银狐繁殖期血浆主要激素变化及其对繁殖功能的调控

通过放射免疫测定技术测定母银狐发情前期和发情期外周血浆雌二醇-17β[E2]、孕酮(P4)浓度以及公狐睾酮(T)浓度,并分析这些技术的变化及其对繁殖功能的调控.结果表明,银狐初配前2～3d,E2浓度达峰值(240.85±39.98)pg/mL,在母狐接受跨时E2浓度降至(146.95±38.21)pg/mL,而在发情前期和发情期,其孕酮浓度范围是0.91～77.43ng/mL,峰值是(54.77±23.66)ng/mL,在雌二酮峰值时,孕酮浓度为(28.57±21.21)ng/mL,配种时,P4浓度(33.12±22.56)ng/mL,初配后4d(排卵结束),P4达(48.28±34.84)ng/mL.公狐配种期,T浓度范围(127.2±444.4)pg/mL,,峰值是(341.2±103.2)pg/mL.     

沼泽型水牛发情周期生殖激素变化的研究

采集9头沼泽型水牛经同期发情处理后的血样,采用放射免疫测定法(RIA)测定其血清生殖激素浓度,并分析了不同年龄水牛的生殖激素变化情况。结果表明:(1)青年水牛FSH、LH峰值分别出现在发情后53.67±15.85h、49.67±15.42h,5h左右出现一个E2峰值(24.12±11.28pg/mL);经产水牛则分别为25.67±12.44h、17.67±6.33h,48h出现E2峰值(21.73±8.72pg/mL)。(2)青年水牛FSH水平在第0、7、15d各出现一个峰值,到下次发情前一天又出现一个高峰值(11.69±0mIU/mL);LH水平第0、8、20d各出现一个峰值,第3～8d维持相对较高的水平(7.99±1.83～11.90±3.63mIU/mL);第14d后E2水平呈上升趋势,第22d达到最高峰(65.23±44.60pg/mL);P4水平在第1～4d呈上升趋势,第14、17、19d最高,此后下降。(3)经产水牛FSH水平除在第0、7、13、18、22d各出现一个峰值外,其他时间以较大的幅度(1.37±0.88～2.67±0.61mIU/mL)波动;LH水平除在第2、6、14、17、20d有峰值出现外,其他时间波动(3.92±2.92～7.85±1.21mIU/mL)也很大;P4水平在发情前4d处于较低水平,第5～11d维持相对较高的水平(0.087±0.0167～0.296±0.282ng/mL),第13～18d呈明显的上升趋势,之后迅速下降;E2水平除在发情第2、10、23d各出现一个峰值,第20～23d迅速升高外,其他时间基本恒定。     

母犬发情周期血中生殖激素变化规律的研究

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)。     

关中驴产后期和发情期血浆17β-雌二醇、孕酮和睾酮浓度的变化

本研究应用放射免疫分析法,测定了关中驴产后期(n=18)和发情期(n=6)血浆17β-雌二醇(E_2)、孕酮(P)和辜酮(T)的浓度。测定结果表明,产后第一次发情前血浆E_2浓度较低(12.22±1.92pg/ml),第一次发情期逐渐上升,排卵前第一天和第二天达到较高水平(19.48±2.16pg/ml和20.41±3.27pg/ml,±SE,P<0.05),排卵后降至基础浓度。产后第一次发情前血浆P浓度较低(2.74±0.51ng/ml),排卵后逐渐上升,第四天和第五天显著和极显著高于排卵前P水平,血浆值为6.19±0.66ng/ml和8.09±1.09ng/ml(P<0.05和P<0.01)。产后第一次发情前血浆T浓度较高,发情期下降,排卵后逐渐上升,第五天和第六天显著和极显著高于发情期T水平,分别为313.11±37.57pg/ml和356.73±46.37pg/ml(P<0.05和P<0.01)。产后第一次排卵前P/E_2和P/T比值均较低,排卵后上升,第五天分别达到861和25.83。产后第一次发情前T/E_2比值较高,发情期下降,排卵后上升,第五天达到33.34。排卵前后间隔6小时采样的分析结果表明,排卵前第30～24小时,E_2浓度急剧上升达到峰值。排卵后P浓度于第78～96小时达到较高水平。血浆E_2与P、E_2与T均呈中等负相关(r=-0.42和r=-0.41)。P与T为极显著正相关(r=0.92)。周期性发情期血浆E_2、P、T浓度的分泌范型和产后第一次发情期基本相似。     

