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1.
LRH—A3对全奶母牦牛的诱导发情效果和作用机理初探   总被引：5，自引：2，他引：3  
《中国畜牧杂志》2002,38(1):14-15
本研究初步探讨了促性腺素释放激素类似物(LRH-A3)对全奶母牦牛(在当年4～6月份产犊的泌乳母牦牛)的诱导发情排卵效果及机理.1998年7月对试验组(n=20)母牦牛注射LRH-A3(300μg/头),对照组(n=42)未作任何处理.9月15日前用普通牛公牛配种,9月15日后用公牦牛补配.1999年产犊率为试验组50.0%(10/20),对照组28.6%(20/42),试验组和对照组差异极显著(P<0.01).对5头母牦牛在注射LRH-A3前30min及注射后30,45和60min血清中促黄体素(LH)浓度测定以进一步探明全奶母牦牛诱导发情第一情期受胎率低的原因.结果发现,虽然注射LRH-A3后60min全奶母牦牛血清中LH浓度显著升高(P<0.05),但该峰值(3.34±0.67ng/ml,n=5)未达到自然发情排卵的LH峰值(17.1829±2.1174ng/ml).  相似文献   

2.
采用犊牛短期断乳方式提高牦母牛繁殖性能的试验   总被引：1，自引：0，他引：1  
对90头带犊大通母牦牛进行了犊牛短期断乳试验.试验组母牦牛在产犊后3月龄时,实行为期10d的短期断乳,断乳后母牦牛有81头发情,发情率90%,第二年产犊78头,繁殖率86.67%.对照组为带犊,但不断乳的母牦牛,试验期共发情2头,发情率2.22%,产犊2头,繁殖率2.22%.试验组母牦牛的发情率和繁殖率比对照组分别提高了87.78%和84.45%(P＜0.01)  相似文献   

3.
[目的]本研究为探讨不同方案诱导牦牛发情效果。[方法]选择放牧的母牦牛60头为试验牛。分2组,每组30头进行试验。其中试验1组带犊母牦牛12头,不带犊母牦牛18头,采用方案Ⅰ;试验2组带犊母牦牛14头,不带犊母牦牛16头,用方案Ⅱ处理。第一针注射黄体酮注射液,以治疗为目的,间隔10天肌注PG,第二天注射血促性素;结果第1组用方案Ⅰ处理后带犊、不带犊母牦牛发情率分别为42%(5/12)、56%(10/18),受胎率分别为60%、80%;第2组用方案Ⅱ处理后带犊、不带犊母牦牛发情率分别为86%(12/14)、100%(16/16),受胎率分别为65%、81%。[结果]表明,通过对牦牛进行冷季补饲,诱导发情及同期发情处理,使93%的母牦牛发情。[结论]方案Ⅱ是较为理想的同期发情处理方案。  相似文献   

4.
本研究采用放射性免疫分析法(RIA)测定了终生产公犊(n=3)、终生产母犊(n=3)的奶牛和普通奶牛(n=4)在排卵日和排卵后第10天血清中睾酮(T)、促卵泡素(FSH)、促黄体素(LH)、雌二醇(E2)的含量.结果显示,在排卵日终生产公犊奶牛血清中的FSH含量(2.42±0.35mIU/mL)均显著高于终生产母犊奶牛(0.96±0.50 mIU/mL,P＜0.05)和普通奶牛(1.30±0.14mIU/mL,P＜0.05)；终生产母犊奶牛血清中的T含量(1.20±0.12mIU/mL)显著低于终生产公犊(2.21±0.12mIU/mL,P＜0.05)和普通奶牛(1.98±0.04mIU/mL,P＜0.05),而3类奶牛之间的E2、LH含量差异不显著(P＞0.05)；在排卵后第10天,3类奶牛之间的T、FSH、LH和E2含量均无显著性差异(P＞0.05).奶牛后代性别决定与T和FSH含量有密切关系,排卵日FSH含量明显升高是终生产公犊奶牛的显著特征,排卵日T含量明显下降是终身产母犊奶牛的显著特征.  相似文献   

