UTERINE INVOLUTION: ITS ROLE IN REGULATING
G. H. KIRACOFE
J ANIM SCI 1980, 51:16-28.
The online version of this article, along with updated information and
services, is located on the World Wide Web at:
Downloaded from jas.fass.org by guest on June 12, 2011
U T E R I N E I N V O L U T I O N : I T S R O L E IN R E G U L A T I N G
POSTPARTUM INTERVALS 1
G. H, K I R A C O F E
Kansas State University, Manhattan 66506
Summary Uterine size has not been a good indicator
of subsequent fertility, but more subtle ana-
AN involuting uterus is a temporary barrier to
tomical changes may continue well beyond the
fertility in cows, ewes and sows. Parturition is
dramatic changes in size noted shortly after
followed by a period when conception is not
parturition. Subsequent fertility is impaired
possible: about 1 week in sows and about 3
when uterine involution is complicated by
weeks in cows and ewes. Estrus and ovulation
pathological conditions induced by dystocia,
seldom occur together during this period and,
retained fetal membranes, metritis or other
if fertilization occurred and the embryo
disorders. However, whether these factors di-
reached the uterus, placentation would be vir-
rectly affect postpartum endocrinology or re-
tually impossible. T h e period of no fertility is
duce fertility by providing an improper milieu
followed by 2 to 3 weeks when fertility is
for spermatozoa and embryos has not been
possible, but not optimal. T h e extent to which
established. Lack of a precise definition of
the involuting uterus contributes to infertility
uterine involution prevents direct comparisons
during the second period is difficult to deter-
of many data. Despite voluminous data con-
mine. Embryonic mortality in sows bred dur-
cerning uterine involution and postpartum
ing this latter period appears to be a major
fertility, specific studies correlating the two
cause of reduced litter size, so changes in
uterine environment associated with involution
may be essential for optimum fertility. Con- This review describes normal processes of
ception rate is lower up to 4 0 days after par- uterine involution in cows, ewes and sows.
turition than later in cows and ewes. Uterine Factors related to normal uterine involution
involution appears not to be a barrier to ferti- are considered to determine if the uterus limits
lity after 3 to 4 weeks postpartum in sows or postpartum fertility.
5 to 6 weeks postpartum in cows and ewes
unless delayed b y inflammation or infection.
(Key Words: Uterine Involution, Postpartum The Process of Uterine Involution. Before
Intervals, Postpartum Conception, Short Es- 1950, postpartum changes in the bovine uterus
trous Cycles, Cattle, Sheep, Swine.) received little attention. Studies were limited
primarily to pathological situations and to pal-
Introduction pation per rectum to determine uterine size,
Processes involved in the return of the post- tone and positional changes; a few uterine
partum uterus to a state capable of support- weights and measures were recorded. Pioneer-
ing another conceptus after parturition are ing studies included those of Hilty ( 1 9 0 8 ) ,
complex and the interrelationship of the uterus Boyd ( 1 9 2 5 ) , Casida and Venzke ( 1 9 3 6 ) and
with the ovaries is not understood. That the Casida and Wisnicky ( 1 9 5 0 ) . Rasbeck ( 1 9 5 0 )
time required for uterine involution limits post- reviewed much of the early research and later
partum fertility under current livestock man- reviews on uterine involution were done by
agement systems is questionable. Considering Casida et al. ( 1 9 6 8 ) , Morrow et al. ( 1 9 6 9 )
only the basics of normal uterine involution, and Moller ( 1 9 7 0 a ) .
the uterus rarely is unprepared for pregnancy Since 1950, regression of uterine size, fac-
when ovulation and estrus occur together, fer- tors affecting postcalving uterine changes, and
tilization has taken place, and the embryo is descriptions of tissue sloughing, vascular
ready for placentation. changes and tissue regeneration have been re-
ported. T h e complexity of the involutionary
Contribution 79-379-J, Dept. of Animal Sci- process and the difficulty in determining ex-
ences and Industry, Kansas Agr. Exp. Sta., Man-
actly when uterine involution is complete has
Downloaded from jas.fass.org by guest on June 12, 2011
U T E R I N E I N V O L U T I O N AND P O S T P A R T U M INTERVALS 17
made comparison of data among investigators which occurred during the first day postcalv-
difficult. Conditions that signify complete uter- ing, receded b y day 8. Rasbeck ( 1 9 5 0 ) , Gier
ine involution are nebulous. Casida et al. and Marion ( 1 9 6 8 ) and Wagner and Hansel
( 1 9 6 8 ) defined uterine involution as complete ( 1 9 6 9 ) described sloughing and regenerative
when the uterus returned to its normal non- changes in histological preparations from ex-
pregnant position and when the two horns cised uteri at various times postpartum. J o -
were similar in diameter and showed normal hanns et al. ( 1 9 6 7 ) , through radiographic stu-
consistency and tonus. Palpation estimates dif- dies of postpartum uteri, showed degenerative
fer widely because of methods used to mea- changes in the epithelium as well as changes
sure the uterus and inherent variation among in the circulatory system.
individuals. Gier and Marion ( 1 9 6 8 ) reasoned Morrow ( 1 9 6 9 ) reported that the caruncular
that a variety of histological and physical stalk disappears, the superficial layer of the
changes must take place in the uterus before caruncle dissolves and uterine lochia form.
involution could be termed complete. They de- T h e bulk of the caruncle had dissolved by 10
scribed uterine involution as having three over- days after calving. Johanns et al. ( 1 9 6 7 ) de-
lapping processes: ( 1 ) reduction in size, ( 2 ) scribed constriction of the caruncular arteries
loss of tissue, and ( 3 ) repair. and decreasing caruncular blood supply dur-
Reduction in Size. Estimates of the time re- ing these 10 days. Endometrial changes re-
quired for complete reduction of uterine size sulting in edema, then regression and folding,
after calving range from 18 (Rasbeck, 1 9 5 0 ) and a general "stalked" appearance of the car-
to 5 6 days (Wiltbank and Cook, 1 9 5 8 ) . Esti- uncle were described by Rasbeck ( 1 9 5 0 ) and
mated intervals from parturition to complete Gier and Marion ( 1 9 6 8 ) . Sloughing of the
uterine involution, ovulation and estrus for necrotic tissue progressed to an extent that
various breeds are listed in table 1. Palpable material of the caruncle came off in chunks
changes in uterine size, tone and position af- b y day 5 and most of the necrotic layer was
ter calving were described by Rasbeck ( 1 9 5 0 ) , gone by 10 days. By 15 days all of the car-
Buch et al. ( 1 9 5 5 ) , Morrow et al. ( 1 9 6 6 ) , uncular mass involved in the placentome was
Bhalla et al. ( 1 9 6 6 ) , Moller ( 1 9 7 0 b ) , Mo- sloughed, and by day 19 the arterioles within
hamed ( 1 9 7 4 ) and El-Fouly et al. ( 1 9 7 6 ) . and beyond the stratum compactum had dis-
Early reduction of uterine size after calving appeared leaving the caruncles relatively
results from vasoconstriction (Morrow, 1 9 6 9 ) smooth (Gier and Marion, 1 9 6 8 ) . T h e deci-
and peristaltic contractions that persist for sev- duum of the caruncle sloughed just basal to the
eral days (Jordan, 1952; Venable and McDon- crypts and regeneration of the epithelium oc-
ald, 1 9 5 8 ) . Weight and size of the uterus curred from the margin of the slough (Wag-
after calving decrease in similar patterns. ner and Hansel, 1 9 6 9 ) .
