An experiment was conducted to examine
the effects of GnRH on the secretion of FSH,
LH, estradiol, and progesterone in serum and
changes in ovarian structures. Dairy cows were
assigned randomly to receive either 100 μg of
GnRH or saline 12 hr after estrus (day 0) was
detected. Blood was collected daily to assess
changes in serum estradiol and progesterone
and every 12 min for 8 hr on days 8 and 15
after estrus to assess concentrations of FSH and
LH. Diameter and number of follicles were
determined daily by real-time ultrasonography.
Two patterns of follicular development were
observed. The day of peak diameter of each
dominant follicle (three or four per cycle) was
synchronous with increases in estradiol in
serum. The dominant follicle grew at a faster
rate in all GnRH-treated cows. We concluded
that administering GnRH at estrus increased the
pulse frequency of FSH on days 8 and 15 of the
cycle, altered follicular dynamics of dominant
follicles of the subsequent estrous cycle, and
tended to increase concentrations of
progesterone in serum of cows

Pursley, J.R.

Stevenson, Jeffrey S.

K-State Research Exchange

31OVARIAN FOLLICULAR WAVES AND SECRETIONOF FOLLICLE-STIMULATING HORMONE AFTERADMINISTRATION OF GnRH AT ESTRUSJ. R. Pursley and J. S. StevensonSummaryAn experiment was conducte  to examinethe effects of GnRH on the secretion of FSH,LH, estradiol, and progesterone in serum andchanges in ovarian structures.  Dairy cows wereassigned randomly to receive either 100 µg ofGnRH or saline 12 hr after estrus (day 0) wasdetected.  Blood was collected daily to assesschanges in serum estradiol and progesteroneand every 12 min for 8 hr on days 8 and 15after estrus to assess concentrations of FSH andLH.  Diameter and number of follicles weredetermined daily by real-time ultrasonography.Two patterns of follicular development wereobserved.  The day of peak diameter of eachdominant follicle (three or four per cycle) wassynchronous with increases in estradiol inserum.  The dominant follicle grew at a fasterrate in all GnRH-treated cows.  We concludedthat administering GnRH at estrus increased thepulse frequency of FSH on days 8 and 15 of thecycle, altered follicular dynamics of dominantfollicles of the subsequent estrous cycle, andtended to increase concentrations ofprogesterone in serum of cows.(Key Words:  GnRH, Ovarian Follicles, FSH,Estradiol, Progesterone.)ProceduresNine mid- to late-lactation dairy cowswere used in a crossover experiment in which13 estrous cycles were studied.  These cowshad failed to conceive to earlier inseminationsand were classified as repeat-breeders.  Duringthe first part of the study, one-half of the cowsreceived 100 µg of GnRH (Cystorelin, SanofiAnimal Health, Inc., Overland Park, KS), andthe remainder received saline at 12 hr afterestrus was detected.  The cows were monitordduring one estrous cycle, with a secondintervening estrous cycle serving as a restcycle.  At the estrus before the third estrouscycle, the cows received the alternate treatmentat 12 hr after estrus was detected and werestudied as in the first cycle.  During the firstand third estrous cycles, blood was collecteddaily to assess concentrations of progesteroneand estradiol-17b, and both ovaries werescanned by ultrasonography to measure andrecor the number and diameter of all ovarianfollicles.  In addition, cows were fitted withjugular catheters, in order to collect bloodsamples on days 8 and 15 of the cycle (every12 min for 8 hr) to monitor characteristics ofgonadotropin (LH and FSH) secretion.  