5.
《畜牧与兽医》2016,(2):40-44
为研究自然发情和诱导发情的母犬发情期体内促卵泡素(FSH)、促黄体生成素(LH)、雌二醇(E2)和孕酮(P4)的分泌规律,将25只母犬随机分成2组:对照组为自然发情组,试验组为诱导发情组。对6只自然发情母犬和5只诱导发情母犬采血制备血浆,放射免疫分析法(RIA)测定FSH、LH、E2、P4的含量,采血时间为出现发情表征的第1、3、5、6、7、8、9、10、11、13、17、24天。对照组母犬FSH、LH和E2最低含量均值分别为(4.35±1.98)ng/m L、(4.95±2.22)ng/m L和(1.33±1.04)pg/m L,FSH、LH和E2峰值均值分别为(134.44±20.97)ng/m L、(117.56±17.49)ng/m L和(6.22±2.16)pg/m L,P4含量均值变化范围是(0.24±03)~(12.51±1.76)ng/m L;试验组母犬FSH、LH和E2最低含量均值分别为(4.19±2.12)ng/m L、(5.64±3.84)ng/m L和(1.57±0.76)pg/m L,FSH、LH和E2峰值均值分别为(172.98±56.40)ng/m L、(159.12±35.87)ng/m L和(6.08±1.16)pg/m L,P4含量均值变化范围是(0.24±0.06)~(12.51±3.95)ng/m L。结果表明:自然发情和诱导发情的母犬体内LH、FSH、E2和P4变化比较复杂,但仍有规律可循;E2对FSH的分泌具有一定的抑制作用,P4的含量变化在LH峰后的显著变化,P4稳定性和规律性更强;外源性PG-CI和FSH激素诱导发情的母犬的方法显著性提高了整个发情周期LH和FSH水平(P0.05),而对发情周期内E2和P4分泌水平均没有显著性影响(P0.05)。  相似文献   

6.
在大通种牛场对126头产后90d以上的母牦牛进行断犊,进行促母牛发情试验。断犊后母牦牛放入水草茂盛的冬季草场放牧饲养,一个情期后,对未发情的母牦牛进行肌肉注射氯前列醇纳促发情处理。试验结果显示,试验组母牦牛发情率达90.48%,对照组发情率为58.73%,试验组母牦牛发情率比对照组高31.75个百分点,差异性极显著(P﹤0.01)。  相似文献   

7.
为了探索补饲对后代增重效果的影响,本研究选用妊娠后期母牦牛14头,随机分为对照组和试验组(每组7头),对试验组母牦牛肌注Se和VE,考察Se和VE补饲对所产犊牦牛体重的影响。结果表明:试验组母牦牛分娩当日和产后第4周血清Se浓度和VE浓度均显著高于对照组(P0.05或P0.01)。试验组犊牦牛初生当日血清Se浓度为27.0±1.8ng/mL,显著高于对照组(P0.01),4周龄时虽然下降为17.5±3.4ng/mL,但仍显著高于对照组的8.9±1.7ng/mL(P0.01)。试验组犊牦牛血清VE浓度在出生当日显著高于对照组(P0.05),但在4周龄与对照组差异不显著(P 0.05)。实验期间试验组犊牦牛增重39.8kg,显著高于对照组的32.1kg (P0.05),平均日增重试验组的300g/日,显著高于对照组的241 g/日(P0.05)。试验组犊牦牛下痢现象减少。结果显示,通过肌注对妊娠末期牦牛补充Se与VE,能够促进犊牦牛生长发育。  相似文献   

8.
为探求LRH—A诱导双峰母驼排卵、受胎效果,应用放射免疫法测定了母驼冷冻精液输精前后外周血清孕酮含量的变化。5峰(头)输精并肌注LRH—A母驼,输精前孕酮值平均为0.15±0.02ng/ml,输精后第3天增加到0.52±0.13ng/ml,第7 天可达1.62 ±0.89ng/ml。怀孕驼第12天孕酮仍维持高水平,为1.72±0.31ng/ml;而未怀孕驼孕酮水平7天开始下降,第12天降为0.32 ±0.06ng/ml(p<0.05)。5峰母驼受胎3峰,产羔3峰。3峰仅输冷冻精液的母驼,输精前后孕酮水平显著低于肌注LRH—A母驼排卵后的孕酮水平(p<0.05),均未受胎,持续发情。  相似文献   