Riesen ( 1 9 6 8 ) and Gier and Marion ( 1 9 6 8 ) , Repair. Several descriptions of tissue repair
who weighed uteri from cows after calving, have been reported. T h e intercaruncular areas
reported the uterine weight at calving was ap- never were devoid of epithelium, and both
proximately 9 kg and was reduced to approxi- degenerative and regenerative epithelial cells
mately 3 kg by 10 days, to 1 kg by 20 to were observed in the intercaruncular areas
3 0 days and to 7 5 0 g by 5 0 days postpartum. before day 15, but after day 15 no degenera-
Fluid is present in the uterus after calving tive cells were observed (Archbald et al,
(Johanns et al, 1967; Gier and Marion, 1 9 6 8 ; 1 9 7 2 ) . Epithelium was reestablished over the
Morrow, 1969; Morrow et al, 1 9 6 9 ) . T h e caruncle 9 to 2 0 days after parturition (Arch-
maximum amount of lochia ( 1 , 0 0 0 to 1,600 bald et al, 1972; Rasbeck, 1950; Roberts,
m l ) is present during the first 4 8 hr and then 1 9 5 6 ) . Gier and Marion ( 1 9 6 8 ) found that
decreases to 4 0 0 to 100 ml by day 8 and epithelial regeneration was not complete b e -
is absent by 14 to 24 days postpartum. fore day 2 5 ; or for at least 10 days after
Loss of Tissue. Gier and Marion ( 1 9 6 8 ) de- sloughing had ceased. Caruncle sites were
scribed early uterine changes. Shedding of fetal covered with epithelium b y postpartum days
membranes appeared to be associated with 10 to 2 0 in the previously nongravid horn,
peristaltic muscular contractions. Reduction in but not until 20 to 3 0 days in the horn which
uterine size progressed in a negative logarith- had been gravid (Riesen, 1 9 6 8 ) .
mic manner so that the postgravid horn dia- Gier and Marion ( 1 9 6 8 ) considered involu-
meter decreased by 50% by day 5 . Loss of tion to be complete and the uterus to be
tissue fluids appeared to be a major factor in restored to a cycling condition by 4 0 to 6 0
early size reduction. Endometrial edema, days when the caruncle had regressed to a
smooth, oblong, epithelial covered, avascular T h e net effect of nutrition on uterine involu-
knob. Caruncles which had been in the proxi- tion appeared to be minimal in the absence of
mity of the fetus required the longest interval specific deficiencies.
to return to normal. Obviously, involution con- A remarkable feature of uterine involution
tinues past the time that uterine regression is in the rat is the loss of collagen (Harkness and
detectable by palpation, but the degree of Harkness, 1954; Harkness and Moralee, 1956;
involution required to support another preg- Woessner, 1 9 6 9 ) ; 85% of the total collagen of
nancy has not been established. the term uterus was removed in the first 4
Many factors delay the normal process of days postpartum. Similar research with large
involution: uterine infections, retained fetal animals on this aspect of involution is lacking.
membranes (Boyd, 1 9 2 5 ; Rasbeck, 1950; Buch Since relaxin can induce breakdown of col-
et al, 1 9 5 5 ; Norwood, 1 9 6 3 ; Gier and Marion, lagen in some circumstances (Frieden and
1 9 6 8 ; Marion et al., 1968; Tennant and Peddi- Hisaw, 1 9 5 3 ) , it would be of interest to deter-
cord, 1 9 6 8 ; Morrow, 1 9 6 9 ) and other peri- mine if relaxin plays a role in uterine involu-
parturient diseases (see reviews by Morrow tion. Kiracofe et al ( 1 9 7 3 a ) did not alter the
et al, 1969; Moller, 1 9 7 0 a ) . involution rate in postpartum cows by intra-
Factors Influencing the Time to Involution. uterine infusion of collagenase. Treating the
Suckling, in contrast to nonsuckling, has been uterus with enzymes, antibiotics or antibac-
reported to promote uterine involution (Casida terial compounds failed to hasten uterine in-
et al., 1 9 6 8 ; Riesen, 1 9 6 8 ) , delay uterine in- volution, but they frequently prolonged the
volution (Wiltank and Cook, 1 9 5 8 ) or have time to involution (Homan, 1969; Kiracofe
little effect on the rate of uterine involution et al, 1973b; Oxender and Seguin, 1976; Se-
(Wagner and Hansel, 1969; Moller, 1970b; guin et al, 1 9 7 4 ) .
Oxenreider and Wagner, 1 9 7 1 ; El-Fouly et al., A profound effect on the size of the post-
1 9 7 6 ) . However, limited or no suckling has- partum uterus resulted from injecting cows
tens resumption of estrous cycles (Wiltbank with GnRH (gonadotropin releasing hormone)
and Cook, 1 9 5 8 ; Moller, 1970b; Oxenreider 14 days after calving (Britt et al, 1974a;
and Wagner, 1 9 7 1 ; Short et al., 1972; Randel Fernandes et al, 1 9 7 8 ) . T h e GnRH accele-
and Welker, 1977; Radford et al, 1 9 7 8 ; Wet- rated reduction in uterine size between 14 and
temann et al., 1 9 7 8 ) . 24 days postpartum. No beneficial effect on
Generally, uterine involution takes a few conception was associated with decreased
days longer in pluriparous cows than in primi- uterine size after GnRH. An increase in serum
parous cows (Rasbeck, 1 9 5 0 ; Buch et al., 1 9 5 5 ; progesterone concentrations after GnRH, noted
Quevedo et al, 1 9 6 5 ; Morrow et al, 1966; by Fernandes et al. ( 1 9 7 8 ) , may have ac-
Marion and Gier, 1 9 6 8 ; Araujo et al, 1 9 7 4 ) . celerated uterine involution by affecting uter-
However, Tennant et al. ( 1 9 6 7 ) and El-Fouly ine blood flow and water imbibition. Riek et al.
et al. ( 1 9 7 6 ) reported that age or number of ( 1 9 7 7 ) showed that GnRH partially syn-
previous pregnancies had no effect on involu- chronized cows in the early puerperium, but the
tion. Several investigators have reported sea- condition of the postpartum uterus appeared
sonal effects on rate of uterine involution. to affect the ability of GnRH to initiate cyclic
Norwood ( 1 9 6 3 ) , Marion et al. ( 1 9 6 8 ) , El- progesterone production. Other postpartum
Fouly et al. ( 1 9 7 6 ) and Gospodinov and Ros- hormone treatments have hastened onset of
tov ( 1 9 7 6 ) found slower involution in the estrous cycles and subsequent conception.
fall than in the spring. Shorter intervals from calving to conception
after administration of progesterone or syn-
Energy and protein level of the diet only
thetic progestogens during the postpartum
slightly affect the rate of uterine involution
period have been reported by Fosgate et al.
but drastically affect the interval from par-
( 1 9 6 2 ) , Norwood ( 1 9 6 3 ) , Foote and Hunter
turition to resumption of estrous cycles (Wilt-
( 1 9 6 4 ) , Saiduddin et al. ( 1 9 6 8 ) , Boyd
bank et al, 1962; Dunn et al., 1969; Clemente
( 1 9 7 0 ) , Britt et al ( 1 9 7 2 ) , Huertas-Vega et
et al, 1 9 7 8 ) . Uteri of cows fed high energy
al. ( 1 9 7 2 ) and Britt et al. ( 1 9 7 4 b ) . Likewise,
diets after calving involuted 3 days sooner than
Casida and Wisnicky (1950), Norwood
uteri of cows fed moderate energy diets, and
( 1 9 6 3 ) , Ulberg and Lindley ( 1 9 6 0 ) , Foote
uteri of Angus cows involuted 3 days sooner
and Hunter ( 1 9 6 4 ) and Brown et al. ( 1 9 7 2 )
than uteri of Hereford cows (Dunn, 1 9 6 4 ) .
reported some beneficial results with either
Kiracofe et al. ( 1 9 6 9 ) found no significant
estrogens or synthetic estrogens alone or in
difference in uterine involution rates in cows
combination with progestogens. However, ef-
fed low or high levels of energy or protein.
UTERINE INVOLUTION AND POSTPARTUM INTERVALS 19
fects of exogenous steriods on conception vary ( 1 9 6 8 ) showed uterine involution time was
widely and the beneficial effects of exogenous unaltered in ovariectomized cows. When beef
steriods cannot be related to hastened uterine heifers were subjected to hypophysial stalk
involution. Marion et al. ( 1 9 6 8 ) showed that transection in middle or late pregnancy, preg-
progesterone actually lengthened the period nancy was maintained and live calves were
of uterine involution. Therefore, if exogenous born, and then the uterus involuted to a size
steriod hormones prove beneficial to postpar- similar to that of a prepuberal heifer (Ander-
tum conception, it is unlikely that success will son et al, 1 9 7 9 ) . Cows can conceive before
be attributed to an effect on uterine involution. uterine involution would b e expected to have
The postpartum uterus contains many types been complete (Buch et al, 1 9 5 5 ; Perkins and
of bacteria (Dawson, 1950; Wulf and Dracy, Kidder, 1 9 6 3 ; Moller, 1 9 7 0 a ; Odde and Kira-
1952; Lindley, 1954; Gunter et al, 1 9 5 5 ; cofe, 1 9 7 8 ) . Olds and Cooper ( 1 9 7 0 ) found
Eliot et al, 1 9 6 8 ; Griffin et al, 1 9 7 4 ; Studer no difference in conception rates of dairy cows
and Morrow, 1 9 7 8 ) . Bacteria of the early post- bred 4 0 to 6 0 days postpartum and those bred
partum uterus do not appear to affect involu- later, although uterine involution would not
tion rate and may or may not b e associated be complete in all cows by day 4 0 . Tudorascu
with subsequent fertility (Graden et al., 1 9 6 8 ; ( 1 9 6 9 ) and Casida et al, ( 1 9 6 8 ) found no
Fuquay et al, 1 9 7 5 ) . Kiracofe et al ( 1 9 7 3 a ) relationship between the postpartum interval
showed no effect on uterine involution and to breeding and embryonic mortality in ani-
fertility from innoculating the early postpar- mals bred after day 3 0 postpartum. Concep-
tum uterus with lactobacillus acidophilus. tion rates appear to b e rather low at less than
Involution and Resumption of Cycles. F e w 3 0 days postpartum (Olds et al., 1949; Van
direct relationships can be made between the Demark and Salisbury, 1950; Norwood, 1 9 6 3 ;
rate of uterine involution and subsequent fer- Perkins and Kidder, 1 9 6 3 ; Odde and Kiracofe,
tility. Albrechtsen ( 1 9 1 7 ) found that if uter- 1 9 7 8 ; also see review by Casida et al., 1 9 6 8 ) .
