Ability of induced corpora lutea to maintain pregnancy in beef cows   总被引：1，自引：0，他引：1  

Bridges PJ  Wright DJ  Buford WI  Ahmad N  Hernandez-Fonseca H  McCormick ML  Schrick FN  Dailey RA  Lewis PE  Inskeep EK 《Journal of animal science》2000,78(11):2942-2949

Experiments were conducted in beef cows without a primary CL, in which pregnancy had been maintained with exogenous progestogen. In preliminary trials, replacement CL induced ipsilateral to the embryo and after, rather than before, d 36 of pregnancy, maintained more pregnancies after withdrawal of exogenous progestogen (13/13 vs 2/6; P < 0.05). In Exp. 1, in cows with replacement CL induced by treatment with hCG on d 28 of pregnancy, treatment with flunixin meglumine on d 31 through 37 did not increase maintenance of pregnancy. Experiment 2 was conducted to evaluate directly the effects of concentrations of PGF2alpha and estradiol-17beta during d 31 through 35 of pregnancy on maintenance of pregnancy by replacement CL induced between d 28 and 31. In cows that maintained pregnancy while progestogen was provided, maintenance of pregnancy after withdrawal of exogenous progestogen tended to be greater with high (5/5) than with low (2/6; P < 0.10) concentrations of PGF2alpha and greater with low (6/7) than with high (2/6; P = 0.10) concentrations of estradiol-17beta. Secretion of progesterone by replacement CL was greater (P < 0.05) in cows with high than in those with low concentrations of PGF2, during d 31 through 35. Prostaglandin F2alpha may facilitate attachment of the bovine embryo (d 30 to 40) in a manner similar to that reported for implantation in other species. Cows that did not form CL in response to hCG on d 28 to 31 responded well when retreated after d 36. Again, maintenance of pregnancy was greater when replacement CL were induced after (9/9) rather than before d 36 (8/16; P < 0.05).  相似文献   

Effect of the previously gravid uterine horn and postpartum interval on follicular diameter and conception rate in beef cows treated with estradiol benzoate and progesterone     

Bridges PJ  Taft R  Lewis PE  Wagner WR  Inskeep EK 《Journal of animal science》2000,78(8):2172-2176

An experiment was performed to evaluate the effect of the side of ovulation with respect to the previously gravid uterine horn on fertility of cows inseminated at one of two periods postpartum. All cows were treated with an intravaginal progesterone insert for 7 d and received estradiol benzoate (2 mg, i.m.) at the time of device insertion, prostaglandin F2alpha (25 mg, i.m.) at the time of device removal, and estradiol benzoate (1 mg, i.m.) 30 h after device removal. All cows were inseminated 28 to 30 h after the second treatment with estradiol benzoate, regardless of observed estrus. Cows treated in Period 1 received inserts at 16 to 20 d postpartum and were inseminated at 25 to 29 d postpartum. Cows treated in Period 2 received inserts at 26 to 30 d postpartum and were inseminated at 35 to 39 d postpartum. Diameter of the largest follicle at insert removal was greater in cows treated in Period 2 (10.1 +/- 0.3; mm +/- SEM) than in cows treated in Period 1 (9.1 +/- 0.3; P < .05). Diameter did not differ with the side of ovulation in respect to the previously gravid uterine horn. Diameter was greater in cows 5 to 9 (10.3 +/- 0.3) than in cows 3 to 4 (9.0 +/- 0.3) or 10 to 13 (9.4 +/- 0.6) yr of age (P < .01). The proportion of cows that ovulated from the ovary contralateral to the previously gravid uterine horn was greater (P < .05) than of those that ovulated from the ipsilateral ovary, and the incidence of ovulation was reduced in cows 3 to 4 yr of age (P < .01). Conception rate tended to be greater for ovulation from the ipsilateral compared with the contralateral ovary, relative to the previously gravid uterine horn (P < .10) and for ovulation from the right than the left ovary (P < .06). Conception rate was less if cows ovulated a follicle that was < 9 mm than a follicle > or = 9 mm in diameter at insert removal (P < .01) and was greater in cows inseminated in June than in April or May (P < .05). In conclusion, in cows in which estrus was synchronized at 25 to 39 d postpartum, ovulation from either the ovary ipsilateral to the previously gravid uterine horn, or the right ovary, tended to increase fertility.  相似文献   

Roles of pattern of secretion of luteinizing hormone and the ovary in attainment of puberty in ewes lambs     

D.H. Keisler  E.K. Inskeep  R.A. Dailey 《Domestic animal endocrinology》1985,2(3):123-132