9.
《畜牧与兽医》2017,(3):5-8
用ELISA对10头发情期内和5头乏情期内的初情期母牦牛进行24 h内血清促性腺激素释放激素(GnRH)、黄体生成素(LH)、卵泡刺激素(FSH)分泌情况检测并比较体重和解剖观察子宫的发育情况。结果显示:发情期母牦牛体重、子宫重、子宫颈-子宫体长、外阴-子宫体长均高于乏情期母牦牛(P0.05),并且在发情期内发情母牦牛高于未发情母牦牛(P0.05);发情期24 h内初情期母牦牛在GnRH、LH、FSH分泌量明显高于乏情期母牦牛(P0.001);在发情期内发情母牦牛GnRH、LH、FSH的分泌量明显高于未发情母牦牛(P0.001)。对比发情期内未发情母牦牛与乏情期母牦牛,二者分泌量均较低,但是发情期内未发情母牦牛激素含量较高并且有较为明显的峰值出现。  相似文献   

10.
[目的]为了对比带犊牦牛同期发情与自然发情繁殖效果的差异,作者根据实施的科研项目进行了两组试验,以便为甘南牦牛产业高质量发展提供参考资料。[方法]于繁殖季节在试验组母牦牛阴道内放置“孕激素阴道栓”并肌肉注射“氯前列稀醇”(CIDR+PG)诱发牦牛集中发情。[结果]结果表明,甘南牦牛在当年生产后,通过犊牛统一断奶,改变营养供给,产后3个月试验组和对照组母牦牛自然发情率分别为8%和19.2%。试验组母牦牛应用“放置孕激素阴道栓+肌肉注射氯前列稀醇”方法诱导发情后,总发情率达89.1%。试验组带犊母牦牛激素处理后受胎率为89.1%,对照组母牦牛自然发情率较低,自然交配后受胎率为100%。试验组和对照组母牦牛繁殖率、犊牛成活率分别为86.9%和19.2%、97.6%和100%,试验组犊牛的平均初生重、断奶重、6月龄重分别比对照组高1.51 kg、2.37 kg、3.28 kg,经差异显著性检验,试验组犊牛相关年龄段体重与对照组犊牛对应指标相比,初生体重差异显著(P<0.05),断奶重和6月龄体重差异极显著(P<0.01)。[结论]使用外源性激素诱发带犊母牦牛当年集中发情,母牦牛当年...  相似文献   

11.
Two experiments were conducted with the opioid antagonist naloxone to determine the effect of opioid receptor blockade on hormone secretion in postpartum beef cows. In Exp. 1, nine anestrous postpartum beef cows were used to measure the effect of naloxone on serum luteinizing hormone (LH), cortisol and prolactin concentrations. Cows received either saline (n = 4) or 200 mg naloxone in saline (n = 5) iv. Blood samples were collected at 15-min intervals for 2 h before and after naloxone administration. Serum LH concentrations increased (P less than .01) in naloxone-treated cows from 1.8 +/- .04 ng/ml before treatment to 3.9 +/- .7 ng/ml and 4.2 +/- .5 ng/ml at 15 and 30 min, respectively, after naloxone administration. In contrast, LH remained unchanged in saline-treated cows (1.6 +/- .3 ng/ml). Serum cortisol and prolactin concentrations were not different between groups. In Exp. 2, 12 anestrous postpartum beef cows were used to examine the influence of days postpartum on the serum LH response to naloxone. Four cows each at 14 +/- 1.2, 28 +/- .3 and 42 +/- 1.5 d postpartum received 200 mg of naloxone in saline iv. Blood samples were taken as in the previous experiment. A second dose of naloxone was administered 2 h after the first, and blood samples were collected for a further 2 h. Serum LH concentrations increased (P less than .01) only in cows at 42 d postpartum.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

