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1.
The weaning to estrus and weaning to ovulation intervals in sows are controlled by ovarian follicular growth after weaning. Longer intervals could be caused by smaller diameter follicles at weaning that take more time to reach a preovulatory size. We addressed this hypothesis by decreasing the diameter of follicular populations before weaning and then measuring follicular development and interval to estrus and ovulation after weaning. The posterior vena cava, cranial to the entry of the ovarian vein, was cathetered for blood sampling and infusion in 20 sows at 12 +/- 1 d after farrowing. Sows were assigned randomly to receive either 30 mL of charcoal-treated follicular fluid (FF, n = 9; a treatment known to decrease serum FSH and follicular diameter) or 30 mL of saline (n = 11) by venous infusion thrice daily (0700, 1500, and 2300 h) for 96 h beginning at 14 +/- 1 d after farrowing. Sows were weaned 48 h after the last infusion. Blood samples were collected for FSH analysis thrice daily beginning on the day of catheterization and continuing until ovulation. Follicular diameter was determined once daily by transrectal ultrasonography. A treatment x time interaction was detected for serum FSH (P < 0.001) and follicular diameter (P < 0.001) because serum FSH and the diameter of follicular populations decreased in FF sows during the infusion period. After the infusion period, serum FSH rebounded in FF sows, and follicles resumed growth but grew at the same rate as those of saline-treated sows, thus failing to achieve equivalent diameters relative to saline-treated sows on a given day after weaning. As a result, sows treated with FF had longer (P < 0.05) weaning to estrus (6.1 +/- 0.4 d) and weaning to ovulation (8.6 +/- 0.5 d) intervals compared with saline-treated sows (4.7 +/- 0.4 d and 7.2 +/- 0.4 d, respectively). We conclude that the diameter of the follicular population at weaning is one factor that controls interval to estrus and ovulation in sows. Small follicles at weaning cannot undergo compensatory growth and require additional time to reach a preovulatory size.  相似文献   

2.
Dihydrotestosterone (DHT) induces follicular atresia under experimental conditions. However, whether it causes any antagonistic effect under natural condition is not known. In the present study, we investigated concentrations of DHT in follicular fluid and correlated them with concentrations of estradiol-17beta (E2) and its androgen substrates, androstenedione (A4) and testosterone (T), in healthy and atretic follicles of sheep. Merino ewes were treated twice with PGF2alpha (PG) to synchronize estrus. The ovaries were recovered at 14 days after the second PG (luteal phase) or 24h after the third PG given 14 days after the second PG (follicular phase). Follicles were dissected and their size and appearance were recorded. Follicular fluid was collected from follicles larger than 3.5mm and concentrations of E2, progesterone (P4), A4, T and DHT were determined by RIA. The inhibitory effect of DHT on conversion of T to E2 was tested in cultured granulosa cells. Appreciable levels of DHT were observed in the follicular fluid of ovine preovulatory follicles. The levels of DHT were much lower than those of E2, A4 and T, irrespective of physiological conditions of follicles. No difference was found in DHT concentration between healthy and atretic follicles. Dihydrotestosterone marginally inhibited aromatization of T in granulosa cells but this effect was only observed when the levels of DHT were 10 times higher than that of T in culture medium. These results indicate that DHT is present in ovine preovulatory follicles but its levels are not sufficient to exert any antagonistic effect on follicular development.  相似文献   

3.
本试验旨在研究代谢产物、代谢激素和生殖激素在湖羊黄体期不同发育卵泡内的变化。选用体质量40kg左右的湖羊11头,同期发情结束后第12天屠宰,按不同大小卵泡分离卵泡液。试验结果表明,与≤2.5mm卵泡相比,>2.5mm卵泡内的葡萄糖浓度显著提高(P<0.05),胰高血糖素浓度显著降低(P<0.05),乳酸脱氢酶(LDH)活性和睾酮浓度极显著降低(P<0.01),雌二醇浓度极显著提高(P<0.01),而血氨、游离脂肪酸、尿素、胰岛素和孕酮浓度差异不显著。雌二醇浓度与LDH活性呈极显著负相关(P<0.01),与葡萄糖浓度呈显著正相关(P<0.05),与胰高血糖素浓度呈显著负相关(P<0.05),与睾酮浓度呈极显著负相关(P<0.01),与孕酮浓度接近正相关(P=0.051)。试验结果表明代谢产物和激素共同参与调节卵泡发育。  相似文献   