Four experiments were conducted to examine (1) how patterns of luteinizing hormone (LH) change as lambs approach first estrus, (2) whether mimicry of these changes by exogenous LH will initiate events of the pubertal process, (3) aspects of possible roles of the ovary and estradiol in the initiation of an ovulatory surge of LH in prepubertal lambs and (4) the time requirements for the presence of the ovary in induction of that surge of LH.In 19 lambs (Exp. 1), concentrations of LH in plasma were higher at puberty than 7 weeks earlier. Increased concentrations of LH in samples taken every 20 min for 6 hr during the luteal and follicular phases preceding first estrus were attributed to increased amplitude, but not increased frequency, of episodic pulses of LH. In Exp. 2, endocrine events which are included in the natural onset of ovarian cyclic activity (i.e. surge of LH and subsequent rise in progesterone) were initiated in $\text{5}\text{6}$, $\text{4}\text{6}$, $\text{1}\text{5}$, $\text{1}\text{6}$, and $\text{3}\text{6}$ lambs, receiving either injections of 7.5 μg/hr, 15 μg/hr, 30 μg/2hr, 45 μg/3hr or constant infusions of 15 μg/hr of purified ovine LH, respectively. However, these lambs did not exhibit estrus or cyclic ovarian activity. In Exp. 3, the mechanism by which hourly injections of LH prompted surges of LH was determined to be mediated through ovarian stimulation and not through a direct effect of exogenous LH on the hypothalamo-pituitary axis. All the intact (n=5) but no acutely (two weeks) ovariectomized (n=5) lambs had a preovulatory-like surge in response to exogenous LH. Further, (Exp. 4) it was shown that the ovarian signal must be maintained or evoked within 6 hr preceding the surge of LH, because lambs (n=20) ovariectomized at or 9, 18 or 27 hr after initiation of the exogenous LH with the one exception failed to show a surge of LH. It could not be demonstrated that the ovarian signal involved changes in peripheral concentrations of androstenedione, testosterone or estradiol-17β, although patterns of LH in ovariectomized lambs were responsive to both negative and positive feedback effects of estradiol (n=6, Exp. 3) and in general estradiol levels were increasing prior to the induced surge of LH.  相似文献   

Changes in hormonal profiles during the estrous cycle in old lactating beef cows   总被引：1，自引：0，他引：1  

R W Bryner  M Garcia-Winder  P E Lewis  E K Inskeep  R L Butcher 《Domestic animal endocrinology》1990,7(2):181-189

Patterns of concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), progesterone (P4) and estradiol-17 beta (E2) during an estrous cycle were compared between 15 lactating beef cows 5 to 7 years of age (young) and 15 cows greater than or equal to 12 years of age (old). Length of estrous cycle did not differ between young and old cows (P = .06). No differences due to age were found for LH. Patterns of concentrations of P4 during the first 15 days of the cycle, of FSH during days 6 through 12 and of E2 during the follicular phase differed with age (P less than .05). An earlier (P less than .025) midcycle elevation of FSH was associated with an earlier rise and greater concentration of E2 (P less than .05) during the follicular phase in old than in young cows. Differences in FSH and P4, although subtle, were consistent with an earlier or more advanced follicular development in old cows, leading to greater secretion of E2 from the preovulatory follicle.  相似文献   

Endocrine profiles associated with life span of induced corpora lutea in postpartum beef cows   总被引：2，自引：0，他引：2  

M Garcia-Winder  P E Lewis  D R Deaver  V G Smith  G S Lewis  E K Inskeep 《Journal of animal science》1986,62(5):1353-1362

Two experiments were designed to examine whether hormonal profiles were related to luteal life span in pluriparous postpartum anestrous beef cows. Cows (Exp. 1, n = 34; Exp. 2, n = 23) received norgestomet (N) for 9 d or served as controls (C). Each cow received 1,000 IU human chorionic gonadotropin (hCG) 48 h after removal of N (d 0). Blood samples collected every 15 min for 8 h on d -5, 3 and 5 (Exp. 1) or on d -10 and -1 (Exp. 2) were assayed for luteinizing hormone (LH) and follicle stimulating hormone (FSH). Cortisol was determined in hourly samples collected on d -5 and in samples collected every 2 min during suckling on the same day (Exp. 1). Concentrations of 15-keto-13,14-dihydro-PGF2 alpha (PGFM) were determined in samples collected at 15-min intervals for 2 h on d -5, 3, 5 and 10 (Exp. 1). Estradiol-17 beta was measured in samples collected on d -5 (Exp. 1) or on d -10 and -1 (Exp. 2). Life span of induced corpora lutea was longer (P less than .05) in N than C cows. Percentages of N cows in which corpora lutea, formed in response to hCG, exhibited a normal life span were 83% on farm 1 and 25% on farm 2 (Exp. 1), and 90% (Exp. 2), compared with 0% in C cows. Concentrations of FSH were not affected by N but were lower (P less than .05) on d -5 in cows on farm 2 (.6 +/- .1 ng/ml) than in cows on farm 1 (.8 +/- .1 ng/ml). On d -5, a treatment X farm interaction (P less than .05) for mean LH was observed and frequency of pulses of LH was higher (P less than .01) in N than C cows (2.7 +/- .4 vs. .8 +/- .8 pulses/8 h). Neither cortisol nor PGFM was affected by N. Estradiol was increased in d -1 (6.1 +/- .5 vs 2.6 +/- .8 pg/ml; P less than .01) by N. It is suggested that pre-treatment with N enhanced life span of induced corpora lutea, in part, by influencing secretion of LH and development of follicles, but a threshold concentration of FSH was required for N to exert this effect.  相似文献   

