Modification of follicular dynamics by exogenous fSH and progesterone, and the induction of ovulation using hCG in postpartum beef cows

https://doi.org/10.1016/S0093-691X(99)00185-5Get rights and content

Abstract

Follicular growth and ovulation in response to FSH, progesterone and hCG were evaluated in postpartum beef cows. In Experiment 1, on Day 21 post partum, cows received an injection of either saline (control; n=6), FSH (200 mg; n=6), or a PRID (n=5) for 10 d. Both FSH and PRID prolonged maintenance of a dominant follicle (15.5 ± 1.16 and 14.4 ± 1.29 d, respectively, vs 8.4 ± 1.22 d in control; P < 0.01), and increased the maximum diameter of the dominant follicle (14.0 ± 0.91 and 16.4 ± 1.01 mm, respectively, vs 10.9 ± 0.95 mm in control; P < 0.05). The PRID-maintained dominant follicle ovulated in 60% of cows, followed by normal estrous cycles (vs 0% in control; P=0.01), whereas the dominant follicle ovulated in 33 % of FSH-treated cows (P=0.08). The PRID regimen shortened the interval to first ovulation preceding a normal cycle and continued cyclicity (44 ± 4.1 vs 60 ± 4.4 d in control; P=0.02). In Experiment 2, on Day 21 post partum, cows received either saline (control), saline+PRID, or FSH+PRID (n= 16/group). Sixty hours after PRID withdrawal, cows received either saline or hCG (1,500 IU, n=8/treatment). The FSH+PRID regimen increased the number of large (>10 mm in diameter) follicles (3.6 ± 0.43 vs 1.9 ± 0.39 in control; P=0.005). Both PRID and FSH+PRID prolonged maintenance of the largest follicle (11.0 ± 0.82 and 11.2 ± 0.91 d, respectively, vs 8.7 ± 0.81 d in control; P < 0.05). The PRID-maintained dominant follicle ovulated in 50% of cows, followed by normal estrous cycles. The FSH+PRID-maintained largest follicle had become atretic at PRID withdrawal and was anovulatory. The FSH+PRID+hCG regimen increased the incidence of ovulation preceding a cycle of normal duration and continued cyclicity (100 vs 50% in PRID; P=0.03), and reduced the interval to first ovulation preceding a cycle of normal duration and continued cyclicity (38 ± 6.5 vs 58 ± 6.3 d in control; P=0.04). The area under the progesterone curve during the induced cycle was reduced after (PRID ± FSH)+hCG than after PRID ± FSH (P=0.002). These results indicate that PRID alone or with FSH/hCG has the potential to modify the dominant follicle and initiate cyclicity in postpartum beef cows.

References (57)

  • SianangamaPC et al.

    Effect of hCG administration on Day 7 of the estrous cycle on follicular dynamics and cycle length in cows

    Theriogenology

    (1996)
  • SianangamaPC et al.

    Characteristics of corpus luteum formed from the first wave dominant follicle following hCG in cattle

    Theriogenology

    (1996)
  • StaggK et al.

    Follicular development in long-term anoestrous suckler beef cows fed two levels of energy postpartum

    Anim Reprod Sci

    (1995)
  • StevensonJS et al.

    Resumption of follicular activity and interval to postpartum ovulation after exogenous progestins

    J Dairy Sci

    (1994)
  • TaylorC et al.

    Ovarian follicular dynamics and plasma luteinizing hormone concentrations in norgestomet-treated heifers

    Anim Reprod Sci

    (1993)
  • TroxelTR et al.

    The effect of progestin and GnRH treatments on ovarian function and reproductive hormone secretions of anestrous postpartum suckled beef cows

    Theriogenology

    (1984)
  • VorstermansJPM et al.

    Effect of intermittent injections of gonadotrophin releasing hormone at various frequencies on the release of luteinizing hormone and ovulation in dairy cows

    Anim Reprod Sci

    (1985)
  • WettemannRP et al.

    Endocrine response of postpartum anestrous beef cows to GnRH or PMSG

    Theriogenology

    (1982)
  • AcostaB et al.

    Nursing enhances the negative effect of estrogen on LH release in the cow

    J Anim Sci

    (1983)
  • AlilaHW et al.

    Control of progesterone production in small and large bovine luteal cells separated by flow cytometry

    J Reprod Fertil

    (1988)
  • BergfeldEGM et al.

    Changing dose of progesterone results in sudden changes in frequency of luteinizing hormone pulses and secretion of 17β-estradiol in bovine females

    Biol Reprod

    (1996)
  • BreuelKF et al.

    Endocrine profiles and follicular development in early-weaned postpartum beef cows

    J Reprod Fertil

    (1993)
  • ComerfordJW et al.

    Effects of early weaning and return to pasture on health and performance of beef calves

    J Anim Sci

    (1995)
  • FieldJ

    Body condition scoring of beef cows. Ontario Ministry of Agriculture and Food

    Factsheet

    (1985)
  • FortuneJE

    Ovarian follicular growth and development in mammals

    Biol Reprod

    (1994)
  • FrickePM et al.

    Effect of human chorionic gonadotropin administered early in the estrous cycle on ovulation and subsequent luteal function in cows

    J Anim Sci

    (1993)
  • Garcia-WinderM et al.

    Effect of suckling and ovariectomy on the control of luteinizing hormone secretion during the postpartum period in beef cows

    Biol Reprod

    (1984)
  • Garcia-WinderM et al.

    Endocrine profiles associated with life span of induced corpora lutea in postpartum beef cows

    J Anim Sci

    (1986)
  • Cited by (0)

    a

    Current address: Toronto Fertility Sterility Institute, 66 Avenue Road, Toronto, Ontario, M5R 3N8, Canada.

    View full text