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1.
The objective of this study was to evaluate the efficiency of gonadotropin releasing hormone (GnRH) and GnRH doses in synchronizing follicular wave emergence as a pretreatment for superovulation in cattle. Fourteen Holstein-Friesian cows 6 days from estrus were randomly assigned to receive 100 microg (n=4), 50 microg (n=5), or 25 microg (n=5) of GnRH. Superovulation was induced with injections of porcine FSH (pFSH) twice daily, decreasing the dose (total 42 AU) over 5 days beginning 2.5 days after receiving GnRH. On the 7th and 8th injections of pFSH, 750 microg of PGF(2alpha) was also given. With the exception of one cow that was given 50 microg of GnRH, ovulation was induced in all cows from the three groups and the new follicular wave emergence was observed. The total number of follicles for the 25 microg GnRH group was less than that observed for the 100 microg GnRH group (P<0.05), although there were no differences between the 100 microg, 50 microg and 25 microg GnRH groups with respect to the number of preovulatory follicles (>or=10 mm) and CL. The numbers of normal embryos were greater for the 25 microg GnRH group than the 100 or 50 microg GnRH groups (P<0.01); however, the numbers of ova/embryos did not differ significantly between the three groups. These results suggest that 25 microg of GnRH was sufficient to induce ovulation and follicular wave emergence. On day 6 of the estrous cycle, a reduction of the dose of GnRH to synchronize follicular wave emergence as a pretreatment for superstimulation promotes transferable embryos.  相似文献   

2.
Relatively few studies have been reported regarding the reproductive physiology of female Thai native cattle. Therefore, the objective of the present study was to evaluate the follicular dynamics and concentrations of follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) during the estrous cycle in Thai native heifers (TNH) and to compare obtained results with those of European and Indian cattle breeds previously reported. For the detection of estrus, ovaries of all 20 heifers were examined twice daily (12 h intervals) by ultrasonography for three consecutive estrous cycles. From data of 60 estrous cycles (n = 60 estrous cycles from 20 heifers), it was found that 14 (70%) and 6 heifers (30%) had two (42 estrous cycles collected from 14 heifers) and three follicular waves (18 estrous cycles collected from 6 heifers), respectively. The days when estrus was detected, interovulatory intervals, life‐spans of corpus lutea (CL), and days for growing and regression of CLs were shorter in the two follicular waves than those in the three follicular waves (P < 0.05). In both two and thre follicular waves, larger maximum diameters and higher growth rates of the dominant follicle (DF) in an ovulatory wave were observed than those of the preceding waves without ovulation (P < 0.05). There was a progressive increase in follicular size and FSH and E2 production during follicular growth in each follicular wave. In addition, the FSH and E2 peak concentrations during the ovulatory wave were higher than those of the anovulation waves (P < 0.05). Moreover, although the ovarian follicular dynamic patterns in Thai native heifers were similar to those previously reported for European and Indian cattle breeds, the diameter of the largest preovulatory follicle (OF), subordinate follicles (SF) and CLs were smaller than those in European and Indian cattle breeds. In conclusion, when compared with European and some breeds of Indian cattle, the length of interovulatory intervals was shorter, and the sizes of dominant SF and CLs were smaller in Thai native heifers.  相似文献   

3.
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   

4.
Following parturition, all cows display a wave of ovarian follicular growth, but a large proportion fail to generate a preovulatory rise in estradiol, and hence fail to ovulate. Follicle-stimulating hormone (FSH) exists as multiple isoforms in the circulation depending on the type and extent of glycosylation, and this has pronounced effects on its biological properties. This study examined differences in plasma FSH, estradiol, and inhibin A concentrations, and the distribution of FSH isoforms in cows with ovulatory or atretic dominant follicles during the first postpartum follicle wave. Plasma FSH isoform distribution was examined in both groups during the period of final development of the dominant follicle by liquid phase isoelectric focusing. Cows with an ovulatory follicle had higher circulating estradiol and inhibin A concentrations, and lower plasma FSH concentrations. The distribution of FSH isoforms displayed a marked shift toward the less acidic isoforms in cows with ovulatory follicles. A higher proportion of the FSH isoforms had a pI>5.0 in cows with ovulatory follicles compared to those with atretic follicles. In addition, cows with ovulatory follicles had greater dry matter intake, superior energy balance, elevated circulating concentrations of insulin and insulin-like growth factor-I, and lower plasma nonesterified fatty acids. The shift in FSH isoforms toward a greater abundance of the less acidic isoforms appears to be a key component in determining the capability for producing a preovulatory rise in estradiol, and this shift in FSH isoforms was associated with more favorable bioenergetic and metabolic status.  相似文献   

