nd pre-wening ADG (r =0.970,P <0.001). The verge BW for the different FW lsses (d 98.8, SD = 0.938) ws 36.5 kg (SD = 3.14), 43.1 kg (SD = 3.07), 47.4 kg (SD = 3.08), nd 53.3 kg (SD = 3.23) for lsses 1 4 respetively. Performne per pen Gender ws eqully distriuted ross tretments (P > 0.05); WW nd pen CV (d 28) did not differ etween strting regimes. Post-wening performne (d 28 to 61) ws not ffeted y strter regime; BW nd pen CV t vrious stges of prodution long with feed intke nd gin to feed rtio were not signifintly different (P > 0.05) etween pigs lloted to the HIGH or CTRL regime. Asolute performne per irth weight lss Tle 2 shows the totl numer of piglets per BiW lss t the different stges of prodution. The highest pre-wening mortlity rte (21.1%) ws oserved for piglets orn light (lss 1), ompred to piglets of BiW lss 2 4 (P < 0.001). Most (46.8%) of these BiW lss 1 piglets were non-vile t irth or died of strvtion, of whih 67.6% were mle nd 32.4% femle pigs (P = 0.003). The numer of piglets per strter regime ws unlned (P < 0.001) for BiW lss 2 nd 4 piglets. Signifintly (P < 0.001) more piglets of BiW lss 2 were lloted to the CTRL versus HIGH regime. The opposite ws the se for piglets of BiW lss 4 (P < 0.001). Within pen vrition ws not signifintly different ross tretments (P < 0.05). Totl post-wening removl

6 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 6 of 14 Tle 2 Totl numer of pigs pre- nd post-wening per irth weight lss. Within th irth weight lsses were reted retrospetively using perentiles (25%) resulting in 4 different groups. Clss 1 represents the lightest piglets nd lss 4 the heviest. At wening pens were rndomly lloted to one of the strter regimes: ontrol (CTRL) vs. nutrient enrihed strter regime (HIGH) Birth weight lss Totl Signifine 1 Strter regime CTRL HIGH CTRL HIGH CTRL HIGH CTRL HIGH CTRL HIGH Numer of pigs 2 Dy Dy < Dy < Dy < Dy < Dy Dy < 0.001, Asolute vlues within irth weight lss with different supersripts differ signifintly (P < 0.05) etween strter regimes 1 A hi squre test ws used to test the overll differene etween the different irth weight lsses x strter regime (entire row, exluding totl) 2 Pigs were followed from irth (d 0), wening (d 27.7, SD = 1.07), grower (d 61.5, SD = 1.17), to finisher (d 96.9, SD = 6.63). Two hundred nd six pigs were sold s growers (32.6 kg, SD = 2.86) t n ge of d 75 (d 74.8, SD = 1.94) of whih 99 were weighed nd the rest (n = 107) no dditionl weights were tken 3 Only those pigs tht rehed finisher ge on site (d 98.8, SD = 0.938) (inluding weight loss, sikness, nd mortlity) ws signifintly ffeted y BiW lss. Signifintly (P = 0.028) more piglets of BiW lss 1 (3.7, 72.7% mles nd 27.3% femles, P = 0.033) were removed thn piglets orn hevy (lss 4, 1.1%). Also, piglets of BiW lss 2 tended (P = 0.065) to e removed in higher quntities ompred to piglets of BiW lss 4 (3.1% vs. 1.1%). Totl post-wening removl ws ffeted y strter regime (P = 0.040), with the highest removl