Mineral Accretion in the Fetus and Adnexa During Late Gestation in Holstein Cows1

Minerai Accretion In the Fetus and Adnexa During Late Gestation In Holstein Cows1 WILLIAM A. HOUSE Agricultural Research Service, USDA Plant, Soil and Nutrition Laboratory ALAN W. BELL Department of Animal Science Cornell University Ithaca, NY 14853 ABSTRACT

(Key words: mineral accretion, fetus, conceptus, Holstein cows)

Multiparous Holstein cows (n = 18) were bred artificially to the same Holstein bull and then slaughtered at times ranging from 190 to 270 d postmating to assess mineral accretion by the conceptus. Fresh weight, OM, and concentrations of Ca, P, Mg, K, Na, Fe, Zn, Cu, and Mn were obtained for the fetus, fetal fluids, fetal membranes, cotyledons, caruncles, and uterine tissues. Rates of accumulation of individual minerals in different components of the conceptus during late gestation were described by either linear or exponential relationships. Estimated Ca accretion rate in the conceptus increased from 2.3 gld at 190 d of gestation to 10.3 gld at 280 d of pregnancy; corresponding P accretions were 1.9 and 5.4 gld. Rates of accretion of Mg, K, and Na in the conceptus in late pregnancy were about .2, 1.0, and 1.4 g/ d, respectively, and Fe, Zn, Cu, and Mn accumulated in the conceptus at rates of 18.0, 11.7, 1.6, and .3 mgld, respectively. These daily rates represent net mineral requirements for conceptus growth during late pregnancy in mature Holstein cows. In general, our values are consistent with current dietary recommendations for minerals during the dry period.

INTRODUCTION

Received March 16, 1993. Accepted May 20, 1993. lMention of trade name or proprietary product does not constitute a guarantee or warranty of the product by USDA or imply its approval to the exclusion of other products or vendors that may be suitable. 1993 J Dairy Sci 76:2999-3010

Mineral requirements of livestock are influenced by factors such as species or breed, age, sex, physiological condition, production rate and environmental conditions (23). ReqUkements by dairy cattle for the major mineral elements have been estimated (1, 18) and usually are expressed as amounts needed daily or as a proportion of the diet. Therefore, optimal formulation of diets for mature cows depends upon reliable estimates of ~eeds during different stages of the reproducuve cycle, including the dry period in late pregnancy. Data on the mineral composition of the developing bovine fetus and other parts. o~ the conceptus during late pregnancy are lImlt~d. Ferrell et al. (8) described patterns of accreUon of Ca, P, Mg, Na, K, Fe, and Zn in the fetuses of crossbred beef heifers mated to Brown Swiss bulls. Moreover, developmental changes in fetal ash content have been measured in Hereford heifers (7) and in mixed breed beef heifers (20). However, except for Ca and P (6), rates of accretion of minerals in fetal Holstein calves have not been determined. Variations in size, age, and breeds of cows used in ~rev~~us studies (6, 7, 8, 20) may limit the applIcabilIty of the mineral composition data to modem Holstein cows. The objective of our study was to describe rates of accretion of Ca, P, Mg, K, Na, Fe, Zn, Cu and Mn in separate components of the gr;vid uterus of Holstein cows during late pregnancy. Data on amounts and rates. of accretion of minerals in the conceptus dunng late pregnancy are necessary for a more precise

2999

3000

HOUSE AND BELL

estimate of requirements for nutritionally important mineral elements in dry dairy cows. MATERIALS AND METHODS Cows and Diets

Multiparous Holstein cows (n = 18) in the herd at the Cornell Animal Science Teaching and Research Center were bred artificially to the same Holstein bull. Pregnancy was confirmed by rectal palpation 35 to 40 d after breeding, and the cows were slaughtered at various times during late pregnancy. At slaughter, live BW of the cows ranged from 579 to 814 kg (X ± SE, 714 ± 16 kg). All cows carried a single fetus. The cows were fed and managed according to usual practice at the Teaching and Research Center for cows in late lactation and the dry period. Each cow consumed daily 10 to 12 kg of a TMR. Also, a mixture of alfalfa and grass hay was available to cows during the early dry period, but the amount of hay consumed was not measured. Concentrations of minerals in the TMR fed during the late stages of the lactation and reproduction cycle are shown in Table 1. Tissue Collection

Cows were slaughtered at times ranging from 190 to 270 d of gestation. The cows were transported to a USDA-inspected facility, weighed, and euthanatized using a penetrating captive bolt followed by exsanguination. The uterus, severed at the cervix, was removed; the fetus was euthanatized by umbilical venous injection of a pharmaceutical agent (Beuthanasia; Schering-Plough, Kenilworth, NJ). Each gravid uterus was weighed and separated into the following components: fetus, fetal fluids (amniotic and allantoic fluid combined), fetal membranes (including umbilical cord and blood vessels), placentomes (cotyledons plus caruncles), and uterine tissue (myometrium and endometrium). Except for fetal fluids, the fetus and adnexa were ground separately, and duplicate 3OO-g samples of each were frozen, stored at -20'C, and then freeze-dried before chemical analyses. Amniotic and allantoic fluids were mixed and weighed, and two 50-ml samples were frozen until analyzed. The fetus was weighed, dismembered, ground in a grinder (model 801B; Journal of Dairy Science Vol. 76. No. 10, 1993

