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1.
Two experiments were conducted to determine the effect of exogenous gonadotropins on follicular development in gilts actively immunized against gonadotropin releasing hormone (GnRH). Four gilts, which had become acyclic after immunization against GnRH, and four control gilts were given 1,000 IU pregnant mare serum gonadotropin (PMSG), while four additional control gilts were given saline. Control animals were prepuberal crossbred gilts averaging 100 kg body weight. Control gilts given saline had ovaries containing antral follicles (4 to 6 mm in diameter). Control gilts given PMSG exhibited estrus and their ovaries contained corpora hemorrhagica and corpora lutea. PMSG failed to stimulate follicular growth in gilts immunized against GnRH, and ovaries contained regressed corpora albicantia and small antral follicles (less than 1 mm in diameter). Concentrations of luteinizing hormone (LH) and estradiol-17 beta (E2) were non-detectable in gilts immunized against GnRH and given PMSG. In the second experiment, five gilts actively immunized against GnRH were given increasing doses of PMSG every third day until unilateral ovariectomy on d 50. PMSG failed to stimulate follicular growth, and concentrations of follicle stimulating hormone (FSH), E2 and LH were not detectable. Six weeks later, gilts were given a booster immunization and then were given 112 micrograms LH and 15 micrograms FSH intravenously every 6 h for 9 d. The remaining ovary was removed on d 10. Although LH and FSH concentrations were elevated, administration of gonadotropins did not stimulate follicular growth or increase E2 concentrations. These results indicate that neither PMSG or exogenous LH and FSH can induce E2 synthesis or sustain follicular development in gilts actively immunized against GnRH.  相似文献   

2.
Characterization of effects of zearalenone in swine during early pregnancy   总被引：2，自引：0，他引：2  
Mature gilts (n = 16) were hand mated and randomly assigned to 1 of 4 groups of 4 gilts each. Treated gilts had 108 mg of purified zearalenone added to their diet on postmating days (PMD) 2 to 6, 7 to 10, or 11 to 15. Control gilts were given the same diet without added zearalenone. On PMD 6, 10, and 15, control gilts had venous cannulas placed in the jugular vein, and blood samples were taken at 20-minute intervals for 4 hours before feeding and 4 hours after feeding. Samples were collected from treated gilts on the last day that zearalenone was consumed. Samples were analyzed for follicle stimulating hormone, luteinizing hormone (LH), and prolactin. Single blood samples were taken by venipuncture on PMD 8, 12, 16, 20, 24, and 28 and at euthanasia and were analyzed for serum concentration of progesterone and estradiol-17 beta. All gilts were euthanatized 30 to 32 days after mating, and fetal development was assessed. Three gilts that were given zearalenone on PMD 7 to 10 were not pregnant and had regressing corpora lutea on the ovaries at euthanasia. All other treated and control gilts were pregnant. Serum samples from treated gilts on PMD 10 and 15 had lower mean prolactin concentrations than did those from controls. The number of LH spikes were fewer (P less than 0.05) in gilts that were given zearalenone on PMD 15 compared with those in controls on PMD 15. Serum progesterone concentrations indicated that corpora lutea regressed between PMD 20 and 28 in nonpregnant gilts.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

3.
The ovaries of 59 pluriparous cows of unknown reproductive history were palpated, scanned and dissected on the day of slaughter to compare the accuracy of rectal palpation and transvaginal ultrasonography with a 5 MHz linear array for the detection of corpora lutea and follicles. The rectal palpation was first carried out to judge the presence of follicles of more than 5 mm diameter, and corpora lutea which were classified as young (days 1 to 4), mid-cycle (days 5 to 16) or old (days 17 to 21) according to morphological criteria. The cows were then examined for follicles and corpora lutea by ultrasonography and the corpora lutea were again classified directly as young, mid-cycle or old according to their appearance. The cows were then slaughtered, their ovaries dissected, and the follicles over 5 mm in diameter were counted and the corpora lutea were classified in the above mentioned age categories. For the detection of a mid-cycle corpus luteum the sensitivity and predictive value of rectal palpation were, respectively, 83.3 per cent and 73.2 per cent and for ultrasonography the sensitivity and predictive value were 80.6 per cent and 85.3 per cent, respectively. However, both techniques were inaccurate for the detection of young and old corpora lutea. For detecting follicles ultrasonography was a significantly better method than rectal palpation. Ultrasonography detected 95 per cent of follicles larger than 10 mm whereas rectal palpation detected only 71 per cent of these follicles. Both techniques failed with follicles 5 to 10 mm in diameter; only 21.5 per cent were detected by rectal palpation and 34.3 per cent by ultrasonography.  相似文献   