东北梅花鹿配种后主要生殖激素变化

采集4头体况良好、健康、配种后梅花鹿的血样,用RIA分析方法对血清中的5种生殖激素(LH、FSH、E2、P4和hCG)的含量进行测定.结果表明:在配种后(第2～38 d)LH含量缓慢地降低,处于较低的水平,平均为29.97±32.70 mIU/mL;FSH的含量稳步上升,平均为1.60±0.66 mIU/mL;E2的含量除了一个较大的峰值(10.20±6.59 pg/mL)外,一直在降低,平均值是6.47±4.28 pg/mL;P4的含量平均为0.05±0.04 ng/mL;hCG的含量呈缓慢下降趋势,平均为22.71±26.48 mIU/mL.     

产单一性别后代奶牛生殖激素的特征

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.     

广西水牛唾液和血清生殖激素在发情周期的变化规律及相关性分析

[目的]对广西水牛发情周期唾液和血液中雌激素(E2)和孕酮(P4)的浓度变化规律及相关性进行了分析,为进一步探讨水牛发情规律来指导生产提供依据。[方法]采用酶联免疫分析方法(ELISA)测定发情母水牛血液和唾液中E2(雌二醇)和P4(孕酮)的浓度变化,并对血液和唾液的激素变化规律进行了相关性分析。[结果]广西水牛血液和唾液中的E2和P4呈波动性变化,结果表明,发情前期,唾液中P4浓度一直维持在6.57.1ng/mL,第13天达到11.09ng/mL以上,随后快速下降。唾液中E2浓度在发情前期第35天出现一个峰值178.528pg/mL,在1417d唾液中E2浓度显著升高,出现第二个峰值达到120.57pg/mL。唾液E2和P4浓度的变化趋势和血清E2和P4浓度的变化趋势基本一致,相关性较好。母水牛唾液和血清样品的P4浓度相关性显著(R=0.4080;P0.05),母水牛唾液和血清标本的E2浓度相关性显著(R=0.5113;P0.05)母水牛唾液E2和P4浓度相关性非常显著(R=0.7754;P0.01)。[结论]唾液和血液中的这两种激素水平起伏变化基本趋于一致,其相关性显著,可以作为监测水牛发情及预测排卵的可靠指标之一。     

维生素C和中草药添加剂对夏季种公鸡血浆生殖激素的影响

选取30只40周龄体重一致的安卡红种公鸡,随机分为3组,分别为维生素C组、中草药组和对照组,分别在两试验组饲喂的基础日粮中添加250 mg/kg的维生素C、1.5%的中草药,对照组饲喂基础日粮,研究维生素C和中草药添加剂对夏季种公鸡血浆生殖激素的影响。结果表明:(1)试验60 d时,与预饲期相比,维生素C组公鸡血浆睾酮、促黄体素、促卵泡素浓度分别增加了0.31 ng/L(P0.05)、0.45 mIU/mL(P0.05)和0.13 mIU/mL(P0.05);中草药组公鸡血浆睾酮、促黄体素、促卵泡素浓度分别增加了1.97 ng/L(P0.01)、1.62 mIU/mL(P0.01)和0.88 mIU/mL(P0.01)。(2)试验期60 d时,不同组别之间进行比较,中草药组公鸡血浆睾酮浓度比对照组提高了82.72%(P0.01),同时维生素C组比对照组提高了18.94%(P0.05);中草药组公鸡血浆促黄体素浓度比对照组提高了77.92%(P0.01),同时维生素C组比对照组提高了22.51%(P0.05);中草药组公鸡血浆促卵泡素浓度比对照组提高了73.28%(P0.01),同时维生素C组比对照组提高了12.98%(P0.05)。说明在热应激条件下,在日粮中添加适量的维生素C和中草药可不同程度地提高种公鸡血浆生殖激素水平。     