ine involution required more than 4 weeks the Perkins and Kidder ( 1 9 6 3 ) reported concep-
onset of first estrus was delayed. However, tion rate to be unaffected b y involutionary
Buch et al. ( 1 9 5 5 ) found only a slight associa- state after directly comparing conception rates
tion between interval to first estrus and degree of cows in which uterine involution was com-
of uterine involution. Other researchers have plete and cows in which uterine involution
found no relationship between uterine involu- was not complete.
tion and interval from calving to first estrus or Another approach to determine factors lim-
conception of clinically normal cows (Foote iting early postpartum conception is to induce
et al, 1960a; Perkins and Kidder, 1963; Dunn, ovulation and inseminate at various postpar-
1964; Tennant and Peddicord, 1 9 6 8 ; Kiracofe tum intervals. Henderson ( 1 9 7 8 ) bred cows
et al, 1 9 6 9 ) . after progestogen and estrogen treatment ( a
Some conditions can delay uterine involu- 6 mg norgestomet implant for 9 days and an
tion, resumption of cycling and conception injection of 6 mg estradiol valerate and 3 mg
(see review by Morrow, 1969; Studer and Mor- norgestomet at the time of implanting). Con-
row, 1 9 7 8 ) . An abnormal uterus may delay ception rates did not differ among cows bred
follicle development and ovulation, but it is less than 4 2 days postpartum and those bred
doubtful that a normal involuting uterus plays later. Further attempts to breed cattle or trans-
a role in reestablishing estrous cycles. Pituitary fer fertilized ova at specific postpartum inter-
gonadotropin content was not altered in cows vals and relate pregnancy maintenance to the
hysterectomized within 2 4 hr after calving degree of involution at the time of insemina-
(Foote, 1 9 7 1 ) . Vital information in regard to tion or transfer are needed.
the role of the uterus in initiating postpartum Follicular activity begins soon after parturi-
estrous cycles might be obtained by observing tion (Morrow, 1969; Wagner and Hansel,
the intervals to ovulation and estrus in cows 1969; Moller, 1 9 7 0 b ) . T h e corpus luteum of
hysterectomized at calving. It had been pro- pregnancy is palpable for about 2 weeks post-
posed that the corpus luteum of pregnancy partum but does not prevent follicular develop-
might delay the onset of the first postpartum ment (Moller, 1970b; Wagner and Hansel,
estrus (McNutt, 1 9 2 7 ) ; however, Morrow 1 9 6 9 ) . Small corpora lutea, similar in size to
( 1 9 6 9 ) showed that the corpus luteum of
pregnancy is nonfunctional after parturition. 3
Progestogen (17a acetoxy — 11/3 methyl —
Apparently the ovaries do not affect the rate 19 norpreg — 4 — ene — 3, 20 — dione) used
in the Syncro-Mate B treatment of G. D. Searle
of uterine involution because Marion et al. and Co.
follicles during the first 3 weeks postpartum, dairy cows than in beef cows; however, this
occasionally are huried in the ovarian stroma difference has not been studied independent
(Moller, 1970b). Moller (1970b) suggested of nutritional level. Many dairy cows have an
that the early developing small corpora lutea ovulation without estrus before their first overt
were inactive and speculated that ovulations estrus (Morrow et ol., 1966; Marion and Cier,
leading to their formation were infertile. 1968; Callahan et al., 1971; Whitmore et al.,
Evidence indicates that the postpartum uter- 1974). In both beef and dairy cows, the corpus
us may influence ovulation. A high percentage luteum resulting from the first ovulation has
of ovulations in the first 20 days postpartum a short life span (Menge et al., 1962; Morrow,
occurs on the ovary opposite the previously 1969; Kiracofe et al., 1969). Perhaps the in-
gravid hom (Saiduddin et ol., 1967; Foote and voluting uterus could affect both the ovula-
Peterson, 1968; Kiracofe et al., 1969); how- tory pattern (i.e., which ovary is involved in
ever, Wagner and Hansel (1969) were unable ovulation) and the life span of the first corpus
to confirm these observations. Ovulations luteum after calving by a mechanism similar
which occur on the ovary opposite the previ- to that shown for uterine dilatation (Hansel
ously gravid horn are more numerous in dairy and Wagner, 1960). However, Ward et al.
cows than in beef cows, and conception at (1979) found that short cycles were frequent
first service is lower if ovulation occurs on the when calves were weaned from anestrous post-
ovary ipsilateral to the previously gravid horn partum cows as late as 68 days after calving
(Foote and Peterson, 1968). when uterine involution should have been
Table 1 lists estimates of the time required completed.
for uterine involution in early studies in which Many attempts have been made to elucidate
breeds were identified and the time of first ovarian function and reproductive hormone
ovulation and estrus were determined. The levels prior to resumption of estrous cycles
average postpartum interval to the first ovula- after calving. An increase in serum or blood
tion is less than that to the first estrus. Data progesterone level occurs in postpartum cows
presented from these early studies indicated before the first estrus (Donaldson et al., 1970;
first ovulation occurred from 35 to 60 days Erb et al., 1971; Henricks et al., 1972; Hum-
postpartum. Other studies, especially with phrey et al., 1976; Echtemkamp and Hansel,
dairy cows, have shown that ovulation oc- 1973; Tribble et al., 1973; Arije et al., 1974;
curred approximately 14 to 22 days postpar- Corah et al., 1974; Prybil and Butler, 1978;
tum (Menge et al., 1962; Morrow et al., 1966; LaVoie et al., 1980). LaVoie et al. (1980)
Marion and Cier, 1968; Callahan et al., 1971; found that when data from cows that had an
Morrow, 1971; Whitmore et al., 1974). The ovulation without estrus were removed, no cow
first postpartum ovulation occurs earlier in had a cyclic luteal phase pattern of preestrus
TABLE 1. EARLY STUDIES ON POSTPARTUM REPRODUCTIVE
FUNCTION IN THE BOVI~E SPECIES
Uterine First First
Reference Breed invol ution ovulation estrus
Casida and Wisnicky (1950) Holstein 28 35 63
Wiltbank and Cook (1958) Shorthorn" 56 53 84
Wiltbank and Cook (1958) Shorthorn" 44 36 M
Foote et al. (1960a) Hereford 44 38 59
Foote et al. (1960b) Angus 41 61 86
Foote et al. (1960b) Shorthorn 43 62 76
Ulberg and Lindley (1960) Hereford 46 38 46
Fosgate ei al. (1962) Holstein 28 45 51
Fosgate et al. (1962) Jersey 27 3.5 45
Foote and Hunter (1964) Hereford 47 44 49
Foote and Saiduddin (1964) Hereford 46 38 46
Saiduddin et al. (1968) Hereford 46 38 46
U T E R I N E I N V O L U T I O N AND P O S T P A R T U M INTERVALS 21
plasma progesterone, but all cows with normal however, suckling intensity or milk removal
postpartum estrous cycles had a preestrus in- appears to be the primary influence (Ward
crease in plasma progesterone level. T h e pro- et al, 1 9 7 9 ) .
gesterone increase was not associated with a Perhaps depressions in conception rate at
palpable corpus luteum. W a r d ( 1 9 7 8 ) demon- the first postpartum estrus have been affected
strated that most postpartum anestrous cows by formation of abnormal corpora lutea, failure
that were suckling a calf had a short estrous to maintain luteal tissue and other factors
cycle (7 to 11 days) if they exhibited the first rather than by delayed uterine involution. Un-
estrus within 12 days after the calf was weaned. der normal conditions, the involuting uterus
It appeared that ovulation did occur, but the appears to be a contributing factor to lowered
corpus luteum in most cases was not palpable fertility for approximately 4 0 days postpartum.
