Short estrous cycles and associated serum progesterone levels in beef cows

THERIOGENOLOGY

SHORT ESTROUS CYCLES AND ASSOCIATED SERUM PROGESTERONE LEVELS IN BEEF COWSayb K. G. Oddec,

H. S. Wardc,

G. H. Kiracofec,

R. M. McKeeC and

R. J. Kittokd Department of Animal Sciences and Industry, Kansas State Manhattan, Kansas 66506 and Department of Animal Science, of Nebraska, Lincoln 68583 Received

for

publication:

University, University

3/19/80

ABSTRACT Short estrous cycles in beef cows were investigated in two experiments. In trial 1, breeding dates from 2,854 fall-calving Angus cows were used to determine the incidence of short estrous cycles. Of 198 cycles of less than 17 days, 170 were between the first and second detected estrus. Estrous cycles of 7 to 10 days occurred more frequently (Pc.005) than other short estrous cycles. Eight-day estrous cycles were most frequent. In the second experiment, calves were weaned from 25 of 33 anestrous spring-calving, crossbred Simmental cows. Compared to herdmates still nursing calves, an increased percentage of cows which had calves weaned were observed in estrus within 10 and 25 days after the date of weaning (Pc.005) and a higher percentage had 7- to lo-day estrous cycles. Cows that were observed in estrus within 10 days after weaning were inseminated with Angus semen at their first estrus and with Simmental semen at their second estrus. No cows conceived on the first estrus of 7- to lo-day estrous cycles; 61.5% conceived on the second estrus. Serum progesterone was higher (Pc.01) before the second estrus than the first. INTRODUCTION Increased use of artificial insemination in the beef industry has increased awareness of estrous-cycle lengths, which normally range from 17 to 24 days (1). In dairy cows, the most frequent length of estrous cycles of less than 17 days was 8- to lo-day (2). Ward (3) observed that 78% of the postpartum anestrous beef cows that exhibited estrus within 10 days after weaning returned to estrus within 7 to 10 days. aContribution No. 80-143-J, Department of Animal Sciences and Industry, Kansas Agricultural Experiment Station, Manhattan 66506. b Paper No. 5945, Journal Series, Nebraska Agricultural Experiment Station, Lincoln 68583. 'Department Manhattan d Department

of Animal 66506.

Sciences

and Industry,

of Animal

Science,

University

AUGUST 1980 VOL. 14 NO. 2

Kansas of Nebraska,

State

University,

Lincoln

68583.

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THERIOGENOLOGY

The objectives of this study were: 1) to determine the incidence and most frequent length of short estrous cycles in beef cattle, and 2) to characterize the incidence, serum progesterone and conception rates associated with short estrous cycles induced by weaning calves from lactating anestrous beef cows. MATERIALS AND METHODS Experiment 1. in the Ramsey Ranch the period from 1970 incidence of estrous data were subjected

Breeding dates from 2,854 fall-calving Angus cows herd, El Dorado, Kans., were obtained and included to 1972. These were utilized to determine the cycles of less than 17 days. Estrous-cycle-length to chi-square analysis.

not being detected in estrus during twice-daily Experiment 2. After observations for 5 weeks nor having a palpable corpus luteum on May 10, 1978, 33 spring-calving, crossbred Simmental cows that were 19 to 68 days postpartum were selected for the experiment. On May 10, the calves were weaned from 25 of the 33 cows. The remaining eight cows were suckled ad libitum by their calves. The day of weaning was designated day 0 forame. After weaning, the cows were observed thrice daily for signs of estrus. Cows were artificially inseminated 12 to after estrus was detected. Angus semen was used during the to inseminate cows that had been separated from their calves first estrus occurred within 10 days of weaning. Simmental utilized at all subsequent services of cows separated from and in all services of lactating cows.

42 days for 18 hours first service if the semen was their calves

Blood was collected via jugular venipuncture between 0630 and 0900 hours on May 3 and daily from May 8 through May 20. If an animal was detected in estrus on or before May 20, daily blood collection was continued for 10 days after a subsequent estrus if that estrus caused the cycle to be classified as short in length. Blood collection was terminated at the subsequent estrus if the cycle was of normal length. Blood samples were allowed to clot, and the serum was separated by centrifugation and stored at -20 C. Serum progesterone was analyzed by radioimmunoassay utilizing methods similar to those previously described (4). Specificity antiserum (UNL-157, 11-21-78) is described elswhere (5).

of the

Serum progesterone data were analyzed by split-plot design occurrence of estrus and incidence of short cycles were analyzed square tests.

(6) and by chi-

RESULTS Experiment 1. Incidence of short estrous cycles was 7% (198 out of 2,854 cows). Eighty-six percent (170 of 198) of short estrous cycles observed in fall-calving Angus cows were between the first and second estrus detected after calving. Of these estrous cycles with lengths less than 17 days, the majority of animals experienced cycles that were from

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THERIOCENOLOGY

7 to 10 days in length 8 days.

(Pc.005;

Fig.

1).