Thesedays were select d because they correspond todays of the estrous cycle when the last twodominant follicles begin to enlarg  in diameter.Results and DiscussionTwo patterns of follicular growth wereobserved.  During six of the cycles, threedominant follicles emerged, whereas in theremaining seven cycles, four dominant follicleswere detected.  Figure 1 illustrates theincreasing diameters of three dominant folliclesin one cow on days 1, 11, and 15 of the cycle,along with corresponding increases in serumconcentration of estradiol produced by thoselarge follicles.  The last follicle (labelled DOFin Figure 1) was the on that ovulated after thesubsequent estrus.As shown in Figure 1, the day eachdominant follicle reached its peak in diame-ter, concentrations of estradiol in serum wereat their highest level in the blood serum,indicating that the dominant follicles wereestrogenic. The dominant follicle that even-tually ovulated grew at a faster rate in allcows treated at the previous estrus with 100µg of GnRH.The percentage of cows with pulses ofFSH were greater (P < .05) on days 8 and15 of the estrous cycle in GnRH-treated cows(Table 1). Although concentrations of FSHin serum were unaffected by treatment withGnRH at estrus, cows having three follicularwaves tended to have lower FSH than thosehaving four follicular waves (measured ondays 8 and 15; Table 2). However, cowswith three waves averaged up to sixfold morepulses of FSH on days 8 and 15. Therewere no differences in LH secretion amongtreatment groups or among cows with threeor four follicular waves.Concentrations of progesterone in serum ofcows having three follicular waves, but notfour waves, tended to be higher after treat-ment with GnRH. We concluded that admin-istration of GnRH at estrus altered folliculardynamics of dominant follicles during thesubsequent estrous cycle and tended to altersecretion of progesterone as we observed inour earlier studies (1991 Dairy Day, Reportof Progress 640, pp 36-39).3233Table 1. Percentage of Cows with Pulses of FSH on d 8 and 15 of the Estrous Cycleafter Treatment with 100 µg GnRH or Saline at Estrus (d 0)TreatmentItem GnRH Saline Wave %Number of follicular wavesb  Three 100.0 (n = 4)c 33.3 (n = 3) 66.7e  Four 66.6 (n = 3)c 0   (n = 3) 33.3Treatment % 83.3 (n = 7)d 16.7 (n = 6)Response was identical on d 8 and 15 of the estrous cycle.aSynchronous development of a group of follicles greater than or equal to 3 mm inbdiameter, which includes a dominant  follicle and several subordinate follicles.Different (P < .05) from saline.cDifferent (P = .01) from saline.dDifferent (P < .10) from corresponding four-wave cows.eTable 2. Concentrations and Number of Pulses of FSH in Serum on d 8 and 15 of theEstrous Cycle  in 13 Cows with either Three or Four Follicular Waves afteraTreatment with 100 µg of GnRH or Saline at Estrus (d 0)TreatmentaItem GnRH Saline Wave meansConcentrations of FSH, ng/ml   Three follicular waves .9 ± .1 .9 ± .1 .9 ± .1d   Four follicular waves 1.2 ± .1 1.1 ± .1 1.1 ± .1   Treatment means 1.0 ± .1 1.0 ± .1No. of pulses of FSH   Three follicular waves 2.1 ± .7 1.8 ± .8 2.0 ± .5c    Four follicular waves .5 ± .8 0 ± .8 .3 ± .6   Treatment means 1.3 ± .5 .9 ± .5Means represent the average response across d 8 and 15 of the estrous cycle.aSynchronous development of a group of follicles greater than or equal to 3 mm inbdiameter, which includes a dominant follicle and several subordinate follicles.Different (P < .01) from corresponding four-wave cows.cDifferent (P = .07) from corresponding four-wave cows.dDifferent (P < .001) from corresponding four-wave cows.eDifferent (P = .05) from corresponding four-wave cows.f

