Programming the offspring through altered uteroplacentalhemodynamics: how maternal environment impactsuterine and umbilical blood flow in cattle, sheep and pigs

Kimberly A. VonnahmeA,B and Caleb O. LemleyA

ACenter for Nutrition and Pregnancy, Department of Animal Sciences, North Dakota State

University, PO Box 6050, NDSU Department 7630 Fargo, ND 58108-6050, USA.BCorresponding author. Email: kim.vonnahme@ndsu.edu

Abstract. As placental growth and vascularity precedes exponential fetal growth, not only is proper establishment of the

placenta important, but also a continual plasticity of placental function throughout gestation. Inadequate maternalenvironment, such as nutritional plane, has been documented to alter fetal organogenesis and growth, thus leading toimproper postnatal growth and performance in many livestock species. The timing and duration of maternal nutritionalrestriction appears to influence the capillary vascularity, angiogenic profile and vascular function of the placenta in cattle

and sheep. In environments where fetal growth and/or fetal organogenesis are compromised, potential therapeutics mayaugment placental nutrient transport capacity and improve offspring performance. Supplementation of specific nutrients,including protein, as well as hormone supplements, such as indolamines, during times of nutrient restriction may assist

placental function. Current use of Doppler ultrasonography has allowed for repeated measurements of uterine andumbilical blood flow including assessment of uteroplacental hemodynamics in cattle, sheep and swine. Moreover, thesevariables can be monitored in conjugation with placental capacity and fetal growth at specific time points of gestation.

Elucidating the consequences of inadequate maternal intake on the continual plasticity of placental function will allow usto determine the proper timing and duration for intervention.

Additional keywords: developmental programming, placenta, umbilical blood flow, uterine blood flow.

Introduction

The trajectory of prenatal growth is sensitive to direct andindirect effects of maternal environment, particularly during

the early stages of embryonic life (Robinson et al. 1995), thetime when placental growth is exponential. Understanding theimpacts of the maternal environment on placental growth and

development is especially relevant as the majority of mam-malian livestock spend 35–40% of their life within the uterusbeing nourished solely by the placenta. Moreover, pretermdelivery and fetal growth restriction are associated with

greater risk of neonatal mortality and morbidity in livestockand humans. Offspring born at an above-average weight havean increased chance of survival compared with those born at

a below-average weight in all domestic livestock species,including the cow, ewe and sow. Just as growth-restrictedhuman infants are at risk of immediate postnatal complications

and diseases later in life (Barker et al. 1993; Godfrey andBarker 2000), there is increasing evidence that productioncharacteristics in our domestic livestock may also be impacted

by maternal diet (Wu et al. 2006). Some of the complicationsreported in livestock include increased neonatal morbiditiesand mortalities (Hammer et al. 2011), intestinal andrespiratory dysfunctions, slow postnatal growth, increased fat

deposition, differing muscle fibre diameters and reducedmeat quality (reviewed in Wu et al. 2006). The maternal sys-tem can be influenced by many different extrinsic factors,

including nutritional status and level of activity, which ulti-mately can program nutrient partitioning and ultimatelygrowth, development and function of the major fetal organ

systems (Wallace 1948; Wallace et al. 1999; Godfrey andBarker 2000; Wu et al. 2006).

The objective of this review is to highlight some of ourlaboratory’s investigations on how maternal environment can

impact uterine and/or umbilical blood flow in cattle, sheep andswine, and potential timing of intervention, or potential thera-peutics, that may increase uteroplacental blood flow.

Placental vascular development

The placenta plays a major role in the regulation of fetal growth.In swine, the diffuse placenta has chorionic villi distributed overthe entire surface of the chorion. The presence of primary and

secondary rugae increases the relative surface area of attach-ment between the endometrium and the fetal membranes(Dantzer 1984). Within the large white breeds of domestic pigs,placental area of attachment continues to increase as gestation

CSIRO PUBLISHING

Reproduction, Fertility and Development, 2012, 24, 97–104

http://dx.doi.org/10.1071/RD11910

Journal compilation � IETS 2012 www.publish.csiro.au/journals/rfd

advances (Knight et al. 1977; Vonnahme et al. 2001) andvascular development of placenta, as measured by the density of

larger blood vessels (i.e. arterioles), increases,200% frommidto late gestation (Vonnahme et al. 2001). In ruminants, the fetalplacenta attaches to discrete sites on the uterine wall called

caruncles. These caruncles are aglandular sites that appear asknobs along the uterine luminal surface of non-pregnantanimals, and are arranged in two dorsal and two ventral rows

throughout the length of the uterine horns (Ford 1999). Theplacental membranes attach at these sites via chorionic villi inareas termed cotyledons. The caruncular–cotyledonary unit iscalled a placentome and is the primary functional area of

physiological exchanges between mother and fetus. In the ewe,the growth of the cotyledonary mass is exponential during thefirst 70–80 days of pregnancy, thereafter slowingmarkedly until

term (Stegeman 1974). In the cow, the cotyledonary growthprogressively increases throughout gestation (Reynolds et al.

1990; Vonnahme et al. 2007).

