in body weight. (-31 kg) occurred in gilts subjected to inanition, fetal survival ..... determined by a previously described method. (DeRoth and. Downie,. 1978). A.
BIOLOGY
OF
REPRODUCTION
27,
79-90(1982)
Interaction Uterine
of Maternal Blood Volume and Flow with Porcine Fetal Development1
Blood D.
L. HARD
L. L. ANDERSON2
and
Department Iowa
of Animal State
Ames,
Science
University
Iowa
50011
ABSTRACT The relationships of maternal nutrition, blood volume and uterine blood flow to porcine fetal development were investigated in domesticated pigs that normally experience 40% fetal loss. Yorkshire pigs were subjected to prolonged inanition (40 days; 0 kcal/day; water only) from Days 50 to 90 of pregnancy and either hysterectomized on Day 90 or realimented to a full diet and allowed to advance to parturition; controls received a full diet (7028 kcal/day) until hysterectomy at Day 90 or throughout gestation. Although a marked decline in body weight (-31 kg) occurred in gilts subjected to inanition, fetal survival rates, litter weight, as well as the number of live Day 90 fetuses or number of live piglets born were similar in starved and full-fed animals. Blood hemoglobin, packed cell volume, plasma protein, erythrocyte and leukocyte populations during inanition were maintained at levels similar to those of controls with the exception of shifts in concentration caused by plasma volume changes. Plasma volume (r=0.65) and blood volume (r’0.58) were highly correlated with body weight in inanition and control dams throughout the period of inanition and realimentation. Uterine blood flow during late pregnancy was similar in all experimental and control dams, and remained constant with time in spite of a 13-fold increase in fetal weight and regardless of marked fluctuations in plasma and blood volumes. Uterine blood flow was highly correlated with Day 90 litter size (r=0.82) and fetal weight (r=0.86). Severe nutrient deprivation during late pregnancy in the pig results in a marked decline in maternal body weight, plasma volume and blood volume; however, maternal uterine blood flow is maintained at a level similar to full-fed controls. Maintenance of uterine blood flow suggests that selective distribution of cardiac output, coincident with adequate blood constituent levels, may allow normal porcine fetal development during prolonged starvation.
INTRODUCTION
Gestation represents in maternal parturition by
the
in mammalian an anabolic process body is greater
weight
conceptuses Thomson, in maternal
of
weight from mating than can be accounted the
uterus
(Newton, 1968; Anderson, dietary
species normally since the increase
intake
and 1952;
conceptus Hytten
1975).
can
alter
to for
as affect and
healthy
pigs,
realized
or
process,
that
function
potential
varying
dietary
energy
during
pregnancy;
has can
and
fetal
al.,
yet
been
In
is not
fully
mortality
1966;
April
et
1973; Pond, slight increases
2444.
the
of
pig
Wrathall,
that provides
fetoplacental system. 79
and
protein
intake
little
positive
Although
high-energy
rates, increase
1971;
embryonic (O’Bannon
Frobish
1973). Caloric restriction in litter size but reduces
and Melampy, 1972). Recent investigations
established
size
ovulation rates also
birth weights (Anderson Changes in protein level on reproductive performance son
and
litter
relatively
obtained.
improve
September
1, 1982. 28, 1981. ‘This work fulfilled partial requirements for the Ph.D. degree by D. L. Hard. It was presented in part at the 73rd Annual Meeting of the American Society of Animal Science (1981), Raleigh, NC (Abstract 493). This study was supported in part by ARS CSRS Grant 701-15-43 from USDA. Journal paper J-10403 of the Iowa Agriculture and Home Economics Experiment Station, Ames; Projects 2228, 2443, and
embryonic
and
conceptuses.
fetal losses by about 40%. Investigators have attempted to improve the efficiency of reproduction in this species by
and
Dept. University,
reproductive reduce
diets
2Reprint requests: Dr. L. L. Anderson, Animal Science, 11 Kildee Hall, Iowa State Ames, IA 50011.