Ovarian follicular waves and secretion of follicle-stimulating hormone after administration of GnRH at estrus

An experiment was conducted to examine the effects of GnRH on the secretion of FSH, LH, estradiol, and progesterone in serum and changes in ovarian structures. Dairy cows were assigned randomly to receive either 100 Î¼g of GnRH or saline 12 hr after estrus (day 0) was detected. Blood was collected daily to assess changes in serum estradiol and progesterone and every 12 min for 8 hr on days 8 and 15 after estrus to assess concentrations of FSH and LH. Diameter and number of follicles were determined daily by real-time ultrasonography. Two patterns of follicular development were observed. The day of peak diameter of each dominant follicle (three or four per cycle) was synchronous with increases in estradiol in serum. The dominant follicle grew at a faster rate in all GnRH-treated cows. We concluded that administering GnRH at estrus increased the pulse frequency of FSH on days 8 and 15 of the cycle, altered follicular dynamics of dominant follicles of the subsequent estrous cycle, and tended to increase concentrations of progesterone in serum of cows.; Dairy Day, 1992, Kansas State University, Manhattan, KS, 1992

Kansas State University

Kansas Agricultural Experiment Station Research Reports Volume 0 Issue 2 Dairy Research (1984-2014) Article 380 1992 Ovarian follicular waves and secretion of follicle-stimulating hormone after administration of GnRH at estrus J.R. Pursley Jeffrey S. Stevenson This report is brought to you for free and open access by New Prairie Press. It has been accepted for inclusion in Kansas Agricultural Experiment Station Research Reports by an authorized administrator of New Prairie Press. Copyright 1992 Kansas State University Agricultural Experiment Station and Cooperative Extension Service. Contents of this publication may be freely reproduced for educational purposes. All other rights reserved. Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. K-State Research and Extension is an equal opportunity provider and employer. Follow this and additional works at: https://newprairiepress.org/kaesrr  Part of the Dairy Science Commons Recommended Citation Pursley, J.R. and Stevenson, Jeffrey S. (1992) "Ovarian follicular waves and secretion of follicle-stimulating hormone after administration of GnRH at estrus," Kansas Agricultural Experiment Station Research Reports: Vol. 0: Iss. 2. https://doi.org/10.4148/2378-5977.3305 Ovarian follicular waves and secretion of follicle-stimulating hormone after administration of GnRH at estrus Abstract An experiment was conducted to examine the effects of GnRH on the secretion of FSH, LH, estradiol, and progesterone in serum and changes in ovarian structures. Dairy cows were assigned randomly to receive either 100 Î¼g of GnRH or saline 12 hr after estrus (day 0) was detected. Blood was collected daily to assess changes in serum estradiol and progesterone and every 12 min for 8 hr on days 8 and 15 after estrus to assess concentrations of FSH and LH. Diameter and number of follicles were determined daily by real-time ultrasonography. Two patterns of follicular development were observed. The day of peak diameter of each dominant follicle (three or four per cycle) was synchronous with increases in estradiol in serum. The dominant follicle grew at a faster rate in all GnRH-treated cows. We concluded that administering GnRH at estrus increased the pulse frequency of FSH on days 8 and 15 of the cycle, altered follicular dynamics of dominant follicles of the subsequent estrous cycle, and tended to increase concentrations of progesterone in serum of cows.; Dairy Day, 1992, Kansas State University, Manhattan, KS, 1992; Keywords Dairy Day, 1992; Kansas Agricultural Experiment Station contribution; no. 93-131-S; GnRH; Ovarian follicles; FSH; Estradiol; Progesterone Creative Commons License This work is licensed under a Creative Commons Attribution 4.0 License. This research report is available in Kansas Agricultural Experiment Station Research Reports: https://newprairiepress.org/kaesrr/vol0/iss2/380 31OVARIAN FOLLICULAR WAVES AND SECRETIONOF FOLLICLE-STIMULATING HORMONE AFTERADMINISTRATION OF GnRH AT ESTRUSJ. R. Pursley and J. S. StevensonSummaryAn experiment was conducted to examinethe effects of GnRH on the secretion of FSH,LH, estradiol, and progesterone in serum andchanges in ovarian structures.  Dairy cows wereassigned randomly to receive either 100 µg ofGnRH or saline 12 hr after estrus (day 0) wasdetected.  Blood was collected daily to assesschanges in serum estradiol and progesteroneand every 12 min for 8 hr on days 8 and 15after estrus to assess concentrations of FSH andLH.  Diameter and number of follicles weredetermined daily by real-time ultrasonography.Two patterns of follicular development wereobserved.  The day of peak diameter of eachdominant follicle (three or four per cycle) wassynchronous with increases in estradiol inserum.  The dominant follicle grew at a fasterrate in all GnRH-treated cows.  We concludedthat administering GnRH at estrus increased thepulse frequency of FSH on days 8 and 15 of thecycle, altered follicular dynamics of dominantfollicles of the subsequent estrous cycle, andtended to increase concentrations ofprogesterone in serum of cows.