oserved for piglets fed the HIGH regime (n = 19, 2.9%) ompred to those fed the CTRL regime (n = 8, 1.2%). Tle 3 shows the effet of BiW lss nd strter regime on susequent performne. Birth weight lss signifintly (P < 0.001) ffeted piglet BW throughout the produtive period; pigs in lss 1 remined lighter throughout the different stges of prodution, weighing > 3 kg lighter (40.9 kg, SD = 10.7) t d 97 thn piglets orn hevier (44.0 kg, SD = 10.5, 44.8 kg, SD = 10.4, nd 45.6 kg, SD = 10.7 for respetively lss 2, 3, nd 4). Although strter regime did not ffet BW t d 48 (P >0.05), it tended to influene piglet BW t d 61 (P = 0.059). Piglets tht were lloted to the CTRL regime weighed 1.00 kg hevier t the end of the nursery (23.1 kg, SD = 8.85) thn piglets fed the HIGH regime (22.1 kg, SD = 8.69). However, t finisher (d 97) the effet of strter regime ws sent (P > 0.05). Aprt from WW (P < 0.001), there ws no signifint intertion etween BiW lss nd strter regime t lter stges of prodution (P > 0.05); the signifint intertion t wening ws result of diet nd pig llotion: following norml frm prties piglets were grouped together on the sis of WW nd not BiW. Asolute performne per wening weight lss A totl of 1362 piglets were wened of whih n = 355 were onsidered lightweight (WW lss 1), n = 342 pigs elonged to WW lss 2, n = 329 to WW lss 3, nd n = 336 to WW lss 4 (P >0.05). The numer of pigs per strter regime within WW lss ws unlned (P < 0.001). Signifintly (P = 0.001) more pigs of WW lss 1 were lloted to the HIGH (n = 155) versus CTRL regime (n = 200). Similrly, more pigs of WW lss 2 (P < 0.001) nd 3 (P = 0.073) were lloted to the CTRL (respetively n =199 nd n = 176) vs. the HIGH regime (respetively n = 143 nd n = 153). The opposite (P = 0.003) ws the se for piglets of WW lss 4 (n = 149 for CTRL vs. n = 187 for HIGH). The differenes in numer of pigs per strter regime ws result of dhering to norml frm prties: nimls were not lloted to different pens on the sis of their tul BW ut on the sis of size (e.g. smll, medium, or lrge). In ddition, sine lsses were reted post-ho, eh pen often onsisted of mixture of vrious WW lsses rther thn one lss only. Nevertheless, pen vrition ws not signifintly different ross tretments (P >0.05). Totl post-wening removl ws 2.0%, with pigs in WW lss 1 eing removed in the highest quntity (6.8%, P <0.001), ompred to pigs of WW lss 2, 3, nd 4 (< 1.0%). Tle 3 shows the effet of WW lss nd strter regime on susequent performne. Wening weight lss influened pigs BW throughout the different stges of growth. Pigs of the lightest WW lss (WW lss 1), remined light throughout the different stges of prodution weighing lmost 8.0 kg lighter t finisher ompred to pigs wened hevy (respetively 39.7 kg, SD = 12.3; nd 47.5 kg, SD = 11.4). No differene (P >0.05) in finl weights (d 97) were oserved etween pigs from WW lss 2 nd 3. Neither strter regime nor the intertion etween strter regime nd WW lss ffeted post-wening performne (P > 0.05).