12.
Cortisol and luteinizing hormone (LH) were measured in serum after the administration of adrenocorticotropic hormone (ACTH) to suckled (S) and nonsuckled (NS) beef cows. Blood was sampled on 2 consecutive days every 2 weeks for four bleeding periods starting 14 days after calving. Cows were injected with 200 IU ACTH or saline in a 2-day switchback design. Serum was collected before ACTH or saline injection and at 30-min intervals thereafter for 8 hours. Average cortisol concentrations in serum were similar in S and NS cows (6.4 +/- .6 and 6.1 +/- .8 ng/ml, respectively) after saline. Average cortisol concentrations in serum collected during an 8-hr period after ACTH on days 14, 28, 42 and 56 postpartum were 24.7 +/- 2.4, 31.8 +/- 3.5, 36.4 +/- 4.2 and 40.7 +/- .5 ng/ml, respectively, for S cows, and 31.1 +/- 2.9, 44.7 +/- 5.2, 45.0 +/- 5.7 and 46.0 +/- 5.4 ng/ml, respectively, for NS cows. Cortisol response to ACTH, measured as area under the response curve, was greater (P less than .05) in NS than in S cows. Amount of cortisol released by 200 IU ACTH was maximal by days 28 to 29 postpartum in NS cows, but the response increased gradually between days 14 to 15 and days 56 to 57 in S cows. overall, LH in serum averaged .55 +/- .08 ng/ml for S cows and .92 +/- .06 ng/ml for NS cows after saline, and .49 +/- .07 ng/ml for S cows and .94 +/- .06 ng/ml for NS cows after ACth. Although mean and peak serum LH concentrations did not differ between cows given ACTH and those given saline, the number of LH peaks and the number of cows having LH after saline. Mean serum LH concentrations were lower (P less than. 05) in S than in NS cows at 28 days postpartum. The number of LH peaks was lower (P less than .05) and the magnitude of the largest LH peak tended to be lower (P less than .06) in S cows at all sampling periods.  相似文献   

13.
Ten gilts on day 6·11 of the estrous cycle (onset of estrus = day 0) were given 115 mg of naloxone (NAL), an opioid antagonist, in saline i.v. (n = 5) or saline Lv. (n = 5). Jugular blood was collected at 15 min intervals for 2 hr before and 4 hr after treatment. Serum LH concentrations were 0.4 ± 0.1 ng/ml before NAL treatment, increased (P<.01) to 4.3 ± 0.7 ng/ml at 15 min following NAL treatment and returned to control concentrations by 75 minutes. Serum PRL concentrations were 5.0 ± 0.1 ng/ml before NAL treatment, increased (P<.05) to 14.8 ± 2.9 ng/ml at 30 min following NAL treatment and returned to control concentrations by 120 minutes. Serum LH and PRL concentrations were 0.5 ± 0.1 ng/ml and 5.2 ± 0.4 ng/ml, respectively, at 15 min following saline treatment and remained unchanged throughout the blood sampling period. Four of the 5 NAL treated gilts responded with an increase in both serum LH and PRL concentrations. The mean of serum progesterone concentrations, quantitated in samples taken every 2 hr, were similar for controls (22.7 ± 1.8 ng/ml) and NAL (26.5 ± 1.4 ng/ml) treated gilts. The gilt which failed to respond to NAL had nondetectable concentrations of serum progesterone and was excluded from analysis. These data indicate that the opioids modulate LH and PRL secretion during the luteal phase of the estrous cycle.  相似文献   

14.
This experiment was conducted to investigate the effect of naloxone (NAL), an opioid receptor antagonist, on pituitary LH secretion in anovulatory Holstein cows during the early postpartum period when cows were expected to be in negative net energy balance. Twenty-three cows (11 primiparous) received either saline (n = 12) or 1 mg/kg BW NAL i.v. (n = 11) on Day 14 or 15 postpartum. Jugular blood samples were collected at 15-min intervals for 2 hr before and 2.5 hr after NAL or saline. All cows received 3 ug gonadotropin releasing hormone (GnRH) at 2.5 hr post-NAL or -saline and blood collection was continued for 1 hr. Mean serum progesterone concentration was 0.33 ± 0.2 ng/ml. Mean net energy balance for all cows was -5.5 ± 0.6 Mcal/day. Naloxone caused a transient increase (P < 0.05) in serum LH concentrations in both primi- and multiparous cows within 45 min after administration. In contrast, serum LH concentrations remained unchanged in saline-treated cows. GnRH increased (P < 0.05) LH and there was no effect of treatment. These results suggest that modulation of LH secretion, at least in part, may be mediated via endogenous opioids in dairy cows before first postpartum ovulation.  相似文献   