5.
A serial ultrasonographic study was conducted on nine jennies aged 5–15 years from January to April 2008 with the objective of studying ovarian follicular dynamics and estrus manifestations under controlled management. Ovarian follicular activity was determined from the number and size distribution of follicles, length of interovulatory interval (IOI), growth rate of preovulatory follicles, diameter of follicles at the onset of estrus, and incidence of ovulation. Estrus manifestations were characterized using length of estrus and estrous cycle. The mean (±SD) number of follicle detected per ovary was 5.45?±?2.3 (range, 1–16) with sizes ranging from 2.9 to 44 mm. The mean (±SD) size of follicle encountered at the onset of estrus was 25.9?±?3.7 mm (range, 20.9–34.4) while that of the preovulatory follicles at ?1 day before ovulation was 36.81?±?3.78 mm. The mean (±SD) IOI, estrus, and estrous cycle length were 25.4?±?3.6, 7.9?±?2.9, and 24.2?±?7.4 days, respectively. The mean (±SD) growth rate of the preovulatory follicle after the day of divergence was 1.9?±?0.3 mm/day. Serum progesterone profile followed the same patterns of ovarian dynamics with maximum values being detected during midluteal phase. Serum progesterone assay revealed blood progesterone profiles of <1.0 ng/ml during estrus and up to 11 ng/ml during midluteal phase with a pattern following follicular dynamics. Body condition of the study jennies steadily increased and was positively correlated (r?=?0.52, p?<?0.001) with the diameter of the preovulatory follicle. In conclusion, the ultrasonic evaluation has revealed that follicular dynamics of jennies were generally related with body condition which might have been influenced by the type of management.  相似文献   

6.
The relationship between the peripheral concentrations of estradiol-17β (E(2)) and the preovulatory characteristics of cumulus oocyte complexes (COCs) during superovulation treatment was investigated in Japanese Black cows. A superovulation regimen with FSH treatment in a descending manner was commenced on day 7 (n=3) or day 10 (n=2) of the estrous cycle (day 0=estrus). Peripheral blood was collected to measure E(2) concentrations twice a day throughout the treatment. Ovariectomies were performed at 100 h after the initial FSH treatment in five cows. Every follicle more than 8 mm in diameter was isolated from the ovaries, and cumulus-oocyte complexes (COCs) were gently aspirated. The COCs were then separated into three groups based on the characteristics of the cumulus (compact, expanded and denuded) and subgrouped based on the stage of the nucleus in the oocytes (GV, GVBD). Plasma E(2) concentrations tended to increase gradually and reached the peak level at around 84 h (E(2)-84: n=3) or 96 h (E(2)-96: n=2) after the initial FSH treatment. The ratio of COCs with expanded cumulus was significantly higher in E(2)-84 than in E(2)-96 (P<0.01). However, there was no difference in the ratio of oocytes showing GVBD between E(2)-84 and E(2)-96 (P=0.73), and the characteristics of the cumulus did not affect the stage of the nucleus in the oocytes in either groups (compact, expanded and nude; P=0.61, 0.81 and 1.00). It was possible that the time until the peak plasma E(2) concentrations after the FSH treatment could become an indicator for the maturation of follicles and oocytes in preovulatory follicles during superovulation treatment in Japanese Black cows.  相似文献   

