(Ped) Ped two stages greater

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Gregory. KE, Echternkamp. SE, Dickerson. GE, Cundiff LV, Koch. RM, Van. Vleck. LD. ..... LH (oW-. 3, AFP 9598B),. NIDDK ovine growth hormone. (oGH-4), and.
962

AL-SHOREPY TABLE

4.

Significance

levels

of orthogonal

contrasts Left

LS, selection ovulation

embryo

survival

eight-cell-stage Advancement study

than

and selection the proportion

may

in a line

1ff 0.05 NS NS NS NS 0.10 NS NS NS NS NS NS

0.06 NS NS NS NS 0.03 NS NS NS 0.19 NS NS

due

selected

selection; UT, of unfertilized

for small

for large litter size of embryos developed

to a change

probably

affected

[19]. stage

in the

by several

genes

litter

in the mouse beyond the

affect

of processes

ultimate

from

independent gle genes

litter

timing

and

ovulation

size

present

of ovulation,

by environmental

through

to term

of ovulation rate may have a significant

the

repthat

complexity

of gestation

(or

those

in the case of UT). While sineffect on variation in litter

size by affecting a single process or through pleiotropy, these selection criteria undoubtedly addressed many loci. The results of this study suggest that the frequencies of alleles affecting some determinant(s) of embryonic stage at implantation have been changed through selection. Alleles

(Ped) (MHC)

of the

preimplantation

embryonic

development

gene, linked to the major histocompatibility complex in the mouse, have been shown to affect rate of division [25]. Ped rate of development

cleavage increased

gene

alleles that resulted in an have more recently been as-

sociated with larger litters [17]. Although changes in the timing of ovulation rate or fertilization cannot be ruled out, it is interesting to speculate that alleles of the Ped gene or loci closely linked to the Ped locus may have been one target of these selection Normally developing at or

beyond

Gates

[12]

the reported

morula that,

criteria. mouse embryos stage

by 3.5

of mouse

LS,

analyses. side

UT

LS

vs. LC

vs.

IX vs.

UT

LS

0.002 NS 0.05 0.04 0.04

0.006 NS

0.20 NS NS NS NS NS NS NS NS NS NS NS

IX,

NS NS NS 0.19 NS NS NS NS NS 0.16

NS NS NS NS NS 0.06

capacity; LC, control. of degenerating embryos;

PTC,

percentage

are days

embryos

early blastocyst, blastocyst, or expanded blastocyst stage by 3.5 days postcoitus, those in the latter two stages had greater implantation success and postimplantation survival rates. A greater proportion

in the

Each selection criterion applied in this study an attempt to increase the frequency of alleles

favorably

univariate

0.04

selection for uterine ova; PD, percentage

of fertilization, or of first cleavage division, a change in the rate of subsequent cell division and embryonic development, or some combination of these factors. Each factor is variation. resents

from

percentage of four-cell embryos; PEC, percentage of eight-cell embryos; PM, percentage of early blastocysts; PB. percentage of blastocysts; PEXB, percentage of expanded bIasdevelopmental stage; SD. standard deviation for developmental stage.

by Day 2 of gestation of average embryonic be

means

IX,

LC

of two-cell embryos; PFC, of morula; PEB, percentage tocysts; STAGE. embryonic cNonsignificant (p > 0.20).

high

IX

0.004

for litter size; IX, index rate; PUFO, percentage

boR

criteriona

Right LS

vs.

0.19 0.01 0.07 NS

STAGE SD

size [18], increased

IX,

NSC 0.20 0.09 0.20 0.13 NS NS

PEXB

of selection

vs. LS

Characteristicb

AL.

side

IX, LS, UT vs.

