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1.
Forty-five Duroc (recognized as not susceptible to stress) and 34 Pietrain (susceptible to stress) pigs were subjected to immobilization stress in a prone position for 5, 15, 30 and 60 min. Plasma concentrations of epinephrine (E), norepinephrine (NE), dopamine (DA) and cortisol (C) were determined in response to restraint stress. The concentrations of E, NE and DA were different between the two strains of pigs (some significant interactions); the highest response was seen after 5 min of stress. The concentration of plasma C increased with duration of stress and there was a significant interaction between strain of animals and the time of stress. Our data substantiate the use of E, NE, DA and C as indicators of stress in swine as early as 5 min after exposure to the stressor. It is also shown that stress-susceptible Pietrain pigs had higher plasma concentrations of E, NE and DA than Duroc pigs.  相似文献   

2.
1. We measured the concentrations of dopamine (DA), norepinephrine (NE), epinephrine (E) and 5-hydroxytryptamine (5-HT) in the hypothalamus of 21-d-old male brown-egg layer-type chicks after intracerebroventricular injection of glucagon-like peptide-1 (GLP-1). 2. The monoamine concentrations of the whole hypothalamus, paraventricular nucleus and lateral hypothalamic area were not significantly affected by GLP-1. 3. However, concentrations of DA, NE and E, but not 5-HT, in the ventromedial hypothalamic nucleus (VMH) were significantly decreased by GLP-1. 4. These observations suggest that the anorexigenic effect of GLP-1 involves catecholaminergic systems in the VMH in the chick.  相似文献   

3.
1. Variations in plasma concentrations of growth hormone (GH) and luteinising hormone (LH) were measured by radioimmunoassay in blood samples taken during the ovulatory cycle of the domestic hen. 2. A peak in LH concentrationas observed 4 h prior to ovulation. 3. Plasma GH concentrations were quite variable but a significant increase was observed between 2 h before and 2 h after ovulation and the concentration remained elevated for about 4 h thereafter.  相似文献   

4.
1. To clarify the difference in behavioural activities and catecholamine metabolism between layer and broiler-type chicks two experiments were conducted. 2. In experiment 1, 1-d-old male layer and broiler chicks were placed in an open-field area and their responses were investigated for 10 min. The responses of the two strains were remarkably different, with broilers being less active than layers. Vocalisations rapidly decreased in broilers whereas those of layers remained elevated during the 10 min. 3. In experiment 2, 1-d-old chicks of both strains were killed and brain catecholamine concentrations were determined in three parts of the brain: telencephalon, optic lobe and brain stem. 4. In the whole brain, dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) were significantly higher in broilers. However, the values for norepinephrine (NE), epinephrine (E) and 4-hydroxy-3-methoxyphenylacetic acid (HVA) were similar between strains. The ratios of metabolite/precursor were also calculated: HVA/DOPAC was higher in layers, while NE/DA, E/NE and DOPAC/DA were not significantly different between strains. 5. These results suggest that behavioural activities differ greatly, while there are some differences in catecholamine metabolism between the two strains.  相似文献   

5.
Sixteen crossbred wethers were distributed among four treatments and fed a control ration based on annual rye-orchardgrass (R-O) for 8 days. Indwelling jugular cannulae were installed and experimental regimes begun the following day (experimental day 1). One-half of the wethers were fed a ration based on endophyte-infected Kentucky-31 fescue while the remainder continued to receive the R-O control diet for 10 days. Spiperone, a dopamine antogonist, was administered to one-half of the wethers receiving each ration on days 8 and 9. Plasma prolactin (PRL), dopamine (DA), norepinephrine (NE) and epinephrine (E) were measured in jugular venous blood on days 1, 3, 5 and 7-10 of the trial. On day 10, the animals were decapitated; and DA, NE, E and 3,4-dihydroxyphenylacetic acid (DOPAC) and monoamine oxidase (MAO) were determined in hypothalamic and pituitary tissue. Plasma DA was elevated (P less than .05) following day 8 in wethers fed infected fescue over those fed (R-O), while plasma PRL was reduced (P = .08). Wethers receiving Spiperone had lowered (P less than .05) plasma DA and elevated (P less than .01) plasma PRL. Plasma DA was negatively correlated (P less than .01) with plasma PRL (r = -0.50) following day 8. Plasma NE and E levels and NE, E, DA and DOPAC tissue concentrations were not affected by Spiperone administration or diet. MAO levels in pituitaries were higher (P less than .01) for Spiperone-treated wethers. Wethers receiving the toxic fescue ration exhibited elevated plasma DA concentrations which was associated with depressed prolactin secretion in wethers.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