The most frequent

length

was

Experiment 2. The percentage of formerly anestrous cows that exhibited estrus within 10 days and within 25 days of day 0 was increased by weaning the calves (P<.OO5; Table I). Of the 25 cows that had their calves weaned, 16 were in standing estrus within 10 days after weaning. Thirteen of these 16 cows had a second estrus within 7 to 10 days after their first estrus. The incidence of short estrous cycles in cows separated from their calves was higher than in suckled herdmates (Pc.005). The remaining three animals of the 16 that were in estrus within 10 days of weaning returned to estrus 23, 27 and 28 days later. There were a variety of observations made on the remaining nine cows that were not observed in estrus within 10 days of weaning. Four were hyperactive within 10 days of calf separation but did not exhibit standing estrus. These animals exhibited estrus 7 to 9 days after the hyperactive period. One cow exhibited estrus on day 12 and returned to estrus 8 days later. One animal exhibited estrus on day 17 and another was observed on day 20. Two cows were not observed in estrus. Of the eight lactating control cows, two animals were observed in estrus within 10 days, and a total of four were in estrus within 25 days. Two of the four conceived at the first service, and the other two subsequently had estrous cycles that were 26 and 38 days in length. One of the animals that conceived at first service had a hyperactive period nine days before being observed in estrus and subsequent insemination. Three of the controls were observed in estrus for the first time after 25 days of observation, and one cow was never detected in estrus. The 16 crossbred Simmental cows that were observed in estrus within 10 days of calf removal were inseminated with Angus semen at the first estrus and Simnental semen at subsequent estrus periods. Thirteen of these cows returned to estrus within 7 to 10 days. Eight animals (61.5%) conceived at the second estrus after weaning and delivered Simmentalsired calves. No Angus-sired calves were produced. The remaining three cows returned to estrus 23, 27 and 28 days later. Serum progesterone levels for cows exhibiting short estrous cycles are shown in Figure 2. Progesterone level was higher (Pc.01) before the second estrus than before the first estrus. Analysis of progesterone data indicated a day of cycle effect within cows (Pc.01) and an interaction between cycle and day (Pc.01). The interassay coefficient of variation for the progesterone analyses was 16.5%. DISCUSSION A high incidence of 7- to lo-day cycles has been reported in dairy cows in New Zealand (2). Also, the commonest short estrous cycles in ewes lambing during the breeding season were 5 to 7 days in length (7). AS 17-day estrous cycles are "normal" for ewes, the 5- to 'I-day short eStrOus cycle in ewes appears to be comparable to the 7- to lo-day short

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Our observations that most short estrous cycles in cows cycle in cows. were between the first and second postpartum estrus and that 7- to lo-day estrous cycles were the most frequent, suggests that the short cycles resulted from a normal physiological phenomenon. Many studies have indicated that the first postpartum ovulation is frequently not accompanied by observable signs of estrus (8,9,10). The life of the resulting corpus luteum is shorter than corpora lutea produced at subsequent ovulations. Our weaning of calves from anestrous cows increased the incidence of cows observed in estrus within 10 days. It appears that completely removing the suckling stimulus not only stimulated ovarian activity, but also allowed cows to show estrus with the Expression of the first estrus, however, was sometimes first ovulation. weak as four cows showed signs of estrus without standing for mounting. Signs of estrus without standing to be mounted have been observed in dairy cows approximately one day before the first postpartum ovulation (11). A rise in serum progesterone has been observed in suckled cows before the first observed estrus (see reviews in 10, 12). Although the adrenal gland and luteinized follicles have been suggested as sources of this progesterone (13), luteal tissue at the site of the first ovulation Others (9) reported that 8 of 9 cows that had may be a likely source. short estrous cycles ovulated at the first estrus. Our data show serum progesterone concentrations observed several days prior to the second estrus were comparable to those reported before the first postpartum estrus by others (13,14). If calf removal before the initial ovulation allows expression of estrus with the first ovulation, then the second estrus in these cows is comparable to the first observed estrus in cows suckling calves and not exhibiting estrus with the first ovulation. We found no progesterone rise before the first estrus of a short cycle. Others (13,15) have also failed to find a pre-estrus progesterone rise before the first estrus of a short cycle. Estrus occurs approximately 3 to 5 days before serum progesterone rises in a high percentage of cows with calves weaned and provides evidence that the corpus luteum is the No difference in progesterone profiles existed for progesterone source. cows designated as "hyperactive" and those with a "standing" first estrus (Fig. 2 and 3). Several mechanisms have been postulated to explain short estrous cycles. Daily oxytocin injections given to dairy heifers beginning the day of estrus suppressed luteal function and shortened estrous cycles (16), and is a suggested explanation for short estrous cycles in ewes It is unlikely that mechanism is evoked in our study since re(17). moving the suckling stimulus greatly increased the incidence of short estrous cycles. Possible reasons for luteal insufficiency tum ovulation include 1) lack of sufficient the luteal tissue to recognize a luteotropin, luteolytic agent.

after the first postparluteotropin, 2) failure of and 3) presence of a

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Weaning of calves from postpartum anestrous cows increased the percentage of cows showing estrus the next 10 days; however, none conceived at the first postweaning estrus, and most returned to estrus in 7 to 10 days. LITERATURE CITED 1.