4.
Comparisons of numbers of antral ovarian follicles and corpora lutea (CL), of blood hormone concentrations, and of follicular fluid steroid concentrations and IGFBP activity were conducted between cows selected (twinner) and unselected (control) for twin births to elucidate genetic differences in the regulation of ovarian follicular development. Ovarian follicular development was synchronized among cows by a single i.m. injection of PGF2alpha on d 18 of the estrous cycle; six cows per population were slaughtered at 0, 24, 48, and 72 h after PGF2alpha. Jugular vein blood was collected from each animal at PGF2alpha injection and at 24-h intervals until slaughter. Ovaries of twinner cows contained more small (< or = 5 mm in diameter, P < 0.05), medium (5.1 to 9.9 mm, P < 0.05), and large (> or = 10.0 mm, P < 0.01) follicles and more (P < 0.01) CL than ovaries of controls. Follicular fluid concentrations of estradiol, androstenedione, testosterone, and progesterone reflected the stage of follicular development and were similar for twinner and control follicles at the same stage. Earlier initiation of follicular development and/or selection of twin-dominant follicles in some twinner cows resulted in greater concentrations of estradiol in plasma at 0, 24, and 48 h and of estradiol, androstenedione, and testosterone in follicular fluid of large follicles at 0 h after PGF2alpha for twinner vs. control cows (follicular status x time x population, P < 0.01). Binding activities of IGFBP-5 and -4 were absent or reduced (P < 0.01) in follicular fluid of developing medium and large estro-gen-active (estradiol:progesterone ratio > 1) follicles but increased with atresia. Only preovulatory Graafian follicles lacked IGFBP-2 binding, suggesting a possible role for IGFBP-2 in selection of the dominant follicle. Concentrations of IGF-I were twofold greater (P < 0.01), but GH (P = 0.10) and cholesterol (P < 0.05) were less in blood of twinners. Three generations of selection of cattle for twin ovulations and births enhanced ovarian follicular development as manifested by increased numbers of follicles within a follicular wave and subsequent selection of twin dominant follicles. Because gonadotropin secretion and ovarian steroidogenesis were similar for control and twinner cattle, enhanced follicular development in twinners may result from decreased inhibition by the dominant follicle(s), increased ovarian sensitivity to gonadotropins, and/or increased intragonadal stimulation, possibly by increased IGF-I.  相似文献   

5.
The influence of litter separation (LS) that included a change in housing environment and social status of sows, boar exposure (BE), and parity on estrous expression by sows during and after lactation was examined in two experiments utilizing 140 crossbred sows. In Exp. 1 (Yorkshire X Duroc sows), limiting duration of LS to 6 or 3 h/d during the last 8 d of lactation in two trials, while maintaining 1 h BE, resulted in similar proportions of sows in estrus during lactation (65 vs 79% for 3- and 6-h sows). However, 6-h LS tended to reduce (P = .08) the interval to estrus by .6 d for those sows that expressed a preweaning estrus. Postweaning intervals to estrus were unaffected by duration of LS in the remaining sows. In Exp. 2, sows (Yorkshire X Duroc X Chester White) were assigned to four treatment groups during the last 8 d of lactation: 1) BE (1 h/d), 2) LS (6 h/d), 3) LS + BE and 4) no LS + no BE (control). Only nine sows expressed estrus during lactation; four of 28 LS sows and five of 28 LS + BE sows. No sows were in estrus before weaning during August 1985 and only one sow (LS group) was in estrus before weaning during October 1986. Postweaning intervals to estrus were reduced (P less than .05) by .9 d after preweaning BE compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

