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11.
E.L. Gastal M.O. Gastal M.A. Beg A.P. Neves B.P.L. Petrucci R.C. Mattos O.J. Ginther 《Journal of Equine Veterinary Science》2008
Recent direct and indirect comparisons between Miniature ponies and larger breeds during the estrous cycle are reviewed. There were many similarities but profound differences in the Miniature ponies, including (1) greatly reduced follicle population within each of several follicle diameter classifications, (2) smaller number of growing follicles 10 mm or larger per ovulatory wave (1.5 ± 0.3 vs. 5.8 ± 0.9 in Miniature ponies vs. horses), (3) lower incidence of detectable diameter deviation, (4) ovulatory luteinizing hormone (LH) surge that involved three distinct phases, and (5) LH increase and decrease during the early luteal phase that followed the ovulatory surge. Diameter of the preovulatory follicle was smaller in Miniature ponies than in horses, but the difference was slight (38 vs. 44 mm; 14%) when compared with an extreme difference in median body weight (123 vs. 465 kg; 74%). The great reduction in follicle population with only a slight reduction in diameter of the preovulatory follicle in Miniature ponies compared with larger breeds is an important consideration during both experimental and clinical examinations. 相似文献
12.
CM Checura MA Beg EL Gastal MO Gastal MC Wiltbank JJ Parrish OJ Ginther 《Reproduction in domestic animals》2009,44(3):504-511
A GnRH antagonist (Acyline) was used to study the role of FSH in early development of a follicular wave in 61 mares. In Experiment 1, a single dose of 3 mg per mare, compared with 0 and 1 mg, suppressed both the FSH and follicle responses to exogenous GnRH. In Experiment 2, high concentrations of FSH were induced by two successive ablations of all follicles ≥ 6 mm on days 10 and 13 (day 0 = ovulation). A single treatment with Acyline resulted in significantly greater suppression of plasma concentrations of FSH than a single treatment with charcoal-extracted follicular fluid (source of inhibin) or oestradiol. Suppression of FSH was not significantly different between the group treated with Acyline alone and a group treated with a combination of Acyline, inhibin and oestradiol. In Experiment 3, all follicles were ablated on day 10 to induce an FSH surge and a new follicular wave. Acyline treatment on day 10 resulted in an immediate decrease in FSH, without a significant effect on day of emergence of a new wave or growth of follicles from 7 to 11 mm on days 11–13. Treatment on day 15, a day before expected follicle deviation and after the peak of the wave-stimulating FSH surge, resulted in an immediate decrease in FSH and cessation of follicle growth. Results indicated that growth of follicles for about 2 days after wave emergence was independent of FSH. In contrast, during the decline in the wave-stimulating FSH surge and before follicle deviation, growth of follicles was dependent on FSH. 相似文献
13.
MAR Siddiqui EL Gastal MO Gastal MA Beg OJ Ginther 《Reproduction in domestic animals》2009,44(3):474-479
Follicle blood flow, follicular-fluid and plasma hormone concentrations, and oocyte quality were studied 30 h after an ovulation-inducing hCG treatment when the pre-ovulatory follicle was 32 mm. Mares were grouped as positive (n = 16) and negative (n = 44) for hCG antibodies before the experimental hCG treatment. Percentage of the follicle wall with blood flow signals was less (p < 0.05) in the antibody positive group than in the negative group. The concentrations of follicular-fluid oestradiol and free IGF1, and plasma oestradiol were greater (p < 0.001), and follicular-fluid progesterone (p < 0.001) and plasma LH (p < 0.02) were less in the antibody-positive group than in the negative group. For recovered oocytes at 30 h (n = 37), the antibody-positive group had fewer (p < 0.001) mature (MII) oocytes than the antibody-negative group. Results were attributable to highly effective neutralization of the hCG in the antibody-positive group. 相似文献
14.