4.
To determine time of occurrence of follicular changes that may be associated with the length of the subsequent luteal phase, follicles were collected at different times before ovulation from cows expected to have corpora lutea of short (control) or normal (norgestomet-treated) life span. Beginning on d 20 to 23 postpartum (d 0 of study), 34 crossbred beef cows received either a 6-mg implant of norgestomet for 9 d or served as untreated controls. Ovaries were removed from norgestomet-treated cows on d 6 (N6; n = 9), d 8 (N8; n = 8), or the day after implant removal (N10; n = 8). Control cows were ovariectomized on d 6 (C6; n = 4) or d 10 (C10; n = 5). The largest and second largest follicles greater than 8 mm (F1 and F2, respectively) were dissected from the ovaries. Granulosal and thecal layers and follicular fluid were separated and assayed for estradiol-17 beta, progesterone, androstenedione, and testosterone. Cyclic 3'5'adenosine monophosphate (cAMP) was determined in thecal and granulosal tissue. Diameters of the F1 (14.6 +/- .4 mm) and F2 (10.6 +/- .4 mm) did not differ due to treatment. A greater proportion (P less than .05) of the F1 (20/33) than of the F2 (4/27) had estradiol:progesterone ratios of greater than 1 in follicular fluid. Contents of estradiol, androstenedione, and testosterone in theca and granulosa and follicular fluid, androstenedione in theca, and testosterone in theca and follicular fluid (all P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
Percentages of normal and apoptotic parenchymal cells, fibroblasts and endothelial cells in ovine corpora lutea at 12, 24 and 36 hr following administration of a luteolytic dose of PGF2 alpha were determined and compared to percentages for identical cell types in corpora lutea removed from control ewes on days 10 (n = 5) and 12 (n = 6) postestrus. In corpora lutea obtained from control ewes greater than or equal to 95% of nuclei examined were scored normal for each of the respective cell types with no difference (P greater than .05) observed between luteal tissue obtained on days 10 and 12 postestrus. Following treatment with PGF2 alpha there were significant (P less than .05) reductions in the percentages of nuclei scored normal. Compared to controls the percentage of endothelial cell nuclei scored normal was reduced at 12 hr following PGF2 alpha-treatment; however significant reductions in percentages of parenchymal and fibroblast nuclei scored normal were not evident until 24 and 36 hr, respectively. Consistent with the concept of apoptosis, nuclear condensation and/or margination indicative of apoptosis did not occur synchronously within a given cell type: i.e., irrespective of the time point examined some cells appeared normal, whereas others had undergone nuclear condensation and/or margination. A sequence of events to explain structural and functional changes that occur during luteolysis following the interaction of PGF2 alpha with specific receptors in large steroidogenic luteal cells is discussed.  相似文献   

6.
This study was undertaken to determine changes in follicular populations on ovaries of dairy cows during three stages of the estrous cycle and their steroidogenic capacity in vitro. Numbers of small (2.0 to 5.0 mm), intermediate (5.1 to 10 mm) and large (greater than 10 mm) antral follicles on ovaries of multiparous cows and heifers (n = 31) in the early luteal (d 4), mid-luteal (d 12) and follicular phase (d 19) of the estrous cycle were determined (d 0 = estrus), and steroidogenic capacity of intermediate and large follicles was measured in vitro. Total number of follicles and number of small follicles were greatest (P less than .05) on d 19 compared with d 12, with numbers on d 4 not different from either d 12 or 19. Intermediate follicles were fewer (P less than .05) on d 19 compared with d 4 or 12. Numbers of large follicles did not change. The proportion of estrogen active (EA) follicles was greater (P less than .05) on d 19 compared with d 4 or 12. Accumulation of estradiol-17 beta (E) into culture medium by intermediate follicles decreased (P less than .05) with increasing days of the estrous cycle, while accumulation of progesterone (P) was greater on d 19. In large follicles, accumulation of E into culture medium was greatest (P less than .05) on d 19 and the lowest on d 12 (P less than .05). In summary, the proportion of EA follicles increases during the preovulatory period, and E production increases in large EA follicles.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