Autio Co., Astoria, OR) with an end-plate screen that had 9-mm holes, mixed, and reground using the same screen. Subsequently, the ground fetal material was mixed thoroughly, ground in a grinder (model 4432; Hobart Corp., Troy, OH) with an end-plate sieve that had 3-mm holes, mixed, and reground in the same machine before samples were collected. Fetal membranes were weighed and ground with a food chopper (model 81810; Hobart Corp.), and duplicate samples were prepared; uterine tissues were processed similarly. Placentomes were dissected into cotyledonary (fetal) and caruncular (maternal) parts, which were weighed and homogenized separately in a Waring high speed blender (Waring Products Division, New Hartford, CI); samples of each tissue were then collected. Chemical Analyses

Freeze-dried samples of the fetus and other tissues were wet ashed in nitric and perchloric acids, diluted in 3N nitric acid, and analyzed

TABLE I. Mineral content of TMR fed to Holstein cows at different stages during late pregnancy. 1 Stage of pregnancy Late lactation

Early dry period 2•3

Late dry period4

- - - (gIkg of DM) - - Macrominerals Ca

P Mg K Na Trace elements Fe

Zn Mn Cu

6.5 3.2 2.5 10.8 2.5

296 63 60 10

6.2 8.5 3.7 2.9 4.0 3.1 13.5 15.8 2.4 1.6 (mglkg of DM) 380 56 59 12

261 78 50 12

IAnalyses provided by DHI Forage Testing Laboratory, Ithaca, NY. 2f'rom dry-off at about 220 d of gestation until 4 wk prepartum. :!Cows had access to hay during this period. Concentrations of Ca, P, Mg, K, and Na in the hay were 5.2, 2.5, 1.7, 20.6, and .2 g1kg of DM, respectively. 4Last 4 wk prepartum.

3001

PETAL MINERAL ACCRETION

for Ca, P, Mg, K, Na, Fe, Zn, Cu, and Mn using an inductively coupled argon plasma emission spectrometer (model 34000; Applied Research Laboratories, Sunland, CA) as described previously (13). Fetal fluids were thawed and mixed; 4-ml samples were wet ashed and analyzed for mineral element content as described. Analytical standards, blanks, and a standard reference material (number 1577b, bovine liver; National Institute of Standards and Technology, Gaithersburg, MD) were prepared in the same matrix as experimental samples. Concentrations of mineral elements in the reference material were within the certified ranges. Statistical Analyses

Data were analyzed by linear and nonlinear regression analysis. Additionally, fetal BW gain and accretion of some minerals in the conceptus were described by an exponential growth model (7, 8, 20). The exponential equations were derived with a program (Sigma Plot™; Jandel Scientific, Corte Madera, CA) that used a least squares, iterative procedure. The functions were differentiated by day of gestation to obtain estimates of daily accretion rates. The regression equations should not be used to predict composition of the conceptus

prior to 190 d of gestation because all data used to derive the functions were collected during the third trimester of pregnancy. RESULTS AND DISCUSSION

Fetal Growth

Both BW and DM of the fetus increased exponentially with gestational age (Table 2 and Figure 1). As reported for crossbred beef fetuses (8), fetal sex did not affect (P > .1) fetal growth. For comparison, Figure I shows fetal BW and DM calculated from data reported for grade Holsteins (6). The exponential relationship describing fetal growth was similar to the model used to describe fetal growth in Hereford heifers (7) and in crossbred beef heifers mated to dairy bulls (8, 20). Other investigators (5) used polynomial regression equations to characterize conceptus development in dairy cattle. The exponential function (Table 2) for fetal BW gain indicates that the initial instantaneous growth rate was about 6.8%/d and that this rate diminished .011 %/d during gestation, which is similar to initial growth rates (6.5 to 7.4%/d) and rates of decline (.010 to .OI2%/d) reported for fetal growth in beef heifers mated to dairy

TABLE 2. Relationship of fresh weight, OM, and mineral composition of the fetus to day of gestation during late pregnancy in Holstein cows. Item

Equation l •2

Fresh weight, kg OM, kg Ca, glkg of OM P, glkg of OM Na, glkg of OM K, g/kg of OM Mg, glkg of OM Ca, g

y = Y = Y= Y= Y= y = y = Y= y = Y= Y= Y= Y= Y= Y= y =

P, g Na, g

K, g Mg, g Fe, mg Zn, mg Cu, mg Mn, mg Iy

r

.00138e(·06801-.000III) .00028e(·06456-.0oo091)

17.98 + .102t 23.83 + .022t 21.95 - .054t 17.23 - .038t 1.41 - .001t

.0216ge(·0S6I6-.00007I) .01842e~0S4~·000071)

-135.63 + .826t -140.23 + .823t -26.91 + .1491 -2797.78 + 16.571t -1874.99 + 1O.296t -278.68 + 1.472t -53.83 + .275t

.95 .96 .46

.16 -.96 -.82

-.13 .95 .96 .96 .96 .94 .90 .93 .86 .77

= Value for trait indicated, and t = day of gestation.