7 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 7 of 14 Tle 3 Effet of irth weight lss (A), wening weight (B) lss nd strter regime on susequent performne. Per th irth weight (BiW, d 0) nd wening weight (WW, d 28) lss were determined retrospetively y grouping piglets into 4 different lsses (25%) using perentiles t irth nd wening. Clss 1 represents the lightest piglets nd lss 4 the heviest. At wening pens were rndomly lloted to one of the strter regimes (Diet): ontrol (CTRL) vs. nutrient enrihed strter regime (HIGH). Dt re expressed s LSM ± SED A Birth weight lss SED Signifine Strter regime CTRL HIGH CTRL HIGH CTRL HIGH CTRL HIGH BiW lss Diet BiW lss *Diet Body weight 1,kg d < d < < d < d < d < Averge dily gin, g/d d < d < d < d < d < B Wening weight lss SED Signifine Strter regime CTRL HIGH CTRL HIGH CTRL HIGH CTRL HIGH WW lss Diet WW lss *Diet Body weight 1,kg d < d < d < d < Averge dily gin, g/d d < d < d < d < , Within BW lss numers with different supersripts differ signifintly (P < 0.05) 1 Pigs were weighed within 12 h post-prtum (d 0), t wening (d 27.7, SD = 1.07), 3 weeks post wening (d 48.0, SD = 0.887), grower (d 61.5, SD = 1.17), nd finisher (d 96.9, SD = 6.63) Growth etween irth nd susequent stges Figure 1 nd 1 show the umultive proility of the vrious BiW lsses to hnge lss etween irth nd wening, nd irth nd finisher respetively. The likelihood to end up light t wening nd finisher inresed with deresing BiW lss. Birth weight lss 1 piglets fed the HIGH regime hd higher likelihood (P < 0.001) to remin light (0.603, SD = vs , SD = 0.044) nd lower likelihood to end up hevy t finisher (0.055, SD = vs , SD = 0.016) thn the sme lss piglets fed the CTRL regime. Signifint orreltions were found etween the different preditor vriles ssessed for eh BiW lss seprte s shown in Additionl file 3: Tle S3. As expeted BMI nd PI were highly orrelted for ll BiW lsses. Additionl files 4 nd 5: Figures S1 nd S2 shows the effet of vrious morphometri hrteristis on pig ility to hnge BW lss from respetively irth to wening nd from irth to finisher. Aprt from HL the mjority of morphometri hrteristis ffeted lss hnge of espeilly BiW lss 1 pigs. The effet of pre-wening performne on pig ility to hnge BW lss etween irth nd finisher is summrised in Additionl file 6: Figure S3. It is evident tht for ll BiW lsses, piglet odds to end up light t finisher deresed with one unit inrese in ADG (P < 0.001). Tle 4 shows the finl multivrite regression models for the vrious BiW lsses nd the effet of different preditor vriles on pre- nd post-wening ADG. The finl multivrite regression model for BiW lss 1 pigs showed

8 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 8 of 14 Proility d d Wening weight lss d d d Finisher weight lss < Finisher weight lss P-trend < < < < < < < < < < d d Fig. 1 Piglet umultive proility to hnge ody weight (BW) lss etween irth (BiW) nd wening, irth nd finisher, nd wening (WW) nd finisher (). Within th, BW lsses were reted using perentiles (25%) resulting in 4 groups. Clss 1 represents the lightest pig, lss 4 the heviest. Dt is represented in proility ± SE. Different olours represent BW lss, with respetively lss 1, lss 2, lss 3, nd lss 4. The omprison is mde etween pigs of different BW lsses (i.e. BiW or WW lss) estimting their proility to end up in one of the finl BW lsses (i.e. wening or finisher). Pigs were weighed within 12 h fter irth (d 0), wening (d 27.7, SD = 1.07), nd finisher (d 98.8, SD = 0.937).,,,d Within BW lss (i.e. wening, finisher) numers with different supersripts differ signifintly (P < 0.05) d tht reltive BiW (P =0.026)ndBMI(P =0.003)werethe most importnt ftors for prediting the pre-wening performne of BiW lss 1 pigs, eing positively ssoited with growth. It hs to e noted however, tht