Salisbury, G. W., N. L. VanDenmark and J. R. Lodge. 1978. ogy of reproduction and artificial insemination of cattle. Ed.) W. H. Freeman and Company, San Francisco, Calif.

2.

Macmillan, New Zealand

3.

Ward, H. 1978. The effects of Syncro-Mate B and/or calf management on reproductive performance in the beef cow. M.S. Thesis, Kansas State Univ., Manhattan.

4.

Louis, T. M., H. A. Hafs and B. E. Seguin. LH, estrus and ovulation after prostaglandin Sot. Exp. Biol. Med. 143:152.

5.

Anthony, R. V., R. J. Kittok, E. F. Ellington and M. K. Nielsen. 1980. Effects of zeranol on reproduction in primigravid beef heifers. J. Anim. Sci. (in press).

6.

Gill, ments

7.

Land, R. B. 1971. The incidence of oestrus Finnish Landrace, Dorset Horn and Finn-Dorset Fertil. 24:345.

8.

Kiracofe, G. H., R. R. Schalles and G. B. Marion. 1969. Effect of wintering ration on reproductive phenomena in beef cows on range. Kansas Agr. Exp. Sta. Bull. 529.

9.

Stevenson, J. S. and J. H. Britt. 1979. Relationships among luteinizing hormone, estradiol, progesterone, glucocorticoids, yield, body weight and postpartum ovarian activity in Holstein J. Anim. Sci. 48:570.

10.

K. L. and J. D. Watson. dairy cattle. J. Dairy

J. L. and H. D. Hafs. of animals. J. Anim.

Kiracofe, G. H. 1980. postpartum intervals. Anim. Sci. (in press).

1971, Short Sci. 54:1526.

1971. Analysis Sci. 33:331.

estrous

Physiol(2nd cycles

in

1973. Progesterone, F2a in heifers. Proc.

of

repeated

measure-

during lactation in sheep. J. Reprod.

milk cows.

Uterine involution: its role in regulating XIV Biennial Symposium on Reproduction. J.

11. Morrow, D. A., S. J. Roberts, K. McEntee and H. G. Gray. 1966. Postpartum ovarian activity and uterine involution in dairy cattle. J. Amer. Vet. Med. Assoc. 149:1596. 12. Wetteman, R. P. 1980. Postpartum endocrine function of cattle, sheep, and swine. XIV Biennial Symposium on Reproduction. J. Anim. Sci. (in press).

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13. Corah,

L. R., Alice P. Queely, T. G. Dunn and C. C. Kaltenbach. Prepartum levels of progesterone and estradiol in beef fed two levels of energy. J. Anim. Sci. 39:380.

1974. heifers

14. Donaldson, L. E., J. M. Bassett and G. D. Thornburn. 1970. Peripheral plasma progesterone concentration of cows during puberty, oestrus cycles, pregnancy and lactation and the effects of undernutrition and exogenous oxytocin on progesterone concentration. J. Endocrinol. 48:599. Verna, 15. LaVoie, Suckling effect tum beef cows.

D. K. Han, D. B. Foster and E. L. Moody. on estrus and blood plasma progesterone J. Anim. Sci. (in press).

D. T. and W. Hansel. 1959. 16. Armstrong, estrous cycle with oxytocin. J. Dairy 17. Edgerton, L. A. 1980. interval. XIV Biennial (in press).

The effect Symposium

Alteration Sci. 42:533.

1980. in postpar-

of the bovine

of lactation upon the postpartum on Reproduction. J. Anim. Sci.

EFFECTS OF WEANING ON SHORT ESTROUS CYCLES IN BEEF COWS

TABLE I.

Cows exhibiting signs of estrusb 10 days 25 days

cows with short cycleb

Treatment group

No.

Average days postpartuma

Cows with calves weaned

25

43.9

20(80.0)’

23(92.oy

18(78.3)C’d

44.5

2(25.0)

4(50.0)

1(25.0)d

Lactating control

cows

8

aAverage

number

of days

bPercentages 'Different dPercentage days.

110

from

calving

to weaning.

in parentheses. from controls, P<.OO5. calculated on basis of cows that

exhibited

estrus

in 25

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THERIOGENOLOCY

70 -

)-

I-

)-

I-

I-

4 Figure

1.

6

6 10 12 EstrousCycle Length(deys)

Occurrence of short estmus cycles Estrous cycles of 7 to 10 days ~4 other short cycles.

AUGUST 1980 VOL. 14 NO. 2

14

16

in fall calving beef cows. mwe frequent (Pc.005) than

111

THERIOGENOLOGY

first

second

I

Days Figure

2.

10

8

-^ E a 5 g 6

Serum progesterone levels of postpartum anestrous beef cows with 7 to 10 days Each point is the mean with standard error. cycles after weaning.

1 weaning

estrus

hyperactive

/

55 z Q h E 2

4-

g

2-

t

I

-5

Figure

112

estrous

3.

Serum progesterone levels of postpartum after their calves were weaned and they point is the mean with standard error.

-2

anestrous returned

0

2

4

6

8

10

beef cows exhibiting hyperactivity Each to estrus 7 to 10 days later.

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