Induced LH Release in Spayed Cows

Short, R. E.; Howland, B. E.; Randel, R. D.; Christensen, D. S.; Bellows, R. A.

doi:10.2527/jas1973.372551x

Cited by 57 publications

(15 citation statements)

References 10 publications

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“…A rise in endogenous estrogen concentrations normally stimulates the preovulatory LH release in cows (Christensen et al, 1971;Henricks et al, 1971). Exogenous administration of estrogens also induced release of LH in cows (Short et al, 1973) and release of LH and FSH in prepubertal beef heifers (Gonzalez-Padilla et al, 1975), in agreement with the results in the present study. Furthermore, we reported that an EB dose as low as .2 in heifers and .25 mg in cows was sufficient to induce the LH surge, which supports results published by Short et al (1979), who indicated that a low dose of .25 mg of estradiol-17b was sufficient to induce the LH surge in ovariectomized and postpartum anestrous cows.…”

Section: Concentrations Of Lh In Serumsupporting

confidence: 90%

“…Time to peak estradiol-17b in serum in heifers was affected only by EC status ( P < .04; Table 3); in cows, increasing EB dose resulted in a linear ( P < .02; Table 3 ) reduction in time to peak estradiol-17b. Short et al (1973) reported that serum peak concentrations of estrogen occurred between 12 and 16 h after an injection of estradiol-17b in ovariectomized cows and that serum estrogen concentrations were increased for up to 28 h, which is nearly identical to the period of elevated serum estradiol-17b after EB in the present study.…”

Section: Concentrations Of Estradiol-17β In Serumsupporting

confidence: 84%

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Induced and synchronized estrus in cattle: dose titration of estradiol benzoate in peripubertal heifers and postpartum cows after treatment with an intravaginal progesterone-releasing insert and prostaglandin F2alpha.

Lammoglia-Villagómez

Short

Bellows

et al. 1998

Journal of Animal Science

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Peripubertal beef heifers (n = 57) and postpartum multiparous cows (n = 52) were used to determine the optimal dose of estradiol benzoate (EB) to induce and synchronize estrus after treatment with intravaginal progesterone inserts (IVP4, EAZI-BREED CIDR). All females received an IVP4 for 7 d (d 0 = insertion day) with a 25-mg injection of PGF2alpha (Lutalyse) on d 6. At 24 to 30 h after IVP4 removal, females were randomly assigned to be injected subcutaneously with EB at the following doses: heifers 0, .2, .38, or .75 mg and cows 0, .25, .5, or 1 mg. Furthermore, seven heifers and seven cows from each dose group were bled every 4 h for 76 h starting at EB injection. Serum was collected and assayed for LH and estradiol-17beta (E2). Observations for signs of estrus were made twice daily for 21 d after removal of IVP4, and females were artificially inseminated 8 to 20 h after detection of estrus. The percentage of females showing estrous behavior was increased by EB (P < .04); the greatest response was at .38 mg in heifers (86%) and 1 mg in cows (100%). Dose x time interaction affected (P < .01) E2 concentrations in heifers and cows; the animals that received the higher doses of EB had greater E2 concentrations in a shorter time than those that received the smaller doses. The percentage of cows and heifers with an acute preovulatory LH release (peak LH) was affected by dose, with a linear (P < .01) and a quadratic (P < .01) response. Highest concentrations of LH during peak LH were affected by dose with a linear (P < .01) response in heifers and linear (P < .01) and quadratic (P < .08) responses in cows. Heifers receiving .38 mg and cows receiving .5 and 1 mg of EB had the highest peak LH. Time to LH peak had a linear (P < .03) response in heifers and had linear (P < .04) and quadratic (P < .05) responses in cows. Pregnancy rate was affected (P < .02) in heifers by whether or not they were anestrous before IVP4 treatment (those with estrous cycles = 52% vs those that were anestrous = 22%) and in cows by dose of EB (P < .01; 8, 23, 21, and 67% for 0, .25, .5, and 1 mg, respectively). In conclusion, in females treated with IVP4 and PGF2alpha to induce and synchronize estrus, an injection of EB increased concentrations of E2 and LH and increased number of animals showing estrus. Also, EB increased pregnancy rates in cows. Optimal responses were at .38 mg EB for heifers and at 1 mg EB for cows.