reltive BiW (P < 0.001) ws highly orrelted (Additionl file 3: Tle S3) with other vriles tht were signifint in the univrite model (Additionl file 7: Tle S4) suh s BiW (r = 0.830), BiW:CC (r = 0.824) nd HL:BiW (r = 0.780). Although, signifintly more (P = 0.003) BiW lss 1 pigs remined light (lss 1) t wening (56.1%), ompred to those tht were le to inrese lss (43.9%), BiW lss 1 pigs tht were le to inrese lss pre-wening, hd signifint (P <0.001) higher OR (95% CI); 5.11 [2.87, 9.10], 7.20 [3.59, 14.5], nd 11.5 [2.53, 52.2] for respetively lss 2 4, to end up hevy t finisher (FW lss 3 nd 4) thn pigs tht remined light t wening (referene). However, the OR to end up hevy t finisher did not differ (P > 0.05) mong BiW lss 1 pigs tht inresed lss (e.g. WW lss 2, 3 or 4 piglets). The est fit multivrite model for post-wening performne (Tle 4) of BiW lss 1 piglets onsisted of only BiW:CC (P =0.011) nd WW (P =0.001). The prinipl luster nlysis of BiW lss 1 piglets showed tht two prinipl omponents hd n Eigenvlue greter thn 1. Together they explined 79.6% of the totl vrition: 59.4% y prinipl omponent 1 nd 20.2% y prinipl omponent 2. Three lusters were formed; the desription of the different lusters sed on the vriles used in the PCA re shown in Tle 5. The mjority of the piglets elonged to luster 1 (44.2%), followed y luster 2 (34.6%) nd luster 3 (21.2%) piglets. Cluster 2 piglets were the lightest t irth, reltively lighter ompred to their verge irth litter nd differed signifintly with respet to the vrious morphometri hrteristis from luster 1 nd 3 piglets. While piglets of luster 1 nd 3 were orn with similr BiW, the differenes in morphometri hrteristis (i.e. HL, CRL, BMI, PI) suggest tht piglets of luster 1 were orn proportionlly long nd thin ompred to luster 3 piglets. Pre-wening mortlity ws signifintly (P = 0.002) higher for luster 2 piglets (34.1%) ompred to luster 1 (16.4%) nd luster 3 (21.5%) piglets. Piglets elonging to luster 2 were wened signifintly (P < 0.001) lighter (5.75 kg, SD = 1.46) ompred to luster 1 nd 3 piglets (respetively 6.11 kg, SD = 1.54 nd 6.33 kg, SD = 1.56), however post-wening performne ws not signifintly (P > 0.05) different mong the different lusters. The mjority of BiW lss 2 pigs were le to inrese lss etween BiW nd WW (44.9%) nd BiW nd FW (47.9%) ompred to those tht remined (respetively 31.3 nd 25.3%) or deresed BW lss (respetively 23.9 nd 26.7%). Those tht deresed lss pre-wening, hd signifint (P < 0.001) lower OR (0.483 [0.273, 0.854]) to end up hevier t finisher (lss 4) ompred to BiW lss 2 pigs tht remined or inresed lss, respetively lss 2 (referene), 3 (1.38 [0.812, 2.36]) nd 4 (3.28 [1.70, 6.31]). On the other hnd, most pigs of BiW lss 3 deresed lss etween BiW nd WW (40.2%) nd

9 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 9 of 14 Tle 4 Finl multivrite models (oeffiient nd SE) of different preditor vriles for pre- (d 0 to 28) nd post-wening ADG (d 28 to 99) for piglets from different ody weight lsses. Within th, BW lsses were reted using perentiles (25%) resulting in 4 groups t irth (d 0) nd wening (d 27.7, SD = 1.07). Clss 1 represents the lightest, lss 4 the heviest pigs. Morphometri mesurements were tken within 12 h post-prtum nd pigs were weighed t irth, wening nd gin t finisher (d 98.8; SD = 0.937) Body weight lss Birth weight lss Wening weight lss Averge dily gin, g/dy d 0 28 d d Clss 1 Clss 2 Clss 3 Clss 4 Clss 1 Clss 2 Clss 3 Clss 4 Clss 1 Clss 2 Clss 3 Clss 4 Preditor vrile Birth weight, kg 54.5 (21.0) Reltive irth weight (21.1) 71.7 (27.1) 75.2 (33.9) Snout to er length, m 12.1 (5.05) Adominl irumferene, m (2.27) (1.77) Body mss index 2, kg/m (1.06) Ponderl index 3, kg/m (0.319) Birth weight: Crnil irumferene, kg/m 1729 (674) Gender (4.53) 2107 (824) Wening