Using the same vascularity determination techniques,capillary area density (CAD, a flow-related measure), capillarynumber density (CND, an angiogenesis-related measure), capil-lary surface density (CSD, a nutrient exchange-related

measure), and capillary size were determined in the sheep andcow. In sheep caruncular tissue, CAD, CND, CSD and capillarysize increased 214, 37, 140 and 45% from Day 50 to Day 140 in

normal pregnancy (gestation length of sheep¼,147 days;Reynolds et al. 2005; Borowicz et al. 2007; Fig. 1). In thesheep cotyledon, CAD, CND and CSD increased 437, 1093 and

576%, while capillary size decreased 25% from Day 50 toDay 140 in normal pregnancy. In cows, caruncular CAD andcapillary size decreased by 30 and 68% respectively, whereas

CND and CSD increased 151 and 32% respectively from Day125 to Day 250 of gestation in control animals (gestation lengthin cattle ,280 days; Vonnahme et al. 2007; Fig. 1). Further-more, cotyledonary CAD, CND, CSD and capillary size

increased by 186, 80, 172, and 71% respectively from Day125 to Day 250 of gestation. Thus, the pattern of placentalangiogenesis (particularly in the maternal tissue) appears to

differ between the cow and sheep.Placental nutrient transport efficiency is directly related to

uteroplacental blood flow (Reynolds and Redmer 1995). All of

the respiratory gases, nutrients and wastes that are exchangedbetween the maternal and fetal systems are transported via theuteroplacenta (Reynolds andRedmer 1995, 2001). Thus, it is notsurprising that fetal growth restriction is highly correlated with

reduced uteroplacental growth and development (Reynolds andRedmer 1995, 2001). Establishment of functional fetal anduteroplacental circulations is one of the earliest events during

embryonic and placental development (Patten 1964; Ramsey1982). It has been shown that the large increase in transplacentalexchange, which supports the exponential increase in fetal

growth during the last half of gestation, depends primarily onthe dramatic growth of the uteroplacental vascular beds duringthe first half of pregnancy (Meschia 1983;Reynolds andRedmer

1995). Therefore, an understanding of factors as well as thetiming and duration of those factors that impact uteroplacentalblood flow will directly impact placental function and thus fetalgrowth.

Nutritional impacts on placental function

Reports of changes in placental vascularity in response to rea-limentation of nutrient-restricted ewes and cows are very lim-

ited, and appear to be largely lacking in swine. McMullen andco-workers (2005) have demonstrated that a short duration(i.e. 7 days) of fasting during mid-pregnancy in the ewe

decreased vascular endothelial growth factor (VEGF) mRNAlevels and placental weights on Day 90. While differences inVEGF mRNA were not evaluated at term, placental weights

were similar at lambing in nutrient-restricted and control ewes.In cows nutrient restricted from Day 30 to Day 125 of gestation,there was a decrease in total placentome weight on Day 125versus control cows. This suppression in total placentome

weight was still observable even after realimentation until Day250 (Vonnahme et al. 2007; Zhu et al. 2007). Looking moreclosely at placentome weight in the cow, both the cotyledonary

and caruncular portions were decreased in nutrient-restrictedversus control cows at the end of the nutrient restriction (Day125); however, only the weight of the cotyledonary tissue

remained suppressed at Day 250 (Vonnahme et al. 2007). Incontrast, several sheep models of maternal nutrient restrictionfrom early to mid-pregnancy followed by realimentation

showed significant compensatory growth of the entireplacentome (Foote et al. 1958; Robinson et al. 1995; Heasmanet al. 1998; McMullen et al. 2005). The differences in theimpacts of nutrient restriction and realimentation in the cow and

the sheep models described above may result from inherentspecies differences in placental development between sheep andcattle (see above; Fig. 1), the duration or intensity of the

restriction, or the duration or intensity of the realimentation.While maternal nutrient delivery during pregnancy has been

shown to program the growth and development of the fetus, both

during pregnancy and later into adult life, it appears thatmaternal nutrition also programs the development of theplacenta. In the cow, realimentation after ,90 days of nutrientrestriction is the stimulus not only for altering placental vascu-

larity and development but also placental function (Vonnahmeet al. 2004a, 2004b). The ability to impact the plasticity of theplacenta by dietary or other managerial means has caused our

laboratory to focus on how modulating placental function canimpact fetal and postnatal growth and development.

Uterine and umbilical blood flows

Adequate uteroplacental blood flow is critical for normal fetal

growth and therefore, not surprisingly, experimental conditionsdesigned to investigate fetal growth retardation and placentalinsufficiency, be it overnutrition, nutrient restriction, hyper-

thermia or high altitude, commonly share reduced uterine andumbilical blood flows (for review see Reynolds et al. 2006).Therefore, modifying uterine blood flow and nutrient transfer

capacity in the placenta allows for increased delivery of oxygenand nutrients to the exponentially growing fetus. Fowden et al.

(2006) reviewed key factors affecting placental nutrient transfer

capacity, which were size, nutrient transporter abundance,nutrient synthesis and metabolism, and hormone synthesis andmetabolism. Discovery of novel therapeutic agents that improveplacental function would decrease the incidence of morbidity

98 Reproduction, Fertility and Development K. A. Vonnahme and C. O. Lemley

and mortality as well as suboptimal offspring growth perfor-mance in livestock species.