JC Jacob EL Gastal MO Gastal GR Carvalho MA Beg OJ Ginther 《Reproduction in domestic animals》2009,44(2):248-254
The follicle and hormone aspects of diameter deviation and development of one dominant (≥28 mm) follicle (1DF) vs two dominant follicles (2DF) were studied in 32 ovulatory follicular waves in mares. Follicles were ranked each day as F1 (largest) to F3. The beginning of deviation was designated day 0 and preceded the first increase in the differences in diameter between F1 and F2 in the 1DF group and between a combination of F1 and F2 vs F3 in the 2DF group. One dominant follicle and 2DF developed in 21 (66%) and 11 (34%) waves, respectively. Double ovulations occurred in only one of the waves with 2DF. In 8/11 waves with 2DF, a second deviation occurred between F1 and F2 on 2.5 ± 0.4 days after the first deviation. On day 0, 1DF and 2DF waves were similar in number of days after ovulation, number of follicles, difference in diameter between F1 and F2, and plasma concentrations of LH, estradiol and immunoreactive inhibin. The interval from maximum FSH concentration to day 0 was longer (p < 0.05) and FSH concentration was lower (p < 0.05) on days -1 to 4 in the 2DF group. The similarities on day 0 in the characteristics of 1DF and 2DF waves despite the differences in the declining portions of the FSH profile indicated that a specific day of the FSH decline or a specific concentration were not factors in initiating deviation. Unlike reported results in heifers, the results in mares did not indicate a hormonal basis for the development of 2DF or two deviations. 相似文献
15.
M.O. Gastal DVM PhD E.L. Gastal DVM PhD M.A. Beg DVM PhD O.J. Ginther VMD PhD 《Journal of Equine Veterinary Science》2007,27(9):390-393
Stallion-like sexual behavior in mares is rare, except in association with ovarian tumors or hormonal treatments. The rarity of the phenomenon was confirmed in a recent 3-year study. The mean number of mares with detected stallion-like behavior, including mounting with thrusts, during an entire ovulatory season was 5.7 (17/3 years) in a herd averaging 105 mares (5% incidence/mare/season). From a total of 17 mountings of an estrous mare by another mare, 15 occurred when the mounting mare was in the follicular phase and two when in the early luteal phase. Plasma testosterone concentration on the day of mounting was higher (P < 0.01) in the mounting mares (17.7 ± 2.3 pg/ml) than in the standing mares (10.9 ± 0.5 pg/ml). No other deviation in the endocrine, behavioral, or morphologic aspects of the estrous cycle was observed. In another study, testosterone was assayed daily from 7 days before to 4 days after ovulation in seven mares during estrous cycles with no detected mare-on-mare mountings. Concentrations during the follicular phase were highest on the days corresponding to when mare-on-mare mounting was detected in the previous study. It is concluded that the rare occurrence of stallion behavior by untreated mares with no detected ovarian tumors is a consequence of an unusually high, apparently transient fluctuation in circulating testosterone at the time of mounting. 相似文献
16.
The MecaNiCAL model of carbon and nitrogen partitioning over a period of regrowth for a mean grass plant as described in Part 1 was fitted and evaluated against data from an experiment under controlled conditions with contrasting light and nitrogen nutrition. In the first investigation, the rate of nitrogen uptake was imposed to limit the compensation of errors between process. The root:shoot ratio was simulated well, with a good estimation of the nitrogen allocation to shoots. Some underestimation of the root weight after the cut and the final shoot weight under the low nitrogen treatment were consequences of both the lack of remobilisation and the high priority given to shoots. The good agreement obtained with the expected trend in simulations conducted with the simple nitrogen aborption submodel in extended conditions (contrasting initial content of nitrogen substrate and temperature change in regrowth) ensures the general consistency of the model in the limit of its area of validity. Partitioning to shoots and forage production seem to be sensitive mainly to the size of the carbohydrate substrate pool and its availibility, particularly under conditions of low light. Estimating the initial carbohydrate substrate pool by biochemical analysis may improve the accuracy of the model. Compared with more simple assumptions of partitioning, MecaNiCAL shows a higher level of agreement with the partitioning response to a wide range of environmental conditions. A simple assumption relating partitioning to plant nitrogen content does not seem to be sufficient to simulate the decrease in the root:shoot ratio observed under conditions of low light. Nevertheless, more data from experiments conducted under a wider range of contrasting conditions are required to estimate the validity of MecaNiCAL attached to the nitrogen absorption submodel and the advantage of its more complex assumptions with even greater accuracy. 相似文献
17.