weight, kg 15.4 (4.50) 1128 (409) 20.7 (8.59) 12.0 (4.24) 11.0 (3.76) 15.1 (3.42) 36.2 (6.57) Pre-wening ADG, g/dy (0.261) 1 Reltive irth weight = (Birth weight piglet/ men irth weight irth litter) 2 Body mss index = irth weight (kg)/[rown rump length (m)] 2 3 Ponderl index = irth weight (kg)/[rown rump length (m)] 3 4 The oeffiient reflets tht of mle, femle ws set s referene (0) 1542 (581) BiW nd FW (42.5%). Consequentilly, BiW lss 2 nd 3 piglets hd similr proility (P > 0.05) to end up in WW lss 3, FW lss 2, nd FW lss 3 s shown in Fig. 1 nd respetively. Gender (P = 0.012) nd BiW: CC (P = 0.012) were le to predit pre-wening performne of BiW lss 2 pigs (Tle 4) wheres, WW ws the sole vrile in the multivrite model nd ws positively ssoited with post-wening performne for BiW lss 2 to 4 pigs. Growth etween wening nd finisher Wening weight lss 1 piglets hd the highest likelihood (P < 0.05) to remin light (lss 1 nd 2) t finisher nd were less likely to end up hevy t finisher (lss 4) ompred to WW lss 2 to 4 piglets (Fig. 1). Although signifintly more WW lss 1 piglets (54.1%) remined light t finisher (P = 0.047), 45.1% were le to inrese lss. Additionl file 6: Figure S3 shows the effet of pre-wening ADG on piglet ility to hnge BW lss etween wening nd finisher. Pre-wening ADG only signifintly influened lss hnge for piglets wened elow verge (lss 1 nd 2). Clss hnge etween WW nd FW ws lso signifintly ffeted y the different morphometri hrterises (see Additionl file 8: Figure S4) nd mostly ffeted WW lss 1 piglets. The mjority (P < 0.001) of piglets wened light (WW lss 1) were orn light (48.1%), the rest ws wened light ut orn hevier: BiW lss 2 (23.3%), 3 (15.7%) nd 4 (12.8%). Piglets orn hevier (BiW lss 2 to 4) ut wened light hd signifintly (P < 0.001) higher OR (respetively, 3.17 [1.80, 5.58], 3.60, [1.87, 6.92], nd 3.67, [1.80, 7.48]) to end up hevy t finisher (lss 4) ompred to piglets of BiW lss 1 (referene). The multivrite regression model (Tle 4) inluding piglets tht were live t finisher (d 99), suggests tht BiW:CC (P < 0.001), PI (P = 0.037), nd WW (P < 0.001) were the est preditors for post-wening performne, eing positively ssoited with growth of WW lss 1 piglets. It hs to e noted tht BiW:CC ws positively orrelted to BiW (r = 0.983), reltive BiW (r = 0.856) nd vrious

10 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 10 of 14 Tle 5 Cluster hrteristis of irth weight lss 1 piglets (smllest 25% t irth) lustered in different groups sed on irth weight nd vrious morphometri hrteristis. Dt re expressed s LSM ± SED 1 Cluster (%) SED P-vlue 44.2% 34.6% 21.2% Cluster hrteristis Body weight, kg d < Reltive BiW < Morphometri hrteristis Adominl irumferenes, m < Crnil irumferenes, m < Snout to er length, m < Crown rump length, m < Body mss index 3, kg/m < Ponderl index 4, kg/m < Birth weight: Crnil irumferenes, kg/m < Snout to er length: Birth weight, m/ kg < 0.001,, Vlues with different supersripts differ signifintly (P < 0.05) 1 Pigs were weighed within 12 h post-prtum (d 0) 2 Reltive irth weight = (Birth weight piglet/ men irth weight irth litter) 3 Body mss index = irth weight (kg)/[rown rump length (m)] 2 4 Ponderl index = irth weight (kg)/[rown rump length (m)] 3 morphometri hrteristis (r > 0.70) suh s AC, CC, BMI, nd HL:BiW (Additionl file 9: Tle S5) tht ppered to e signifint in the univrite nlysis (Additionl file 10: Tle S6). The desription of the luster nlysis for WW lss 1 piglets sed on the vriles used in the PCA is shown in Tle 6. Three prinipl omponents hd n Eigenvlue greter thn 1 nd together explined 87.4% of the totl vrition: 57.9% prinipl omponent 1, 16.0% prinipl omponent 2, nd 13.5% prinipl omponent 3. The mjority of the piglets elonged to luster 2 (61.9%), followed y luster 3 (22.0%), nd luster 