2Equations describe changes during the third trimester of pregnancy and should not be used to predict weight or mineral composition of the fetus prior to 190 d of gestation. Journal of Oairy Science Vol. 76, No. 10, 1993

3002 50

HOUSE AND BELL

0 T

PRESENT STUDY ELLENBERGER ET AL. (6)

40

..: :J:

30

0

~

LoJ

~ ..J

"...

...

fRESH WEIGHT

....'"

20

0

...

... ......

0 ...

Dlot

LoJ

'0

o 190

210

230

250

270

GESTATION, d

Figure I. Fresh BW and DM content of fetus by day of gestation during late pregnancy. Lines represent exponential functions.

bulls (8, 20). For beef heifers mated to Hereford bulls (7), both the initial rate of fetal BW gain (5.1 %/d) and rate of decline ('(XJ7%/ d) were lower than that for the Holstein fetuses in the present study. Daily rates of fetal BW gain increased from 329 g at 200 d after breeding to a maximum of 456 g at 242 d postmating and then declined to 296 g at 280 d of gestation. These rates were calculated by differentiation of the function for fetal BW (Table 2) at various times during late pregnancy. Similarly, for beef heifers mated to dairy bulls, the daily rate of fetal BW gain reached a maximum of 400 g at 250 d postmating and declined to 313 g at 280 d of gestation (8). Andersen and Plum (2) reported that the gestation period in Holsteins averaged 280 d and that BW at birth was about 44 kg for males and about 41 kg for females. Evaluation of the equation describing fetal BW gain (Table 2) at 280 d after breeding, the expected time of parturition, indicates that BW at birth of the calves in our study would have been about 46 kg. This estimated birth BW is higher than the average reported (2) for Holsteins because the fetuses may have been larger than average. With few exceptions, BW reported (6) for fetuses from grade Holstein cows were Journal of Dairy Science Vol. 76, No. 10. 1993

lower than the BW that we found for fetuses at comparable stages of development (Figure 1). The fetuses in our experiment may have been heavier than those observed in other studies because we used only multiparous Holstein cows, which were relatively large. At slaughter, BW of the cows ranged from 579 to 814 kg (X ± SE, 714 ± 16 kg), and body condition scores were 3 to 4 (five-point scale where 1 = thin and 5 = fat). Birth BW of calves and, presumably, fetal BW are influenced by breed, age, and BW of the darn, as well as by sire genotype (2). The score for calving ease of the single bull used in this study (11%) is consistent with a small positive sire effect on fetal size. Macromlneral Composition of Fetus

On a DM basis, fetal concentrations of Ca and P, elements found mainly in the skeleton, varied markedly during late gestation (Figure 2), and the correlation with fetal age was low

•

2

c

60

~

p

0

K lotg

...

Na

•

0

... ....... go

Ca

0

50

•

••

•

go

z 0

i= 40 oC

DI: I-

•

Z

LoJ

u

z

30

0

u

0 00

"0 0

0

..J

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.0

0

0

0

oC

...

0

0

en

0

0

0

20

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:::Ii 0

DI:

u

oC :::Ii

10

0

~~2i~9

B=§I

•• ••• •• •• ••• • •• 190

210

230

250

270

GESTATION. d

Figure 2. Concentrations of Ca. P. K, Na. and Mg in the fetus by day of gestation. Lines represent linear regressions that describe changes during the third trimester of pregnancy.

3003

FErAL MINERAL ACCRETION

(Table 2). On a fresh weight basis, fetal Ca and P concentrations increased with fetal age in dairy cows (6, 11) and in beef heifers (8). Moreover, fetal concentrations of Ca and P increased with fetal growth in other livestock (9, 14, 15, 19). Fetal concentrations of K and Na, elements occurring predominantly in soft tissues, decreased (P < .1) with gestational age (Table 2 and Figure 2). Similarly, Na and K concentrations declined with fetal development in beef heifers (8) and in single and twin lamb fetuses (9). Other investigators observed that Na decreased and that K increased in fetal sheep (14, 15) and in fetal swine (19). Fetal Mg concentration varied little during late pregnancy and averaged 1.24 ± .03 g/kg of OM (Figure 2). However, on a fresh weight basis, the concentration of Mg in the fetus increased with fetal age and was calculated to be .32 g/kg of BW at 280 d postmating. Earlier reports indicated that fetal Mg concentration increased with gestational age in crossbred beef heifers (8) and in sheep (9, 15). Moreover, at parturition, Mg concentration was about .28 g/kg in fetal calves (8) and .3 g/kg in fetal lambs (9, 10, 15). Although fetal concentrations of some macrominerals declined during late pregnancy (Figure 2), the fetal content of each element increased (P < .05) as gestational age increased (Table 2 and Figure 3). The increase in total macromineral content of the fetus during late pregnancy generally paralleled the gain in fetal OM. Macrominerals accounted for about 9 to 10% of the OM in the fetus. Much of the increase in total fetal mineral content during late pregnancy resulted from Ca and P accretion. As shown in Figure 4, amounts of Ca and P in the fetus at different gestational ages were similar to data reported (6) for grade Holsteins. In beef cattle (8), sheep (9, 10, 14, 15), and swine (19), the total amount of Ca, P, Mg, K, and Na in the fetus increased with fetal growth. Fetal Ca and P accretion were represented by exponential functions, and accumulation of Na, K, and Mg were described by linear equations (Table 2). Although linear functions adequately described fetal accretion of Na, K, and Mg in Holstein cows in late gestation (Figure 3), the equations should not be used to predict fetal composition or rates of mineral accretion prior to 190 d of pregnancy. In contrast to our