OR PUFO PD PTC PFC PEC PM PEB PB

ET

expected

to be

postcoitus

[26].

at the

morula,

stages

of embryos

of development

survival. Variability

in the

stage

prolific

previously

breed

expense of their embryos from

of pigs

develop

faster

delayed or the highly

and

with

some of the difference in embryonic survival bebreeds (28]. Results from the present study reveal selection criteria decreased variability among

lations of

mity

over time embryonic

decreased right side

it

was

erations

horn at Day the distribution

3.5

of gesof ovu-

in the pig [29]), the uniforor both. Also, selection

of degenerating While it is not

embryos from

on the which

known

of degenthat they embryos

a horn. these

genetic selection size in the mouse

criteria

perhaps

stage the additional proportion in LC were lost, it is possible variability and the loss of delayed

In summary,

of genes bryonic

uterine altered

described development,

the frequency of the uterus.

developmental erating embryos reflect greater within

(as

contemporaries,

less

explaining tween the that these

the right may have

White

to contribadvanced

than

within Selection

Large

at

variability

embryos tation.

their

were increased

development

has been shown loss [14, 27]; more

to survive at the cohorts. Littermate

Meishan

UT

with

of preimplantation

among littermate pig embryos ute ultimately to embryonic embryos tend less advanced

in LS, IX, and

associated

that affect development. on not

results

for litter changed

provide size the

evidence

that

characteristics of preimplantation emIf the effects of the LS, IX, and UT

these characteristics discernable from

of selection

initial

or for components of litter frequencies of allelic forms

on

these

differed from these analyses. criteria,

litter

one After size

another, 13 genof [S and

EMBRYONIC

IX was significantly preimplantation contributed

greater embryonic

DEVELOPMENT

than that of LC [11]. Changes in development have probably

to response

in litter

size.

IN

14. Pope

WF,

1986;

AM,

mouse.

of Reproduction 2. Tess

MW,

efficiency 1983;

in sheep.

London:

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GL, Dickerson

of pork

production.

In: Land

RB, Robinson

Butterworths;

(eds.),

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of components

changes

in life

cycle

J Anim

on effIciency.

effects

on twinning GE.

weight

in mice. LD,

netic

G, Ollivier

antagonistic 1978;

ovariectomv

genetic

RM, Van

and

Vleck

presence

and

of

of mice

at a selection

limit.

J Anim

L, Dando

Livestock as a model

litter

size

and

DR

for prebreeding Sci 1978;

DR.

Kittok

to evaluate

traits,

Heritabilities and reproductive

traits

and

Genet

in the pig.

Sel Evol

RJ. Selection

1989;

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of an

21:93.

for components

of reproduc-

11:541-558.

uterine

of unilateral

capacity

in swine.

hysterectomyJ Anim

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1987;

II. Response

MK. Alternative

to thirteen

generations

methods

of selection

of selection.

J Anim

for litter

size

Sci 1990; 68:3543-

3556. AM.

stenholme ton:

GEW,

Little,

13. Wilmut prenatal

Rate Brown

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development M (eds.),

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I, Sales Dl, Ashworth loss in mammals.

as a factor

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Preimplantation

Stages

survival. of Pregnancy.

In; WolBos-

1965:270-293.

CJ. Maternal J Reprod

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factors associated with

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prenatal

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in

and

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cleavage

of

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in

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the

Bradford

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JL, Becker

uterine horns

tocvsts

SB, Warner Biol

28. Barer

Xie

CM.

Exp

and body

ovarian weight.

of selection

for litter of methods.

mouse

egg. Contrib

Em-

RC. Analysis

RE, Roberts ovaries

tran.sformations

of mice

for the

bi-

48:433-440.

during

of differences natural

oestrus

in the or after

2:418-437.

affect

of the

right

Fertil

1987;

79:125-134.

the

timing

of early

and

left ovaries

mouse

embryo

and de-

27:419-424. affecting

Morphol ML, Pope

synchronous

the time of formation

1977; WF.

Survival

and

of the mouse

bIas-

41:79-92. of small

asynchronous

and

large

transfer

littermate

procedures.

bIasTher-

30:1069-1074. WW,

Martinat-Botte

Large White and prolific Chinese 29. Pope WF, Wilde MU, Xie S. Effect 1988;

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R, McLaren

27. Wilde

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26. Smith

for litter

Inst 1935; 25:113-144.