6.
The aim of this study was to compare changes in epinephrine (E), norepinephrine (NE) and dopamine (DA) levels in blood plasma of two racehorses breeds: Arabian and Thoroughbred during moderate intensity exercise performed in the same conditions. The increase in plasma E level just after exercise was higher in Thoroughbreds than in Arabians. During the whole test, the Arabians showed the higher levels of NE and DA as compared to those found in Thoroughbreds.  相似文献   

7.
The effects of a serum gonadotropin (SG) superovulation hormonal preparation were investigated on catecholamine levels (norepinephrine, dopamine and epinephrine) in the blood plasma of ewes with synchronized oestrus in the oestrus period. In this trial the blood plasma of eleven ewes of the Slovak Merino breed was analyzed to detect catecholamines in the oestrus period. Superovulation was induced by an i.m. administration of 1500 IU SG as soon as oestrus synchronization with Agelin vaginal tampons finished (20 mg chlorsuperlutin) which lasted for 10 days. Catecholamines were detected in the blood plasma before synchronization, on the day of Agelin vaginal tampons application, and in 48 and 72 hours after the hormone administration--on the days of the expected ovulation. Catecholamine concentrations in the blood plasma were determined by a radioenzymatic assay using a Catechola test (Praha). The results indicate that synchronization and hormonal stimulation influence plasma catecholamine levels. The norepinephrine (NE) concentration in the blood plasma of the control samples has the value of 8.31 +/- 0.732 pmol/ml. An insignificant increase in the NE levels (13.12 +/- 0.120 pmol/ml; Fig. 1) was recorded on day 1 of the trial, after the start of synchronization. On the day of the expected ovulation the NE concentrations rose to 17.12 +/- 1.289 pmol/ml (P less than 0.001) and they remained significantly increased (P less than 0.01) at the level of 12.89 +/- 1.020 pmol/ml on the following day of the experiment. The dopamine level (DA) in the plasma of a control sample is 6.42 +/- 0.350 pmol/ml (Fig. 2).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
The objective of the present study was to examine the changes in innate immune factors in milk during the estrous cycle in dairy cows. Milk was collected from cows with a normal ovulatory cycle and cows subjected to the OVSYNCH protocol, and somatic cell counts (SCC), lingual antimicrobial peptide (LAP) concentrations and lactoperoxidase (LPO) activity in milk were measured. In cows with a normal ovulatory cycle, there was no significant change in LAP concentrations and SCC during the ovulatory cycle. However, LPO activity at days 0 and 19 (day 0 = day of ovulation) were significantly higher than those at days 10, 12 and 15. In cows subjected to the OVSYNCH protocol, a significant increase in SCC was observed at day 9 (2 days after prostaglandin treatment) compared with that at day 11 (2 days after second administration of gonadotropin). There were no significant changes in LAP concentrations and LPO activity during the OVSYNCH protocol. These results indicate that LPO activity, an innate immune factor, was enhanced in the preovulatory period.  相似文献   