6.
Seventeen Landrace X Large White primiparous sows that farrowed in August 1982 were fed ad libitum (AL, n = 8) or their intakes were restricted (R, n = 9) during lactation. Litter sizes were equalized after farrowing and pigs were not allowed creep feed. Pigs were weaned 23.8 +/- .4 d postpartum. On d 6, 12 and 20 postpartum, all sows were fasted for 16 h and blood samples were collected prior to feeding for analysis of plasma glucose (GLU), urea nitrogen (UN), free fatty acids (FFA), prolactin (PRL) and serum insulin (INS). On d -2, 2 and 4 from weaning, sows were fasted for 16 h and then blood samples were collected hourly from 0 to 6 postprandial for analysis of GLU, UN, FFA, PRL and INS. Serum for analysis of luteinizing hormone (LH), progesterone and estradiol was collected every 6 h from 1 d before until 12 d after weaning. Samples for LH were also collected at 15-min intervals for 3 h at -18, -6, 6, 18, 78, 102, 126, 150, 240 and 480 h from weaning. After weaning all sows were fed 1.8 kg X d-1, and were checked for estrus twice daily. Daily intakes of metabolizable energy (ME) during lactation were greater in AL (12,194 +/- 465 kcal) than in R sows (8,144 +/- 90 kcal). Compared with AL sows, R sows lost more weight and backfat during lactation and had higher postprandial UN levels 2 d before and 4 d after weaning. Reproductive performance and reproductive hormones were not affected by restriction of energy, but frequency of episodic release of LH prior to weaning was greater in sows that exhibited estrus after weaning (n = 12) than in anestrous sows (n = 5). After weaning, LH and estradiol concentrations were similar between estrous and anestrous sows until onset of the preovulatory increase in estradiol in the sows that exhibited estrus. Energy intake, body condition and productivity were similar between anestrous sows and sows that exhibited estrus. On d 12 and 20 of lactation, preprandial levels of GLU were greater and FFA were lower in anestrous than estrous sows. We conclude that restriction of feed intake during lactation affected body condition and metabolism of primiparous sows, but reproductive performance and productivity were not affected. Aberrations in partitioning of energy during lactation may predispose primiparous sows to postweaning anestrus, but the mechanisms by which this occurs have yet to be defined.  相似文献   

7.
Four experiments involving 265, 410, 894, and 554 sows (Exp. 1 to 4, respectively) were conducted to determine the effect of spray-dried plasma (SDP) at 0 or 0.25% (Exp. 1 and 2) and 0 or 0.50% (Exp. 3 and 4) in lactation diets on average daily feed disappearance (FD), sum of sow BW, fetal and placental loss from d 110 gestation to weaning (SWL), litter size at weaning, litter weight at weaning, and average days from weaning to first estrus (WEI). Experiments 1, 3, and 4 were conducted during summer months, and Exp. 2 was conducted during fall to winter months. Experiment 1 used only parity 1 and parity 2 sows and Exp. 4 used only mature (>2 parities) sows, whereas Exp. 2 and 3 used all parity groups. Sows fed SDP in Exp. 1 had increased (P < 0.01) FD and a tendency for reduced (P = 0.06) SWL and WEI (P = 0.06). Sows fed SDP in Exp. 2 had a tendency for increased (P = 0.09) sow BW at weaning and reduced (P = 0.09) SWL, whereas other variables were not different between diets. Parity 1 and 2 sows fed SDP in Exp. 3 had increased (P < 0.01) FD, but mature sows fed SDP had reduced (P = 0.02) FD. Pig survival and litter size at weaning for all parity groups was not different between diets. The WEI for parity 1 sows fed SDP was reduced (P = 0.02) and tended to be reduced (P = 0.10) for mature sows fed SDP, but was not different between diets for parity 2 sows. More parity 1 sows fed SDP were detected (P = 0.01) in estrus 4 to 6 d after weaning, and fewer were detected (P < 0.01) in estrus 6 d after weaning compared with control parity 1 sows. In Exp. 4, FD was reduced (P < 0.01) for mature sows fed SDP; however, litter weight and average pig BW at weaning was increased (P < 0.01) with more (P < 0.01) marketable pigs (pig BW > 3.6 kg) weaned per litter. Relatively low dietary levels of SDP (0.25 to 0.50%) fed to parity 1 sows farrowed during summer months increased lactation FD and reduced WEI. Mature sows fed SDP during summer months consumed less lactation feed without compromising WEI, but had an increased litter weight, average pig BW, and number of marketable pigs at weaning.  相似文献   