during the short cycle and the corpus luteum Lack of early large follicle development, ovula-
regressed before it was fully formed ( W a r d tion in the absence of behavioral estrus, the
et al, 1 9 7 9 ) . Corpora lutea induced by G n R H requirement of preestrus progesterone secre-
at 30 or 4 8 days postpartum in anestrous cows tion to establish cycle patterns, failure of the
also had a short life span (Lishman et al., first ovulation to result in a normal corpus
1 9 7 9 ) . Cows with a short estrous cycle did luteum and other factors may supercede the
not have a preestrus blood progesterone peak effects of the involuting uterus. In dairy cat-
in data reported b y Corah et al ( 1 9 7 4 ) and tle, in which ovulation frequently occurs be-
LaVoie et al. ( 1 9 8 0 ) . T h e preestrus blood fore day 2 0 , uterine involution certainly could
progesterone measured by many researchers contribute to infertility. However, a low per-
before the first postpartum estrus of a normal centage of cows displays an estrus accompany-
cycle may have come from a corpus luteum ing ovulation before day 2 0 and conception
formed from the first postpartum ovulation, before uterine sloughing would be difficult.
since the first ovulation in lactating cows is Once the uterine milieu returns to near the
sometimes unaccompanied by estrus and the nonpregnant condition (i.e., relatively sterile,
resulting corpus luteum has a short life span repaired, cleared of lochia, e t c . ) , there appears
(Ward et al, 1 9 7 9 ) . A source of preestrus to be no direct evidence that the uterus inter-
progesterone appears to be important to the feres with conception. Unless complications
resumption of normal cycles; however, the develop, the uterus is apparently repaired b y
source of this progeterone in the postpartum 4 0 days after calving.
cow has not been determined and may or may
not be different in postpartum cows and Ovine Species
prepuberal heifers. T h e source of preestrus
Uterine Involution and Associated Factors
progesterone in prepuberal heifers appears to
Affecting Fertility. Limited data are available
be from small stromal follicles that luteinized
on uterine involution in the ewe. However, the
(Berardinelli et al, 1 9 7 8 ) . Connor et al.
process appears to be similar to that in the
( 1 9 7 4 ) postulated that luteinization of fol-
cow, in that necrotic tissue over the caruncle
licles may be necessary to initiate the first
was very loosely attached b y day 15 postpar-
postpartum estrus with ovulation, and others
tum and was sloughed b y day 2 0 to 2 5 (Uren,
have suggested that luteal function may be
1 9 3 5 ) . Kohl ( 1 9 7 1 ) found shrinkage in uter-
deficient during early estrous cycles (Short et
ine size relatively complete and necrotic tissue
al., 1972; Edgerton and Hafs, 1 9 7 3 ) .
absent from the uterus by 25 days. Epithelium
Since the short life span of the first corpus had also regenerated from the uterine glands
luteum occurs independent of the time post- and intercaruncular areas. Caruncles were cov-
partum, uterine involution appears to have no ered with epithelium by 2 5 to 3 0 days. In-
role in early regression of the first corpus vestigators agree on description of involution
luteum unless a different mechanism is in- processes and the time they occur. T h e uterus
volved during the early postpartum period appears to be near its nonpregant state by 2 5
than is involved later. Lack of an overt estrus days after lambing (Uren, 1 9 3 5 ; Foote et al,
at the first postpartum ovulation is related to 1967; Foote, 1 9 6 8 ; Hulet, 1968; Kohl, 1 9 7 1 ;
deficient ovarian function (Whitemore et al, Jennings and Tisdall, 1974; Call et al, 1 9 7 6 ) .
1 9 7 4 ) . Nonstanding estrous behavior decreases Time of first ovulation after lambing has
as the postpartum interval increases (Saidud- not been adequately determined in the ewe.
din et al, 1968; LaVoie et al, 1 9 8 0 ) . Lack of Thus, the role of the uterus in regulating the
uterine involution could be a factor in sup- first postpartum ovulation is unknown. T h e
pressing ovarian function and, thus, estrus; first postpartum ovulation usually is not as-
sociated with estrus (Call et al, 1 9 7 6 ; Hulet, uterine weight remained fairly constant, ex-
1 9 7 9 ) . Estimates of the interval from lambing cept that Svajgr et al ( 1 9 7 4 ) reported that
to ovulation have ranged from 18 days (Hulet, involution time was slightly longer, with endo-
1 9 7 9 ) to approximately 3 5 days (Foote et metrial repair essentially complete beween 13
al, 1967; Hunter and Lishman, 1 9 6 7 ) unless and 17 days.
lambing occurred during seasonal anestrus. A T h e number of muscle cells of the myo-
review of postpartum anestrous intervals and metrium declines with involution, and muscle
factors that influence those intervals in ewes cell size and amount of connective tissue de-
was reported by Hunter ( 1 9 6 8 ) . T h e average creases (Graves et al., 1 9 6 7 ) . Palmer et al.
interval from lambing to first estrus was found ( 1 9 6 5 b ) found that the uterine epithelium,
to b e 3 5 days (Hulet, 1 9 7 9 ) ; however, the which is degenerated during the early post-
interval to conception was 44 days. Barker and partum period, started regenerating 7 days
Wiggins ( 1 9 6 4 ) found the postpartum interval postpartum and appeared complete by 2 1 days.
to conception to be about 8 0 days for Ram- T h e uterus involutes more rapidly in the sow
bouillet and 5 5 days for Dorset ewes. T h e than in the ewe or cow; the sow's lack of
single earliest postpartum conception reported necrotic tissue to be sloughed appears to be
has been 9 days, but average time of concep- the primary difference.
tion was greater than 4 0 days postpartum One cannot consider uterine involution and
(Hulet, 1 9 6 8 ) . its relation to postpartum fertility in the sow
Suckling inhibits estrus (Shevah et al., without considering weaning effects. To deter-
1 9 7 5 ) and ovulation (Foote et al, 1 9 6 7 ) . mine how quickly the uterus can support a
Since no difference in uterine involution rates new pregnancy, one must eliminate the sup-
was found between lactating and nonlactating pressing effect of suckling on the reproductive
ewes (Foote, 1 9 6 8 ) , the suckling effect on endocrine system. Morphologically and his-
resumption of estrous cycles apparently was tologically, uterine involution requires approxi-
not mediated through delayed uterine involu- mately 3 weeks. In the sow, however, uterine
tion. Follicles larger than 3mm in diameter size has decreased considerably and epithelial
began appearing on the ovaries after 10 days repair is well underway by 1 week postpartum.
postpartum, and the number of follicles ex- There is no evidence to suggest the extent of
ceeding 3mm remained constant after 14 or repair or reduction in size required before
2 0 days postpartum (Kohl, 1 9 7 1 ) . B y 2 0 days conception can occur in the postpartum sow.
postpartum, follicle growth and turnover were According to Polge ( 1 9 7 2 ) , uterine involution
normal. Ovaries appear capable of responding may not limit reproductive ability after par-
to gonadotropins relatively early postpartum turition because blastocyst attachment does not
(Hulet, 1 9 6 8 ) . However, the estrogen-induced occur until 12 to 13 days after ovulation.
luteinizing-hormone-release mechanism appears Hays et al. ( 1 9 7 8 ) found at 3 days post-
to recover relatively slowly after parturition mating that ovulation rate, ova recovered and
(Wright and Findlay, 1 9 7 7 ) . fertilization rate were not affected by length
Seasonal anestrus has been a complicating of lactation ( 6 , 12, 18, or 24 days). Generally,
factor in determining the influence of uterine ovulation and fertilization rates have been
involution on early postpartum fertility. T h e similar in sows bred before 2 1 days postpar-
uterus appears to be completely involuted b y tum and those bred later (Baker et al, 1953;
30 to 3 5 days after lambing, and no direct evi- Moody and Speer, 1 9 7 1 ; Svajgr et al., 1974;
dence is available to attribute low fertility Rampacek, 1974; Varley and Cole, 1 9 7 6 ) . Far-
after lambing to a lack of involution of the rowing rates were slightly lower in sows bred
uterus. Data concerning fertility at the first after 6- and 12-day lactations than in sows
ovulation after lambing, a time when uterine bred after 18- or 24-day lactations (Hays et
involution might be incomplete, is lacking. al, 1 9 7 8 ) . Pay ( 1 9 7 3 ) and Svajgr et al.