Therapeutic agents targeting placental blood flow increased

fetal growth in compromised pregnancies due to alteredmaternal nutritional plane (Reynolds et al. 2006). For example,supplementing arginine, the precursor for nitric oxide produc-tion (an important regulator of blood flow), increased birth-

weights in compromised pregnancies (Vosatka et al. 1998).Kwon et al. (2004) nutrient restricted ewes from Day 28 to

Day 135 of gestation and reported lowered amino acids andpolyamines inmaternal and fetal plasma aswell as fetal allantoicand amniotic fluids at both mid and late gestation. There is an

ever-increasing wealth of data that are demonstrating howrealimentation, or other therapeutic agents, may be used torescue at-risk pregnancies. In our laboratory, we have investi-gated the role that realimentation, protein supplementation,

melatonin supplementation, and maternal activity has onuteroplacental blood flow and/or vascular reactivity of the

Caruncular (maternal) tissue

CAD CND CSD Cap size

CAD CND CSD Cap size

Cha

nge

from

mid

to la

te p

regn

ancy

, %

�100

�50

0

50

100

150

200

250

Cotyledonary (fetal) tissue

Cha

nge

from

mid

to la

te p

regn

ancy

, %

�200

0

200

400

600

800

1000

1200

Vascular measurements

Ovine

Bovine

Ovine

Bovine

Fig. 1. Comparison of percentage change in capillary vascularity from mid to late pregnancy in sheep

(Day 50 toDay 140; black bars) and cattle (Day 125 toDay 250;white bars). CAD, capillary area density;

Cap size, capillary size; CND, capillary number density; CSD, capillary surface density. Ovine data are

adapted from Borowicz et al. (2007) and bovine data are adapted from Vonnahme et al. (2007). Used

with permission from the Journal of Animal Science.

Maternal environment and uteroplacental blood flow Reproduction, Fertility and Development 99

placental arteries. In order to perform the former, we haveemployed the use of Doppler ultrasonography. Other methods

of determining blood flow are very invasive and requireincreased numbers of animals to determine blood flow atdifferent time points during pregnancy. While these are effective,

they are also labour intensive and time consuming, resulting indecreased number of animals monitored throughout a study. Bycontinuously monitoring the same animal, which has not under-

gone surgical manipulation, we feel that we can effectivelydetermine how different interventions may regulate uteroplacen-tal blood flow. Our current animal models are outlined below.

Nutrient restriction

In normal pregnancies, resistance of the uteroplacental arterieshas been documented to decrease as gestation advances. Our

laboratory has reported that when pregnant ewes are nutrientrestricted from mid to late gestation, their lamb’s birthweight isreduced compared with control-fed ewes (Swanson et al. 2008;

Meyer et al. 2010). Moreover, we have demonstrated thatnutrient-restricted pregnant ewes showed a ,33% decrease inendothelial nitric oxide synthase mRNA expression on Day 130of gestation in the maternal portion of the placenta compared

with control-fed animals (Lekatz et al. 2010a).We hypothesisedthat this reduction in birthweight was due to a greater placentalvascular resistance in nutrient-restricted ewes compared with

control ewes. In order to evaluate the effects of maternal nutri-tion on the percentage change in pulsatility and resistanceindices (PI and RI, respectively) pregnant ewes receiving either

100%of nutrient requirements or 60%of the controls were fed toindividually housed ewes once daily from Day 40 to Day 108 ofgestation. Umbilical cord hemodynamics were assessed by

using a duplex B-mode (brightnessmode) andD-mode (Dopplerspectrum) program of the colour Doppler ultrasound instrument(Aloka SSD-3500; Aloka America, Wallingford, CT, USA)fitted with a 5.0MHz finger transducer (Aloka UST-672).

Ultrasonography was performed on Days 40, 45, 52, 80, 94 and108 of gestation. In B-mode a longitudinal section of theumbilical cord was visualised and the pulsatile umbilical artery

was confirmed by switching to a duplex screen containingB-mode imaging and Doppler spectrum waveform plots.Measurements were obtained by placing the sample cursor over

the vessel in B-mode while simultaneously recording pulsatilewaves in D-mode. PI and RI were calculated using presetfunctions on the ultrasound instrument.Maternal diet altered thepercentage change of both PI and RI with restricted ewes having

increased (P¼ 0.01) PI and RI compared with control ewes(Fig. 2). We are continuing to evaluate how maternal restrictionmay impact vascular function and nutrient delivery in pregnant

ewes. Moreover, we are developing methodologies to reversethe negative effects of nutrient restriction (see below).

In cattle, nutrient restriction, followed by realimentation,

resulted in alterations in placental vascularity and function(Vonnahme et al. 2004a, 2004b, 2007). Our hypothesis wasthat, upon realimentation, the vascular resistance of the uterine

artery would overcompensate for the previously nutrient-restricted dam. In order to test this hypothesis, pregnant cows(n¼ 18) were randomly assigned to receive no restriction(control), or either a short (55 days) or long (110 days) period

of nutrient restriction (60% intake of control). Nutrient restric-tion began on Day 30 of gestation. Uterine artery RI wasmeasured every 14 days from Day 30 of gestation and continu-

ing until Day 254 of gestation. While there was no treatment byday interaction in RI, there was a main effect of treatment(Fig. 3). Cows restricted for the longer duration had an overalldecrease in RI compared with the short-restricted and control

cows, which did not differ (Fig. 3; Camacho et al. 2011).Interestingly, the RI decreased upon realimentation in thosecows that experienced the longer duration of restriction. The

ability of the uteroplacenta to compensate upon realimentationis quite intriguing and we are continuing our studies to deter-mine which portions of the placenta (i.e. maternal or fetal) may

contribute to compensatory prenatal growth of the fetus.