7.
Fifty crossbred gilts immunized against bovine serum albumin (BSA) or androstenedione conjugated to BSA (AD) were used in three experiments. Primary immunizations were given at 120 d of age and boosters at 148 and 176 d. Gilts were moved to pens containing four to five animals each and exposed to boars beginning at 180 d of age. Immunization against AD did not affect age at puberty, percentage of gilts exhibiting estrus or duration of first estrous cycle. Over the three experiments, ovulation rate was 24% greater for AD-immunized gilts than for controls, and the number of corpora lutea was related positively (r = .82) to the log of the antibody titer. Number of ovulations decreased as interval from booster immunization to onset of estrus increased. During diestrus of the first estrous cycle, gilts immunized against AD had more follicles 5 to 10 mm in diameter, more total ovarian follicles and more total ovarian structures (corpora lutea plus follicles) than controls. Immunization against AD increased the frequency of LH pulses on d 16 but not on d 17 or 18, of the estrous cycle. However, average serum concentrations of LH, FSH and estradiol from 5 d before until 2 d after expected estrus were not different between treatment groups. Concentrations of AD in follicles 4 to 6 and greater than 7 mm in diameter were greater in gilts immunized against AD. Mean serum progesterone was higher on d 9 and 12 after mating in AD immunized gilts than in controls. Immunization against AD had no effect on maintenance of pregnancy or embryo survival rate.  相似文献   

8.
Pituitary-ovarian function was analyzed in a strain of miniature swine previously shown to produce a low ovulation rate resulting in the formation of only 8.6 corpora lutea (CL)/animal. Five multiparous (M) and four nulliparous (N) miniature pigs with a mean inbreeding coefficient of .39 were monitored for estrous behavior through four consecutive estrous cycles. Daily blood samples were collected from 5 d before to 5 d after the onset of the second, third and fourth estrus and at 48-h intervals during the remainder of the second and third estrous cycle. Laparoscopy was used to examine the ovaries 1 and 5 d after onset of the third estrus and 2 d after the beginning of the fourth estrus. For the entire group, temporal fluctuations among serum estradiol-17 beta, luteinizing hormone (LH) and progesterone concentrations and sexual behavior were similar to previously published data in standard swine breeds. Although the mean lengths of the estrous cycle were not different (P greater than .05) between parity subgroups (M, 23 +/- 1.3 vs N, 22 +/- .7 d), multiparous pigs were in estrus longer (P less than .05) than nulliparous females (M, 3.7 +/- .2 vs N, 2.2 +/- .4 d). Parity subgroups were similar with respect to the mean number of follicles forming CL (M, 8.8 +/- .7 vs N, 9.2 +/- .2). Although an average of 6.2 +/- 2.1 CL had formed by 24-h after onset of estrus in the nulliparous subgroup, no CL were detected in the multiparous subgroup at this time.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
This study was conducted to determine the effects of testosterone-propionate exposure during fetal development on sexual differentiation and growth rates in heifers. Ten pregnant cows were given subcutaneous injections of testosterone-propionate (250 mg/injection) every other day during d 40 to 60 of gestation. Four cows aborted after the end of testosterone treatment, while four heifers (androgenized females) and two bulls (androgenized males) were produced from the six remaining pregnant, testosterone-propionate treated cows. Calves from cows that did not receive exogenous hormone treatment were used as controls. At 8 mo of age, the androgenized heifers and control heifers and control steers were challenged with 1 mg estradiol-17 beta to induce a preovulatory luteinizing hormone (LH) surge. Two weeks later, pituitary responsiveness to exogenous luteinizing hormone releasing hormone (LHRH; 75 micrograms) was evaluated in androgenized heifers and in control heifers and control steers. To monitor growth rates, all animals were weighed at 28-d intervals from birth to 380 d of age. Androgenized females exhibited a partially masculinized phenotype as well as internal male reproductive structures. Treatment with estradiol-17 beta first depressed (P less than .05) serum LH concentrations in all animals, then induced (P less than .05) a preovulatory-like LH surge in control and androgenized females. Control steers did not (P greater than .05) exhibit a preovulatory-like LH surge following administration of estradiol-17 beta. Exogenous LHRH treatment stimulated peak LH concentrations (P less than .05) to a greater extent in control and androgenized females than in control steers.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
Anovulatory haemorrhagic follicles (AHFs) are often the reason for ovulation failure in the mare. As the underlying factors that lead to AHF development are not well understood, it was of interest to investigate the vascularization of AHFs compared with normal follicles and corpora lutea (controls). In the present study, the ovarian cell populations investigated immunohistochemically included granulosa and luteal cells as well as various vascular structures. None of these cell types showed differences in the expression of vascular endothelial growth factor A (VEGF-A) between control ovaries containing normal follicles and corpora lutea and ovaries with AHFs. In contrast, a considerable reduction in the proportion of Flk-1-expressing cells, together with a decreased intensity of staining, was apparent in the AHFs. This greatly reduced expression of Flk-1 in the luteinized cells and the vascular structures of AHFs may lead to a distinct decrease in the potential pro-angiogenic activity of VEGF-A in these structures compared with the situation in normal follicles and corpora lutea. Furthermore, the authors suspect that the distinct expression of angiopoietin2 and VEGF-A seen in the cells within the inner fibrous layers of the AHFs was caused by hypoxia resulting from deficient vascularization, as suggested by the irregularity of the capillaries present in the luteinized wall of the AHF. In addition, whereas LH-receptor (LH-R) expression occurred uniformly in all stages of development of the corpora lutea in normal control ovaries, there was highly variable labelling for LH-R in all the AHFs examined, thereby indicating a possible numerical deficiency of LH-receptors in AHFs. The authors concluded that, despite the apparent expression of sufficient VEGF-A in the AHFs allows ovulation and corpus luteum formation, a relative lack of receptor, Flk-1, effects the pro-angiogenic activity of VEGF-A which could be a reason for ovulation failure associated with AHF formation.  相似文献   