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Section: Concentrations Of Lh In Serumsupporting

confidence: 90%

Section: Concentrations Of Estradiol-17β In Serumsupporting

confidence: 84%

Induced and synchronized estrus in cattle: dose titration of estradiol benzoate in peripubertal heifers and postpartum cows after treatment with an intravaginal progesterone-releasing insert and prostaglandin F2alpha.

Lammoglia-Villagómez

Short

Bellows

et al. 1998

Journal of Animal Science

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“…The pattern of response is practically identical to that observed in prepuberal heifers given 2 mg estradiol-173 after progesterone (Gonzalez-Padilla et al, 1975a), except that the LH peak occurred 6 to 12 hr later in our study. This variation in temporal response may be dose-related, but the relationship apparently is not linear, since a 10-mg dose of estradiol-173 resulted in an LH surge 23 hr after injection in spayed cows (Short et al, 1973), a time relationship similar to the one we observed after injection of 4 milligrams. Estrogen-induced LH release is diminished during the luteal phase of cows (Hobson and Hansel, 1972), and pituitary response to GnRH is also decreased during midcycle in ewes (Reeves et al, 1971).…”

Section: Discussionmentioning

confidence: 50%

“…Estrogen-induced LH release is diminished during the luteal phase of cows (Hobson and Hansel, 1972), and pituitary response to GnRH is also decreased during midcycle in ewes (Reeves et al, 1971). However, exogenous progesterone fails to inhibit LH release when exogenous estradiol is administered concomitantly (Short et al, 1973;Swanson, 1974;Hausler and Malven, 1976), and presensitization with exogenous progesterone appears to mimic normally-occurring changes and to enhance ovulation induction with estrogen in rats (Docke and D/Srner, 1966;Ying and Greep, 1971;Caligaris et al, 1972) and heifers (Gonzalez-Padilla et al, 1975a). The mechanism by which progesterone acts synergistically with estradiol to promote ovulation remains unknown, but evidence (Gonzalez-Pedilla et al,, 1975a,b) indicates that the ovary may be the site of action since pituitary LH releases of similar magnitude can be caused by estradiol with or without progesterone pretreatment.…”

Section: Discussionmentioning

confidence: 99%

Hormonal and Reproductive Profiles of Early Postpartum Beef Heifers after Prolactin Suppression or Steroid-Induced Luteal Function3