7.
Factors that affect ovarian follicular dynamics in cattle.   总被引：1，自引：0，他引：1  
Studies of ovarian follicular dynamics in cattle may lead to methods for improving fertility, for synchronizing estrus with more precision, and for enhancing superovulatory responses. Within an estrous cycle, two or three large (> 10 mm) follicles develop during consecutive waves of follicular growth. The last wave provides the ovulatory follicle, whereas preceding wave(s) provide follicles that undergo atresia. The life span of large follicles seems to depend on the pulsatile secretion of LH; decreased frequency of LH pulses results in atresia of large follicles. Aromatase activity in the walls of the largest follicles is greatest during the first 8 d of the estrous cycle and decreases by d 12. Steroidogenesis of the largest and second-largest ovarian follicles differs on d 5, 8, and 12 of the estrous cycle. Follicular dynamics are altered by negative energy balance and lactation. The number of large follicles and concentration of estradiol during the preovulatory period differs between postpartum lactating and nonlactating cows. Dietary fats stimulate follicular growth when they are fed to increase energy balance. Administration of bovine somatotropin decreases energy balance and has a differential effect on ovarian follicular responses; growth of the largest follicle does not change, but growth of the second-largest follicle is stimulated by somatotropin. Studies of follicular dynamics in lactating cows demonstrate changes in ovarian function associated with energy balance that may be related to inefficient reproductive performance of cows producing high yields of milk.  相似文献   

8.
Chronic, subclinical intramammary infection depresses fertility. We previously found that 30% of subclinical mastitic cows exhibit delayed ovulation, low circulating estradiol levels, and delayed luteinizing hormone surge. We examined the function of preovulatory follicles of cows experiencing subclinical mastitis or a past event of acute clinical mastitis. Cows were diagnosed for mastitis by somatic cell count and bacteriological examination. All clinical infections were caused by Escherichia coli, and most subclinical infections were caused by Streptococcus dysgalactiae and coagulase-negative staphylococci. On day 6 of the cycle, cows received PGF2α; 42 h later, follicular fluids and granulosa cells or theca cells were aspirated from preovulatory follicles in vivo or following slaughter, respectively. Overall, follicular estradiol and androstenedione concentrations in the subclinical group (n = 28) were 40% lower (P < 0.05) than those in uninfected cows (n = 24) and lower than in past clinical mastitic cows (n = 9). Distribution analysis revealed a clear divergence among subclinical cows: one-third (9/28) exhibited low follicular estradiol; the other two-thirds had normal levels similar to all uninfected (P < 0.01) and most clinical cows (P < 0.08) that had normal follicular estradiol levels. Subclinical normal-estradiol cows had twofold higher (P < 0.05) circulating estradiol concentrations and sevenfold and fourfold higher (P < 0.05) follicular androstenedione levels and estradiol-to-progesterone ratio, respectively, than subclinical low-estradiol cows. Follicular progesterone level was not affected. Reduced expression (P < 0.05) of LHCGR in theca and granulosa cells, CYP11A1 (mRNA and protein) and CYP17A1 in theca cells, and CYP19A1 in granulosa cells may have contributed to the lower follicular steroid production in the subclinical low-estradiol subgroup. StAR and HSD3B1 in theca cells and FSHR in granulosa cells were not affected. Mastitis did not alter follicular growth dynamics, and no carryover effect of past clinical mastitis on follicular function was detected. These data indicate that a considerable proportion (one-third) of subclinical mastitic cows have abnormal follicular steroidogenesis, which can explain the reproductive failure associated with this disease.  相似文献   