ovarian of the
gestation
effect
Accepted Received
maternal
development
in
during
Variations
this
as well growth
inanition a useful demands
Prolonged
inanition
and also
et
al., in
results
neonatal
Melampy, 1972). have little effect in the pig (Ander-
in our during model
laboratory for
upon
in
elucidating
the
of
have
pregnancy
Yorkshire
maternal
gilts
80
HARD
during
the
nancy
has
early,
middle
little
or
effect
neonatal
survival
Anderson
et
on
al.,
40
during
early,
middle
on
ovarian
(Anderson
et
al.,
opment
fetuses
early dams
starved
exhibit normal
of
is retarded,
fetoplacental
these
growth
of severe
body
The
weight
roles
gifts
of
development of the
for
and
1980), uterine
and blood
cows flow
interactions
I
blood
1980), decreased
total
and
uterine
flow,
and
fetuses.
The
primary
was
90 after maternal uterine
to
mating
ewes
results
volume
and
growth
and retardation
in
uterine
body blood
weight, flow
the blood with
interactions volume porcine
of and fetal
development.
FULL-FED THROUGHOUT
Experimental
AND
70
I
90
AFTER
110
190
150
MATW.53
CONTROLS PREGNANCY
2’ 0
a INANITION U
( I-
50
TO
2.71..
90
DAYS MATING
AFTER
F-D.i8i:a
z MMIn9
- -.-
i
I -4yt.r.ctOny
0
0
= = 10
90
DAYS
P.O I
=
AL FIG. 1. Experiments day of mating
=
50 AFTER
70
90
MATIN(3
gr.do.I f,,II
ifl,,Itlon
d
Description of experimental groups in I, II and Ill indicating dietary intake, and day of hysterectomy or parturition.
observed estrus; first day of estrus 0. Management and housing were and have been described previously son. 1979).
Experimental MATERIALS
I
50 DAYS
W.anlng
of
objective of the present investiutilize inanition from Days 50 to to determine
MATING
91
SR
et al.,
(Morriss
restriction
plasma
blood
placentae
and
dietary
maternal
arterial
gation
1980)
I
EXPERIMENT
with porcine fetal development have not defined. In rats (Rosso and Streeter, 1979; Kava,
AFTER
PrturItion
in spite
and allow rates The
and
90
dam.
increases markedly during pregnancy, blood volume expansion may simply for this increase while maintaining normal of flow to the bodies’ various organs.
Rosso
TO
Anderson,
expansion
volume
50
3R
10
ewes and
blood
DAYS
M.tIn9
to
1976), (Ferrell
of
INANITION
estrus, repro-
mobilized
loss
volume
9
blood flow in the development and of the mammalian fetus are unclear. In (Blechner et al., 1974), rats (Bruce,
flow been
F-D
9 0.
recover
and
al.,
CONTROLS PREGNANCY
,
these
puberal normal are
et 1980),
U
a
uterine growth women
(Morriss Ford,
.nd
1979).
from
and
plasma
al.,
gilts
of and
components
little
proteins,
et
(Hard
Maternal
I
FULL-FED THROUGHOUT
sustained at and devel-
are survival
growth
EXPERIMENTS
Anderson, of
(Kertiles
performance
1982).
and
also
an earlier onset estrous behavior
ductive
starvation
levels
minerals to maintain
Although
of
has
DESIGN
secretion
Hard
serum
the
Anderson,
pregnancy
1979;
EXPERIMENTAL
or
1975;
progesterone
electrolytes and levels adequate of
fetal
and
days
or late
Maternal
1979).