Protein supplementation

While the literature is now booming with increasing evidence of

how nutrient restriction impairs several physiological para-meters, few concentrate on enhancing postnatal growth inlivestock species. In a recent series of papers in cattle, cowsgestated on range (where crude protein of forage is ,6%) that

were protein supplemented during late gestation had calvessimilar in birthweight, but had calves with increased weaningweight compared with protein unsupplemented cows (Stalker

et al. 2006; Martin et al. 2007; Larson et al. 2009). It is valuableto note that the protein supplementation enhanced growth afterbirth. Furthermore, the pregnancy rates in heifer calves born

from protein-supplemented cowswere enhanced compared withcontrol cows (93 v. 80%; Martin et al. 2007). It was ourhypothesis that the increased fertility and growth rate of thecalves from supplemented damsmay be due to enhanced uterine

blood flow and/or placental nutrient transfer. Ongoing studies inour laboratory are investigating how protein supplementation

Resistance indexPulsility index

Per

cent

age

chan

ge

�20

�10

0

10

20

30

a

b

a

b

60%

100%

Fig. 2. Change in the pulsatility index (PI) and resistance index (RI) in the

umbilical cord from Day 40 to Day 108 of gestation in restricted (60% of

nutrient requirements) and control (100% of nutrient requirments) ewes.

PI (PI¼ (peak systolic velocity (cm s�1) – end diastolic velocity (cm s�1))/

mean velocity (cm s�1)), and RI (RI¼ peak systolic velocity (cm s�1) – end

diastolic velocity (cm s�1)/peak systolic velocity (cm s�1)) were calculated

using preset functions on the ultrasound instrument. abMeans� s.e.m. within

a measure differ, P, 0.03.

100 Reproduction, Fertility and Development K. A. Vonnahme and C. O. Lemley

during late gestation can impact uterine blood flow. In our study,cows were individually fed a 6% crude protein hay with orwithout (control) a protein supplement beginning on Day 190 of

gestation. Within 30 days after receiving the protein supple-ment, uterine blood flow was increased ,2-fold in protein-supplemented versus control cows (K.A.Vonnahme,C. Zimprich,

L. E. Camacho, M. L. Bauer, unpubl. data; Vonnahme et al.

2011). The increase in uterine blood flow would be expected toincrease nutrient transfer to the fetus, and while birthweightsmay not be altered (as reported by Stalker et al. 2006; Martin

et al. 2007; Larson et al. 2009), growth trajectory of the mus-culoskeletal and reproductive systems of the offspring may beenhanced.

In order to more fully understand the impacts of maternalprotein on uteroplacental blood flow and placental vasculardevelopment, we are currently utilising an ovine model where

the diets are isocaloric, with differing levels of protein in thediet. Singleton fetuses from ewes consuming the high-proteindiet are heavier on Day 130 of gestation compared with fetuses

from ewes consuming the low-protein diet, with no differencesin placental weight apparent (Camacho et al. 2010). Whenuterine blood flow was obtained from a single time point(Day 130 of gestation), ewes consuming the high-protein diet

had a decrease in uterine blood flow compared with the lowgroup, with the control being intermediate (Camacho et al.

2010). Moreover, when investigating the ability of the fetal

placental arteries to vasodilate to increasing concentrationsof bradykinin, placental arteries from high-protein eweshad a decreased responsiveness compared with control and

low-protein ewes (Lekatz et al. 2010b). Understanding ifadditional calories (i.e. cow study), or a greater proportion oftotal calories coming from protein (i.e. sheep study), needs to be

elucidated, and further work is underway in our laboratory.

Melatonin

Therapeutic supplements thought to target placental blood flowand nutrient delivery to the fetus have been shown to increasefetal growth in animal models of intrauterine growth restriction(Vosatka et al. 1998; Richter et al. 2009; Satterfield et al. 2010);

however, few studies have addressed uteroplacental hemo-dynamics in models of improved fetal growth. For instance,melatonin supplementation was shown to negate the decreased

birthweight in nutrient-restricted rats (Richter et al. 2009),which was attributed to increased placental antioxidant enzymeexpression in nutrient-restricted rats supplemented with

melatonin. Our hypothesis was that dietary melatonin treatmentduring a compromised pregnancy would improve fetal growthand placental nutrient transfer capacity by increasing uterine and

umbilical blood flow. The uteroplacental hemodynamics andfetal growth were determined in ewes that received a dietarysupplementationwith or withoutmelatonin (5mg) in adequatelyfed (100% of nutrient requirements) or nutrient-restricted

(60% of nutrient requirements) ewes. Dietary treatments wereinitiated on Day 50 of gestation, and umbilical blood flow as wellas fetal growth (measured by abdominal and biparietal distances)

were determined every 10 days from Day 50 to Day 110 ofgestation. By Day 110 of gestation, fetuses from restricted eweshad a 9% reduction (P¼ 0.01) in abdominal diameter compared

Res

ista

nce

inde

x

Trt, P � 0.001Day, P � 0.001Trt*day, P � 0.46

0.85

0.80

CCC

RCC

RRC

0.70

0.75

0 8 a a

0.65 SEM

0.0

0.2

0.4

0.6

b

Day of gestation

30 44 58 72 85 100

114

128

140

156

170

184

198

212

226

240

254

0.60

Fig. 3. Resistance index (RI) of cows fed 100%of nutrient requirments throughout gestation (CCC;

blue), fed 60% of controls from Day 30 to Day 85, then realimented to control levels (RCC; red), or

fed 60% of controls from Day 30 to Day 140 of gestation, then realimented to control levels (RRC,

green). RI (RI¼ peak systolic velocity (cm s�1) – end diastolic velocity (cm s�1)/peak systolic

velocity (cm s�1)) was calculated using preset functions on the ultrasound instrument. abMeans� s.e.

m differ, P, 0.001.