9.
The hypothesis of the present study is that active immunization of cows against inhibin would neutralize endogenous inhibin, increase circulating levels of follicle stimulating hormone, and subsequently affect follicular dynamics and the ovulation rate during the estrous cycle. Thirteen cows were immunized against inhibin alpha-subunit and, 6 cows were immunized with a placebo. Both groups were given 4 booster immunizations 7, 14, 21, and 34 weeks after the primary injection. Ovaries were examined daily after the 2nd, 3rd, and 4th booster immunizations by transrectal ultrasonography for 25 days. After the 4th booster immunization, blood samples were collected daily for one complete estrous cycle to measure FSH and LH. The results showed that the immunized cows generated antibodies against inhibin, and that they had higher FSH levels compared with the controls. The number of follicular waves during the estrous cycle was higher in the immunized cows (3 or 4 waves) than in the controls (2 or 3 waves). Moreover, the immunized cows had a greater number of follicles during the estrous cycle compared with the control cows. The maximum number of follicles was 14.8 +/- 1.7 vs 5.4 +/- 0.2 in inhibin-immunized and control cows, respectively, during the first follicular wave and 13.9 +/- 1.9 vs 5.6 +/- 0.7, respectively, during the ovulatory wave. Multiple ovulations were increased in the immunized cows. However, the ovulation rate varied greatly in the immunized animals. In conclusion, immunization against inhibin increased FSH secretions during the estrous cycle in the cows. Moreover, the immunized cows had a greater number of follicular waves during the estrous cycle and a greater number of follicles, and this could be used as a potential source of oocytes for use in IVF/embryo transfer programs.  相似文献   

10.
This study aimed to evaluate gonadotropin secretion and the developmental competence of follicular oocytes in dairy cattle during the early postpartum (PP) period. The number of follicles developed after transvaginal ultrasound-guided ovum pick-up (OPU) and fertilizability of retrieved oocytes were compared between cows in which the first dominant follicle (DF) ovulated (ovulated group, n=4) and did not ovulate (non-ovulated group, n=3), and between early PP (early PP group, n=2) and after the resumption of the estrous cycle (cyclic group, n=2). Follicular ablation was performed 2-4 days after the detection of DF in the second follicular wave PP. OPU was repeated 3-5 times at 3 or 4-day intervals from 3-4 days after the follicular ablation. At OPU, the follicles were enumerated and all those > or = 5 mm in diameter were aspirated. Recovered oocytes were subjected to in vitro maturation and fertilization. Both criteria were similar between ovulated and non-ovulated groups, and between early PP and cyclic groups. These results suggest that FSH/LH secretions required for follicle recruitment and subsequent follicular growth during the early PP period are similar to those after resumption of the estrous cycle. They also indicate that follicular oocytes during the early PP period have developmental competence.  相似文献   

11.
We studied the effects of administering estradiol benzoate (EB) plus progesterone (P4) as part of a CIDR-based protocol during the growth or static phases of dominant follicle development on follicular wave emergence, follicular growth, synchrony of ovulation and pregnancy rate following CIDR withdrawal, treatment with PGF(2alpha) and GnRH, and fixed-time artificial insemination (TAI). Forty-one previously synchronized lactating Holstein dairy cows were randomly allocated to three treatment groups. The control group (n=14) received a CIDR on the third day after ovulation only (Day 0). The two treatment groups were administered CIDRs comprising 2 mg EB and 50 mg P4 either on the third (T1, n=14) or eighth day (T2, n=13) after ovulation (Day 0). All cows received PGF(2alpha) after CIDR removal on Day 7, GnRH on Day 9, and TAI 16 h after GnRH treatment. The proportion of cows with follicular wave emergence within 8 days of treatment differed (P<0.01) among the control (14.3%), T1 (85.7%), and T2 groups (92.9%). However, the mean intervals between treatment and wave emergence were not significantly different. There were significant differences in the diameters of the dominant follicles on Day 7 (P<0.01) and in preovulatory follicles on Day 9 (P<0.01), with the largest follicles observed in the control group and the smallest follicles observed in the T2 group. In contrast, the numbers of cows showing synchronous ovulation after GnRH treatment (92.9 to 100.0%) and pregnancy following TAI (46.2 to 50.0%) were similar between the treatment groups. The results showed that, irrespective of the phase (growth or static) of the dominant follicle, administration of 2 mg EB plus 50 mg P4 to CIDR-treated lactating dairy cows induced consistent follicular wave emergence and development, synchronous ovulation after GnRH administration, and similar pregnancy rates following TAI.  相似文献   