1 (16.1%) piglets. Cluster 1 piglets were orn nd wened signifintly lighter nd differed to luster 2 nd 3 piglets with respet to vrious morphometri hrteristis (e.g. CC, HL, BIW:CC nd HL:BiW). Cluster 3 piglets hd the highest BiW, hd signifintly (P < 0.001) higher BMI, PI, AC, nd BiW:CC ompred to luster 2 piglets, ut were wened with similr BW (P > 0.05). Post-wening mortlity (d 28 to 61) did not differ etween the different lusters (P >0.05); with 10.9, 5.21, nd 6.67% for respetively luster 1, 2, nd 3. However, luster 1 piglets remined the lightest (P < 0.001; 35.3 kg, SD = 6.73) post-wening, weighing 5 to 6.8 kg lighter t finisher ompred to luster 2 nd 3 piglets (respetively 40.2 kg, SD = 7.21 nd 42.1 kg, SD = 6.33). Although, luster 3 piglets hd signifintly lower pre-wening ADG (P = 0.027) thn luster 2 piglets, t finisher luster 3 piglets tended (P = 0.073) to weigh lmost 2 kg hevier t finisher ompred to luster 2 piglets. The mjority of lss 2 piglets (49.0%) were le to inrese lss t finisher, wheres the mjority (41.6%) of WW lss 3 piglets deresed lss etween WW nd FW. As result, piglets of WW lss 2 hd higher proility to finish in FW lss 3 ompred to WW lss 3 piglets (respetively 0.337, SD = nd 0.247, SD = 0.022, Fig. 1). Adominl irumferenes (P = 0.010), gender (P = 0.017), nd pre-wening ADG (P = 0.011) were signifint in the finl model for WW lss 2 piglets (Tle 4). None of the morphometri hrteristis were signifint in the univrite models for WW lss 3 piglets nd only reltive BiW ppered to e signifint (P = 0.028). The finl multiftoril model of WW lss 4 piglets onsisted of BiW:CC (P = 0.009) only. Disussion Mximising sow reprodutive potentil vi geneti seletion for the totl numer of piglets orn or wened hs resulted in inresed litter sizes nd thus the numer of piglets wened per sow per yer [22]. Although the numer of piglets produed per sow per yer is n importnt eonomi trit, s result of limittions in the uterine pity nd mternl resoures lrger litter sizes inrese the proportion of piglets orn light [23 26], the numer of intruterine growth restrited (IUGR) piglets [26] nd onsequently inrese within-litter vrition [23]. To ensure tht piglet qulity nd welfre is not ompromised, pig produers re inresingly hllenged to keep lightweight piglets live nd to improve wening weight, minimising th ineffiieny. Knowing whih

11 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 11 of 14 Tle 6 Cluster hrteristis of wening weight lss 1 piglets (smllest 25% t wening) lustered in different groups sed on irth weight, vrious morphometri hrteristis, nd pre-wening growth. Dt re expressed s LSM ± SED 1 Cluster (%) SED P-vlue 16.1% 61.9% 22.0% Cluster hrteristis Body weight, kg d < Reltive BiW < d < Morphometri hrteristis Adominl irumferenes, m < Crnil irumferenes, m < Snout to er length, m < Crown rump length, m < Body mss index 3, kg/m < Ponderl index 4, kg/m < Birth weight: Crnil irumferenes, kg/m < Snout to er length: Birth weight, m/ kg < Averge dily gin, g/dy d < 0.001,, Vlues with different supersripts differ signifintly (P < 0.05) 1 Pigs were weighed within 12 h post-prtum (d 0) nd t wening (d 27.7, SD = 1.07) 2 Reltive irth weight = (Birth weight piglet/ men irth weight irth litter) 3 Body mss index = irth weight (kg)/[rown rump length (m)] 2 4 Ponderl index = irth weight (kg)/[rown rump length (m)] 3 piglets would enefit from intervention strtegies t different stges of growth is importnt, s some lightweight pigs my e le to perform etter without intervention, minimising vrile growth rtes within group nd possile eonomi losses. Although, reent reserh suggests tht ody shpe t irth (e.g. BMI, AC) nd not BiW were le to predit postntl growth of piglets orn light [9], reserh ssessing the effet of ody shpe t irth together with