Hard
ANDERSON
of preg-
(Anderson,
1979;
effect
third
embryonic,
rates
Furthermore,
1979).
last
AND
METHODS
Animals
Thirty nulliparous Yorkshire gilts, 5-7 months old and weighing approximately 120 kg at mating, were used in these experiments. Gifts were checked daily for estrous behavior in the presence of fertile boars but were not allowed to mate. Gifts exhibiting normal estrous cycles (20 ± 2 days) were assigned randomly to either the inanition or control groups. The gilts were bred by fertile boats on the first day of the third
was designated Day similar for all gilts (Hard and Ander-
Groups
Mated gilts were subjected to a prolonged period of inanition during the last third of pregnancy, and their reproductive performance was compared with that of full-fed controls. The description of dietary regimens for experimental and control guts for the 3 experiments is presented in Fig. 1. In Experiments I and II, control gilts were fed a full diet (2.72 kg/day; 7028 kcal/day) of a previously described 16% protein ration (Hard and Anderson, 1979) from mating (Day 0) to Day 112 of pregnancy. These animals then were allowed free access to the ration throughout the remainder of gestation and lactation. The experimental
PORCINE
gifts
in Experiments
I and
UTERINE
II were
fed
BLOOD
2.72
kg/day
FLOW
of
the same diet from mating until Day 50. From Days 50 to 90 after mating (40 days), these pigs were subjected to inanition (0 kcal/ day; water only). Beginning on Day 90, the starved pigs were gradually realiinented by increments of 0.21 kg/day during a period of 13 days to a full diet (2.72 kg/day; 7028 kcal/day). Beginning on Day 112, animals subjected to inanition also were allowed free access to the 16% protein ration throughout the remainder of gestation and lactation. The experimental and control gilts in Experiment Ill were fed the same as the gilts in the corresponding groups in Experiments I and II until the time of hysterectomy at Day 90 when the experiment was terminated (Fig. 1). Body weight, total litter weight, as well as the number of live Day 90 fetuses or number of live piglets born (litter size) from all experimental and control dams were determined at hysterectomy on Day 90 or within 6 h of birth. Experiment
I
Hematologic analysis. Six experimental and 6 control gilts were weighed at 10-day intervals from the beginning of treatment (Day 50) to Day 100 after mating. Blood was obtained from the anterior vena cava every fifth day from all gifts. Hemoglobin, hematocrit, erythrocyte and leukocyte counts, and total peripheral plasma protein concentrations were determined by a previously described method (DeRoth and Downie, 1978). A blood smear stained with Wright’s stain was prepared for determination of leukocyte differential, and the differential was determined on 200 randomly selected cells. Experiment
II
Plasma volume determination. Experimental (n=6) and full-fed control (n=6) gifts were weighed at 20-day intervals from the beginning of treatment (Day 50) to Day 110 after mating. Plasma volume and hematocrit were measured in all experimental and control animals on Days 50, 70, 90 and 110 after mating utilizing the techniques of Anderson et al. (1969) with the following modifications. Feed was removed from the pens of all animals the afternoon of the day preceding plasma volume determination. Animals received a polyethylene jugular catheter between 0800 h and 0900 h on the day of plasma volume determination, which began at 1400 h. Any blood lost during the cannulation procedure was collected, and the volume (usually less than 20 ml) was considered in the calculations of plasma and blood volume. It was determined in a preliminary study, by using gifts at similar stages of pregnancy and of similar body weight, that the base10 logarithm of measured dye concentration declined linearly with time for up to 120 mm (r> 0.95) when a dose of approximately 150 mg T-1824 dye (Evans blue, Sigma Chemical Co.) was injected. The T-1824 dye, diluted in 40 ml of sterile normal saline, was injected through the jugular catheter and flushed with 8 ml heparinized (100 i.u./ml) saline. The exact quantity of dye injected was determined after the injection by differential weight of the syringe (Rosso and Streeter, 1979). The concentrations of dye in the plasma were determined from their optical densities measured at 620 tm in a Beckman DU spectrophotometer (Beckman Instruments Inc.). Red cell volume
AND
and
FETAL
total
volume similar plasma
Experiment
DEVELOPMENT
blood
volume
and hematocrit. among groups, was made.