9.
Mature gilts classified by low (12 to 16 corpora lutea [CL], n = 6) or high (17 to 26 CL, n = 5) ovulation rate (OR) were compared for plasma follicle-stimulating hormone (FSH), luteinizing hormone (LH), progesterone, estradiol-17beta, and inhibin during an estrous cycle. Gilts were checked for estrus at 8-h intervals beginning on d 18. Blood samples were collected at 8-h intervals beginning on d 18 of the third estrous cycle and continued for one complete estrous cycle. Analysis for FSH and LH was performed on samples collected at 8-h intervals and for ovarian hormones on samples collected at 24-h intervals. The data were standardized to the peak of LH at fourth (d 0) and fifth estrus for the follicular phase and analyzed in discrete periods during the periovulatory (-1, 0, +1 d relative to LH peak), early-luteal (d 1 to 5), mid-luteal (d 6 to 10), late-luteal (11 to 15), periluteolytic (-1, 0, +1 d relative to progesterone decline), and follicular (5 d prior to fifth estrus) phases of the estrous cycle. The number of CL during the sampling estrous cycle was greater (P < 0.005) for the high vs low OR gilts (18.8 vs 14.3) and again (P < 0.001) in the cycle subsequent to hormone measurement (20.9 vs 14.7). For high-OR gilts, FSH was greater during the ovulatory period (P = 0.002), the mid- (P < 0.05) and late-luteal phases (P = 0.01), and tended to be elevated during the early-luteal (P = 0.06), but not the luteolytic or follicular periods. LH was greater in high-OR gilts during the ovulatory period (P < 0.005), but not at other periods during the cycle. In high-OR gilts, progesterone was greater in the mid, late, and ovulatory phases (P < 0.005), but not in the follicular, ovulatory, and early-luteal phases. Concentrations of estradiol-17beta were not different between OR groups during the cycle. Inhibin was greater for the high OR group (P < 0.005) during the early, mid, late, luteolytic, and follicular phases (P < 0.001). The duration of the follicular phase (from last baseline estrogen value to the LH peak) was 6.5 +/- 0.5 d and was not affected by OR group. These results indicate that elevated concentrations of both FSH and LH are associated with increased ovulation rate during the ovulatory phase, but that only elevated FSH during much of the luteal phase is associated with increased ovulation rate. Of the ovarian hormones, both inhibin and progesterone are highly related to greater ovulation rates. These findings could aid in understanding how ovulation rate is controlled in pigs.  相似文献   

10.
The present study was undertaken to determine changes in circulating levels of immunoreactive (ir)-inhibin, FSH, LH, estradiol-17beta, progesterone, and testosterone during the ovulatory cycle of Shao ducks. Serial blood samples were taken from two groups of laying ducks for measurement of ir-inhibin, gonadotropins, and steroid hormones at 2 h intervals for 24 h. Plasma concentrations of ir-inhibin did not change significantly during the ovulatory cycle. The highest level of plasma ir-inhibin was observed 6 h prior to ovulation, which coincided with a decreased level of plasma FSH. One FSH surge was found 12 h after ovulation. Estradiol-17beta, progesterone, and testosterone were also determined during the ovulatory cycle. Two peak values were detected for estradiol-17beta 8 h before ovulation and 4 h after ovulation, while progesterone started to increase 4 h before ovulation and reached a peak at ovulation. The highest level of plasma testosterone was detected around the time of ovulation. These results suggest that inhibin may be involved in the control of FSH secretion during the ovulatory cycle. In addition, both LH and progesterone are of importance in the ovulation process of Shao ducks.  相似文献   

11.
The effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given 100 microg of GnRH im were determined in three experiments. In Experiment 1, heifers were given GnRH 3, 6 or 9 days after ovulation; 8/9, 5/9 and 2/9 ovulated (P<0.02). Mean plasma concentrations of progesterone were lowest (P<0.01) and of LH were highest (P<0.03) in heifers treated 3 days after ovulation. In Experiment 2, heifers received no treatment (Control) or one or two previously used CIDR inserts (Low-P4 and High-P4 groups, respectively) on Day 4 (estrus=Day 0). On Day 5, the Low-P4 group received prostaglandin F(2alpha) (PGF) twice, 12 h apart and on Day 6, all heifers received GnRH. Compared to heifers in the Control and Low-P4 groups, heifers in the High-P4 group had higher (P<0.01) plasma progesterone concentrations on Day 6 (3.0+/-0.3, 3.0+/-0.3 and 5.7+/-0.4 ng/ml, respectively; mean+/-S.E.M.) and a lower (P<0.01) incidence of GnRH-induced ovulation (10/10, 9/10 and 3/10). In Experiment 3, 4-6 days after ovulation, 20 beef heifers and 20 suckled beef cows were given a once-used CIDR, the two largest follicles were ablated, and the cattle were allocated to receive either PGF (repeated 12h later) or no additional treatment (Low-P4 and High-P4, respectively). All cattle received GnRH 6-8 days after follicular ablation. There was no difference between heifers and cows for ovulatory response (77.7 and 78.9%, P<0.9) or the GnRH-induced LH surge (P<0.3). However, the Low-P4 group had a higher (P<0.01) ovulatory response (94.7% versus 61.1%) and a greater LH surge of longer duration (P<0.001). In conclusion, although high plasma progesterone concentrations reduced both GnRH-induced increases in plasma LH concentrations and ovulatory responses in beef cattle, the hypothesis that heifers were more sensitive than cows to the suppressive effects of progesterone was not supported.  相似文献   