15.
Morphine (M), an opioid agonist, was administered to postpartum (PP) Angus cows to investigate opioid modulation of gonadotropin secretion. In Exp. 1, eight PP cows (36.9 +/- 2.3 d) received either M (1 mg/kg; n = 4) or saline solution (S) (n = 4) via i.v. injection 36 h after calf removal. Morphine decreased (P less than .01) the number of serum LH pulses (3.0 +/- 1.1 pre- vs .3 +/- .3 post-pulses/h) and, compared with pretreatment values (3.3 mg/ml), decreased (P less than .05) mean LH at 105 min (2.1 ng/ml) through 270 min 1.9 ng/ml +/- .4). Serum prolactin (PRL) increased (P less than .01) following M from 16.4 ng/ml to a peak of 59.3 ng/ml (+/- 3.9). Serum FSH concentrations were unaffected. In Exp. 2, M (.31 mg/kg i.v. injection followed by .15 mg/(kg.h) infusion; n = 6) or S (n = 6) treatments were given for 7 h beginning 36 h after calf removal. Serum LH was similar between groups during the pretreatment and the first 6 h of infusion, but M decreased (P less than .001) the number of serum LH pulses (.44 +/- .09 vs .06 +/- .04 pulses/h). Morphine increased (P less than .05) serum PRL. It is concluded that M differentially modulated gonadotropin secretion in the cow such that PRL increased, LH decreased and FSH was unchanged.  相似文献   

16.
Twelve anestrous, postpartum beef cows were used to determine the effect of calf removal on the effect of naloxone on serum luteinizing hormone (LH) concentrations. On d 1, six cows were injected iv with saline and six with 200 mg naloxone dissolved in saline. Blood samples were taken at 15-min intervals for 2 h before and 2 h after naloxone or saline administration. At the beginning of blood sampling, calves were removed from three cows in each treatment. At 48 h after calf removal (d 3), all cows were injected iv with 200 mg naloxone and blood samples were collected as on d 1. On d 1, naloxone treatment increased (P less than .01) serum LH concentrations from 1.2 +/- .3 ng/ml at time 0 to 4.3 +/- .6 ng/ml and 4.7 +/- .8 ng/ml at 15 and 30 min, respectively. Injection of saline had no effect on serum LH concentrations. Forty-eight-hour calf removal increased (P less than .01) serum LH concentrations in five of six cows (1.7 +/- .8 vs 4.4 +/- 1.2 ng/ml). Naloxone treatment failed to increase serum LH concentrations in these cows. Injection of naloxone increased (P less than .01) serum LH concentrations in the one cow that did not exhibit an LH increase after calf removal and in six cows whose calves were not removed (1.4 +/- .2 vs 4.4 +/- .5 ng/ml). The present study provides additional evidence that endogenous opioids regulate LH in the postpartum beef cow. We hypothesize that suckling stimulates an opioid inhibition of LH secretion and removal of the suckling stimulus removes the opioid inhibitory tone.  相似文献   

17.
Release of oxytocin at suckling or milking may delay onset of estrous cycles in postpartum cows. Twenty lactating Holsteins of mixed parity were given 100 mU oxytocin iv (n = 10) or 2 ml saline (control; n = 10) via jugular catheters at 0530, 0930, 1730 and 2130 daily from calving (d o) until 28 d postpartum. All cows were milked twice daily at 0130 and 1330. Blood was collected thrice weekly (Monday, Wednesday, Friday at 0530) for 12 wk and analyzed by radioimmunoassay for progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) in serum. On d 12, blood was collected every 15 min for 6 h via jugular catheters and concentrations of luteinizing hormone (LH), cortisol and PGFM were determined. Rate of involution of the reproductive tract was estimated twice weekly by palpation per rectum. Overall mean, baseline concentrations, number of pulses/6 h, and pulse duration of LH on d 12 were similar among treatment groups. However, oxytocin seemed to reduce (P less than .10) pulse amplitude of LH in multiparous cows (.4 +/- .2 vs .8 +/- .1 ng/ml), but not in primiparous cows. Concentrations of cortisol and PGFM in serum on d 12 were unaffected by treatment. The average intervals from calving to first ovulation, based on changes of progesterone in serum and the intervals to first estrus, were similar between treatment groups. Rates of involution of the cervix and uterus also were similar between treatments. Milk yield, percent protein in milk and somatic cell counts did not differ between treatment groups. However, percent fat in milk tended to be higher (P less than .10) in cows given oxytocin than in controls (3.99 +/- .22 vs 3.68 +/- .21). These data indicate that multiple daily injections of oxytocin did not affect: 1) length of anestrus and anovulation in postpartum dairy cows, 2) LH release and 3) rates of cervical and uterine involution.  相似文献   