study, exponential functions described changes in amounts of all macrominerals in fetuses of beef heifers during the last two trimesters of pregnancy (8). This variation between studies possibly results from disparity in numbers and gestational ages of cows used to derive the functions rather than to physiological differences between breeds. Trace Element Composition of Fetus

Relatively little change occurred in the concentration of trace elements in the fetus during late gestation. Fetal concentrations of Fe, Zn, Cu, and Mn during late pregnancy were (X ± SE) 176 ± 7,81 ± 3, 9.3 ± .7, and 1.4 ± .2 mgt kg of OM, respectively. However, the total amount of individual trace elements in the fetus generally increased as fetal development increased (Figure 5). Some of the diversity in fetal Fe content possibly resulted from using steel grinders to prepare the tissues. Linear functions were used to describe accumulation of individual trace elements in the fetus during late gestation (Table 2). Published data on the trace element content of fetal ruminants at different gestational ages

600

•

o

'" 500 ~

p

•

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,.: z z

•

- - Co

•

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400

a

u ~

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300

~ 200

•

""

u

ooC ::IE

100

o

•• 190

• • • • • • • III

210

230

GESTATION,

250

270

d

Figure 3. Macromineral content of fetus by day of gestation during late pregnancy. Lines represent exponential or linear functions that describe changes during the third trimester of pregnancy. Journal of Dairy Science Vol. 76, No. 10, 1993

3004

HOUSE AND BELL

500

ELLENBERGER ET AL. (I)

••

500

~

Ca P

PR£SENT STUDY 0

0

Ca p

the fetus. Our estimate for fetal Fe is lower than that reported for fetal beef cattle (8), but concentrations of Zn and Cu are similar to those reported for beef cattle (8) and sheep (10, 12, 17, 24). Other than one report of Mn in fetal lambs (10), we are not aware of published reports of Mn concentration in fetal ruminants.

co

Growth of Nonfetal Conceptus

,.: 400

...... z

No apparent differences (P > .1) in fresh weights of fetal fluids, fetal membranes, cotyledons, caruncles, or uterine tissues were due to the sex of the fetus. Weights of fluids and tissues generally increased with gestational age (Table 3), but variations among fetuses of similar gestational age were relatively high. Weights of the various nonfetal tissues approximately doubled during the time of gestation studied. Growth of some nonfetal components of the conceptus have been determined in beef cattle (7, 20) and in dairy cattle (5). Comparison of

Z 0

(,)

lL

300

0

z


200

0

100

o 190

210

230

GESTATION,

250

270

d

Figure 4. Comparison of Ca and P content of fetuses in the present study with that reported (6) for fetuses of grade Holstein cows.

2000

0

1600

are limited. Fetal concentrations of Fe and Zn increased during late fetal development in crossbred beef heifers and averaged 62 and 20 mg/kg of BW, respectively, at 280 d of gestation (8). Williams et al. (24) reported that Zn and Cu concentrations in single lambs at term were 18.8 and 2.7 mg/kg of BW, respectively. A 140-d-old fetal lamb contained 20 mg of ZnI kg of BW (12), and the concentration of Cu in a 136-d-old lamb fetus was 2.7 mg/kg of BW (17). At 143 d of pregnancy in monotocous ewes, fetal concentrations of Fe, Zn, Cu, and Mn were about 41.2,20.6,2.7, and I mglkg of BW, respectively (10). In our study, estimated concentrations of Fe, Zn, Cu, and Mn in the fetus at term were 39.6, 21.7, 2.9, and .5 mg! kg of BW, respectively. These values were obtained by extrapolation of the appropriate regression functions (Table 2) to 280 d of gestation (2) and then division of the estimated trace element content by the estimated BW of Journal of Dairy Science Vol. 76, No. 10, 1993

0

F.

A-

Zn

0

0 0

0 0

co 1200

e

A-

,.:

z

...

\oJ

800

Z

0 (,)

...

... ... ...... Z

400

2

...J

)-

(,)

...'"•

0

150 100 50 0

Cu

0

0

~• o

190

0

••

210

230

GESTATION,

250

270

d

Figure S. Trace element content of the fetus during late pregnancy in Holstein cows. Lines represent linear regressions that describe changes during the third trimester of pregnancy.