12.
The aim of this research was to analyse the composition of oviduct fluid (ODF) in buffalo cows at different oestrous cycle phases to fulfil the requirements of buffalo embryos in vitro. ODF was collected by chronic cannulation from three cows that were synchronized by administering a synthetic prostaglandin. Based on hormonal profiles, the pre‐ovulatory, ovulatory, post‐ovulatory and luteal phases of the oestrous cycle were defined. The volume of ODF produced (ml/24 h) was influenced by the oestrous cycle, with values (mean ± SE) around ovulation (1.0 ± 0.2) greater (p < 0.05) than in both the luteal (0.4 ± 0.1) and the post‐ovulatory phases (0.5 ± 0.1), but not different from the intermediate values in the pre‐ovulatory phase (0.8 ± 0.2). Among cycle phases, no differences were found in sodium, potassium, calcium and magnesium concentrations (130.0 ± 1.1, 5.1 ± 0.3, 2.8 ± 0.1 and 0.59 ± 0.04 mmol/l respectively). Interestingly, the chloride secretion (μm /24 h) was higher (p < 0.05) at ovulation (150.2 ± 16.5) than during both the luteal (73.7 ± 22.0) and the post‐ovulatory phases (63.7 ± 11.2), with intermediate values in the pre‐ovulatory phase (113.4 ± 23.5). Glucose concentration (mmol/l) was higher (p = 0.056) in the pre‐ovulatory phase (0.06 ± 0.02) than in the luteal (0.02 ± 0.01) and post‐ovulatory (0.02 ± 0.01) phases but not different from values in the ovulatory phase (0.04 ± 0.02). Concentrations of pyruvate and lactate among oestrous cycle phases were similar (0.08 ± 0.01 and 1.0 ± 0.1 mmol/l respectively). The total quantity of phospholipids (μmol/24 h) was greater (p < 0.05) at ovulation (0.21 ± 0.02) compared with the luteal, pre‐ovulatory and post‐ovulatory phases of the cycle (0.09 ± 0.02, 0.13 ± 0.02 and 0.09 ± 0.01 respectively). No differences were found in either the protein concentration (1.8 ± 0.3 mg/ml) or the quantity of proteins secreted in 24 h (1.8 ± 0.4 mg) among oestrous cycle phases. In conclusion, this study provides the first characterization of buffalo ODF during the oestrous cycle, showing species‐specific differences that may be useful for developing suitable media for buffalo in vitro embryo production.  相似文献   

13.
The objective of the present study was to establish the changes in plasma concentrations of LH, FSH, estradiol 17-beta (E2) and progesterone (P4), as well as to understand their temporal relationships during oestrus in mithun (Bos frontalis). The experiment was conducted on 11 mithuns during third or fourth postpartum oestrous cycle. Since oestrus onset the jugular vein blood samples were collected every 2 h for 72 and 96 h, respectively from the animals without and with standing heat. The LH, FSH, E2 and P4 concentrations were estimated in plasma. The P4 concentration was fluctuated throughout the oestrus period and the average P4 concentration was found significantly (p<0.05) lower on the day of oestrus onset. The multiple rises in LH and FSH concentrations above the basal level in spike like fashion were observed throughout the oestrus period irrespective of the occurrence of standing heat. A significant (p<0.01) gradual increase in the average daily E2 concentration was observed till day 2 following oestrus onset irrespective of the occurrence of standing heat. A significant (p<0.05) simultaneous increase in LH, FSH and E2 concentrations and a transient increase in P4 concentration at approximately the time of standing heat onset were observed. During investigation a definite temporal coupling between LH and FSH rises was absent throughout the oestrus period. The results suggest that (1) the multiple short-duration low-amplitude LH and FSH surges during oestrus may be crucial for the final maturation of ovulatory follicle and subsequent ovulation in mithun; (2) a differential mechanism for controlling LH and FSH secretions probably exists in mithun.  相似文献   