Maternal environment and uteroplacental blood flow Reproduction, Fertility and Development 101

with fetuses from adequately nourished ewes, whereas fetusesfrom melatonin-supplemented ewes tended to have (P¼ 0.08) a

9% increase in biparietal diameter (Lemley et al. 2011).Umbilical artery blood flow across all treatment groups from

Day 48 to Day 110 of gestation are illustrated in Fig. 4. Means

were not separated due to the lack of a melatonin treatment bynutritional plane by gestational day interaction (P¼ 0.15;Fig. 4a). However, we did observe a significant melatonin

treatment by day interaction (P, 0.001) for umbilical arteryblood flow (Fig. 4b), which was increased in melatonin-supplemented ewes from Day 60 through Day 110 of gestationcompared with control (no melatonin supplementation). More-

over, at Day 110 of gestation melatonin-supplemented ewes hada 20% increase in umbilical artery blood flow compared withcontrol ewes. In addition, a significant nutritional plane by day

interaction (P, 0.0001) was observed for umbilical arteryblood flow (Fig. 4c), which was decreased in restricted ewesfrom Day 80 through Day 110 of gestation compared with

adequately fed ewes. Moreover, at Day 110 of gestationrestricted ewes had a 23% decrease in umbilical artery bloodflow compared with adequately fed ewes (Lemley et al. 2011).While we are continuing our investigations into the impacts of

melatonin supplementation in at-risk pregnancies, we feel thatmelatonin treatmentmay be useful in negating the consequencesof intrauterine growth restriction that occur due to specific

abnormalities in umbilical blood flow.

Maternal activity

In the swine industry within the USA, the individual stall iscommonly used during gestation; however, producers may berequired to modify this widely used housing practice to increase

animal mobility. Lammers et al. (2007) hypothesised that theincrease in litter size and decrease in stillborn fetuses from sowshoused in groups during gestation occurred due to the females’ability to move about during gestation. Exercise during gesta-

tion has been studied in several animal species including the rat(Garris et al. 1985; Houghton et al. 2000) and sheep (Lotgeringet al. 1983a, 1983b; Chandler et al. 1985), with the duration and

intensity of exercise impacting both umbilical and uterine bloodflows (Lotgering et al. 1983a; see review by McMurray et al.

1993) as well as birthweight (Garris et al. 1985). Our laboratory

hypothesised that umbilical blood flow to the fetus wouldincrease in gilts that were given the ability to increase theiractivity during gestation. Pregnant gilts were individuallyhoused, and beginning on Day 40 of gestation (gestation

length¼ 114 days), a subset of gilts were selected to increasetheir activity levels. Whereas control gilts remained in theirgestation stall for the duration of pregnancy, gilts selected for

exercise were individually walked for 30min, three times aweek, at the pace of each individual. All animals received thesame diet and were housed in the same room. Beginning on

Day 39, and approximately every 14 days until Day 94 ofgestation, umbilical blood flow was determined from twoindependent fetuses per litter by Doppler ultrasonography and

when gilts were in a recumbent position. Gilts that had increasedactivity levels exhibited an increase in umbilical blood flowcompared with their control counterparts (Fig. 5; Harris et al.2010). Gestation length, obstetrical interventions, length of

Gestation (day)

40 50 60 70 80 90 100 110

Gestation (day)

40 50 60 70 80 90 100 110

Gestation (day)

40 50 60 70 80 90 100 110

Um

bilic

al B

F (

mL

min

�1 )

0

100

200

300

400

500

CON-RES (n � 8)

CON-ADQ (n � 7)

MEL-RES (n � 8)

MEL-ADQ (n � 8)

Um

bilic

al B

F (

mL

min

�1 )

0

100

200

300

400

500

CON (n � 15)

MEL (n � 16)

*

*

*

*

*

*

Um

bilic

al B

F (

mL

min

�1 )

0

100

200

300

400

500

(a)

(b)

(c)

ADQ (n � 15)

RES (n � 16)

*

*

*

*

Fig. 4. Umbilical artery blood flow (BF) throughout gestation. BF was

evaluated at least 1 h post-feeding and before lights off (5 h post-feeding).

Baseline measurements were taken on Day 48 of gestation and treatments

commenced on Day 50 of gestation. Ewes were supplemented daily with

(MEL) or without (CON) melatonin and fed at 100% (adequate; ADQ) or

60% (restricted; RES) of nutrient requirements. (a) Individual groups. The

three-way interaction ofmelatonin treatment by nutritional plane by daywas

not significant (P¼ 0.15). Significant interactions were observed for

(b) melatonin treatment by day (P, 0.001) and (c) nutritional plane by

day (P, 0.0001). Asterisks represent differences (P, 0.05) amongstmeans

within the same time point. Values are expressed as means� s.e.m.

102 Reproduction, Fertility and Development K. A. Vonnahme and C. O. Lemley

parturition, average birthweight, and placental weight did notdiffer (P. 0.15). Upon harvest at 6 months of age, it was

determined that while hot carcass weight was not differentbetween groups, pigs from the exercised gilts had increasedcarcass quality as measured by muscle colour (Minolta L*),muscle pH at 45min, and water content of the muscle

(Vonnahme et al. 2011). Studies are currently underwayinvestigating muscle fibre development within these offspring.

Summary and conclusions

We hope to improve approaches to management of livestockduring pregnancy, which may impact not only that dam’s

reproductive success, but her offspring’s growth potential andperformance later in life. Future applications of this researchmay be used to develop therapeutics for at-risk pregnancies inour domestic livestock. If these therapeutics can be used

on-farm, producers would have the ability to increase animalhealth while also reducing costs of animal production. Whileeach species is unique in its placental development and vascu-

larity, comparative studies may ultimately assist researchers inunderstanding how the maternal environmental impactsplacental, and thus fetal, development.