3005

FETAL MINERAL ACCRETION

our results with those reported previously may not be meaningful because of differences in breeds of cattle and lack of sufficient anatomical descriptions of the tissues measured. For example, weights of fetal fluids (fable 3) were greater than those reported for beef cattle (7, 20) at similar stages of gestational development. This difference between studies with beef heifers and our data for dairy cattle may reflect breed size as well as parity of the dam. Moreover, weights of fetal membranes observed herein (fable 3) were lower than those reported (5) for dairy cows (predominantly Jerseys). This apparent variation in membrane weight between studies may reflect breed differences or measurement of different tissues. In our study, the combined weights of fetal cotyledons and fetal membranes were similar to values reported as "fetal membranes" (5).

obtaining homogeneous samples as well as minor contamination of a few samples with blood. Average concentrations of macrominerals in tissue components of the nonfetal conceptus are shown in Table 4, and trace element concentrations are shown in Table 5. Bitman et a1. (3) reported that Na and K concentrations in the uterus and placenta of cows (breed not specified) were relatively constant during the last 2 mo of pregnancy. Similarly, concentrations of most mineral elements in uterine tissues and placentomes changed very little during the stages of pregnancy studied. However, P, K, Na, and Cu concentrations in fetal membranes declined (P < .1) during late gestation (Figure 6).

Minerai Composition of Nonfetal Conceptus

Concentrations of minerals in fetal fluids varied substantially among fetuses, and no obvious relationship existed between concentration and fetal age. The major cation in fetal fluid was Na; its concentration was 1.97 ± .13 gIL. Concentrations of K, Mg, Ca, and P in fetal fluid were lower than that of Na and averaged 394 ± 111,286 ± 54, 59 ± 11, and 58 ± 7 mgIL, respectively. Iron was the predominant trace element in fetal fluids; Fe concentration was 1.5 ± .5 mgIL. Concentrations of Zn, Cu, and Mn in the fluids were low and averaged about 348, 27, and 14 p.gIL, respectively. Some of the variability in mineral content of fetal fluids possibly resulted from difficulty in

• 25

20

vi

...J

...:

...z a:

:::E

:::I

c

0

15

'" ......

....0 '"

0

10

0

5

a:

I-

Equation 1.2

r

(kg) Fetal fluids Cotyledons Carunc\es Fetal membranes Uterine tissues

.. -Y

p

...z <.J Z

0

Component

o o ~ .... •• ..... ........ ... " ... = 0

VI

z 0 ;:: ...:

<.J

TABLE 3. Relationship of fresh weight of various components of the nonfetal conceptus to day of gestation during late pregnancy in Holstein cows.

•• •

0

-'"

:::I

c

10

'0

'" ......

5

E

0

-'"

'"

~ 80

0

190

=

210

230

GESTATION,

y y y y y

= = = = =

-28.885 + .182t -.025 + .000t -1.841 + .022t -.081 + .000t -4.469 + .04lt

.82 .41 .61 .67 .82

I y = Value for trait indicated, and t = day of gestation. 2Equations describe changes during the third trimester of pregnancy but should not be used to predict weight of the components prior to 190 d of gestation.

0

0

0

Cu

250

270

d

Figure 6. Concentrations of Na, K, P, and Cu in fetal membranes by day of gestation. Lines represent linear regressions as follows: Na (gIkg of OM) = 53.65 - .l45X (r = -.81); K (gIkg of OM) = 15.73 - .029X (r = -.49); P (gJ kg of OM) = 9.24 - .019X (r = -.89); and Cu (mglkg of OM) = 22.89 - .07IX (r = -.83) where X = day of gestation. The functions describe changes in concentrations beginning at 190 d of gestation to the end of pregnancy. Journal of Oairy Science Vol. 76, No. 10, 1993

3006

HOUSE AND BELL

TABLE 4. Concentrations of macrominerals in nonfetal components of the conceptus of 18 Holstein cows. Component Element

Uterine tissues

Carunc1es

Fetal membranes

Cotyledons (g/kg of DM)

Ca pI Mg

KI Na l

X

SE

X

SE

X

SE

X

SE

.51 5.66 .71 12.66 10.84

.01 .09 .03 .16 .57

.52 11.65 .81 18.09 7.23

.01 .12 .01 .22 .11

1.00 11.74 1.04 18.18 10.92

.03 .17 .02 .23 .28

1.18 4.81 1.04 9.13 20.20

.06 .13 .09 .35 1.06

IConcentration in fetal membranes declined with fetal age.

Tissues of maternal origin contained more Zn than did tissues derived from the fetus; Zn concentration in the uterine tissues, caruncles, cotyledons, and fetal membranes averaged 112 ± 2,88 ± 1,72 ± 1, and 48 ± 1 mglkg of DM, respectively. Conversely, Fe concentrations were higher in tissues of fetal origin than in maternal tissues (Table 5). Changes in mineral content of the nonfetal conceptus during late gestation were described by linear functions (Table 6). Accumulation of individual macrominerals (Figure 7) and trace elements (Figure 8) in the constituents of the nonfetal conceptus varied but generally increased with day of pregnancy. Accretion of Ca and P in the nonfetal conceptus was relatively insignificant compared with that in the fetus. Mineral Accretion in Conceptus