12.
The hypothesis that ovulation in response to short-term (48 h) calf removal (CR) is dependent on the developmental stage of the dominant follicle was tested in two studies. The objective of Exp. 1 was to characterize the fate of a dominant follicle following 48-h CR on d 2, 4, or 8 of a postpartum follicular wave. Ovaries of 61 beef cows were examined daily by transrectal ultrasonography starting at d 20 to 21 postpartum. Treatments were no CR (n = 14) and CR on d 2 (n = 12), 4 (n = 16), or 8 (n = 10) of first detected follicular wave. Percentage of cows that ovulated a dominant follicle following treatment was not different among groups (P = 0.62). Maximum size of dominant follicles was larger in cows that ovulated (P = 0.002) than in cows that did not ovulate. The objectives of Exp. 2 were 1) to determine whether a follicular wave could be synchronized in anestrous cows following injection of 1 mg of estradiol benzoate (EB) and 200 mg of progesterone (P4; EB + P4); 2) to characterize the fate of dominant follicles following 48-h CR at three stages of a synchronized follicular wave; and 3) to determine whether estrous cycles of normal length followed ovulation in cows pretreated with EB + P4. Ovaries of 50 anestrous beef cows were examined daily as in Exp. 1. Treatments were sesame oil (SO) injected (i.m.) on d 25 postpartum and no CR (n = 9); EB + P4 and no CR (n = 9); EB + P4 and CR on 6 (n = 12), 8 (n = 9), or 12 (n = 11) d after injection. The EB and P4 injections were given on d 25 postpartum. Variability in day of emergence of subsequent follicular waves was lower in cows receiving EB + P4 than in SO-injected cows (P < 0.05). The percentage of cows that ovulated was not different (P = 0.16), but CR increased the percentage of cows that ovulated when groups that received EB + P4 were compared to the EB + P4 group that did not have CR (53.1 vs 11.1%, respectively; P < 0.05). Maximum diameter of dominant follicles was larger (P = 0.05) in ovulatory follicles. The luteal phase was longer (P < 0.03) in cows receiving EB + P4 injection (10.6 +/- 1.2 d) than in cows receiving SO (4.4 +/- 2.2 d). In summary, the maximum size of ovulatory follicles was greater than that of nonovulatory follicles, the ovulatory response of postpartum anestrous cows was maintained through d 8 of a follicular wave, synchronization of follicular waves was accomplished in postpartum cows using EB + P4, and the subsequent luteal phase length was increased in animals that were administered EB + P4.  相似文献   

13.
Abundance of IGF-2 receptor (IGF2R), FSH receptor (FSHR), and LH receptor (LHCGR) mRNA in granulosa cells (GCs) or theca cells (TCs) or both cells as well as estradiol (E2), progesterone (P4), and androstenedione concentrations in follicular fluid were compared in cows genetically selected (Twinner) or not selected (control) for multiple ovulations and twin births. Cows were slaughtered at day 3 to 4 (day 3) and day 5 to 6 (day 5) of an estrous cycle, and ovaries, follicular fluid, GCs, and TCs were collected. The two largest (F1 and F2) E2-active (EA) and E2-inactive (EI) follicles were selected according to their E2-to-P4 ratio and diameter. Androstenedione levels in EA F1 and F2 follicles were 5-fold greater (P < 0.05) in Twinner cows than in control cows on day 3 but did not differ on day 5. Twinner cows also had greater (P < 0.05) E2 and P4 concentrations, whereas steroid levels in EI follicles did not differ (P > 0.10) between genotypes. In EA F2 follicles, IGF2R levels in GCs were greater (P < 0.05) in control cows than in Twinner cows on day 3 and day 5, whereas IGF2R mRNA in TCs did not differ (P > 0.10). On day 3, FSHR mRNA levels were greater (P < 0.05) in GCs of EA F1 and EI F2 follicles of control cows than of Twinner cows. LH receptor mRNA expression was less in GCs and greater in TCs of EA F2 follicles in control cows than in Twinner cows (P < 0.05). We hypothesize that reduced GC IGF2R expression in F2 follicles of Twinner cows may play a role in the development of 2 or more dominant follicles.  相似文献   