( 1 9 7 4 ) found that reductions in litter size
Porcine Species were more pronounced when sows were
Uterine Involution and Associated Factors weaned less than 7 days postpartum than in
Affecting Fertility. Numerous investigators those weaned later. Reduced litter size from
have reported similar decreases in uterine size sows bred less than 3 weeks postpartum has
until 3 weeks after farrowing (Palmer et al., been attributed to increased embryonic loss
1965a,b; Graves et al, 1967; Smidt et al., by Varley and Cole ( 1 9 7 6 ) and Svajgr et al.
1969; Svajgr et al, 1974; Varley and Cole, ( 1 9 7 4 ) . T h e involuting uterus may limit re-
1976; Hays et al, 1 9 7 8 ) . After 3 weeks, productive efficiency if the sow is bred less
UTERINE INVOLUTION AND POSTPARTUM INTERVALS 23
than 2 1 days postpartum. Embryo mortality histological study of the post partum bovine
uterus. J . Reprod. Fertil. 29:133.
rather than fertilization failure appears to
Arije, F. R., J . N. Wiltbank and M. L. Hopwood.
cause smaller litter size in sows bred early 1974. Hormone levels in pre- and post-parturient
postpartum. Hays et al. ( 1 9 7 8 ) concluded that beef cows. J . Anini. Sci. 39:338.
weaning pigs when they are 1 8 days old re- Baker, L. N., H. L. Woehling, L. E . Casida and
R. H. Grummer. 1953. Occurrence of estrus in
sults in maximum sow productivity in terms
sows following parturition. J . Anim. Sci. 12:33.
of the number of pigs produced per year. Barker, H. B. and E. L. Wiggins. 1964. Estrual
Other data also indicate that weaning less activity in lactating ewes. J . Anim. Sci. 23:973.
than 3 weeks after farrowing increases the in- Berardinelli, J . G., R. L. Butcher and R. A. Daily.
1978. Source of progesterone prior to puberty
terval from weaning to estrus, reduces litter
in beef heifers. Beltsville Symp. in Agr. Res.
size, and increases both frequency of cystic (BARC) III. Anim. Reprod. (Abstr.).
follicles and embryo mortality (Baker et al., Bhalla, R. C , B. K. Soni and D. P. S. Sengai.
1953; Self and Grummer, 1 9 5 8 ; Smidt et al., 1966. Studies on reproduction in Murrah buf-
1965; Moody et al, 1 9 6 9 ; Peters et al, 1969; faloes. II. Involution of the uterus. Indian Vet.
J . 43:892.
van der Heyde, 1972; Cole et al., 1975; Hays Boyd, W. L. 1925. A study of the physiological
et al, 1 9 7 8 ) . and pathological changes occurring in the re-
Attempts to accelerate normal postpartum productive organs of the cow following parturi-
uterine involution in the sow have been unsuc- tion. Minnesota Agr. Exp. Sta. Bull. No. 23.
Boyd, L. J . 1970. Effects of feeding melengestrol
cessful. Hayes et al. ( 1 9 7 8 ) found no change acetate (MGA) on occurrence of estrus fertility
in involution rate after administration of pro- and milk yield in dairy cows. J . Anim. Sci. 3 1 :
staglandin or aspirin. 751.
If uterine involution is a limiting factor in Britt, J . H., E . Huertas-Vega and L. C. Ulberg.
1972. Managing reproduction in dairy cattle.
reproductive efficiency in the sow, the limiting 1. Progrestogens for control of estrus in dairy
factor is an unsuitable milieu for embryo sur- cows. J . Dairy Sci. 55:598.
vival for approximately the first 3 weeks after Britt, I. H., R. I. Kittok and D. S. Harrison.
farrowing. Segerson and Murray ( 1 9 7 8 ) have 1974a. Ovulation, estrus, and endocrine response
after GnRH in early postpartum cows. J. Anim.
shown that the uterus may not be completely Sci. 39:915.
functional until 3 to 4 weeks postpartum be- Britt, J . H., D. A. Morrow, R. J . Kittok and B.
cause the percentage and quantity of uterine- E . Seguin. 1974b. Uterine involution, ovarian
specific acidic proteins secreted before this activity, and fertility after melengestrol acetate
and estradiol in early postpartum cows. J . Dairy
stage were lower than at later stages. Total Sci. 57:89.
uterine protein per corpus luteum, percentages Brown, J . G., D. W. Peterson and W. D. Foote.
of uterine serum-like protein, total uterine- 1972. Reproductive response of beef cows to
specific acidic protein were all significantly af- exogenous progestogen, estrogen and gonado-
tropins at various stages of postpartum. J . Anim.
fected by postpartum interval. Whether these Sci. 35:362.
secretions contribute to embryonic survival or Buch, N. C , W. J . Tyler and L. E . Casida. 1955.
mortality during the early postpartum period Postpartum estrus and involution of the uterus
or are associated with involutionary changes in an experimental herd of Holstein-Fresian
cows. J . Dairy Sci. 38:73.
in the uterus has not been established. There
Call, T. W., W. C. Foote, C. D. Ecker and C. V.
seems to be little doubt, however, that repro- Hulet. 1976. Postpartum uterine and ovarian
ductive efficiency is impaired in sows bred changes, and estrous behavior from lactation
early postpartum even though the role of the effects in normal and hormone treated ewes.
uterus is not clear.
Callahan, C. J., R. E. Erb, A. H. Surve and R . D .
Randel. 1971. Variables influencing ovarian
Literature Cited cycles in postpartum diary cows. J . Anim. Sci.
Albrechtsen, J. 1917. Sterility of cattle and meth-
Casida, L. E., W. E . Graves, J . W. Lauderdale,
ods of treatment. Cornell Vet. 7:57. J. W. Riesen, S. Saiduddin, E . R. Hauser and
Anderson, L. L., D. L. Hard, L. S. Carpenter and W. J. Tyler. 1968. Studies on the postpartum
E. E. Awotwi. 1979. Pregnancy, parturition and cow. Res. Bull. 270. Univ. of Wisconsin, Madi-
ovarian function after hypophysial stalk tran- son.
section in beef heifers. The Endocrine Society Casida, L. E. and W. G. Venzke. 1936. Observa-
61st Annu. Meet. 126. tions on reproductive processes in dairy cattle
Araujo, P. C , G. N. Pizelli, M. R. de Carvalko and their relation to breeding efficiency. Proc.
and C. A. Menegnelli. 1974. Postpartum uterine of Amer. Soc. Anim. Prod. 36:221.
involution and ovarian activity in crossbred Casida, L. E . and W. Wisnicky. 1950. Effects of
dairy cattle. Pesq. Agropec. Boras. Ser. Vet. 9 : 1 . diethylstilbestrol dipropionate upon postpartum
Archbald, L. F., R. H. Schultz, M. L. Fanning, changes in the cow. J . Anim. Sci. 9:238.
H. I. Kurtz and R. Zemjanis, 1972. A sequential Clemente, P. F., R. E . Short, R. B. Staigmiller and
R. A. Bellows. 1978. Effect of precalving nutri- ovulation, estrus and uterine involution in the
tion, early weaning, CB-154, and antiprolactin ewe. J . Anim. Sci. 26:943 (Abstr.).
treatment on postpartum interval length in beef Foote, W. D., E. R. Hauser and L. E. Casida.
cows. J . Anim. Sci. 47(Suppl. 1 ) : 3 5 1 . 1960a. Some causes of variation in postpartum
Cole, D. J . A., M. A. Varley and P. E. Hughes. reproductive activity in Hereford cows, J . Anim.
1975. The effect of lactation length on the Sci. 19:238.
subsequent reproductive performance of the Foote, W. D., E. R. Hauser and L. E. Casida.
sow. Anim. Prod. 20:401. 1960b. Influence of progesterone treatment on
Connor, J . S., R. L. Tribble, T. L. Woodward, J. postpartum reproductive activity in beef cattle.
L. Fleeger, J . R. Beverly and A. M. Sorensen, J. Anim. Sci. 19:674.
Jr. 1974. Postpartum ovarian activity in first- Foote, W. D. and J. E. Hunter. 1964. Postpartum
calf Hereford heifers. Beef Cattle Research in intervals of beef cows treated with progesterone
Texas. Texas Agr. Exp. Sta. Progress Rep. 3216. and estrogen. J. Anim. Sci. 23:517.
Corah, L. R., A. P. Queely, T. G. Dunn and C. Foote, W. D. and D. W. Peterson. 1968. Rela-
C. Kaltenbach. 1974. Prepartum and postpartum tionship between side of pregnancy and side of
levels of progesterone and estradiol in beef subsequent ovarian activities in beef and dairy
heifers fed two levels of energy. J . Anim. Sci. cattle. J . Reprod. Fertil. 16:415.