Amounts of mineral elements present in the conceptus (fetus and associated tissues) at vari-

ous times during late gestation are shown in Figure 9 (macrominerals) and in Figure 10 (trace elements). Simple linear functions fit the data as well as several curvilinear models. Therefore, linear regression coefficients (Table 7) were used to estimate rates of accretion of most elements in the conceptus (Table 8). Because the functions (Table 7) were derived from data collected during the third trimester of pregnancy, the equations should not be used to predict mineral composition or rates of accretion prior to 190 d of gestation. Notable exceptions to linearity were the exponential increases in Ca and P accretion (Tables 3 and 8). The marked increase in the rate of deposition of fetal Ca and P during late pregnancy probably was associated with an accelerating rate of bone mineralization. The fetus contained about 99% of the Ca in the conceptus, and about 98% of the fetal Ca occurs in the skeleton (18). Our data for Ca and P accumulation in the fetus (Figure 4 and Table 8) agree well with

TABLE 5. Concentrations of trace elements in nonfetal components of the conceptus of 18 Holstein cows. Element Component

CuI

Zn

Fe

Mn

(mglkg of DM) Uterine tissues Carunc1es Cotyledons Fetal membranes

X

SE

X

SE

X

SE

X

SE

173 86 211 239

9 4 12 16

112 88 72 48

2 1 1 1

4.3 11.7 5.9 6.4

.2 .3 .3 .5

.6 2.5 2.1 .8

.1 .1 .1 .1

IConcentration in fetal membranes declined with fetal age. Journal of Dairy Science Vol. 76. No. 10, 1993

3007

FETAL MINERAL ACCRETION TABLE 6. Relationship of mineral content of the nonfetal conceptus to day of gestation during late pregnancy in Holstein cows. Element!

Equation 2,3

K, g Na, g P, g Mg, g Ca, g K + Na + Mg +P+Ca,g Fe, mg Zn, mg Cu, mg Mn, mg

y Y Y Y Y Y y y y y

500 400

r

= -14.51 + .203t = -84.60 + .563t = -11.08 + .116t = -1.51 + .026t = -2.18 + .018t = -114.70 + .932t = -80.43 + l.607t = -146.13 + 1.395t = --6.94 + .086t = -2.18 + .02lt

.60 .76 .88 .33 .53 .89

III

E

..: z

.......z ...z 0 0

.54 .91 .70 .71

"

0

Cu

0

0

0

0

300 200 100

~ ....

20

...

16

-

......J c

...'"'

12

= Value for trait indicated, and t = day of gestation. 3Equations describe changes in mineral content during

S

late pregnancy and should not be used to predict the composition prior to 190 d of gestation.

4

2y

Fe

Zn

.... 0

!Total amount in fetal fluids, fetal membranes, cotyledons, caruncles, and uterine tissues.

0

0

0

0

Mn

0

.. -_. . •• .-- .- . _

190

210

230

GESTATION,

250

270

d

Figure 8. Trace element content of nonfetal conceptus by day of gestation. Lines represent linear regressions that describe changes during the third trimester of pregnancy.

100

75

Illl

..: z

...

I-

Na

"0

K

0

P

l:J.

Ca

50

25

z

0

U ....I


...'"'

20

0

11\

Z :::I Ill: U

•

t.4g


:::I

12 S -4

0

... & 190

-... •

Ali

21 A

210

••• l:J. AA

•• ,,~

230

GESTATION,

.•

lil:J.

250

•

6!~ 270

d

Figure 7. Macromineral content of nonfetal conceptus by day of gestation. Lines represent linear regressions that describe changes during the third trimester of pregnancy.

the one other published study (6) of fetal accretion of these elements in dairy cattle but differ from that reported for beef cattle (8). In our study, daily rates of accretion of Ca and P in the fetus and conceptus had not reached a maximum by the expected time of parturition. In contrast, daily rates of accumulation of macrominerals in the fetus and in the gravid uterus of beef heifers reached a maximum at about 250 d of gestation and then declined (8). Moreover, the rates of deposition of macrominerals in the fetus and gravid uterus of the crossbred beef heifers (8) during late gestation were markedly lower than the rates observed by us (Table 8). These differences between dairy and beef cattle may be due to variations in the age, parity of the dam, and size of the breeds. However, rates of accretion of Fe in the fetus and gravid uterus of the Holstein cows (Table 8) were lower than the rates reported for beef heifers (8); rates of Zn accretion were similar in both breed types. We are not aware of published data for Cu and Mn accretion rates in fetal cattle. Generally, the Journal of Dairy Science Vol. 76, No. 10, 1993

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HOUSE AND BELL

mineral data presented herein are unique for dairy cattle in general and for Holsteins in particular. Consequently, our data are the most comprehensive set of values available for assessing mineral needs for conceptus growth in multiparous dairy cattle during late gestation. Minerai Requirements

Rates of mineral accretion presented in Table 8 represent net mineral requirements for growth of the fetus and adnexa during the last trimester of pregnancy in mature Holstein cows. Also, minerals are required for development of the mammary gland and for prepartum lactogenesis during late pregnancy, but these requirements should be low compared with those of the fetus and adnexa in mature, multiparous cows. Because only mature, multiparous cows were used, and because both cow and fetal BW were greater than the average for Holsteins, our data may represent the

600

• •

500

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..: z

...... z

400

Co p No K

....I


2.0

0

...

0

Fe Zn

0

'"

..: z

...... ...z ...