8.
Primiparous sows (n = 36) were used to evaluate the effects of dietary lysine intake in lactation on follicular development and oocyte maturation after weaning. Sows were assigned randomly to one of three diets containing .4% (low lysine, LL), 1.0% (medium lysine, ML), or 1.6% (high lysine, HL) total lysine. All diets contained 2.1 Mcal NE/kg and exceeded NRC (1988) requirements for all other nutrients. Actual lysine intakes over an 18-d lactation were 16, 36, and 56 g/d for sows consuming LL, ML, and HL, respectively. Ovarian data were analyzed for sows determined to have been slaughtered during the first proestrus period after weaning, using previously established criteria. Compared with sows fed ML and HL, sows fed LL tended to have lower uterine weight, follicular fluid volume, and follicular fluid (FF) estradiol (E2) content (P < .15), but similar ovarian weight and follicular fluid IGF-I concentration. Within the largest 15 preovulatory follicles, sows fed LL had a lower percentage of large (> or = 7.0 mm) follicles (33 vs 50 and 58%; P < .01) and a higher percentage of medium (5.5 to 7.0 mm) follicles (62 vs 44 and 39%; P < .01) but a similar percentage of small (< or = 5.5 mm) follicles (4.4 vs 5.9 and 3.7%; P > .15), respectively, compared with sows fed ML or HL. Standardized pools of oocytes aspirated from follicles of prepubertal gilts were incubated for 44 h with pooled FF recovered from the largest 15 follicles of each experimental sow. Fewer oocyte nuclei matured to metaphase II of meiosis when cultured with FF recovered from sows fed LL, than from sows fed ML or HL (47.1 vs 59.8 and 63.8%, respectively; P < .01). Our results suggest that low lysine (protein) intake in primiparous lactating sows impaired follicular development and reduced the ability of follicles to support oocyte maturation. However, high compared with medium lysine (protein) intake had no further positive effects on ovarian function.  相似文献   

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

10.
Previous research revealed that treatment with vitamin A approximately 5 d before ovulation may increase litter size in weaned sows and improve embryonal survival in gilts fed high-energy diets that reduced embryonal survival. For the current study, the hypothesis was that administration of vitamin A before ovulation would alter development of follicles and oocytes in a way favorable to enhanced embryonal survival. (Landrace x Large White) x (Duroc x Hampshire) gilts (n = 44) were fed 11.0 Mcal ME x gilt(-1) x d(-1) beginning 7 d after second estrus and given (i.m.) corn oil or 1 x 10(6) IU of vitamin A (retinyl palmitate) on d 15 after second estrus. Gilts were checked for estrus every 4 h, mated naturally at third estrus, and assigned randomly to undergo midventral laparotomy beginning at 24 to 28, 28 to 32, 32 to 36, or 36 to 40 h after onset of third estrus. At laparotomy, ovulated oocytes and early-stage embryos were recovered from oviducts, and ovaries were removed for aspiration of oocytes and granulosa cells from unovulated follicles. Oocytes and embryos were stained for assessment of stage of development. Granulosa cells were cultured to assess their ability to secrete progesterone. Follicular fluid was assayed for progesterone, estradiol-17beta, IGF-I, and PGF2alpha. Treatment with vitamin A altered development of oocytes and embryos by decreasing the percentage at the germinal vesicle stage and increasing the percentage at advanced stages. Mean stage of development was increased by vitamin A, but variation in stage was decreased. Among follicles matched by meiotic stage of oocyte, follicular fluid concentrations of progesterone, IGF-I, and PGF2alpha were greater in vitamin A-treated gilts than in controls, but treatment with vitamin A in vivo did not affect LH-stimulated or unstimulated secretion of progesterone by granulosa cells in vitro. These data provide evidence that vitamin A may influence embryonic development by advancing resumption of meiosis and altering follicular hormonal environment during follicle maturation.  相似文献   