Maintenance of pregnancy in postpartum beef cows that have short-lived corpora lutea.     

R L Butcher  J E Reber  A W Lishman  K F Breuel  F N Schrick  J C Spitzer  E K Inskeep 《Journal of animal science》1992,70(12):3831-3837

The first two experiments examined the role of the uterus in low pregnancy rates of beef cows induced to ovulate by early weaning. At 20 to 25 d postpartum, one-half of the cows in Exp. 1 and 2 received a s.c. implant containing 6 mg of norgestomet (NOR) for 9 d (NOR-pretreated) and the remaining cows were untreated controls (CON). Lengths of first postpartum luteal phase after weaning of calves at d 7 after implant insertion were expected to be normal in NOR-pretreated and short in CON cows. In Exp. 1, cows of both groups received an implant containing 3 mg of NOR at d 4 after first estrus and a silastic implant with 15 or 25 mg of NOR at d 7 after first estrus. At 7 d after first estrus, two embryos were transferred into the uterus of each cow and pregnancy was diagnosed by ultrasonography at d 35. Blood samples were collected daily from onset of treatment to d 8 after estrus and then every other day to d 24. Only 4 of 22 cows were pregnant at d 35, concentrations of estradiol (E2) were elevated after luteolysis, and large follicles were present at d 35. In Exp. 2, all cows were injected with 100 mg of progesterone (P4) twice daily from d 4 to 35 after first estrus. Embryos were transferred, pregnancy was diagnosed, and blood samples were collected as in Exp. 1, except blood sampling was continued to d 34.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Preovulatory changes prostaglandins E2 and F2 alpha in ovine follicles     

W J Murdoch  R A Dailey  E K Inskeep 《Journal of animal science》1981,53(1):192-205

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Effects of cyclophosphamide in rams     

E K Inskeep  J C Herrington  I L Lindahl 《Journal of animal science》1971,33(5):2022-2025

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Local effect of intrauterine devices on prostaglandin F2alpha in uterine venous plasma of gilts     

R J Magrini  G S Lewis  E K Inskeep 《Journal of animal science》1978,47(3):682-685

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Growth hormone at breeding modifies conceptus development and postnatal growth in sheep     

Costine BA  Inskeep EK  Wilson ME 《Journal of animal science》2005,83(4):810-815

Experiments were performed to determine the effects of components of the GH-IGF axis on conceptus development and postnatal growth in sheep. In Exp. 1, ewes received one of the following treatments: 1) sustained release GH at breeding, 2) sustained release GH at breeding and estradiol-17beta at d 5 and 6, 3) only estradiol-17beta at d 5 and 6, or 4) no treatment. Uteri were flushed on d 7, and flushings were analyzed for content of IGF-I. A single injection of sustained-release bovine GH at breeding increased IGF-I content in uterine luminal flushings compared with control ewes (P < 0.05). Treatment with estradiol-17beta on d 5 and 6 after breeding did not alter IGF-I content compared with control ewes, and it blocked the effect of GH on uterine luminal IGF-I content. In Exp. 2, sustained release GH or no treatment was administered at breeding, and gravid uteri were collected at d 25, 80, or 140 of gestation. On d 80, GH-treated ewes had smaller chorioallantoic weights (P < 0.05) and tended to have more efficient placentae (fetal weight/total placental weight; P = 0.052), with a higher percentage of placental weight as cotyledons (P = 0.068) compared with control ewes. In Exp. 3, ewes were treated with or without sustained release GH at progesterone withdrawal. Lambs from GH-treated ewes were heavier at birth (P < 0.05). Lambs from GH-treated ewes reared as singles, but not lambs reared as multiples, were heavier at 30, 60 (P < 0.05), and 75 d (P = 0.075) of age than lambs from control ewes. In conclusion, ewes treated with sustained-release GH at breeding developed smaller, more efficient placentas, and had larger lambs at birth.  相似文献