39:380. Foote, W. D. and S. Saiduddin. 1964. Hormone
Dawson, F . L. M. 1950. The microbial content treatment of postpartum beef cows. J. Anim.
and morphological character of the normal Sci. 23:592 (Abstr.).
bovine uterus and oviduct. J . Agr. Sci. (Camb.) Fosgate, O. T., N. W. Cameron and R. J. McLeon.
40:150. 1962. Influence of 17-alpha-hydroxyprogesterone-
Donaldson, L. E., J . M. Bassett and G. D. Thorn- n-caproate upon postpartum reproductive activ-
burn. 1970. Peripheral plasma progesterone con- ity in the bovine. J . Anim. Sci. 21:791.
centration of cows during puberty, oestrus cy- Frieden, E. H. and F. L. Hisaw. 1953. The bio-
cles, pregnancy and lactation and the effects chemistry of relaxin. Rec. Prog. Horm. Res;
of undernutrition and exogenous oxytocin on 8:333.
progesterone concentration. J . Endocrinol. 4 8 : Fuquay, J . W., R. H. Harris, W. H. McCee, J . F.
599. Beatty and B. L. Arnold. 1975. Routine post-
partum treatment of dairy cattle with intra-
Dunn, T. G. 1964. Influence of energy intake uterine neomycin sulfate boluses. J. Dairy Sci.
upon reproductive performance and milk pro- 58:1367.
duction of 2-year-old beef heifers. M. S. Thesis, Gier, H. T. and G. B. Marion. 1968. Uterus of
Univ. of Nebraska, Lincoln. cow after parturition: Involutional changes.
Dunn, T. G., J . E. Ingalls, D. R. Zimmerman and Amer. J . Vet. Res. 29:83.
J. N. Wiltbank. i969. Reproductive perfor- Gospodinov, G. and L. Rostov. 1976. Clinical and
mance of 2-year-old Hereford and Angus heifers endocrinological studies on the puerperium in
as influenced by pre- and post-calving energy cows. Veterinarnomeditsinski Nauki 13:93.
intake. J . Anim. Sci. 29:719. Graden, A. P., O. Olds, C. R. Mockow and L. R.
Echternkamp, S. E. and W. Hansel. 1973. Con- Mutter. 1968. Causes of fertilization failure in
current changes in bovine plasma hormone levels repeat breeding cattle. J . Dairy Sci. 51:778.
prior to and during tire first postpartum estrous Graves, W. E., J. W. Lauderdale, R. L. Kirkpa-
cycle. J. Anim. Sci. 37:1362. trick, N. L. First and L. E. Casida. 1967. Tissue
Edgerton, L. A. and H. D. Hafs. 1973. Serum changes in the involuting uterus of the post-
luteinizing hormone, prolactin, glucocorticoid partum sow. J . Anim. Sci. 26:365.
and progestin in dairy cows from calving to Griffin, J . F. T., P. J. Hartigan and W. R. Nunn.
gestation. J . Dairy Sci. 56:451. 1974. Non-specific uterine infection and bovine
El-Fouly, M. A., E . A. Kotby and H. E. El-Sobhy. fertility. Theriogenology 1:91.
1976. Effect of suckling on uterine and cervical Gunter, J. J., W. J. Collins, J. Owen, A. M. Soren-
involution in post-partum Egyptian buffaloes. sen, J . W. Scales and J. A. Alford. 1955. A
Indian J . Anim. Sci. 46:221. survey of the bacteria in the reproductive tract
Elliot, L., K. J . McMahon, H. T. Gier and G. B. of dairy animals and their relationship to in-
Marion. 1968. Uterus of the cow after parturi- fertility. Amer. J. Vet. Res. 16:282.
tion: bacterial content. Amer. J . Vet. Res. 29:77. Hansel, W. and W, C. Wagner. 1960. Luteal in-
Erb, R. E., A. H. Surve, C. J . Callahan, R. D. hibition in the bovine as a result of oxytocin
Randel and H. A. Garverick, 1971. Reproductive injections, uterine dilation, and intrauterine in-
steroids in the bovine. VII. Changes postpartum. fusions of seminal and preputial fluids. J. Dairv
J. Anim. Sci. 33:1060. Sci. 43:796.
Fernandes, L. C., W. W. Thatcher, E. P. Call, Harkness, M. L. R. and R. D. Harkness. 1954.
C. J . Wilcox. 1978. Responses to PGF „ and: The collagen content of the reproductive tract
GnRH in postpartum dairy cows, J . Anim. Sci. of the rat during pregnancy and lactation. J .
47 (Suppl. 1):359. Physiol. 123:492.
Foote, W. C. 1968. Control of reproduction with Harkness, R. D. and B. E . Moralee. 1956. The
or without hormones. Proc. Symp. on Physiol, time course and route of loss of collagen from
of Reprod. in Sheep Amer. Sheep Prod. Council the rat's uterus during post-partum involution.
and USDA, Beltsville. J. Physiol. 132:502.
Foote, W. D. 1971. Endocrine changes in the Hayes, S. H., L. A. Edgerton, G. L. Cromwell, T.
bovine during the postpartum period. J. Anim. S. Stahly and R. H. Dutt. 1978. Prostaglandin
Sci. (Suppl. I ) 32:73. Fi effect upon rate of uterine involution in
Foote, W. C , J . W. Call and C. V. Hulet. 1967. postpartum gilts. J . Anim. Sci. 47(Suppl. l ) :
Effects of lactation and hormone treatment on 365.
U T E R I N E INVOLUTION AND POSTPARTUM INTERVALS 25
Hays, V. W., J. L. Krug, G. L. Cromwell, R. H. apy postservice in infertile dairy cattle. J . Amer.
Dutt and D. D. Kratzer. 1978. Effect of lacta- Vet. Med. Assoc. 120:12.
tion length and dietary antibiotics on reproduc- Lishman, A. W., S. M. J . Allison, R. L. Fogwell,
tive performance of sows, J . Anim. Sci, 46:884. R. L. Butcher and E . K. Inskeep. 1979. Folli-
Henderson, K. A. 1978. Conception rates of beef cular development and function of induced
cows synchronized at different post-partum in- corpora lutea in underfed postpartum anestrous
tervals. J . Anim. Sci. 47(Suppl, 1 ) : 3 6 5 . beef cows. J . Anim. Sci. 48:867.
Henricks, D. M., J . F. Dickey, J . R. Hill and W. Marion, G. B. and H. T. Gier. 1968. Factors af-
E. Johnston. 1972. Plasma estrogen and proges- fecting bovine ovarian activity after parturition.
terone levels after mating and during late preg- J . Anim. Sci. 27:1621.
nancy and in postpartum cows. Endocrinology Marion, G. B., J . S. Norwood and H. T. Gier.
90:1336. 1968. Uterus of the cow after parturition: Fac-
Hilty, H. 1908. Untersuchungen iiber die evolu- tors affecting regression. Amer. J . Vet. Res.
tion and involution der uterus mucosa vom rind. 29.71.
Schweiz Arch. f. Tierheilk. 50:353. McNutt, G. W. 1927. The corpus luteum of preg-
Homan, A. E . 1969. The effect of nitrofurazone nancy in the domestic cow (Bos Taurus) and
and proteolytic enzymes on the postpartum bo- a brief discussion of cyclical ovarian changes.
vine uterus. M. S. Thesis, Kansas State Univ., J. Amer. Vet. Med. Assoc. 72:286.
Manhattan. Menge, A. C , S. E. Mares, W. J. Tyler and L. E.
Huertas-Vega. E., J . H. Britt and L. C. Ulberg. Casida. 1962. Variation and association among
1972. Svstem managing reproduction in dairy postpartum reproduction characteristics in Hol-
cattle, j ' Dairy Sci. 55:401 (Abstr.). stein-Fresian cattle. J . Dairy Sci. 45:233.
Hulet, C. V. 1968. Factors affecting fertility in Mohamed, A. A. 1974. Physiological changes in
the ewe and ram. Proc. Symp. on Physiol, of the reproductive organs of buffaloes from par-
Reprod. in Sheep. Amer. Sheep Prod. Council turition to conception. Ph.D. Thesis, El-Azhar
and USDA, Beltsville. Univ., Cairo, Egypt.
Hulet, C. V. 1979. Reproduction in Sheep. In Moller, K. 1970a. A review of uterine involution
Reproduction in Farm Animals. E. S. E . Hafez, and ovarian activity during the postparturient
Ed. 4th Ed., Lea & Febiger. (In press). period in the cow. New Zealand Vet. J . 18:83.