14.
Acid and alkaline phosphatase in bovine antral follicles   总被引：1，自引：0，他引：1  
Acid and alkaline phosphatases were measured in the follicular fluid of 766 individual follicles from 96 cows. Follicles were obtained by bilateral ovariectomy or at slaughter from animals at various stages of the estrous cycle and pregnancy. Mean follicle size varied with the physiological state of the cow (P less than .0001). Acid phosphatase activity (U/microliters) varied inversely with follicle size (P less than .001) but not with stage of the estrous cycle or gestation. Total acid phosphatase activity per follicle increased with follicle size (P less than .05). Neither acid phosphatase nor alkaline phosphatase concentration was associated with atresia. Alkaline phosphatase activity (U/microliters) was greater in the smallest follicles (less than 50 microliters) than in other size groups (P less than .0001). Alkaline phosphatase activity (U/microliters) was greater (P less than .05) during the preovulatory phase of the estrous cycle than during other phases. A high concentration of follicular fluid phosphatases cannot be used as a marker for atresia but is characteristic of healthy small antral follicles.  相似文献   

15.
Cows with two waves of follicular growth during the estrous cycle yield follicles that are older and larger at ovulation compared with cows having three waves. The objectives of the current research were 1) to compare fertility in cows with two or three follicular waves and 2) to examine associations between luteal function, follicular development, and fertility after breeding. Follicular waves were monitored by ultrasonography during the estrous cycle before insemination in 106 dairy cows. Fewer cows had three follicular waves before next estrus and ovulation than two waves (P < 0.01; 30% vs 68%, respectively), but pregnancy rate was higher (P = 0.058; 81 vs 63%, respectively). Cows with two waves had shorter estrous cycles (P < 0.01), with the ovulatory follicle being both larger (P < 0.05) and older (P < 0.01). In cows with three waves, luteal function was extended (P < 0.05) and the peak in plasma progesterone occurred later (P < 0.05) in the estrous cycle compared to two wave cows. Considering cows that became pregnant, luteal phase length was shorter (P < 0.05) during the estrous cycle preceding insemination than for nonpregnant cows. In conclusion, fertility was greater in lactating cows inseminated after ovulation of the third-wave follicle that had developed for fewer days of the estrous cycle as compared with two-wave cows.  相似文献   