11.
Experiments were conducted to examine the cellular localization of inhibin alpha-subunit, protein kinase B (PKB/Akt), and FoxO3a proteins in the ovaries of minipigs, Chinese Xiang pigs, by immunohistochemistry. The results indicated that inhibin alpha-subunits were localized in the granulosa cells of follicles at all stages but were not localized in corpora lutea. PKB was localized in the granulosa cells of primordial follicles and in the basal layers of the granulosa cells of preantral and antral follicles, but were not localized in atretic follicles and corpora lutea. FoxO3a was localized in the granulosa cells of follicles at all stages and was extensively localized in the cytoplasma of the luteinized granulosa cells of corpora lutea. Together, the stage- and cell-specific expression patterns of inhibin alpha-subunit, FoxO3a, and PKB suggest that these proteins might play potential roles in follicular development, atresia, and luteinization in the minipig.  相似文献   

12.
Forty-four female American Shorthair cats with inflammatory uterine disease or infertility were evaluated. Data collected included age, month of diagnosis, housing, reproductive history, results of bacteriologic culture of uterine specimens, serum concentrations of estrogen, progesterone, and prolactin and histopathologic features of the ovaries and uterus. Histologically, the ovaries of 19 cats were dominated by active or cystic follicles, whereas 25 cats had luteal-phase ovaries. Of the 25 cats with active corpora lutea, 20 had either recently weaned litters (n = 11) without subsequent exposure to a male cat, or had been housed individually for lengthy periods (n = 9). The finding of active corpora lutea under these circumstances indicates that in queens, ovulation may occur by mechanisms not involving coitus. Prominent, active corpora lutea on the ovaries were associated with adenomatotic proliferative changes in the superficial and glandular epithelium of the uterus and with myometrial hyperplasia, compared with the uterus of cats with follicular ovaries (P less than 0.01). Serum progesterone concentration greater than or equal to 1.87 ng/ml was consistently associated with luteal-phase ovaries. Serum progesterone values less than or equal to 0.15 ng/ml were consistently associated with follicular-phase ovaries. Escherichia coli was the organism most commonly isolated from uterine contents.  相似文献   