Humphrey, W. D., D. R. Koritnik, C. C. Kalten- Moller, K. 1979b. Uterine involution and ovarian
bach, T. G. Dunn and G. D. Niswender. 1976. activity after calving. New Zealand Vet. J . 18;
Progesterone and LH in postpartum suckled 140.
beef cows. J . Anim. Sci. 43:290 (Abstr.). Moody, N. W., D. S. Baker, V. W. Hays and V.
Hunter, G. L, 1968. Increasing the frequency of C. Speer. 1969. Effect of reduced farrowing
pregnancy in sheep. I. Some factors affecting re- interval on sow productivity. J . Anim. Sci. 28:
breeding during the post-partum period. Anim. 76.
Breed. Abstr.36:347. Moody, N. W. and V. C. Speer. 1971. Factors af-
Hunter, G. L. and A. W. Lishman. 1967. Post- fecting sow farrowing interval. J . Anim. Sci.
partum ovulation and estrus in spring lambing 32:510.
ewes. J. Reprod. Fertil. 14:473. Morrow, D. A. 1969. Postpartum ovarian activity
Jennings. J. and G. Tisdall. 1974. Uterine involu- and involution of the uterus and cervix in dairy
tion in the postpartum ewe. An Foras Talun- cattle. Vet. Scope Vol. 14 No. 1 The Upjohn
tais Research Rep., Co. Meath, Ireland. Co. p. 2.
Johanns, G. J., T. L. Clark and J . B. Herrick. Morrow, D. A. 1971. Effects of periparturient
1967. Factors affecting calving interval. J . disease on post-partum reproduction in dairy
Amer. Vet. Med. Assoc. 151:1692. cattle. J . Anim. Sci. 32 (Suppl. I ) : 1 7 .
Jordan, W. S. 1952. The puerperium of the cow: Morrow, D. A., S. J . Roberts and K. McEntee.
A study of uterine motility. J . Comp. Path, and 1969. A review of postpartum ovarian activity
Therapy 62:54. and involution of the uterus and cervix in cat-
Kiracofe, G. H., G. R. Brower and R. R. Schalles. tle. Cornell Vet. 59 (No. 1):134.
1973a. Effects of various uterine treatments on Morrow, D. A., S. J . Roberts, K. McEntee and
calving-to-conception interval. Kansas Agr. Exp. H. G. Gray. 1966. Postpartum ovarian activity
Sta. Bull. 568. and uterine involution in dairy cattle. J . Amer.
Kiracofe, G. H., A. E. Homan, G. B. Marion, H. Vet. Med. Assoc. 149:1596.
T. Gier and R. R. Schalles. 1973b. Post-calving Norwood, J. W. 1963. Factors affecting postpar-
intrauterine infusion of nitrofurazone and en- tum regression of the bovine uterus. Ph.D.
zymes. J . Anim. Sci. 37:318 (Abstr.). Thesis, Kansas State Univ., Manhattan.
Kiracofe, G. H., R. R. Schalles and G. B. Marion. Odde, K. G. and G. H. Kiracofe. 1978. Effect of
1969. Effect of wintering ration on reproductive postpartum breeding interval on conception
phenomena in beef cows on range. Kansas Agr. rates in beef cows, Kansas Agr. Exp. Sta. Bull.
Exp. Sta. Bull. 529. 320.
Kohl, L. E. 1971. Uterine involution and post- Olds, D. and T. Cooper. 1970. Effect of postpar-
partum conception in the ewe. M. S. Thesis, tum rest period in dairy catde on the occur-
Kansas State Univ., Manhattan. rence of breeding abnormalities and on calving
LaVoie, V., D. K. Han, D. B. Foster and E. L. intervals. J . Amer. Vet. Med. Assoc. 157:92.
Moody. 1980. Suckling effect on estrus and Olds, D., H. B. Morrison and D. M. Seath. 1949.
blood plasma progesterone in postpartum beef Efficiency of natural breeding in dairy cattle,
cows. J. Anim. Sci. (In press). Kentucky Agr. Expt. Sta. Bull. 539.
Lindley, D. C. 1954. Intra-uterine antibiotic ther- Oxender, W. D. and B. E. Seguin. 1976. Bovine
intrauterine therapy. J . Amer. Vet. Med. Assoc. pregnancy on postpartum function in the cow.
168:217. J . Dairy Sci. 50:1846.
Oxenreider, S. L. and W. C . Wagner. 1971. Ef- Segerson, E . C. and F. A. Murray. 1978. Uterine
fect of lactation and energy intake on postpar- protein secretions in postpartum sows. J. Anim.
tum ovarian activity in die cow. J . Anim, Sci. Sci. 46:1730.
33:1026. Seguin, B. E., D. A. Morrow and W. D. Oxender.
Palmer, W. M., H. S. Teague and W. G. Venzke. 1974. Intrauterine therapy in the cow. J . Amer.
1965a. Macroscopic observations on the repro- Vet. Med. Assoc. 164:609.
ductive tract of sows during lactation and early Self, H. F . and R. H. Grummer. 1958. The rate
weaning. J . Anim. Sci. 24:541. and economy of pig gains and the reproductive
Palmer, W. M„ H. S. Teague and W. G. Venzke. behavior in sows when litters are weaned at
1965b. Histological changes in the reproductive 10 days, 21 days, or 56 days of age. J . Anim.
tract of the sow during lactation and early post- Sci. 17:862.
weaning. J . Anim. Sci. 24:1117. Shevah, V., W. J . M. Black and R. B. Land. 1975.
Pay, M. G. 1973. The effects of short lactations The effects of nutrition on the reproductive
on the productivity of sows. Vet. Rec. 92:255. performance of Finn x Dorset ewes. II. Post-
Perkins, J . L. and H. E. Kidder. 1963. Relation partum ovarian activity, conception and plasma
of uterine involution and postpartum interval to concentrations of progesterone and LH. J. Re-
reproductive efficiency in beef cattle. J . Anim. prod. Fertil. 45:289.
Sci. 22:313. Short, R. E., R. A. Bellows, E . L. Moody and B.
Peters, J . B., R. E. Short, N. L. First and L. E . E. Howland. 1972. Effects of suckling and
Casida. 1969. Attempts to induce fertility in mastectomy on bovine postpartum reproduction.
postpartum sows. J . Anim. Sci. 29.20. J . Anim. Sci. 34:70.
Polge, C. 1972. The endocrinology of the sow in Smidt, D., B. Schwven and J . Steinbach. 1965.
relation to early weaning. Proc. Symp, on Im- The influence of lactation on sexual functions
provement of Sow Productivity. Rowett Res. in sows. Zuchtungdkunde 37:23.
Inst., Aberdeen, Scotland. Smidt, D., O. Thume and W. Jockle. 1969. In-
Prybil, M. K. and W. R. Buder. 1978. The rela- vestigations on sexual regeneration postpartum
tionships between progesterone secretion and in suckling and non-lactating sows. Zuchtung-
the initiation of ovulation in postpartum beef skunde 41:36.
cows. J . Anim. Sci. 47(Suppl. 1 ) : 3 8 3 . Studer, E. and D, A. Morrow. 1978. Postpartum
Quevedo, M. M„ S. Saiduddin and W. D. Foote. evaluation of bovine reproductive potential:
1965. Influence of estradiol on reproductive ac- comparison of findings from genital tract ex-
tivity in postpartum dairy cows. J . Anim. Sci. amination per rectum, uterine culture, and en-
24:587 (Abstr.). dometrial biopsy. J . Amer. Vet. Med. Assoc.
Radford, H. M., C. D. Nacarrow and P. E . Matt- 172:498.
ner. 1978. Ovarian function in suckling and non- Svajgr, A. J., V. W. Hays, G. L. Cromwell and
suckling beef cows postpartum. J . Reprod. R. H. Dutt. 1974. Effect of lactation duration
Fertil. 54:49. on reproductive performance of sows. J. Anim.
Rampacek, G. B. 1974. Investigations into repro- Sci. 38:100.
duction in the pre-puberal gilt, the early- Tennant, B., J. W. Kendrick and R. G. Peddicord.
weaned sow and uterine capacity in the female 1967. Uterine involution and ovarian function
pig. Ph.D. Thesis, North Carolina State Univ., in die postpartum cow. A retrospective analysis
Raleigh. of 2,338 genital organ examination. Cornell Vet.