18.
An attempt was made to determine plasma concentrations of, 13, 14‐dihydro‐15‐keto‐prostaglandin F2α (PGFM), cortisol and progesterone during periparturient period in yak. Plasma PGFM level showed an increasing trend beginning day 5 prior to parturition (0.48 ± 0.14 ng/ml) and increased steeply thereafter to reach a peak level (17.16 ± 1.31 ng/ml) on the day of parturition. The levels, then, declined sharply on day 1 postpartum to reach 1.20 ± 0.40 ng/ml and thereafter declined gradually over the days to reach 0.28 ± 0.09 ng/ml on day 20 postpartum and this level was maintained with fluctuation within narrow limits thereafter till conclusion of the blood sampling on day 90 post‐calving. The plasma progesterone concentration on days 7 and 6 before parturition was high (2.10 ± 0.10 and 2.12 ± 0.10 ng/ml, respectively). The level then decreased gradually and abrupt fall was observed 1–2 days before parturition and became basal on day of parturition (0.24 ± 0.04 ng/ml). This basal level was maintained till the end of the blood sampling on day 90 postpartum. Plasma cortisol level showed an increasing trend beginning day 2 prior to parturition (2.36 ± 0.65 ng/ml) and increased steeply thereafter to reach a peak level (26.65 ± 5.28 ng/ml) on the day of parturition. The levels, then, declined gradually over the days and touched 2.36 ± 0.25 ng/ml on day 3 postpartum and this level was maintained with fluctuation within narrow limits thereafter till day 7 post‐calving.  相似文献   

19.
Carprofen, a non-steroidal anti-inflammatory drug (NSAID), was injected intravenously in six cows after calving, either as a single or a daily dose of 0.7 mg/kg for five days. Carprofen was well tolerated by the cows at this dose rate, the milk production and biochemical variables remaining within the normal ranges. The plasma elimination half-life of carprofen ranged from 44.5 to 64.6 h after repeated daily injections. These values are longer than those reported for other NSAIDs used in veterinary medicine, e.g. flunixin and phenylbutazone. The volume of distribution and the clearance values calculated after a single intravenous injection amounted to 0.09 l/kg and 9.0 ml/min. The concentration of carprofen in milk collected twice daily (morning and evening) was, in general, below the sensitivity limit of the analytical method (25 ng/ml) up to five days after the last carprofen injection; the concentration of carprofen reached about 30 ng/ml in only a few milk samples collected after the fourth or fifth injection. This indicates that carprofen is poorly excreted in the milk.  相似文献   

20.
The effect of suckling on depletion of hypothalamic LHRH from the median eminence (ME) following ovariectomy (OVX) was determined in cattle. Multiparous, postpartum Holstein cows were assigned randomly to three groups: intact, nonsuckled (INT, n = 4); ovariectomized (3 to 5 d after parturition), nonsuckled (OVX, n = 4); and ovariectomized (3 to 5 d after parturition) and suckled by three calves (OVX-S, n = 5). Blood samples were collected at three periods (1 to 7 d before parturition and 3 to 5 d and 31 to 37 d after parturition) to determine plasma LH concentration. At 31 to 37 d after parturition, all cows were slaughtered and each ME was collected and mid-sagitally sectioned. The left half of each ME was used to determine content and concentration of LHRH. Concentrations of LH and LHRH were determined by RIA. Plasma LH concentration was similar among the three groups at 1 to 7 d before parturition and 3 to 5 d after parturition; however, at 31 to 37 d after parturition, OVX cows had a greater (P less than .05) concentration of LH (2.25 +/- .64 ng/ml) than either INT (.47 +/- .10 ng/ml) or OVX-S (.92 +/- .14 ng/ml) cows. Content of LHRH in the ME of INT (80.12 +/- 15.0 ng) and OVX-S 109.8 +/- 16.4 ng) cows was similar but was greater (P less than .05) than that in OVX cows (48.95 +/- 5.9 ng).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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