13.
A study was done to test whether ovulatory follicles destined to form subfunctional corpora lutea differed from normal ovulatory follicles in steroidogenic function. Twenty-five ewes were treated with prostaglandin F2 alpha on d 11 of the estrous cycle, then unilaterally ovariectomized before (n = 13) or after (n = 12) the surge of luteinizing hormone (LH) at the induced estrus to collect "control" follicles, which would have produced normal corpora lutea. In 15 ewes, the second ovary was removed 63 to 84 h later to collect "treated" follicles before (n = 7) or after (n = 8) the second expected surge of LH. Five ewes (control) were allowed to ovulate from the remaining ovary at first estrus and another five (treated) at the second estrus (3 to 4 d later). Treated ewes had lower serum progesterone than control ewes during the ensuing cycle (P less than .05). Treated follicles contained less estradiol in the theca (4.4 +/- .6 vs 10.0 +/- 2.5 ng; P less than .05), less androstenedione (.1 +/- .1 vs 1.0 +/- .2 ng) and estradiol (.5 +/- .1 vs 2.9 +/- 2.2 ng) in the granulosa (P less than .05) and less progesterone in the follicular fluid (.8 +/- .4 vs 3.3 +/- .8 ng; P less than .05) than control follicles, when removed before the surge of LH. Follicles removed after the surge of LH did not differ. In conclusion, ovulatory follicles with low steroidogenic function became corpora lutea that secreted lower-than-normal quantities of progesterone.  相似文献   

14.
Corpora lutea were collected from 18 beef heifers on day 4 or 12 of the estrous cycle, 1 hour after prostaglandin (PG) F2 alpha or saline (control) treatment. Five heifers also were treated with PGF2 alpha on day 4, but their corpora lutea were not collected until day 12. The relative percentage of cytoplasm occupied by granules decreased only in large luteal cells (LLC) in heifers given PGF2 alpha on day 12, compared with the percentage in controls. Small luteal cells (SLC) were not as affected. The luteal concentration of progesterone was similarly decreased only in heifers given PGF2 alpha on day 12. Treatment of heifers with PGF2 alpha on day 4 had no marked effect on progesterone values or on the relative percentage of cytoplasm occupied by granules in LLC or SLC. Seemingly, LLC were more responsive to PGF2 alpha than were SLC, and PGF2 alpha treatment of beef heifers at day 4 did not markedly impair luteal function.  相似文献   

15.
In this study diagnostic certainty of ultrasonography and rectal palpation concerning the detection of follicles and C.I. was compared by evaluation of the findings obtained with ultrasonography in waterbath and dissection of the ovaries after slaughter. Clinical examinations were performed on a total of 30 cows (transrectally and ultrasonographically, 5.0 mhz, linear) in slaughterhouse. In the laboratory ovaries were evaluated after slaughter both macroscopically and by ultrasonography in waterbath. Diagnostic reliabilities of these methods were compared. No difference between the methods was determined concerning the longitudinal measurements of corpora lutea (19.96 +/- 4.83 mm, 20.41 +/- 5.41 mm, 21.45 +/- 5.26 mm by ultrasonography, waterbath and macroscopy respectively). By means of determining the correct identification of corpora lutea, the error rate was 24.1% and 17.2% for rectal palpation and ultrasonography respectively. The comparison of rectal palpation and macroscopy showed that three small corpora lutea and two corpora lutea with small cavity were determined wrongly as small follicles and two corpora lutea were determined whereas they were not present actually. With ultrasonography four small C.I. could not be detected and one C.I. with cavity was wrongly determined as follicle. It was noticed that follicles bigger than 10 mm (F2 = 10-15 mm, F3 = 16-20 mm) could be determined more accurately by means of ultrasonography than by rectal palpation (with ultrasonography: F2 = 90.48%, F3 = 100.0%; with rectal palpation, F2 = 61.9%, F3 = 200.0%). The correlation of the findings of rectal palpation or ultrasonography and blood progesterone levels was 86.2% and 89.7% respectively. This accordance was 96.6% for progesterone levels and waterbath and macroscopic findings.  相似文献   