Poisson

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rate, embryo

selected

59:329-339.

Falconer

on

of early

19:303-313.

MK, Johnson

F, Youtz and

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12. Gates

Reprod

68:3536-3542.

Cornegie

tocoele.

JM, Clutter AC, Nielsen

in mice:

1990; Wright

25. Goldbard

W. Justification

and

I. Characterization

Sd

nomial 23.

timing

in vurv MF.

EJ, Ulberg

1980;

WA,

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65:738-744.

11. Gion

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ge.

46:937-949. for prolificacv

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KA, Young

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J Anim

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30:491-498.

phenotype

SE, Anderson on

AC, Nielson

22. Mosteller

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Prod

for

PJ, Zimmerman

P. Selection

RK, Levmaster

selection

index

on the

1973;

Rothschild

to gonadotrophins

size in mice:

in a strain

1991;

BS, Eisen

20. Clutter

58:283-295.

MS,

Donahue

sensitivity

absence

superinduction

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51:300-303.

Reprod

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Brownell

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19. Durrant

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88:781-811.

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U,

21. Lewis

RK, Zimmerman

10. Christenson

and

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Immunol

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68:1867-1876.

size

RA, Cunningham

eleven-generation 9. Johnson

1968;

of litter

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8. Bolet

1990;

LV, Koch

Cundiff

17:215.

and phenotvpic

principal

Sci

Genetics

EJ. Single-trait and

7. Young

GE,

animals

for littersize in mice

Improvement

Res 1971;

6. Fisen

rate. J Anim

treatment.

DS.

Genet

I. Foundation

Selection

gonadotropin 5. Falconer

SE, Dickerson

in cattle:

M,

CM,

18. Moler

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development

in different strains of mice. Biol Reprod

Reprod

of genetic

of blastocs’st

P. Genetic Exp

differing in Ped gene

mice

1985:3-17.

GE. Simulation II. Effects

DW

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Bowman

K, Araki

1980;

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4. Bradford

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56:354-368.

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REFERENCES

LINES

SELECTED

morphological 9:882-887.

F, Terqui

M. Conceptus

Meishan Pigs. J Reprod Fertil of electrocauterv of nonovulated variation

among

day

11 porcine

development

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Biol

BIOLOGY

OF REPRODUCTION

46, 964-971

of Nutritional

Effect

VASANTHA

Repletion on Pituitary and Serum Follicle-Stimulating Isoform Distribution in Growth-Retarded Lambs’

PADMANABHAN,2 FRANCIS

Departments

(1992)

KATHLEEN

J.P.

of Pediatrics, Program,

EBLING,3

M. RENO, DOUGLAS

Pharmacology, The Universiiy

MARIA

THOMAS

BORONDY,

L. FOSTER,

and

Biology, Obstetrics and of Michigan, Ann Arbor,

INESE

Hormone

D. LANDEFEW,

Z. BEITINS

Gynecology, Michigan

and Reproductive 49109-0718

Sciences

ABSTRACT Using creases but

nutritionally

in GnRH also

alter

the

ovariectomized restricted diet. ovine

Bioactive

(B)

feeding

increased

both,

pituitary

in the

I-oFSH

isoforms

concentrations

activities.

alter

the

pH

3.5-5.6

In summary,

distribution

This

(
5.6, a mock chromatofocusing

pH

no sample) were similar and averaged 111.0 ± SE). Recovery of B-0FSH in the same pools ± 4.3% and were not significantly different

3.9

±

and

Representative

Serum

oFSH

profiles

5.6% (mean averaged 122.0 between pH

in two

re-

stricted-fed lambs (lambs 769 and 740 with mean concentrations of 1.9 and 5.8 ng/ml I-oFSH, respectively) and one ad libitum-fed lamb (lamb 715 with circulating FSH of 25.6 ng/ml) are depicted in Figure 4 (oW patterns are shown

0.01)