14.
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.
Mares are seasonally polyoestrous breeders. Therefore, the first ovulation of the season, following winter anoestrus, is the only cycle in which mares ovulate without the presence of an old CL from the previous cycle. The objective of this study was to compare the length of oestrous behaviour, and plasma progesterone concentrations during the early post-ovulatory period between mares after the first and second ovulation of the breeding season. Overall, 38 mares and 167 oestrous periods were used in the study. From those, 11 mares were used during the first and subsequent oestrous period to measure and compare the post-ovulatory rise in progesterone concentration, whereas all the mares were used to compare the length of the post-ovulatory oestrous behaviour between the first and subsequent cycles of the breeding season. The persistence of the post-ovulatory oestrus was longer (p < .001) following the first ovulation of the year (median of 52 h) compared with the subsequent ovulations (median of 36 h for second and later ovulations groups; n = 38 mares). The progesterone concentration at any of the four 8 h-intervals analysed (28, 36, 76 and 84 h post-ovulation) was lower (p < .01) following the first versus the second ovulation of the year. By 36 h post-ovulation the progesterone concentration of mares at the second ovulation of the year had passed the threshold of 2 ng/ml (2.1 ± 0.33 ng/ml), whereas in the first cycle it was 1.2 ± 0.13 ng/ml. In conclusion, mares had lower progesterone concentrations in their peripheral circulation and longer persistence of oestrous behaviour following the first ovulation of the year compared with the second and subsequent ovulatory periods of the breeding season.  相似文献   

16.
The ovulatory response of ewes from breeds that differ widely in prolificacy (Ile-de-France, ++ Booroola Merino, Romanov, F+ Booroola Merino and F+ Booroola Romanov with adult ovulation rates of about 1.5, 1.2, 3, 3 and 3.5 respectively) to 750 IU of hCG given at different physiological stages (before puberty, during anestrus or during the luteal phase) was compared. In all except one experiment, hCG induced ovulation in 73 to 98% of the lambs, indicating that follicles sensitive to LH were present at all stages studied. Ranking of the breeds according to hCG-induced ovulation rate in prepuberal lambs was similar to that based on adult ovulation rate. Furthermore, hCG induced more ovulations in prepuberal F+ than in ++ lambs (3.7 +/- 1.4 vs 1.7 +/- .8 at 4.5 mo of age) as well as in anestrous ewes (F + at 3.1 +/- 1.8 vs ++ at 1.6 +/- .7). Within ewes, the correlation between hCG-induced ovulation rate and mature ovulation rate was positive in nonprolific breeds but not significant in prolific breeds. We conclude that 1) the number of hCG-induced ovulations can be used to identify sheep that are carriers of the Booroola gene and 2) the mechanisms responsible for a number of large ovulatory follicles typical of a breed are present at stages (prepuberal, anestrus, luteal phase) other than the follicular phase.  相似文献   