JC Jacob EL Gastal MO Gastal GR Carvalho MA Beg OJ Ginther 《Reproduction in domestic animals》2009,44(1):92-99
Data were collected daily from 23 mares during two consecutive interovulatory intervals (IOIs). Several significant (p < 0.05) new observations on temporal relationships were made. The FSH increase that begins before ovulation temporarily plateaued on the day of discharge of follicular fluid into the peritoneal cavity in association with ovulation. During the declining portion of the pre-ovulatory oestradiol surge, an abrupt reduction in the rate of decrease occurred in synchrony with the peak of the LH surge and is consistent with a negative effect of LH on oestradiol. Repeatability within mares was based on the following positive and significant correlations between the two IOIs: (i) length of the interval between ovulations and between ovulation and the beginning of follicle deviation; (ii) diameter of the pre-ovulatory follicle on days -3 to -1; (iii) number of follicles in diameter classes of 2–5 mm (correlation for 22/23 days of the IOI), 5.1–10 mm (18/23 days), 10.1–15 mm (12/23 days) and 15.1–20 mm (12/23 days) and (iv) concentrations of FSH (18/23 days) and LH (22/23 days). The greatest repeatability for the follicle-diameter classes occurred in the 2–5 mm class, and thereafter the repeatability progressively decreased as the diameters for the classes increased. Results demonstrated measurable repeatability within mares for several end points between consecutive IOIs. 相似文献
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19.
E.L. Gastal DVM PhD J.C.F. Jacob DVM MS M.O. Gastal DVM PhD O.J. Ginther VMD PhD 《Journal of Equine Veterinary Science》2007,27(6):251-259
The funnel-shaped cranial portion (infundibulum) of the oviduct is contiguous with the ovulation fossa in mares. An accumulation of fluid in the infundibular area was discovered by transrectal ultrasonic imaging and was studied daily in both oviducts of 12 mares from day –10 to day 10 (day 0 = ovulation), and from day –6 to day 6 during 35 estrous cycles of young, intermediate, and old mares (n = 8 mares/group). The infundibulum was identified by processes (fimbriae) and folds in the pocket of fluid. The amount of fluid accumulation was scored from 0 to 3 (nil to maximum). Frequency of detection of fluid in the infundibular area increased between day –10 (46% of oviducts) and day –3 (88%), and decreased between day –3 and day 7 (8%; P < .002). The day-to-day profile for changes in the score for amount of fluid was significant (P < .0001) and similar to the profile for frequency of detection of the infundibulum. The profiles for the two infundibular end points and scores for endometrial echotexture (an indicator of edema) were similar to the reported profile for systemic estradiol concentrations. The frequency of infundibulum detection was greater (P < .0009) for the side ipsilateral to the preovulatory follicle and ovulation (51%) than for the opposite side (36%). No difference among ages was found for either oviductal end point. Results indicated that changes in the amount of fluid accumulation in the infundibular area and endometrial edema were estrous cycle dependent and similar to previously reported changes in systemic concentrations of estradiol. 相似文献
20.
E.L. Gastal DVM M.O. Gastal DVM O.J. Ginther DVM 《Journal of Equine Veterinary Science》2006,26(2):67-73
The incidence of discrete structural changes in the preovulatory follicle as ovulation approaches was studied sequentially by ultrasonography. Examinations were done every 12 hours in 27 mares, beginning when the follicle was ≥35 mm. The following discrete end points were recorded as present or absent: 1) serration of granulosa, indicated by an irregular or notched appearance; 2) decreased turgidity, indicated during transducer pressure; 3) loss of spherical shape; 4) an apex, indicated by a reduced area at one end; and 5) echoic spots floating in the antrum. When the records were examined as though scanning had been done only every 24 hours beginning at 35 mm, distinct serration was detected at the examination before ovulation in 37% of mares but not earlier. When mares were examined every 12 hours, serration was detected at the last examination in 59%. Decreased turgidity at the last 12-hour examination was detected concomitantly with serration, but was detected alone in 9% to 12% of previous examinations. Mares with serration at the last examination at 12-hour intervals were examined every hour thereafter (n = 14). Serration and decreased turgidity were present at each examination until ovulation 4.9 ± 0.7 hours later. Loss of spherical shape initially occurred less frequently than decreased turgidity, but the incidence increased from 50% to 100% during 6 to 1 hours before ovulation. The incidence of an apical area reached 100%, and echoic spots increased to 50% during the few hours before ovulation. Results indicated that serrated granulosa and the other discrete indicators were useful for predicting impending ovulation; however, optimal efficiency would require examinations every few hours. 相似文献