Williams

Ray

1980

Journal of Animal Science

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Two trials were conducted with 24 primiparous suckled beef heifers to determine independent and combined effects of a prolactin-suppressing agent and exogenous steroids on serum hormones and reproductive activity. Heifers were assigned in groups of six to one of four treatments: 1. (C)-subcutaneous control injections administered once a day for 2 days, followed by 2 days of no injections; sequence repeated from day 5 through day 40 postpartum or until first naturally occurring estrus; 2. (CB)-subcutaneous injections of 80 mg CB-154 (2-bromo-~-ergokryptine) (Sandoz) in ethanol once a day for 2 days, followed by 2 days of no injections; sequence repeated from day 5 through day 40 postpartum or until first naturally occurring estrus; 3. (PE)-intramuscular (IM) injection of 25 mg progesterone in sesame oil on day 15 postpartum, followed by IM injection of 4 mg estradiol-17 in sesame oil 48 hr later, or 4. (CBPE)-treatments 2 (CB) plus 3 (PE). A marked reduction in serum prolactin was observed after a single injection CB-154 in all CB and CBPE treated heifers, reaching minimum concentrations by day 7 postpartum after a second injection on day 6. Continued treatment decreased (P<.01) prolactin concentrations over the 35 day blood sampling period to an average of .9 + .2 ng/ml as compared to 19.2 + 5.6 ng/ml for non-CB-154 treated (C and PE) heifers. In non-CB-154treated heifers, serum prolactin was higher during the spring (33.5 -+ .9 ng/ml) than the fall (2.6 + .9 ng/ml). Treatment CB had no effect on serum concentrations of LH, estradiol-17/3 or progesterone. The resumption of cyclic activity in C and CB heifers prior to day 40 postpartum was characterized in four of six animals by 4-to 5-day elevations of serum progesterone and 7-to 8-day cycles, which were preceded in every case by peaks of estradiol-17/3 (9 + 1.9 pg/ml) and nonstanding estrous behavior (three of four) or no behavior (one of four). Palpable corpora lutea were detected in two of four animals during these progesterone increases. Subnormal luteal function was followed by another estradiol-i7/3 peak (7 ---2 pg/ml) and estrus (three of four) or nonstanding estrus (one of four). Injection of progesterone followed by injection of estradiol-17/3 resulted in a preovulatory discharge of LH in 12 of 12 PE and CBPE heifers, with eight of 12 initiating luteal function within 72 hr after the LH surge. On the basis of endocrine data, suppression of endogenous prolactin release did not (P<.05) potentiate steroid treatment effects. Treatments PE and CBPE resulted in a reproductive trend which reflected endocrine findings. Data fail to provide evidence that prolactin is antigonadotropic in bovine heifers. (

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“…Previous reports have indicated that oestrogen injections may produce oestrous behaviour in ovariectomized cows but the results have been inconsistent (Asdell, De Alba & Roberts, 1945;Melampy, Emmerson, Rakes, Hanka & Eness, 1957;Melampy & Rakes, 1958; Ray, 1965;Hobson & Hansel, 1972;Short, Howland, Rändle, Christensen & Bellows, 1973;Nancarrow & Radford, 1976). Some of the differences observed might be due to the various doses of oestrogen administered, the duration of administration, the injection vehicle, or synergism with other hormones.…”

Section: Introductionmentioning

confidence: 57%

Sexual behaviour in ovariectomized cows treated with oestradiol benzoate and testosterone propionate

Nessan¹,

King²

1981

Reproduction

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Sexual behaviour was not induced in ovariectomized cows by single doses of 100 or 250 micrograms oestradiol benzoate or by 3 injections of 50 micrograms oestradiol benzoate given at 12-h intervals. Treatment with 3 doses of 250 or 500 micrograms oestradiol benzoate at 12-h intervals produced plasma levels that were similar to those during pro-oestrus and oestrus in intact cows, and 11 of 12 treated animals showed oestrous behaviour. The higher dose resulted in a more pronounced response in 'mounting' and 'mounted' behaviour and a shorter interval to the onset of behavioural signs of oestrus. Oestrous behaviour was not observed in any ovariectomized cows treated with 1,2 or 20 mg testosterone propionate, doses that resulted in plasma levels comparable to those in intact pro-oestrous animals. Treatment with pharmacological doses of testosterone propionate resulted in transient mounting and interest in similarly treated females, but the results were inconsistent.

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Induced LH Release in Spayed Cows

Cited by 57 publications

References 10 publications

Induced and synchronized estrus in cattle: dose titration of estradiol benzoate in peripubertal heifers and postpartum cows after treatment with an intravaginal progesterone-releasing insert and prostaglandin F2alpha.

Induced and synchronized estrus in cattle: dose titration of estradiol benzoate in peripubertal heifers and postpartum cows after treatment with an intravaginal progesterone-releasing insert and prostaglandin F2alpha.

Hormonal and Reproductive Profiles of Early Postpartum Beef Heifers after Prolactin Suppression or Steroid-Induced Luteal Function3

Sexual behaviour in ovariectomized cows treated with oestradiol benzoate and testosterone propionate

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