(Key Words:  GnRH, Ovarian Follicles, FSH,Estradiol, Progesterone.)ProceduresNine mid- to late-lactation dairy cowswere used in a crossover experiment in which13 estrous cycles were studied.  These cowshad failed to conceive to earlier inseminationsand were classified as repeat-breeders.  Duringthe first part of the study, one-half of the cowsreceived 100 µg of GnRH (Cystorelin, SanofiAnimal Health, Inc., Overland Park, KS), andthe remainder received saline at 12 hr afterestrus was detected.  The cows were monitoredduring one estrous cycle, with a secondintervening estrous cycle serving as a restcycle.  At the estrus before the third estrouscycle, the cows received the alternate treatmentat 12 hr after estrus was detected and werestudied as in the first cycle.  During the firstand third estrous cycles, blood was collecteddaily to assess concentrations of progesteroneand estradiol-17β, and both ovaries werescanned by ultrasonography to measure andrecord the number and diameter of all ovarianfollicles.  In addition, cows were fitted withjugular catheters, in order to collect bloodsamples on days 8 and 15 of the cycle (every12 min for 8 hr) to monitor characteristics ofgonadotropin (LH and FSH) secretion.  Thesedays were selected because they correspond todays of the estrous cycle when the last twodominant follicles begin to enlarge in diameter.Results and DiscussionTwo patterns of follicular growth wereobserved.  During six of the cycles, threedominant follicles emerged, whereas in theremaining seven cycles, four dominant follicleswere detected.  Figure 1 illustrates theincreasing diameters of three dominant folliclesin one cow on days 1, 11, and 15 of the cycle,along with corresponding increases in serumconcentration of estradiol produced by thoselarge follicles.  The last follicle (labelled DOFin Figure 1) was the one that ovulated after thesubsequent estrus.As shown in Figure 1, the day eachdominant follicle reached its peak in diame-ter, concentrations of estradiol in serum wereat their highest level in the blood serum,indicating that the dominant follicles wereestrogenic. The dominant follicle that even-tually ovulated grew at a faster rate in allcows treated at the previous estrus with 100µg of GnRH.The percentage of cows with pulses ofFSH were greater (P < .05) on days 8 and15 of the estrous cycle in GnRH-treated cows(Table 1). Although concentrations of FSHin serum were unaffected by treatment withGnRH at estrus, cows having three follicularwaves tended to have lower FSH than thosehaving four follicular waves (measured ondays 8 and 15; Table 2). However, cowswith three waves averaged up to sixfold morepulses of FSH on days 8 and 15. Therewere no differences in LH secretion amongtreatment groups or among cows with threeor four follicular waves.Concentrations of progesterone in serum ofcows having three follicular waves, but notfour waves, tended to be higher after treat-ment with GnRH. We concluded that admin-istration of GnRH at estrus altered folliculardynamics of dominant follicles during thesubsequent estrous cycle and tended to altersecretion of progesterone as we observed inour earlier studies (1991 Dairy Day, Reportof Progress 640, pp 36-39).3233Table 1. Percentage of Cows with Pulses of FSH on d 8 and 15 of the Estrous Cycleafter Treatment with 100 µg GnRH or Saline at Estrus (d 0)TreatmentItem GnRH Saline Wave %Number of follicular wavesb  Three 100.0  (n = 4)c 33.3 (n = 3) 66.7e  Four 66.6  (n = 3)c 0   (n = 3) 33.3Treatment % 83.3  (n = 7)d 16.7 (n = 6)Response was identical on d 8 and 15 of the estrous cycle.aSynchronous development of a group of follicles greater than or equal to 3 mm inbdiameter, which includes a dominant  follicle and several subordinate follicles.Different (P < .05) from saline.cDifferent (P = .01) from saline.dDifferent (P < .10) from corresponding four-wave cows.eTable 2. Concentrations and Number of Pulses of FSH in Serum on d 8 and 15 of theEstrous Cycle  in 13 Cows with either Three or Four Follicular Waves afteraTreatment with 100 µg of GnRH or Saline at Estrus (d 0)TreatmentaItem GnRH Saline Wave meansConcentrations of FSH, ng/ml   Three follicular waves .9 ± .1 .9 ± .1 .9  ± .1d   Four follicular waves 1.2 ± .1 1.1 ± .1 1.1 ± .1   Treatment means 1.0 ± .1 1.0 ± .1No. of pulses of FSH   Three follicular waves 2.1 ± .7 1.8 ± .8 2.0 ± .5c    Four follicular waves .5 ± .8 0 ± .8 .3 ± .6   Treatment means 1.3 ± .5 .9 ± .5Means represent the average response across d 8 and 15 of the estrous cycle.aSynchronous development of a group of follicles greater than or equal to 3 mm inbdiameter, which includes a dominant follicle and several subordinate follicles.Different (P < .01) from corresponding four-wave cows.cDifferent (P = .07) from corresponding four-wave cows.dDifferent (P < .001) from corresponding four-wave cows.eDifferent (P = .05) from corresponding four-wave cows.f

Ovarian follicular waves and secretion of follicle-stimulating hormone after administration of GnRH at estrus

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