16.
The effects of progesterone (P4) on follicular growth and fertility in ewes were examined. In Experiment 1, 22 ewes received either one or three packets of P4 (5 g/packed) or an empty packet subcutaneously (sc) from Days 5 to 15 of the estrous cycle (estrus = Day 0). On Day 6, P4-treated ewes received 12.5 mg of prostaglandin F2α. Follicles ⩾3 mm in diameter were observed via transrectal ultrasonography daily from Day 4 through estrus, corpora lutea (CL) were observed 5 to 7 d after estrus. Ewes with low (LOW; ⩽1 ng/ml; n = 5), intermediate (MED; > 1 and <2 ng/ml; n = 10), or normal (NOR; ⩾2 ng/ml; n = 7) P4 in jugular plasma on Days 7 through 15 differed in follicular development. The largest follicle at estrus was larger in ewes with LOW vs. MED and NOR P4 (7.8 ± 0.3 vs. 6.9 ± 0.2 mm; P < 0.05). Treatments differed in proportions of multiple-ovulating ewes, in which the oldest ovulatory follicle was first observed before Day 10 (LOW: 3 of 3, MED: 6 of 10, NOR: 0 of 5, respectively; P < 0.05). Estradiol was higher early in the treatment period in LOW ewes than in MED and NOR ewes (day × treatment; P < 0.05). In Experiment 2, ewes received 5 mg of P4 in corn oil (low progesterone [LP]; n = 51) or 2 ml of corn oil (CON; n = 49) sc every 12 hr on Days 6 through 14 of the estrous cycle before mating. LP ewes received 15 mg of prostaglandin F2α on Day 6. Mean serum P4 on Days 7 through 15 was 0.6 ± 0.1 ng/ml in LP and 1.9 ± 0.1 ng/ml in CON ewes. Eleven LP and 12 CON ewes were scanned daily from Day 4 through mating, and in all ewes (n = 93), CL were counted 10 d after mating and embryos were counted at 25, 40, and 60 d of gestation. In multiple-ovulating ewes, day of cycle of appearance was earlier for the oldest (Day 6.1 ± 0.8 vs. 10.4 ± 0.8) but not second oldest (Day 11.7 ± 1.0 vs. 12.2 ± 0.9) ovulatory follicles in LP compared with CON ewes. The conception rate was lower in LP (72%) than in CON ewes (98%; P < 0.01). However, numbers of CL 10 d after mating, and in pregnant ewes, numbers of embryos 25 d after mating and lambs born, did not differ with treatment. In summary, low P4 increased the size of the largest follicles and the age of the oldest ovulatory follicles. Embryos resulting from the ovulation of older and younger follicles in the same ewe did not differ in their ability to survive.  相似文献   

17.
The characteristics of the major follicular waves (primary and secondary) throughout estrous cycle were studied in 7 healthy Caspian mares (age, 4-15 years; weight, 198.6 ± 0.9 kg) during the breeding season. Ovarian follicular dynamics were monitored by using an ultrasound scanner equipped with a 5-MHz, B-mode, linear-array, rectal transducer throughout 2 complete estrous cycles. The diameters of antral follicles (5 mm) were measured, averaging the narrowest and widest dimensions. To detect follicular wave emergence, the diameter profile of the 3 largest follicles per ovary of each mare was determined without considering day-to-day identity of follicles but with maintenance of distinction between left and right ovaries. The primary waves originated on day 6.4 ± 0.81 (ovulation = day 0) when the mean diameter of ovarian follicles was 9.6 ± 1.05 mm. Divergence between the dominant preovulatory follicle and subordinate follicles occurred on day 13.4 ± 0.81, when the dominant follicle was 18.1 ± 2.67 mm in diameter. The intervals from emergence to divergence and from divergence to ovulation were 7 ± 0.68 and 8.7 ± 0.68 days, respectively. Secondary major follicular waves were not observed during this study. In conclusion, only 1 major follicular wave was detected in a Caspian mare, confirming the data previously described in other equine breeds. It is also indicated that the occurrence of 1 major follicular wave per cycle is a more common phenomena in equine species.  相似文献   

18.
To elucidate the effects of ultrasound-guided transvaginal follicular aspiration, plasma concentrations of FSH, LH, inhibin, estradiol-17beta and progesterone, and folliculogenesis were examined in Holstein cows. Four clinically healthy cows with regular estrous cycles were scanned by ultrasound per rectum once a week for 9 weeks before the commencement of follicular aspiration. All visible follicles were divided into 3 categories based on their sizes (2 < or = small < 5 mm; 5 < or = medium < 10 mm, large > or = 10 mm). The follicular aspiration was started at random during the estrous cycle and conducted under epidural anesthesia induced with 5 ml of 2% lidocaine once a week for 6 weeks. The average number of total visible follicles > or = 2 mm in diameter at 7 days after aspiration (21.7 +/- 7.4, n = 24) was similar to that before starting aspiration (26.7 +/- 10.5, n = 36). Plasma inhibin and estradiol-17beta declined and fell to a trough on 1.5 days and returned to pre-aspiration values by 5 days after aspiration. Plasma concentrations of FSH increased and reached peak levels between 1 and 1.5 days after aspirations. Plasma concentrations of LH also increased and reached peak levels between 0.5 and 1.5 days after aspirations. Both plasma FSH and LH had returned to pre-aspiration levels by 5 days after aspirations. Plasma concentrations of progesterone did not change with the follicular aspiration. These results demonstrate that follicular aspiration decreases plasma concentrations of inhibin and estradiol-17beta, which in turn leads to a rise in plasma concentrations of FSH and LH. It is suggested that marked increases in plasma concentrations of FSH and LH after the aspiration stimulate the development and maturation of a new cohort of follicles within one week in cows.  相似文献   