17.
Prolactin may play multiple roles in equine reproduction. Prolactin appears to be associated with seasonal reproduction, and fluctuating prolactin levels during the estrous cycle suggest that it may play a role in estrous cyclicity as well. The purpose of this research was to investigate the activity of prolactin during the follicular phase of the estrous cycle. In experiment 1, prolactin concentrations were determined from plasma samples collected at least every other day throughout the estrous cycle. Periovulatory (ovulation ± 1 day) prolactin concentrations were compared with concentrations during early diestrus (days 2−10 postovulation). In experiment 2, prolactin concentrations were measured in follicular fluid collected from 74 follicles of various sizes. Follicles were grouped into small (≤20 mm), medium (21−35 mm), and large (>35 mm) size categories. Prolactin concentrations increased during the periovulatory period in cycling mares. This periovulatory surge was superimposed on baseline prolactin concentrations that varied with season. Prolactin was present in significant quantities in the follicular fluid. Follicular fluid prolactin concentrations were lowest in small follicles and increased in medium and large follicles. Concentrations did not differ between medium and large follicles. Follicular fluid prolactin concentrations were lower in autumnal follicles compared with summer follicles of comparable size. It is possible that the short-term surge in circulating prolactin around ovulation could be linked to the significant levels of prolactin in follicular fluid. Ovulation releases a relatively large volume of fluid into the peritoneum. The prolactin in this fluid could be a contributor to the periovulatory prolactin surge.  相似文献   

18.
The effects of the SAS gene on follicular growth were studied by feeding Sudan IV and Sudan Black B, on follicular maturity by measuring P4 and E2 output of the 5 largest follicles (F1 to F5) in vitro, and on ovarian response (plasma progesterone, P4, and oestradiol, E2) to administration of porcine follicle-stimulating hormone (pFSH) and porcine luteinising hormone (pLH) in old laying hens. Albino hens had fewer dye rings in the yolks of their eggs than non-albinos (8.32 compared to 8.59) and the yolks from albinos weighed less. The numbers of normal and atretic follicles larger than 3 mm in diameter did not differ between the two genotypes. The P4 outputs from the F1 and F2 follicles were significantly greater for albino hens, but P4 production of other follicles was not different for the two genotypes. The P4 output of the F1 follicle in response to pLH was dose-dependent and greater for albino hens than for non-albinos. Porcine LH did not increase the follicular E2 output in either genotype. Administration of pLH, but not pFSH, increased plasma P4 and E2 concentrations, with no difference between genotypes. These data suggest that the F1 follicles for albino hens are precocious, resulting in a reduced growth period and a smaller weight at ovulation.  相似文献   

19.
We tested the hypothesis that a small dose of estradiol benzoate (EB) at the midstage of the estrous cycle in cattle would synchronize the subsequent pattern of ovarian follicular development, estrus, and ovulation. Nonlactating Friesian cows received either 1 mg of EB i.m. on d 13 of the estrous cycle (T; n = 12; estrus = d0) or served as untreated controls (C; n = 12). Their ovaries were examined daily with transrectal ultrasonography from d 7, and blood samples were collected 0, 2, 4, 8, 24, and 48 h after treatment on d 13. Plasma concentrations of estradiol-17beta were elevated to 12 pg/mL during the initial 24 h following treatment, compared with a baseline of 1 pg/mL in untreated controls (P < .001). Progesterone concentrations in cows of the T group declined between 24 and 48 h after treatment (-3.2 +/- .5 ng/mL) compared with little change in concentrations of progesterone in cows of the C group at this time (P < .01). This difference was coincident with an earlier time to regression of the corpus luteum in cows of the T group. Disregarding treatment groups, the second dominant follicle of the estrous cycle (DF2) emerged on d 10.6 +/- .3 and was 9.4 +/- .4 mm in diameter on d 13. Further growth of the DF2 was halted by EB treatment on d 13. Cessation of growth occurred irrespective of whether the DF2 was in the early or late growth phase, and a new follicular wave emerged 4.5 +/- .2 d later. The dominant follicle from this wave (DF3) ovulated 5 d after emergence in most cases. During the estrous cycle of every cow in the T group, there were three waves of follicular development (3-wave), whereas the ratio of 2:3 waves of follicular development in cows of the C group was 1:3. Consequently, the interval from emergence to ovulation of the ovulatory dominant follicle in cows of the C group ranged from 3 to 11 d. The dynamics of ovarian follicular wave development during the estrous cycle can be strategically manipulated by treating with a small dose of EB to synchronize proestrous development of the ovulatory follicle.  相似文献   

20.
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