00

0

I§J

1.5

~g

... 0

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300

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upper end of the range of mineral requirements for conceptus growth in the wider population of dairy cows. Nutritional requirements of pregnancy increase markedly during the last trimester (22). In our study, about 80, 85, 84, 81,70, and 71% of the fetal DM, Ca, P, Mg, K, and Na, respectively, accumulated during this stage of pregnancy. Much of this important time for fetal mineral accumulation corresponded to the period when cows in most dairy herds would be on drylot. In addition to the quantity of minerals required for conceptus growth during the dry period, minerals are needed to maintain maternal functions. Using the average BW of the cows at slaughter (714 kg), we estimated that the cows needed to absorb daily about 11 g of Ca and 109 of P to meet the maintenance requirements for these elements (18). Additionally, the cows needed to absorb 10.3 g of Ca and 5.4 g of P to meet the maximal require-

....I

200

... ...'" <.J

.2


100

0

•• •••• • 190

210

.- • 230

GESTATION,

=• 250

• •• 270

d

Figure 9. Macromineral content of conceptus by day of gestation. Lines represent linear regressions that describe changes during the third trimester of pregnancy. Journal of Dairy Science Vol. 76, No. 10, 1993

., 0

a

Cu

a

a

~ 190

210

230

GESTATION,

250

270

d

Figure 10. Trace element content of conceptus by day of gestation. Lines represent linear regressions that describe changes during the third trimester of pregnancy.

3009

PETAL MINERAL ACCRETION TABLE 7. Relationship of mineral content of conceptus to day of gestation during late pregnancy in Holstein cows.

TABLE 8. Accretion of mineral elements in the fetus and conceptus of Holstein cows during late gestation.

Element l )

Bquation3A

Element

Ca, g

y .02456e(.o558l-.00007(1 y = .02743e(·05527-.0000751) y = -1049.19 + 5.69Ot y -663.53 + 3.715t Y = -29.23 + .I8U y = -154.85 + 1.027t y = -220.48 + 1.39Ot y -2.87 + .018t y -2.02 + .012t y = -288.61 + 1.569t y = -55.99 + .297t

p, g Ca, g P. g

Mg. g K, g Na, g Fe. g Zo. g Cu. mg Mn. mg

= = = =

r .95 .97 .95 .96 .87 .94 .91 .88 .95 .87 .79

lTotal amount of each element in the fetus. fetal fluids, fetal membranes. cotyledons. caruncles. and uterine tissues.

Fetus l

Conceptus 2

- - - - (gId) - - - Macrominerals

Ca3 p3 Mg K Na

2.21 and 10.27 1.30 and 5.01 .15 .82 .83

2.31 and 10.32 1.78 and 5.35 .18 1.03 1.39

- - - - (mgld) - - - -

Trace elements Fe

Zo

Cu Mn

16.6 10.3 1.5 .28

18.0 11.7 1.6 .30

2Ca and P contents of conceptus were described by both linear and exponential functions.

IValues were calculated by differentiation of appropriate equations shown in Table 3.

3y = Value for trait indicated. and t = day of gestation.

2lncludes fetus, fetal fluids, fetal membranes. cotyledons, caruncles, and uterine tissues. Values calculated by differentiation of appropriate equations shown in Table 7.

4Bquations describe changes in mineral content during late pregnancy and should not be used to predict the composition prior to 190 d of gestation.

ments for conceptus growth (fable 8). At the rate at which the TMR was consumed (10 to 12 kg/d), the TMR provided sufficient amounts of Ca and P (Table 1) to meet apparent daily needs of these elements for maternal maintenance and conceptus growth during late gestation if the bioavailabilities of Ca and P were 38 and 50%, respectively (18). Moreover, the daily intake of other minerals by the cows exceeded apparent needs for conceptus growth (Table 8) if the bioavailabilities of Mg, K, Na, Cu, Fe, Mn, and Zn were 20, 100, 100,50,25, 1, and 50%, respectively (1, 8, 18, 23). However, amounts of various minerals that need to be absorbed to meet maternal maintenance requirements are not well defined. Maternal nutrition in ruminants generally does not affect fetal size or composition except when nutritional levels are markedly low or deficient (7, 20, 21, 22). High maternal nutrition may increase the incidence of some health problems (16, 18) but decrease the risk of other disorders (4) in the periparturient period. Current dietary Ca and P recommendations for dairy cattle (18) appear to be adequate and to accommodate easily the apparent requirements for maintenance and for conceptus growth. Studies on bioavailability and utilization of

3Values for Ca and P were derived from exponential functions (Tables 3 and 8) differentiated by time at d 190 and 280 of gestation, respectively.

other mineral elements during late gestation are needed to assess accurately the partitioning of absorbed mineral elements among tissues in pregnant animals. CONCLUSIONS

An extensive set of values on the mineral composition of the conceptus of dairy cattle is presented. Except for the exponential increases in fetal Ca and P accretion, simple linear functions fit the data reasonably well. Consequently, linear regression coefficients were used to estimate rates of accretion of most elements in the conceptus during late gestation. These data provide a basis for determining net mineral requirements for conceptus growth during late pregnancy in Holstein cows. The mineral requirements for conceptus development should be added to maternal maintenance allowances to obtain estimates of total mineral needs during late pregnancy in dairy cattle. Such factorial estimates of total mineral requirements of dairy cows during the dry period appear to be compatible with current dietary recommendations. Journal of Dairy Science Vol. 76. No. 10, 1993