16.
Seventy-one 10th-generation gilts from White Line-1 (WL-1 = randomly selected control line) and White Line-2 (WL-2 = selected for an index of ovulation rate and prenatal survival rate) were used to compare the pattern of follicular development and atresia during the follicular phase of the estrous cycle. Gilts were treated with PGF(2alpha)on d 13 of the estrous cycle (d 0 of induced follicular development) to induce luteolysis and assigned randomly within line and sire for ovary recovery on d 0, 2, 3, 4, 5, and the day after estrus. Ovaries were evaluated for numbers of corpora albicantia and small (2 to 2.9 mm), medium (M1 = 3 to 4.9 mm; M2 = 5 to 6.9 mm), and large (>or=7 mm) follicles. The concentration of estradiol-17beta in follicular fluid was used to classify individual M2 and large follicles as estrogen-active (>or=100 ng of estradiol-17beta/mL) or inactive (<100 ng of estradiol-17beta/mL). The WL-2 gilts had a greater ovulation rate than WL-1 gilts at their pre-treatment estrus (20.4 vs. 13.8 corpora albicantia; P < 0.001). The small and M1 follicle populations decreased rapidly in both lines over time (P < 0.001). The M2 follicle population increased in both lines between d 0 to 4 and then decreased. Mean estradiol concentration of M2 follicles increased in both genetic lines over time (P < 0.02). All large follicles were estrogen-active in both lines; the number of large follicles increased with day (P < 0.001) and was similar in both lines. The number of estrogen-active M2 follicles was similar in both lines, increasing to d 3 and 4 and then decreasing (P < 0.01) thereafter. However, the total number of estrogen-active follicles (sum of estrogen-active M2 and large follicles) was greater in WL-2 than in WL-1 gilts (P < 0.04), increasing to the ovulatory potential by d 3 in WL-1 gilts, but continuing to increase through d 4 in WL-2 gilts. Selection of an additional six ovulatory follicles from the estrogen-active M2 follicle pool after d 5 was required in both lines to achieve the projected ovulation rate, and after estrus, the number of large follicles remained insufficient to attain the ovulatory potential of each line.  相似文献   

17.
Two experiments were conducted to compare pregnancy rates resulting from fixed-time AI (FTAI) after administration of 1 of 2 long-term controlled internal drug release (CIDR)-based protocols. Heifers were assigned to treatment by age, BW, and pubertal status. The CIDR Select-treated heifers (Exp. 1, n = 37; Exp. 2, n = 192) received a CIDR (1.38 g of progesterone) from d 0 to 14, followed by 100 μg of GnRH, intramuscularly (i.m.) 9 d after CIDR removal (d 23) and PGF(2α) (25 mg, i.m.) 7 d after GnRH treatment (d 30). Heifers assigned to the Show-Me-Synch protocol (Exp. 1, n = 40; Exp. 2, n = 200) received a CIDR from d 0 to 14, followed by PGF(2α) 16 d later (d 30). Artificial insemination was performed at 72 or 66 h after PGF(2α) treatment for the CIDR Select- and Show-Me-Synch-treated heifers, respectively, and each heifer was given GnRH (100 μg, i.m.) at the time of AI. In Exp. 1, ovaries of each heifer were examined by transrectal ultrasonography on d 23 and 30 to characterize follicular dynamics. Follicles ≥5 mm and the presence of corpora lutea were recorded. On d 25, ovaries of each heifer were examined to characterize the status of dominant follicles recorded on d 23. Heifers were fitted with HeatWatch (DDx Inc., Denver, CO) estrus-detection transmitters at PGF(2α) to characterize estrus distribution up to FTAI. The diameter of dominant follicles on d 23 at PGF(2α) and on d 30, and the estrous response after PGF(2α) treatment up to the point of FTAI did not differ between CIDR Select- and Show-Me-Synch-treated heifers. Concentrations of progesterone in serum at PGF(2α) were greater (P = 0.07) in Show-Me-Synch- than CIDR Select-treated heifers (6.0 vs. 4.8 ng/mL, respectively). Pregnancy rates of heifers resulting from FTAI did not differ (P = 0.33) between CIDR Select- and Show-Me-Synch-treated heifers (CIDR Select, 59%; Show-Me-Synch, 70%). In Exp. 2, FTAI pregnancy rates tended (P = 0.07) to be greater in Show-Me-Synch-treated (62%) than in CIDR Select-treated (51%) heifers. Pregnancy rates at the end of the breeding season did not differ (P = 0.72; CIDR Select, 85%; Show-Me-Synch, 83%) between treatments. In summary, pregnancy rates resulting from FTAI were comparable for heifers assigned to each of the 2 long-term progestin-based protocols. The reduced treatment cost and animal handling associated with administration of the Show-Me-Synch protocol offer distinct advantages over the CIDR Select protocol despite similarities in pregnancy rates resulting from FTAI.  相似文献   