were
81
calculated
Since hematocrit no correction
from
plasma
values were for trapped
III
Uterine blood flow measurement. Six gifts of similar body weight (121 ± 3.0 kg) were assigned randomly at mating to either the experimental (n3) or full-fed control (n3) group. All animals were weighed at mating (Day 0) and Days 50, 70 and 90. Factory-calibrated electromagnetic blood-flow transducers (18- and 20-mm internal circumference) were implanted surgically around either 1 or both middle uterine arteries as described previously (Ford and Christenson, 1979). Post-implantation verification of factory calibration has been performed on transducers of the same model and of similar size by an investigator in our laboratory (Ford and Christenson, 1979; Ford et al., 1979). Furthermore, Astley et al. (1979) have indicated that preand post-implantation in vitro sensitivities, as well as relative in vivo to in vitro sensitivities, are similar for up to 17 weeks of implantation in electromagnetic blood-flow transducers of the lumen circumference utilized in this investigation. On Day 47 or 48, 1 animal in each group received transducers bilaterally, and the remaining 2 animals in each group received 1 transducer on a randomly selected middle uterine artery. The gilts used in this experiment were confined in modified (raised) farrowing crates 1 week before surgery and allowed to acclimate. All animals readily adjusted to handling and confinement during this period. Food was removed from the gilts 24 h before surgery. General anesthesia was induced by intravenous injection of sodium thiamylal (0.5-1.0 g; Surital, Parke.Davis). The animals then were maintained on a closed-circuit system of halothane (3-6%, Ayerst Labs.) and oxygen (800-1200 mI/mm). The uterus was exposed by midventral laparotomy, adventitia was removed from a 1-cm segment of the middle uterine artery 1 to 2 cm upstream from its first bifurcation and its diameter determined. A flow transducer(s) head was introduced into the abdominal cavity via a small paralumbar incision, placed around the artery and secured within the mesometrium with silk sutures. The electrical connector for each probe was secured to an elastic patch and cemented to the flank at the site of entry. After surgery, until Day 90 after mating, all gifts remained in the modified crates, which permitted animals to stand or lie down. Beginning with treatment at Day 50, blood flow (ml/min) through the middle uterine arteries was monitored daily between 0800 and 1000 h. Blood flow values in digital display by the flowmeter (Model 501D, Carolina Medical Electronics, Inc.) were recorded at 15-sec intervals for a 12-mm monitoring period each day. The average of the values recorded during this period was considered to be an estimate of uterine arterial blood flow for that day. Each day, the order of monitoring the animals was randomized. Full-fed animals were not fed until monitoring had been completed each day. Pregnancy status and conceptuses development were determined and flow transducer placement was verified at midventral laparotomy on Day 90.
82
HARD
AND
ANDERSON
Abbreviations
N
).
Abbreviations are designated for pigs subjected to inanition from Days 50 to 90 after mating as (1) and for full-fed controls as (C). Abbreviations also have been designated for body weight (BW), total plasma volume (PV), total blood volume (BV) uterine blood
flow
(UBF),
(FW) Statistical
litter
size
Analysis
(LS)
and
fetal
body
u
C U
‘
98 I0
. ‘-
of Data
.
In these experiments, females were assigned to 1 of 2 treatments in a completely randomized design. Each gilt or litter was considered an experimental unit receiving 1 of the treatments. Comparisons among attributes of offspring produced by these females were based on analysis of litter means. A one-way analysis
ment III, the correlation between blood-free measureand blood volume in Experiment III. Also in Experiments in bilateral uterine horns was not significant and low; therefore, data from each blood-flow transducer were considered as independent observa-
0,
.
l-’v
weight
of variance and Student’s t test for continuous variables and a chi-square test for discrete variables were used to compare differences between the 2 treatment groups. A simple linear regression model was used in Experiment II to develop the linear prediction equations for maternal plaama and blood volume from dam body weight. These equations were used to predict plasma
-
.2
.,
U
..1. 0. N
ti-
.