well-known preditor vriles suh s BiW, WW nd pre-wening ADG on susequent performne under ommeril onditions is sre. Our work is the first ttempt tht ddresses these issues up to finishing stge. In ddition, we hve pplied novel sttistil methodologies to nswer these questions. This llows us to mke preditions out the effets of morphometri mesurements on susequent performne. Furthermore, we investigted piglet ility for improved performne when given ess to nutrient enrihed regime, i.e. with higher EAA:NE rtio, t wening. Improved strter regimes tilored on the sis of lightweight piglet requirements rther thn the verge piglet, hve een shown to e effetive in improving post-wening performne for lightweight pigs [10, 11]. The low feed intke [12, 13], the lower serum onentrtions of EAA [5] nd possile higher protein turnover [14], suggest tht lightweight piglets my enefit from n EAA enrihed diet. Piglets wened light pper to hve n immture digestive system [27, 28] nd higher epithelil ell turnover [29], nd therefore my enefit from n inresed supply of threonine [30] nd methionine [31]. Their lower ghrelin expression [32] nd serotonin onentrtions [33] suggest tht n inresed supplementtion of tryptophn my stimulte ppetite [30]. The results of our study did not support the hypothesis tht piglets wened light would improve performne when hving ess to regime higher in EAA. In the nutrient enrihed regimes lysine ws inresed y 20% with the other EAA eing lned to lysine, ensuring the pproprite rtios were mintined [18]. Resons for the lk of effet ould e result of: 1) lightweight pigs tully not hving the hypothesised higher EAA requirements post-wening [15], 2) lightweight piglets not hving ess to enough energy to use the extr EAA supplied, nd 3) n sene of speifi response to the supplemented AAs, inluding their rtios to lysine. For exmple, there re suggestions tht individul AA, suh s rginine nd glutmine [34], my enhne the growth of lightweight piglets. Although studies looking t infnts tht were orn extremely light suggest tht more onentrted diet with inresed levels of energy nd AA elerte weight gin [35], others [12] who hve hypothesised tht piglets wened light would enefit from more nutrient dense

12 Huting et l. Porine Helth Mngement (2018) 4:21 Pge 12 of 14 diet (i.e. different energy levels), were lso unle to find positive effet on the post-wening performne. Birth [1, 2, 36] ndweningweight[3 6, 36] hve een identified s preditors of post-wening growth. Although, piglets orn light (< 1.00 kg) hve higher mortlity rte [8], higher feed onversion rtio [13] nd need more time to reh mrket weight [24], one should disriminte etween piglets tht hve een orn light for gesttionl ge e.g. proportionlly smll [26] nd piglets tht hve suffered from growth restrition in utero. Different outomes my e expeted, with IUGR piglets elieved to remin stunted throughout life [37]. In ddition, the severity of IUGR might vry etween pigs nd is suggested to e dependent on the stge of gesttion nd durtion; the longer the period of growth restrition in utero the lesser the ility to reover post-prtum [37]. Although piglets orn light hve higher likelihood to remin light t wening nd finisher, our results suggest tht not ll lightweight pigs re the sme nd tht some re tully le to do etter thn others. This is supported y the following: 1) pre-wening ADG nd not BiW, ws highly orrelted with WW, 2) BW lss hnge etween irth nd susequent stges ws under the influene of vrious morphometri hrteristis, nd 3) the multivrite nlysis showed tht reltive BiW nd BMI were positively ssoited with pre-wening growth for BiW lss 1 piglets rther thn BiW per se. Dougls et l. [9] hve put forwrd severl resons why suh morphometri mesurements my e etter preditors of postntl performne. The positive