18.
The effects of pregnancy and number of corpora lutea on luteal regression induced with prostaglandin F2 alpha (PGF2 alpha) were examined in 93 ewes. Bred and nonpregnant ewes were assigned randomly to receive a single im injection of PGF2 alpha: 0, 2, 4, 6, 8 or 10 mg/58 kg body weight. Injections were given on d 13 postestrus. The concentration of progesterone in serum 24 h after PGF2 alpha injection was affected by dose (P less than .001). The effect of pregnancy and the interaction of pregnancy with number of corpora lutea on levels of progesterone in serum were significant (P less than .05); therefore, data were partitioned according to pregnancy status and analyzed separately. There was an effect of number of corpora lutea on serum concentration of progesterone in pregnant (P less than .01) but not nonpregnant ewes (P greater than .10). Similar relationships among groups were observed for the concentration of progesterone in luteal tissue. In nonpregnant ewes the minimum dose of PGF2 alpha to produce a significant suppression of progesterone in serum (P less than .05) was 4 mg/58 kg body weight. In pregnant ewes with one or two corpora lutea, the minimum effective doses were 6 and 10 mg/58 kg body weight, respectively. The concentration of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) in serum was related to the dose of PGF2 alpha injected. There were no differences in the concentration of PGFM in serum between pregnant and nonpregnant ewes either before or after injection. Corpora lutea of early pregnancy appear to be resistant to the luteolytic effect of PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
Estimation of superovulation response in donor cows   总被引：1，自引：0，他引：1  
Estimates were made of the superovulation response in donor cows using ovarian size, the number of corpora lutea (palpated per rectum) and blood progesterone levels. Neither the estimated number of corpora lutea nor ovarian size gave a satisfactory prediction of superovulation response. There was a large discrepancy between the number of corpora lutea present on the ovaries of nine superovulated cows (166) and the estimated number (106). All the corpora lutea on superovulated ovaries were smaller than normal (1.95 g). Blood progesterone levels at the time of embryo recovery were correlated with both the number of corpora lutea on the superovulated ovaries (r = 0.9, P less than 0.001) and the weight of the corpora lutea (r = 0.95, P less than 0.001). There were 67 embryos and ova recovered from the nine donors, representing 40 per cent of the actual and 63 per cent of the palpated corpora lutea. However, neither ovarian size, the number of corpora lutea nor blood progesterone levels were correlated with embryo production.  相似文献   

20.
We determined the effects of hCG on ovarian response, concentration of progesterone, and fertility in a fixed-time AI (TAI) protocol. Four hundred forty-four crossbred beef heifers were synchronized with the CO-Synch + CIDR (controlled internal drug-releasing insert) protocol. In addition, heifers were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement of treatments with main factors being 1) pretreatment, no treatment (control), or treatment with 1,000 IU of hCG 14 d before the initiation of the CO-Synch + CIDR protocol and 2) treatment, administration of 1,000 IU of hCG or 100 μg of GnRH at CIDR insertion of the CO-Synch + CIDR protocol. Blood samples were collected from all heifers on d -21, -14, -7, 0, and 2 relative to PGF(2α) injection. Transrectal ultrasonography was used to examine ovaries in a subset of heifers (n = 362) on d -7 and 0 relative to PGF(2α), and to determine pregnancy status of all heifers on d 33 and 82 relative to AI. Pregnancy rates were similar for heifers pretreated with control (33.0%) or hCG (36.4%), whereas pregnancy rates were greater (P < 0.01) for heifers treated with GnRH (40.1%) compared with hCG (29.0%) at CIDR insertion. Heifers pretreated with hCG had more (P < 0.01) corpora lutea present on the day of CIDR insertion and the day of CIDR removal compared with untreated heifers. A greater proportion (P < 0.01) of heifers ovulated as a result of administration of hCG at the time of CIDR insertion (59.0%) compared with GnRH (38.7%). Heifers treated with hCG at CIDR insertion had greater (P < 0.01) concentrations of progesterone compared with those receiving GnRH at the time of CIDR removal (2.42 ± 0.13 vs. 1.74 ± 0.13 ng/mL; P < 0.01) and at fixed-time AI (0.52 ± 0.03 vs. 0.39 ± 0.03 ng/mL; P < 0.01). Therefore, hCG was more effective than GnRH in its ability to ovulate follicles and to increase concentrations of progesterone in beef heifers. Presynchronization with hCG 14 d before CIDR insertion did not alter pregnancy rates, whereas replacing GnRH with hCG at CIDR insertion decreased pregnancy rates.  相似文献   

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