Acknowledgements

The authors would like to thank individuals in the North Dakota State

University Physiology, Nutrition, and Muscle Biology groups for their

assistance with experimental design and collection of data. Specifically, the

authors would like to recognise Eric P. Berg, Joel S. Caton, Dale A. Redmer

and Lawrence P. Reynolds, and Erin Harris, Leslie Lekatz and Leticia

Camacho. These projects were supported in part by funding from the NDSU

Agricultural Experiment Station, United States Department of Agriculture-

National Institute of Food and Agriculture, Lalor Foundation, and North

Dakota State Board of Agriculture Research and Education.

References

Barker, D. J. P., Hales, C. N., Fall, C. H. D., Osmond, C., Phipps, K., and

Clark, P. M. S. (1993). Type 2 (non-insulin-dependent) diabetes

mellitus, hypertension and hyperlipidaemia (syndrome X): relation to

reduced fetal growth. Diabetologia 36, 62–67.

Borowicz, P. P., Arnold, D. R., Johnson, M. L., Grazul-Bilska, A. T.,

Redmer, D. A., and Reynolds, L. P. (2007). Placental growth throughout

the last two-thirds of pregnancy in sheep: vascular development and

angiogenic factor expression. Biol. Reprod. 76, 259–267. doi:10.1095/

BIOLREPROD.106.054684

Camacho, L. E., Lekatz, L. A., VanEnom, M. L., Schauer, C. S., Maddock

Carlin, K. R., and Vonnahme, K. A. (2010). Effects of maternal metabo-

lizable protein supplementation in late gestation on uterine and umbilical

blood flows in sheep. J. Anim. Sci. 88(E-Suppl 2), 106. [Abstract]

Camacho, L. E., Lemley, C. O., Neville, B. W., Dahlen, C. R., Lardy, G. P.,

and Vonnahme, K. A. (2011). Effects of realimentation after nutrient

restriction during early to mid-gestation on uterine blood flow in

pregnant beef cows. J. Anim. Sci. 89(E-Suppl), 339.

Chandler, K. D., Leury, B. J., Bird, A. R., and Bell, A. W. (1985). Effects of

undernutrition and exercise during late pregnancy on uterine, fetal, and

uteroplacental metabolism in the ewe. Br. J. Nutr. 53, 625–635.

doi:10.1079/BJN19850072

Dantzer, V. (1984). Scanning electronmicroscopy of exposed surfaces of the

porcine placenta. Acta Anat. (Basel) 118, 96–106. doi:10.1159/

000145827

Foote, W. C., Pope, A. L., Earl, C. R., Chapman, A. B., and Casida, L. E.

(1958). Reproduction in the yearling ewe as affected by breed and

sequence of feeding levels: II. Effects on fetal development. J. Anim. Sci.

18, 463–474.

Ford, S. P. (1999). Cotyledonary placenta. In ‘Encyclopedia of Reproduc-

tion’. (Eds E. Knobil, J. Neill.) pp. 730–738. (Academic Press: Salt Lake

City, UT.)

Fowden, A. L., Ward, J. W., Wooding, F. P. B., Forhead, A. J., and

Constancia, M. (2006). Programming placental nutrient transport

capacity. J. Physiol. 572, 5–15.

Garris, D. R., Kasperek, G. J., Overton, S. V., and Alligood, G. R., Jr (1985).

Effects of exercise on fetal-placental growth and uteroplacental blood

flow in the rat. Biol. Neonate 47, 223–229. doi:10.1159/000242120

Godfrey, K. M., and Barker, D. J. (2000). Fetal nutrition and adult disease.

Am. J. Clin. Nutr. 71, 1344S–1352S.

Hammer, C. J., Thorson, J. F., Meyer, A. M., Redmer, D. A., Luther, J. S.,

Neville, T. L., Reed, J. J., Reynolds, L. P., Caton, J. S., and Vonnahme,

K. A. (2011). Effects of maternal selenium supply and plane of nutrition

during gestation on passive transfer of immunity and health in neonatal

lambs. J. Anim. Sci. doi:10.2527/JAS.2010-3724

Harris, E. K., Bartling, B. J., Neville, T. L., Kirsch, J. D., Magolski, J. D.,

Berg, E. P., andVonnahme, K. A. (2010). Impact ofmaternal exercise on

maternal body composition, fetal growth, and umbilical blood flow in

the pig. J. Anim. Sci. 88(E-Suppl. 3), 27.

Heasman, L., Clarke, L., Firth, K., Stephenson, T., and Symonds, M. E.

(1998). Influence of restricted maternal nutrition in early to mid gesta-

tion on placental and fetal development at term in sheep. Pediatr. Res.

44, 546–551. doi:10.1203/00006450-199810000-00013

Houghton, P. E., Mottola, M. F., Plust, J. H., and Schachter, C. L. (2000).

Effect of maternal exercise on fetal and placental glycogen storage in the

mature rat. Can. J. Appl. Physiol. 25, 443–452. doi:10.1139/H00-029

Knight, J.W.,Bazer, F.W., Thatcher,W.W.,Franke,D.E., andWallace,H.D.

(1977).Conceptus development in intact and unilaterallyhysterectomized-

ovariectomized gilts: interrelations among hormonal status, placental

development, fetal fluids and fetal growth. J. Anim. Sci. 44, 620–637.