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ACKNOWLEDGMENTS

The excellent technical assistance of Ramona Slepetis and Magda Southworth is acknowledged. REFERENCES 1 Agricultural Research Council. 1984. The Nutrient Requirements of Ruminant Livestock. Suppl. 1. Commonw. Agric. Bur., Slough, Engl. 2 Andersen, H., and M. Plum. 1965. Gestation length and birth weight in cattle and buffaloes: a review. J. Dairy Sci. 48:1224. 3 Bitman, J.• H. W. Hawk. H. C. cecil. and J. F. Sykes. 1961. Water and electrolyte composition of the bovine uterus in pregnancy. Am. I. Physiol. 200:827. 4 Curtis, C. R.• H. N. Erb. C. J. Sniffen, R. D. Smith, and D. S. Kronfeld. 1985. Path analysis of dry period nutrition, postpartum metabolic and reproductive disorders, and mastitis in Holstein cows. J. Dairy Sci. 68: 2347. 5 Eley, R. M., W. W. Thatcher, F. W. Bazer. C. J. Wilcox. R. B. Becker, H. H. Head, and R. W. Adkinson. 1978. Development of the conceptus in the b0vine. J. Dairy Sci. 61:467. 6 ElIenberger, H. B.• J. A. Newlander. and C. H. Jones. 1950. Composition of the bodies of dairy cattle. Univ. Vermont Agric. Exp. Sin. Bull. No. 558, Burlington. 7 Ferrell, C. L., W. N. Garrett. and N. Hinman. 1976. Growth, development and composition of the udder and gravid uterus of beef heifers during pregnancy. J. Anim. Sci. 42:1477. 8 Ferrell, C. L., D. B. Laster, and R. L. Prior. 1982. Mineral accretion during prenatal growth of cattle. J. Anim. Sci. 54:618. 9 Field, A. C.• and N. F. Suttle. 1967. Retention of calcium, phosphorus, magnesium, sodium and potassium by the developing sheep foetus. I. Agric. Sci. (Camb.) 69:417. 10 Grace, N. D., J. H. Watkinson. and P. L. Martinson. 1986. Accumulation of minerals by the foetus(es) and conceptus of single- and twin-bearing ewes. N.Z. I. Agric. Res. 29:207.

Journal of Dairy Science Vo!. 76, No. 10, 1993

II Haigh, L. D., C. R. Moulton, and P. F. Trowbridge. 1920. Composition of the bovine at birth. Univ. Missouri Agric. Exp. Sin. Res. Bull. No. 38, Columbia. 12 Hansard, S. L., and A. S. Mohammed. 1968. Maternal-fetal utilization of zinc by sheep. J. Anim. Sci. 27:807. 13 House. W. A.• B. A. Crooker, and D. E. Bauman. 1991. Utilization of sulfur and other mineral elements by growing dairy heifers treated with bovine somatotropin. J. Anim. Sci. 69:3817. 14 Langlands, J. P.• and HAM. Sutherland. 1968. An estimate of the nutrients utilized for pregnancy by Merino sheep. Br. J. Nutr. 22:217. 15 McDonald. I., J. J. Robinson, C. Fraser, and R. I. Smart. 1979. Studies on reproduction in prolific ewes. 5. The accretion of nutrients in the foetuses and adnexa. I. Agric. Sci. (Camb.) 92:591. 16 Morrow, D. A. 1976. Fat cow syndrome. J. Dairy Sci. 59:1625. 17 Moss, B. R., F. Madsen, S. L. Hansard, and C. T. Gamble. 1974. Maternal-fetal utilization of copper by sheep. I. Anim. Sci. 38:475. 18 National Research Council. 1989. Nutrient Requirements of Dairy Cattle. 6th rev. ed. Nat!. Acad. Sci.. Washington, DC. 19 Pomeroy, R. W. 1960. Infertility and neonatal mortality in the sow. III. Neonatal mortality and foetal development. J. Agric. Sci. (Camb.) 54:31. 20 Prior, R. L., and D. B. Laster. 1979. Development of the bovine fetus. J. Anim. Sci. 48:1546. 21 Rattray. P. V., W. N. Garrett, N. E. East, and N. Hinman. 1974. Growth, development and composition of the ovine conceptus and mammary gland during pregnancy. I. Anim. Sci. 33:416. 22 Rattray, P. V., D. W. Robinson, W. N. Garrett, and R. C. Ashmore. 1975. Cellular changes in the tissues of lambs during fetal growth. J. Anim. Sci. 40:783. 23 Underwood, E. J. 1981. The Mineral Nutrition of Livestock. 2nd ed. Commonw. Agric. Bur.• Slough. Eng!. 24 Williams, R. Bo, I. McDonald, and I. Bremner. 1978. The accretion of copper and of zinc by the foetuses of prolific ewes. Br. I. Nutr. 40:377.