ssoition etween BMI nd pre-wening ADG my e result of: 1) differenes in surfe re: volume rtio [38] influening metoli rte or 2) differenes in the mount of mternl resoures quired during gesttion importnt for development [9, 39, 40]. Reltive irth weight, on the other hnd, my suggest tht the lightest piglet of the litter might hve een t ompetitive disdvntge for olostrum intke [41]. In ontrst to wht hs een previously found [9], post-wening ADG for BiW lss 1 pigs ws positively ssoited with WW nd hed shpe t irth (i.e. BiW:CC), with the sene of WW in the previous study [9] most likely hve ontriuted to the differenes seen. The positive ssoition etween BiW:CC nd post-wening performne suggests tht pigs with lrger hed size in reltion to BiW (low BiW:CC) hve n impired post-wening performne. The dolphin-like forehed, the dptive rin spring effet s result of plentl insuffiieny, hs een used for the identifition of IUGR piglets [8]: piglets tht might not e le to disply norml growth nd remin stunted throughout life [38]. Also in our study BiW:CC disriminted etween piglets tht suffered from ertin degree of IUGR. On the other hnd, these findings lso emphsize the importne of wening weight: good strt is essentil nd inresing BW lss pre-wening hs een shown enefiil for susequent performne. Wening weight does not only influene susequent performne [11 13, 36], with higher likelihood for slower post-wening growth rte for WW lss 1 (ottom 12.5% t wening) ompred to BiW lss 1 pigs (ottom 12.5% t irth) [3], ut is lso n importnt ftor influening disese risks [42], post-wening mortlity [36] nd th effiieny in ll-in-ll-out systems, espeilly for pig enterprises from the ottom qurtile [43]. This suggests tht the emphsis should e on the pre-wening mngement [44 48] for improving the performne of piglets orn light. At the sme time our results point towrds whih piglets re most likely to enefit from suh sometimes time onsuming nd expensive strtegies. There re severl resons why piglet orn hevy might end up light t wening, suh s: diret nd indiret ompetition for milk intke [45] nd sikness. In our experiment 51.9% of piglets orn hevy (e.g. BiW lss 2 to 4) fell into this tegory. However, suh piglets were still t n dvntge for ompenstory growth post-wening, hving higher OR to end up hevy t finisher, ompred to piglets orn nd wened light. Compenstory growth fter period of stunting hs previously een shown for piglets orn hevier one hving ess to n etter qulity strter regime [49]. However, differenes in pre-wening nutrient intke might hve set ppetite during susequent stges [50] nd therefore piglets with poor pre-wening ADG hieve lower growth potentil thn similr sized piglets with greter pre-wening ADG. In ddition, the multivrite nd luster nlysis emphsised tht not ll piglets wened light re the sme: the distintion etween piglets wened light tht n or nnot exhiit ompenstory growth ws not under the influene of BiW only. Our dt suggest tht piglets orn nd wened light nd orn disproportionl (luster 1), were unle to improve performne under the ommeril onditions of our experiment. Piglets of luster 2 nd 3, on the other hnd, were wened reltively hevier ut differed from one nother with respet to ody shpe t irth, with luster 3 piglets hving greter post-wening growth thn luster 2 piglets tht were orn lighter nd reltively disproportionl. The multivrite nlysis for WW lss 1 piglets, on the other hnd, showed tht post-wening performne ws not under the influene of BiW, ut similrly to BiW lss 1 piglets were positively ssoited with WW, nd severl morphometri hrteristis i.e. PI nd hed shpe t irth (BiW:CC). These morphometri hrteristis [8, 38] my differentite etween pigs tht hve suffered from ertin degree of IUGR s disussed previously. Piglets tht re orn disproportionl (e.g.