Kwon, H., Ford, S. P., Bazer, F. W., Spencer, T. E., Nathanielsz, P. W.,

Nijland, M. J., Hess, B. W., and Wu, G. (2004). Maternal nutrient

restriction reduces concentrations of amino acids and polyamines in

ovine maternal and fetal plasma and fetal fluids. Biol. Reprod. 71,

901–908. doi:10.1095/BIOLREPROD.104.029645

Lammers, P. J., Honeyman,M. S., Mabry, J. W., and Harmon, D.M. (2007).

Performance of gestating sows in bedded hooped barns and confinement

stalls. J. Anim. Sci. 85, 1311–1317. doi:10.2527/JAS.2006-437

0

200

400

600

800

1000

1200

1400

1600

39 55 66 80 94

Um

b bl

ood

flow

, per

cent

age

chan

ge fr

om d

39

Day of gestation

CON EX

Fig. 5. The percentage change in umbilical blood flow from Day 39

(baseline) through Day 94 of gestation from fetal piglets of gilts housed in

individual stalls during gestation (CON) or exercised from Day 40 to

Day 104 of gestation (EX) (P, 0.01).

Maternal environment and uteroplacental blood flow Reproduction, Fertility and Development 103

Larson, D. M., Martin, J. L., Adams, D. C., and Funston, R. N. (2009).

Winter grazing system and supplementation during late gestation influ-

ence performance of beef cows and steer progeny. J. Anim. Sci. 87,

1147–1155. doi:10.2527/JAS.2008-1323

Lekatz, L. A., Caton, J. S., Taylor, J. B., Reynolds, L. P., Redmer, D. A., and

Vonnahme, K. A. (2010a). Maternal selenium supplementation and

timing of nutrient restriction in pregnant sheep: Impacts on maternal

endocrine status and placental characteristics. J. Anim. Sci. 88, 955–971.

doi:10.2527/JAS.2009-2152

Lekatz, L.A.,VanEmon,M.L., Shukla, P.K.,O’Rourke, S.T., Schauer, C. S.,

Carlin, K. M., and Vonnahme, K. A. (2010b). Influence of metabolizable

protein supplementation during late gestation on vasoreactivity of mater-

nal and fetal placental arteries in sheep. J. Anim. Sci. 88(E-Suppl. 2),

869–870.

Lemley, C. O.,Meyer, A.M., Camacho, L. E., Neville, T. L., Newman, D. J.,

Caton, J. S., and Vonnahme, K. A. (2011). Melatonin supplementation

alters uteroplacental hemodynamics and fetal development in an ovine

model of intrauterine growth restriction (IUGR). Am. J. Physiol., in press.

Lotgering, F. K., Gilbert, R. D., and Longo, L. D. (1983a). Exercise

responses in pregnant sheep: oxygen consumption, uterine blood flow,

and blood volume. J. Appl. Physiol. 55, 834–841.

Lotgering, F. K., Gilbert, R. D., and Longo, L. D. (1983b). Exercise

responses in pregnant sheep: blood gases, temperatures, and fetal

cardiovascular system. J. Appl. Physiol. 55, 842–850.

Martin, J. L., Vonnahme, K. A., Adams, D. C., Lardy, G. P., and Funston,

R. N. (2007). Effects of dam nutrition on growth and reproductive

performance of heifer calves. J. Anim. Sci. 85, 841–847. doi:10.2527/

JAS.2006-337

McMullen, S., Osgerby, J. C., Milne, J. S.,Wallace, J. M., andWathes, D. C.

(2005). The effects of acute nutrient restriction in the mid-gestational

ewe on maternal and fetal nutrient status, the expression of placental

growth factors and fetal growth. Placenta 26, 25–33. doi:10.1016/

J.PLACENTA.2004.04.010

McMurray, R. G., Mottola, M. F., Wolfe, L. A., Artal, R., Millar, L., and

Pivarnik, J. M. (1993). Recent advances in understanding maternal and

fetal responses to exercise. Med. Sci. Sports Exerc. 25, 1305–1321.

doi:10.1249/00005768-199312000-00001

Meschia, G. (1983). Circulation to female reproductive organs. In ‘Hand-

book of Physiology’. (Eds J. T. Shephard, F. M. Abboud.) pp. 241–269.

(American Physiological Society: Bethesda.)

Meyer, A. M., Reed, J. J., Neville, T. L., Taylor, J. B., Hammer, C. J.,

Reynolds, L. P., Redmer, D. A., Vonnahme,K. A., and Caton, J. S. (2010).

Effects of nutritional plane and selenium supply during gestation on ewe

and neonatal offspring performance, body composition, and serum

selenium. J. Anim. Sci. 88, 1786–1800. doi:10.2527/JAS.2009-2435

Patten, B. M. (1964). ‘Foundations of Embryology.’ 2nd edn. (McGraw-

Hill: New York.)

Ramsey, E. M. (1982). ‘The Placenta, Human and Animal.’ (Praeger:

New York.)

Reynolds, L. P., and Redmer, D. A. (1995). Utero-placental vascular

development and placental function. J. Anim. Sci. 73, 1839–1851.

Reynolds, L. P., and Redmer, D. A. (2001). Angiogenesis in the placenta.

Biol. Reprod. 64, 1033–1040. doi:10.1095/BIOLREPROD64.4.1033

Reynolds, L. P., Ferrell, C. L., Robertson, D. A., and Klindt, J. (1990). Growth

hormone, insulin and glucose concentrations in bovine fetal and maternal

plasmas at several stages of gestation. J. Anim. Sci. 68, 725–733.

Reynolds, L. P., Borowicz, P., Vonnahme, K. A., Johnson, M. L., Grazul-

Bilska, A. T., Wallace, J. M., Caton, J. S., and Redmer, D. A. (2005).