41
+1
.
-‘0
.2
RI RI
*
RI
VI
-.
-
0U
C 0U
,
N
..
U.
-_ .
‘0
;
‘0
C
RIRI
i
V
C .
-
V
I-.
0.
E
V o
,, V
ON
N
N
0
4444 0.
O.
N
0
0.
tions.
u
NO ON
as’ 00
0.
‘U 0’.
0
Inanition Performance
on
Reproductive of the RESULTS Dams
Reproductive
--
performance control
and
periments
I
of experimental
(n=12)
plus
II),
gills
at
birth
reproductive
and
‘-‘
0 0U
-
0
I-
per-
ON
0
0, I.. 0
of experimental (n=3) and control dams at Day 90 of pregnancy (Experiment III) are presented in Table 1. Live fetal body weight, litter weight and number of live fetuses at Day (P>0.05)
The total and body of dead
number weight piglets
90
or at birth
(litter
in inanition
and
size) control
were similar (P>0.05). in gifts starved from Days
Gestation
also
50
to
90
-U U
N
I
were
,
b...
2a
a. RIOO N
i
-
ui
‘‘
0.1
. N
>
.a
0
10
n
as
4198 ‘0 **
similar
to that in full-fed organs recovered
at
controls. Of hysterectomy
reproon
‘
‘
,,,0
RI
*
+1
U TM
0
.
U
44 VI
‘6
‘0
.
U
,C
RIN
(P>0.05) ductive
C
ATM
I
length was
9., 0
RI
#{149}
gilts.
(0.7 ± 0.19 vs. 0.8 ± 0.32) (0.7 ± 0.18 vs. 0.7 ± 0.19 kg) in inanition and control gifts
‘0 VI
0
(n=3)
similar
0
‘oso
#{149}V0,
.
(Ex-
formance
or piglets
0
r
.
C
(n=12)
U
RI .
RI
.
-
-
V
Day 90, number
total and
animals. during cant at Day
was to It
late effect
weight, weight
in experimental a trend, however, be lower in the
(P>0.05)
There weight
ovarian uterine
is evident pregnancy on
that had
reproductive
90 or parturition.
corpora were
lutea similar
and control gilts. for Day 90 ovarian I as compared to C inanition of 40 days little, if any, signifiperformance
a. 0.
..
0.
o.
‘
-l
C
0
V
2 CU
I-
un (flU 0.
0 U
“
either .u
V
2
.
RI
u,
V’0
U
PORCINE
Experiment
UTERINE
BLOOD
FLOW
full-fed
(P>0.05) to that of gifts subjected from Days 50 to 90 after mating
to inanition (1, 163 kg).
After
I dams
20
days
inanition,
By
Day
89,
realimentation, the
C gifts
Day 100, decreased weight
BW of the
less (P0.05)
and
control
83
Q,.J
(142
controls through
than
(P I-
*3.0 +2.0
groups.
during
realimentation Eosinophil
in both and
monocyte
experimental percentages
021
(BODY
also
= ____
=
BLOOD ,
*1,0
WEIGHT.
kg)
I
li:
VOLUME,
L
571
50
FIG. Mean Days
027
(BODy
kg)
A
90 AFTER
5. Body weight, plasma changes during prolonged
± SEM. 50 to 90
WEIGHT.
70 DAYS
volume
+
osa. p< o,
3.31
and
*
If
-20 0
vs. 64.1 ± 3.80; P0.05) after the period of starvation
310
-1.0
were the
percentage was increased ± 3.59; P0.05)
pig;
prediction H for gifts
equations from the
and of similar (P>0.05) age, stage of pregnancy. Estimated (P>0.05)
in
experimental
gained were
body PV and
±
SEM.
at Day
50.
in PV had compared
difference 90 in las as
Mean
gifts
(P