19.
To evaluate the effects of hypothyroidism on ovarian function, multiparous, nonlactating Brahman cows (n = 18) were assigned randomly to dietary treatments containing either 0 (C; n = 9) or 4 mg x kg BW(-1) x d(-1) 6-n-propyl-2-thiouracil (PTU; n = 9), to suppress thyroid function, in the feed concentrate. Weekly changes in BW and body condition score (BCS) were recorded. Dietary treatments began on d 10 of the estrous cycle. Ten days after the first treatment estrus, all cows received daily i.m. injections of 25 IU of porcine FSH over a 3-d period. Seven days after AI, embryos were collected nonsurgically, and the ovaries were removed via midflank laparotomy. Based on thyroxine (T4) concentrations after 49 d of treatment, five cows were hypothyroid (H-PTU) and four were partially suppressed (P-PTU). Cows in the PTU group had greater (P<.01) ADG, (P<.05) ovarian weights, and numbers of large (> or =8 mm) (P<.05) follicles. Cows in the PTU group had lower embryo recovery rate (P<.001), fertilization rate (P<.001), and percentage of blastocysts (P<.1) than C cows. The H-PTU cows had greater numbers of luteinized follicles (P<.06), greater concentrations of progesterone (P4) in the follicular fluid at all size categories (P<.1), and greater numbers of corpora lutea (P<.05) than C cows. The ratio of luteal to serum P4 on d 7 was greater (P<.05) in hypothyroid cows. Induced hypothyroidism improved weight gain and BCS, increased ovarian response to FSH, and affected ovulation, fertility, and P4 secretion in superovulated Brahman cows.  相似文献   

20.
In 7 instances, cystic ovarian follicles resulted when adrenocorticotropin (ACTH) was administered daily during the follicular phase of the estrous cycle in cows. Two cows given daily injections of hydrocortisone (cortisol) during the follicular phase of the estrous cycle did not develop cystic ovaries. Plasma concentrations of estradiol in cows with induced cystic ovarian follicles were similar to the peak values observed at estrus and were between 6 and 12 pg/ml. Progesterone concentrations in plasma of cows with cystic ovaries were low, between 1 and 2 ng/ml. Ovulation occurred when 2 cows were given human chorionic gonadotropin (HCG) during the period of ovarian cyst development with ACTH administration. Several days of administration of ACTH was required to cause cyst development. Ovulation occurred at the expected time in 1 cow when injections began on day 19, that is, late in the follicular period. In another cow, when treatment was stopped on day 3, after the expected time of estrus a delayed ovulation occurred. In 2 cows with induced cystic ovarian follicles, cyst atresia occurred spontaneously about day 13 to 17 of the cycle. In these cows, new follicular growth and ovulation followed (although delayed in 1 cow). The time of atresia of cystic follicles was not influenced by the intrauterine injection of 10 ml of sterile saline solution on days 8, 9, and 10 in 1 cow. When 5 mg of prostaglandin F2alpha in 10 ml of sterile saline solution was given (uterine injection) in 2 cows on days 8, 9, and 10, cyst atresia occurred earlier than the time of spontaneous atresia. Intrauterine administration of 100 mg of indomethacin in 10 ml of sterile saline solution daily for 13 or 14 days to 2 cows, starting on day 12 or 13 of the cycle, resulted in persistence of the induced cystic ovarian follicles. After cessation of indomethacin treatment, atresia of cysts followed and new follicular growth and ovulation occurred.  相似文献   

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