11.
This study determined whether the interval from estrus to ovulation was altered by giving P.G. 600 to sows at weaning. Mixed-parity sows received P.G. 600 i.m. (n = 72) or no treatment (n = 65) at weaning (d 0). Beginning on d 0, sows were observed for estrus twice daily. At the onset of estrus and thereafter, ultrasound was performed twice daily to determine the average size of the largest follicles and time of ovulation. Weaning age (20.1+/-0.4 d) did not differ (P > 0.10) between treatments. More P.G. 600 sows expressed estrus within 8 d (P < 0.01) than controls (94.4% vs 78.4%, respectively). Parity was associated with expression of estrus (P < 0.02), with 78% of first-parity and 93% of later-parity sows exhibiting estrus. However, no treatment x parity effect was observed (P > 0.10). The interval from weaning to estrus was reduced (P < 0.0001) by P.G. 600 compared with controls (3.8+/-0.1 d vs 4.9+/-0.1 d). Follicle size at estrus was not affected by treatment (P > 0.10). The percentage of sows that ovulated did not differ (P > 0.10) for P.G. 600 and control sows (90.3% vs 81.5%, respectively). Time of ovulation after estrus was not affected by treatment and averaged 44.8 h. However, univariate analysis indicated that the interval from weaning to estrus influenced the interval from estrus to ovulation (r = 0.43, P < 0.0001). Further, multivariate analysis showed an effect of treatment on the intervals from weaning to estrus, weaning to ovulation (P < 0.0001), and estrus to ovulation (P < 0.04). Within 4 d after weaning, 81% of the P.G. 600 sows had expressed estrus compared with 33% of controls. However, this trend reversed for ovulation, with only 35% of P.G. 600 sows ovulating by 36 h after estrus compared with 40% of controls. The estrus-to-ovulation interval was also longer for control and P.G. 600 sows expressing estrus < or = 3 d of weaning (45 h and 58 h, respectively) than for sows expressing estrus after 5 d (39 h and 32 h, respectively). Farrowing rate and litter size were not influenced by treatment. However, the interval from last insemination to ovulation (P < 0.02) indicated that more sows farrowed (80%) when the last insemination occurred at < or = 23 to > or = 0 h before ovulation compared with insemination > or = 24 h before ovulation (55%). In summary, P.G. 600 enhanced the expression of estrus and ovulation in weaned sows but, breeding protocols may need to be optimized for time of ovulation based on the interval from weaning to estrus.  相似文献   

12.
This study investigated whether injections of ACTH for 48 h, from the onset of the second standing estrus after weaning, had any impact on time of ovulation and patterns of progesterone, estradiol, luteinizing hormone (LH), and inhibin alpha. The studied sows (n=15) were fitted with jugular vein catheters and randomly divided into a control (C group) and an ACTH group. From the onset of standing estrus, the sows were injected (NaCl or synthetic ACTH, 5 microg/kg) every 4h; blood samples were collected immediately before and 45 min after each injection. Ovulation was monitored using ultrasonography. The ACTH-group sows stopped displaying signs of standing estrus sooner after ovulation in their second estrus, but no impact was found on time of ovulation. There were no significant differences in the intervals between LH peak, estradiol peak, and the onset of standing estrus between the C and ACTH groups. The cortisol and progesterone concentrations were significantly elevated (p<0.001) in samples taken 45 min after ACTH injection. There were minor differences in estradiol and LH concentrations between the groups. Overall inhibin alpha concentrations were significantly higher during the treatment period in the ACTH than in the C group, but there were no significant differences between samples taken either 45 min or 4h after injection. In conclusion, injections of synthetic ACTH during estrus in the sow apparently disturb the duration of signs of standing estrus and the hormonal pattern of progesterone, and possibly of inhibin alpha, estradiol and LH.  相似文献   