Animal models of placental angiogenesis. Placenta 26, 689–708.

doi:10.1016/J.PLACENTA.2004.11.010

Reynolds, L. P., Caton, J. S., Redmer, D. A., Grazul-Bilska, A. T., Vonnahme,

K. A., Borowicz, P. P., Luther, J. S., Wallace, J. M., Wu, G., and

Spencer, T. E. (2006). Evidence for altered placental blood flow and

vascularity in compromised pregnancies. J. Physiol. 572, 51–58.

Richter, H.G., Hansell, J. A., Raut, S., andGiussani, D.A. (2009).Melatonin

improves placental efficiency and birth weight and increases the placen-

tal expression of antioxidant enzymes in undernourished pregnancy.

J. Pineal Res. 46, 357–364. doi:10.1111/J.1600-079X.2009.00671.X

Robinson, J., Chidzanja, S., Kind, K., Lok, F., Owens, P., and Owen, J.

(1995). Placental control of fetal growth. Reprod. Fertil. Dev. 7,

333–344. doi:10.1071/RD9950333

Satterfield,M.C., Bazer, F.W., Spencer, T. E., andWu,G. (2010). Sildenafil

citrate treatment enhances amino acid availability in the conceptus and

fetal growth in an ovinemodel of intrauterine growth restriction. J. Nutr.

140, 251–258. doi:10.3945/JN.109.114678

Stalker, L. A., Adams, D. C., Klopfenstein, T. J., Feuz, D. M., and Funston,

R. N. (2006). Effects of pre- and postpartum nutrition on reproduction in

spring calving cows and calf feedlot performance. J. Anim. Sci. 84,

2582–2589. doi:10.2527/JAS.2005-640

Stegeman, J. H. J. (1974). Placental development in the sheep and its relation

to fetal development. Bijdragen tot de dierkunde 44, 3–72.

Swanson, T. J., Hammer, C. J., Luther, J. S., Carlson, D. B., Taylor, J. B.,

Redmer, D. A., Neville, T. L., Reed, J. J., Reynolds, L. P., Caton, J. S.,

and Vonnahme, K. A. (2008). Effects of plane of Nutrition and selenium

supplementation on colostrum quality and mammary development in

pregnant ewe lambs. J. Anim. Sci. 86, 2415–2423. doi:10.2527/JAS.

2008-0996

Vonnahme, K. A., Wilson, M. E., and Ford, S. P. (2001). Relationship

between placental vascular endothelial growth factor expression and

placental/endometrial vascularity in the pig. Biol. Reprod. 64, 1821–

1825. doi:10.1095/BIOLREPROD64.6.1821

Vonnahme, K. A., Ford, S. P., Nijland, M. J., and Reynolds, L. P. (2004a).

Alteration in cotyledonary (COT) vascular responsiveness to angioten-

sin II (ANG II) in beef cows undernourished during early pregnancy.

Biol. Reprod. 70(Suppl. 1), 110. [Abstract]

Vonnahme, K. A., Reynolds, L. P., Nijland, M. J., and Ford, S. P. (2004b).

Impacts of undernutrition during early tomid gestation on basal vascular

tone of the cotyledonary and caruncular arterial beds in the bovine

placentome. J. Soc. Gynecol. Investig. 11(Suppl.), 222A.

Vonnahme, K. A., Zhu, M. J., Borowicz, P. P., Geary, T. W., Hess, B. W.,

Reynolds, L. P., Caton, J. S., Means,W. J., and Ford, S. P. (2007). Effect

of early gestational undernutrition on angiogenic factor expression and

vascularity in the bovine placentome. J. Anim. Sci. 85, 2464–2472.

doi:10.2527/JAS.2006-805

Vonnahme, K. A., Lemley, C. O., Camacho, L. E., Lekatz, L. A., Redmer,

D. A., Reynolds, L. P., and Caton, J. S. (2011). Placental programming:

how the maternal environment can impact placental growth and func-

tion. J. Anim. Sci. 89(E-Suppl. 1), 443. [Abstract]

Vosatka, R. J., Hassoun, P. M., and Harvey-Wilkes, K. B. (1998). Dietary

L-arginine prevents fetal growth restriction in rats. Am. J. Obstet.

Gynecol. 178, 242–246. doi:10.1016/S0002-9378(98)80007-0

Wallace, L. R. (1948). The growth of lambs before and after birth in relation

to the level of nutrition. J. Agric. Sci., Cambridge. 38, 243–302.

doi:10.1017/S0021859600006079

Wallace, J. M., Bourke, D. A., and Aitken, R. P. (1999). Nutrition and fetal

growth: paradoxical effects in the overnourished adolescent sheep.

J. Reprod. Fertil. Suppl. 54, 385–399.

Wu, G., Bazer, F.W.,Wallace, J. M., and Spencer, T. E. (2006). Board invited

review. Intrauterine growth retardation: implications for the animal

sciences. J. Anim. Sci. 84, 2316–2337. doi:10.2527/JAS.2006-156

Zhu, M. J., Du, M., Hess, B. W., Means, W. J., Nathanielsz, P.W., and Ford,

S. P. (2007). Maternal nutrient restriction upregulates growth signaling

pathway in the cotyledonary artery of cow placentomes. Placenta 28,

361–368. doi:10.1016/J.PLACENTA.2006.04.005

www.publish.csiro.au/journals/rfd

104 Reproduction, Fertility and Development K. A. Vonnahme and C. O. Lemley