Randel, R. D. and G. A. Welker. 1977. Effect of 57:543.
energy intake and once daily suckling on post- Tennant, B. and R. G. Peddicord. 1968. Influence
partum interval in Brahham x Hereford heifers. of delayed uterine involution and endometritis
J. Anim. Sci. 45 (Suppl. 1 ) : 1 9 8 . on bovine fertility. Cornell Vet. 58:185.
Rasbeck, N. O. 1950. Den normale involutio uteri Tribble, R. L., A. M. Sorensen, Jr., T. L. Wood-
hos koen. Nord. Vet. Med. 2:655. ard, J . S. Connor, J . R. Beverly and T. L. Flee-
Riek, P. M., N. Butendieck, E . A. B. Oltenacu ger. 1973. Serum progestins and luteinizing
and R. H. Foote. 1977. Response of early post- hormone levels in non-suckled primiparous
partum dairy cows to GnRH. J . Anim. Sci. 4 5 heifers. Nature 246:495.
(Suppl. 1 ) : 2 0 1 . Tudorascu, R, 1969. Investigations concerning the
frequency of embryonic mortality in cows in-
Riesen, J . W. 1968. The effects of suckling on
seminated at different postpartum intervals.
reproductive function in postpartum dairy cows
Anim. Breed. Abstr. 37:55.
—pituitary prolactin, corpora lutea, and uterine
Ulberg, L. C, and C. E. Lindley. 1960. Use of
histology. Ph.D. Thesis, Univ. of Wisconsin,
progesterone and estrogen in the control of
reproductive activities in beef catde. J . Anim.
Roberts, S. J . 1956. Veterinary obstetrics and Sci. 19:1132.
genital diseases. P. 123. Published by the Uren, A. W. 1935. Involution of the uterine mu-
author. Ithaca, NY, cosa in the ewe. Michigan State Coll. of Agr.
Saiduddin, S., W. D. Foote and M. M. Quevedo. and Appl. Sci. Tech. Bull. No. 144.
1968. Response of beef cows to exogenous pro- Van Demark, N. L. and G. W. Salisbury. 1950.
gesterone and estradiol at various stage postpar- The relation of the post-partum breeding in-
tum. J . Anim. Sci. 27:1015. terval to reproductive efficiency in the dairy
Saiduddin, S., J . W. Riesen, W. J . Tyler and L. cow. J . Anim. Sci. 9:307.
E . Casida. 1967. Some carry-over effects of van der Heyde, H. 1972. A practical assessment
U T E R I N E INVOLUTION AND POSTPARTUM INTERVALS 27
of early weaning. Proc. Brit. Soc. Anim. Prod. intensity on reproductive performance of range
1:33. cows. J . Anim. Sci. 47:342.
Variey," M. A. and D. J . A. Cole. 1976. Studies Whitmore, H. L., W. J . Tyler and L. E. Casida.
in sow reproduction. 5. The effect of lactation 1974. Effect of early postpartum breeding in
length of the sow on the subsequent embryonic dairy catde. J . Anim. Sci. 38:339.
development. Anim. Prod. 22:79. Wiltbank, J . N. and A. C. Cook. 1958. The com-
Venable, J . H. and L. E. McDonald. 1958. Post- parative reproductive performance of nursed
parturient bovine uterine motility—normal and milked cows. J . Anim. Sci. 17:640.
after experimentally produced retention of fetal Wiltbank, J . N., N. W. Rowden, J . E. Ingalls, K.
membranes. Amer. J . Vet. Res. 19:308.
E . Gregory and R. M. Koch. 1962. Effects of
Wagner, W. C. and W. Hansel. 1969. Reproduc-
energy level on reproductive phenomena in ma-
tive physiology of the postpartum cow. J . Re-
prod. Fertil. 18:493. ture Hereford cows, J . Anim. Sci. 21:219.
Ward, H. S. 1978. The effects of Syncro-Mate B Woessner, J. F. 1969. Inhibition by oestrogen of
and/or calf management on reproductive per- collagen breakdown in the involuting rat uterus.
formance in the beef cow. M. S. Thesis, Kansas Biochem. J . 112:637.
State Univ., Manhattan. Wright, P. I. and J . K. Findlay. 1977. LH release
Ward, H. S., K. C. Odde, C. H. Kiracofe and R. due to LH-RH or oestradiol-17 beta in postpar-
M. McKee, 1979. Short estrous cycles after tum ewes. Theriogenology 8:191.
weaning in anestrous beef cows. J . Anim. Sci. Wulf, F. F. and A. E. Draey. 1952. A survey of
49(Suppl. 1):345. the microflora obtained by flushing the normal
Wettemann, R. P., E. J . Turman, R. D. Wyatt bovine uterus. Proc. South Dakota Acad. Sci.
and R. Totusek. 1978. Influence of suckling 31:116.
Question: Dr. Bellows Cooper ( J . Amer. Vet. Med. Assoc. 1 5 7 :
Your paper was very interesting, but I am 9 2 ) . I think data can be found both ways;
not sure if I followed one point that you some have reported no effect and others
made regarding the reason for short cycles. indicate a detrimental effect.
Specifically, in relation to the size of the Question: Dr. Pickett
follicle from which the C L was derived. If
I understand you correctly, you were imply- Do you think it has an effect?
ing that the size of the ovulating follicle Dr. Kiracofe: In my opinion there is no effect,
was involved here? although I do not have the data to support
that opinion. I do not feel that breeding
Dr. Kiracofe: I do not think size of the ovulat-
cows during the early postpartum period
ing follicle is playing a role in short cycles
effects subsequent fertility.
in our data. In that respect, I was referring
to the research of Moller in Australia, who Question: Dr. Pickett
observed luteinized stromal follicles in post-
partum cows. I think they were similar to Is there a possibility that there is a differ-
the luteinization noted b y the West Virginia ence between dairy and beef cattle in this
investigators in prepuberal heifers. T h e data regard?
of Berardinelli et al. at West Virginia indi- Dr. Kiracofe: There could be. B y putting se-
cates that these are stromal follicles that are men in the early postpartum uterus there
small and luteinized. However, in postpar- may be a chance of causing an inflammatory
tum cows we do not feel that it was a response or low grade bacterial infection.
small follicle that ovulated. Since the dairy cow tends to ovulate earlier,
many times before uterine involution is com-
Question: Dr. Pickett
plete, she could be more susceptible.
D o you have any information on the effect
Question: A Questioner
on subsequent fertility of those animals that
were bred early, say quite soon after par- On the basis of our knowledge of follicular
turition, and did not conceive? development, is it not true that follicles
have to pass through a certain stage before
Dr. Kiracofe: I do not have any data on the
they will ovulate and that the size of the
effect of early postpartum insemination on
follicles that ovulate really is fairly consis-
subsequent fertility. I think there are some
tent within species?
in the literature, particularly the earlier re-
search of Van Demark and Salisbury ( J . Dr. Kiracofe: That may be true in cycling
Anim. Sci. 9 : 3 0 7 ) and that of Olds and animals where definite endocrine patterns
exist, but in animals that are ovulating for matter of observing small luteinized follicles
the first time in their life or after a pro- or corpora lutea in the ovary.
longed period of anestrus, such as postpar- Question: A Questioner
tum animals, it could be different. In the
In these luteinized follicles, were ova
case of prepuberal heifers, the follicle is
trapped in them or were they actually small
probably luteinizing without ovulation; how-
ever, our limited data in the postpartum
cow indicate she does ovulate, but we do Dr. Kiracofe: Maybe there is someone here
not know anything about the size of follicle. who could comment on the West Virginia
Question: A Questioner
Question: Dr. Lauderdale
T h e evidence is that the corpora lutea are You are talking about short cycles, there-
smaller that develop from these ovulations. fore, the corpus luteum ( C L ) has obtained
Did you find any of these small follicles or its lifespan and the discussion so far has
follicles of large size prior to the ovulation? indicated what I would refer to as an in-
What kind of evidence is there for smaller herent decrease in its lifespan. Does the CL
follicles ovulating? have an inherent lifespan, and with short
Dr. Kiracofe: I may be misinterpreting your cycles is the inherent lifespan of the C L
altered or is there a "superluteolytic" factor
Downloaded from jas.fass.org by guest on June 12, 2011
question. All data that we have with respect
in the postpartum animal?
to the postpartum cow indicate the corpus
luteum is normal size at day 4 of the short Dr. Kiracofe: W e have investigated this to
cycle and that short cycles are a result of some extent. T h e data are incomplete so
failure to maintain the corpus luteum, not far, but I think that in this respect an in-
a result of small follicles that luteinize. T h e herent lifespan might be a possibility. I
only evidence where there is a possibility think that the inherent lifespan would be
of ovulation of small follicles, is in the cases due to a lack of gonadotropin or lack of a
I indicated, i.e., the prepuberal heifers in luteotropic substance rather than a luteolytic
the research at West Virginia or the research factor. However, we have not tested the
of Moller in Australia, and this is just a luteolytic aspect.
Citations This article has been cited by 1
Downloaded from jas.fass.org by guest on June 12, 2011