13.
To examine ovarian follicular response to low-dose injections of luteinizing hormone-releasing hormone (LHRH), 32 anovulatory, suckled beef cows were allotted to one of four treatment groups and injected with either saline or 500 ng LHRH every 2 h for 48 or 96 h, starting 21.4 +/- .4 d after parturition. Two hours after the last injection of LHRH, cows were ovariectomized and 10 to 15 ovarian follicles per pair of ovaries were removed and categorized by diameter as small (1.0 to 3.9 mm), medium (4.0 to 7.9 mm) or large (greater than or equal to 8.0 mm). Injections of LHRH did not affect (P greater than .10) steroid levels in small follicles or numbers of gonadotropin receptors in small and medium follicles. Concentrations of progesterone in fluid of medium follicles increased 1.5-fold (P less than .05) after 96 h of LHRH, whereas concentrations of estradiol and androstenedione were unchanged. In fluid of large follicles, concentrations of progesterone were fourfold greater (P less than .05) in LHRH-treated than in control cows at 48 h, but by 96 h progesterone was twofold greater (P less than .05) in control than LHRH-treated cows. In large follicles, concentrations of estradiol were unchanged (P greater than .10) after 48 h of LHRH injections but after 96 h estradiol was twofold greater (P less than .05) in LHRH-treated than control cows. Increased concentrations of estradiol in large follicles coincided with increased numbers of binding sites for human chorionic gonadotropin (hCG) but not follicle stimulating hormone (FSH) in granulosa and theca.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

14.
Thirty-four gilts in two experiments were fed altrenogest for 18 d to block spontaneous growth of ovulatory follicles after luteolysis. They were injected with estradiol or charcoal-extracted porcine follicular fluid (pFF) to determine 1) whether gonadotropin secretion could be depressed and 2) whether exposure to reduced levels of gonadotropins would result in decreased numbers of medium follicles (3 to 6 mm in diameter). Gilts in Exp. 1 received treatments in a 2 X 2 X 2 factorial arrangement starting 48 h before the last feeding of altrenogest. Corn oil or estradiol (2 micrograms/kg body weight), 5 ml of charcoal-extracted porcine serum (pS) or pFF were injected im four times at 8-h intervals and gilts were sacrificed 24 or 96 h after last feeding of altrenogest. In Exp. 2, gilts received one of four treatments consisting of 1) pS, injected iv nine times at 8-h intervals starting 48 h before the last feeding of altrenogest; 2) pFF, with injection protocol the same as for pS; 3) estradiol injected im three times and 4) four times at 8-h intervals starting 0 and 24 h, respectively, before the last feeding of altrenogest. Compared with pS or corn oil, estradiol increased (P less than .001) plasma estrogen and decreased (P less than .05) plasma luteinizing hormone (LH) without a significant effect on plasma follicle stimulating hormone (FSH). Estradiol, compared with corn oil, decreased (P less than .01) the number of medium follicles from 24.8 to 0/gilt and decreased (P less than .05) the weight of ovarian follicular fluid from 4.2 to 2.1 g/gilt at 72 h after the first injection. Five milliliters of pFF had no significant effect on plasma gonadotropins or number of medium follicles. However, 20 ml of pFF, compared with pS, decreased (P less than .05) plasma FSH from 45 ng/ml to 9 ng/ml 32 h after the first injection, had no effect on plasma LH, decreased (P less than .01) the number of medium follicles from 29.2 to 2.2/gilt and decreased (P less than .01) follicular fluid weight from 3.9 to 1.6 g/gilt by 72 h after the first injection. These results indicate that estradiol or a non-steroidal component of follicular origin can decrease secretion of gonadotropins and suppress recruitment of medium follicles in the pig.  相似文献   

15.
To determine if (1) levels of pregnancy-associated plasma protein-A (PAPP-A) mRNA and insulin-like growth factor binding protein (IGFBP) (-2, -3, -4 and -5) mRNAs differ between the dominant and subordinate follicles during the follicular phase of an estrous cycle, and (2) these differences are associated with differences in follicular fluid (FFL) concentrations of steroids (estradiol, androstenedione, and progesterone), total and free IGF-I, or IGFBPs, estrous cycles of non-lactating Holstein dairy cows (n = 16) were synchronized with two injections of prostaglandin (PGF2 alpha) 11 days apart. Granulosa cells and FFL were collected either 24 h or 48 h after the second injection of PGF2 alpha. FFL from dominant follicles had lower concentrations of progesterone (P < 0.08) and higher concentrations of estradiol (P < 0.05), androstenedione (P < 0.0001), estradiol:progesterone ratio (P < 0.0001), free IGF-I (P < 0.0001), and calculated percentage free IGF-I (P < 0.01) than large subordinate follicles. Levels of IGFBP-2, -4, and -5 in FFL were 3.0- (P < 0.05), 2.4- (P < 0.06), and 3.4-fold (P < 0.05) greater, respectively, in subordinate than in dominant follicles. IGFBP-3, IGFBP-4 and PAPP-A mRNA expression and IGF-II concentration did not differ (P > 0.10) between dominant or subordinate follicles. Levels of IGFBP-2 and -5 mRNA were severalfold greater (P < 0.05) in subordinate than dominant follicles. IGFBP-5 mRNA in granulosa cells decreased (P < 0.05) 62% to 92%, between 24h and 48 h post-PGF2 alpha. We conclude that decreased levels of IGFBP-2 and -5 mRNA in granulosa cells may contribute to the decrease in FFL IGFBP-2 and -5 protein levels of preovulatory dominant follicles, and that changes in granulosa cell IGFBP-3 and -4 mRNA and PAPP-A mRNA levels do not occur during final preovulatory follicular development in cattle.  相似文献   

16.
Duroc sows farrowed second litters in March and lactated 35 +/- 2 days. At 36 hr before weaning, electrocautery of follicles greater than or equal to 3 mm in diameter (n = 8) or sham surgery (n = 5) was performed to test the hypothesis that ablation of medium-sized follicles would prolong the duration of postweaning anestrus. Number of follicles and diameters at surgery were: 1.3 +/- .6 (greater than 5 mm diameter), 26 +/- 1 (3 to 5 mm) and greater than 20 (less than 3 mm). Blood samples were collected at 15 min intervals for 3 hr beginning at -12, 0, 12, 60 and 96 hr from weaning. Interval to estrus was 3.4 +/- .2 days in seven of eight cauterized sows and 3.6 +/- .6 days for sham-surgery sows. The remaining cauterized sow was anestrus at slaughter, 40 days after weaning. Number of corpora lutea and pregnancy rate were 15.8 +/- .6 and 92%, respectively, and were similar between sham-surgery and cauterized sows. Concentration of follicle stimulating hormone (FSH) at 12 hr before weaning was greater in sows subjected to electrocautery than for sham-surgery sows, but FSH values were similar at other sampling times. Concentrations of estradiol were similar at all times for both treatment groups. Luteinizing hormone (LH) was higher (P less than .05) at 60 hr in cauterized sows because of the onset of the preovulatory LH surge in one sow. We conclude that destruction of medium-sized ovarian follicles before weaning did not influence postweaning reproductive performance.  相似文献   

17.
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   

18.
Sixteen third-parity sows maintained under two photoperiod treatments (16 h light: 8 h dark [16 h] or 4 h light: 20 h dark [4 h]) were assigned to be unilaterally ovariectomized (left ovary) at weaning on d 28 after farrowing a small litter (12 or fewer piglets; S) or a large litter (more than 12 piglets; L). Antral follicles were classified as atretic or nonatretic and divided into six size classes. The right ovary was obtained at slaughter, 16 d after estrus was detected. Number of antral follicles in the left ovary was greater (P less than .05) for L sows (540) than for S sows (427). Sows exposed to 16 h of light with large litters had a higher number of atretic follicles than all other groups (litter size x photoperiod interaction, P less than .05). Number of nonatretic follicles were similar between groups. However, when nonatretic follicles were classed by size (1 = smallest; 6 = largest), their distribution differed. In Class 1, L sows had more follicles than S sows (P less than .05). For Classes 3 and 4, photoperiod interacted with litter size to decrease the number of follicles in L 16 h sows (litter size x photoperiod interaction, P less than .05). These lower numbers of nonatretic follicles were related to a higher rate of follicular atresia in L 16 h sows. In Classes 2, 3 and 4, L 16 h sows had more atretic follicles than any other group (litter size x photoperiod interaction, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
The objectives of this study were to determine factors affecting the reproductive performance of primiparous sows early weaned (EW; n = 35) at d 14 or conventionally weaned (CW; n = 35) at d 24 of lactation. Sow BW and backfat were recorded at farrowing, weekly until weaning, and at standing heat. Feed intake was controlled throughout lactation to standardize nutritional effects on subsequent reproductive performance. Litter size was standardized across treatments within 48 h after farrowing, and litter weight was recorded until weaning. In subsets of sows, blood samples were collected from 10 h before to 10 h after weaning, and then every 6 h until ovulation. Sows were heat checked twice daily and bred at 24-h intervals during standing heat using pooled semen. Ultrasonography every 6 h determined time of ovulation. Sows were either slaughtered within 24 h after ovulation to assess ovulation rate, fertilization rate, and embryonic development in vitro, or at d 28 of gestation to determine ovulation rate and embryonic survival. Compared with CW sows, EW sows had more backfat at weaning (15.9 +/- 0.5 vs. 14.7 +/- 0.5 mm; P < 0.001). Also, CW sows tended to lose more BW and to have lower IGF-I concentrations, indicating poorer body condition. Duration of lactation did not affect ovulation rate (EW = 17.6 +/- 0.7; CW = 18.7 +/- 0.6), fertilization rate (EW = 96.0 +/- 2.2; CW = 88.2 +/- 4.7%), or embryo survival to d 28 (EW = 62.5 +/- 4.5; CW = 63.1 +/- 5.0%). There was a marginal effect of duration of lactation on weaning-to-estrus interval (EW = 120 +/- 3; CW = 112 +/- 3 h; P < 0.06) and duration of estrus (EW = 52.4 +/- 2.3; CW = 46.3 +/- 2.2 h; P < 0.08). Overall, embryonic survival, not ovulation rate, seems to be the limiting factor for potential litter size in the second parity. Although fertility in both EW and CW sows studied was compromised, endocrine and metabolic data indicate that the mechanisms affecting reproductive performance may differ between the two weaning systems. The LH, FSH, and estradiol data from the EW sows are characteristic of animals with limited follicular development and incomplete recovery of the hypothalamic-pituitary-ovarian axis; consequently, the integrity of the uterine environment may be adversely affected and limit embryonic survival. In CW sows, variability in metabolic state seemed to be the key factor limiting the fertility, again adversely affecting embryonic survival.  相似文献   

20.
Prepubertal gilts of obese (n = 24) or lean (n = 24) genetic lines were injected (s.c.) daily with 0, 2, or 4 mg of porcine somatotropin (pST) for 6 wk starting at 160 d of age to determine whether pST affects follicular function. Blood and ovaries were collected at slaughter 24 h after the last injection. Surface follicles greater than or equal to 1.0 mm in diameter were counted, and pools of follicular fluid (FFL) and granulosa cells were collected from 1.0- to 3.9-mm (small) and 4.0- to 6.9-mm (medium) follicles. Oocytes were collected from small and medium follicles and evaluated for maturational stage and viability. Porcine somatotropin increased (P less than .08) the numbers of small but not the numbers of medium follicles per gilt (P greater than .10). Oocyte maturation and viability were not affected by pST or genetic line. Porcine somatotropin increased (P less than .05) concentrations of insulin-like growth factor I (IGF-I) in serum and FFL of both obese and lean gilts; IGF-I was lower (P less than .01) in lean gilts. Treatment with pST decreased (P less than .05) IGF-II in FFL of lean but not in that of obese gilts. Dose of pST and line had no effect on concentrations of progesterone in FFL of small or medium follicles or on concentrations of estradiol in FFL of small follicles.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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