番鸭就巢期生殖激素水平的变化规律

对番鸭就巢期不同时间的血浆生殖激素水平进行测试,揭示了不同就巢时间血浆生殖激素浓度变化的规律,并对就巢与激素之间的相关性进行分析。结果表明:(1)抱窝期血浆PRL含量(0.68±0.11ng/mL)极显著高于醒抱期的含量(0.33±0.04ng/mL)(P<0.01);(2)醒抱前后血浆LH含量差异很大,醒抱后LH含量(33.17±15.49mIU/mL)极显著高于抱窝期含量(5.56±1.99mIU/mL)(P<0.01);(3)抱窝期血浆E2含量(0.9±0.65ng/mL)极显著低于醒抱期含量(1.9±1.17ng/mL)(P<0.01);(4)PRL与LH、PRL与E2、LH与E2之间的相关系数分别为-0.923、-0.666和0.641。     

非繁殖季节中国美利奴羊血清E2、P4、FSH、LH激素变化规律研究

为了在非繁殖季节判断绵羊的发情状况,试验以新疆高海拔地区中国美利奴羊为研究对象,采用酶联免疫测定(ELISA)法测定绵羊血清中雌二醇(E2)、孕酮(P4)、促卵泡素(FSH)、促黄体生成素(LH)的含量,研究激素诱导发情羊、发情症状不明显羊、不发情羊体内激素分泌规律的差异。结果表明:激素诱导发情羊的E2含量比不发情羊高,差异显著(P<0.05);但是在P4、FSH、LH水平上,激素诱导发情羊要低于不发情羊,差异不显著(P>0.05)。发情羊与发情不明显羊在4种激素含量上差异不显著(P>0.05),说明公羊试情存在一定缺陷,而通过测定E2含量判定绵羊发情状态将成为未来研究的重点。     

H5N1亚型禽流感灭活疫苗免疫鸵鸟后抗体消长规律及免疫程序的研究

为了探讨鸵鸟对H5亚型禽流感灭活疫苗的免疫原性,做好鸵鸟禽流感的防控工作,采用哈尔滨兽医研究所研制的重组H5N1亚型禽流感疫苗,不同剂量免疫鸵鸟,用HI方法检测母源抗体和免疫抗体,根据母源抗体的衰减和免疫抗体的消长规律确定首免和再免日龄.结果表明,雏鸵鸟母源抗体能维持约3周～8周;8周龄时分组首免,C1组产生的免疫反应优于C2组,抗体峰值能达到7.50 log2,维持时间为9周左右;17周龄时C1组以3.0 mL/羽进行二免,2周后抗体达到7.40log2,3周～7周抗体维持在高峰值,最高达8.80log2,以后逐渐下降,有效抗体水平能维持至接种后25周左右.二免后25周进行三免,以5 mL/羽三免后2周抗体可达到9.80log2,2周～4周抗体维持在最高峰,以后缓慢下降,期间抗体时有起伏,但有效抗体水平约可维持1年时间.三免后45周内抗体水平合格率均在70%以上.根据抗体消长规律,初步推荐了鸵鸟的免疫程序.     

Vitamins a, e and selenium blood levels in the fat cow syndrome

Blood plasma analyses for vitamins A, E and selenium were performed from calving to five weeks of lactation in 29 cows. Twelve of the 29 cows had fat cow syndrome. The healthy cows had significantly higher (P<0.01) plasma vitamin A (40 μg/dL) and vitamin E (5 μg/mL) levels than the cows with fat cow syndrome (29 μg vitamin A/dL and 3 μg vitamin E/mL). At parturition, vitamin A level in plasma was low (25 μg/dL) but increased progressively thereafter (up to 51 μg/dL) in healthy cows, whereas cows with fat cow syndrome had lower levels of vitamin A, bordering on deficiency. The possible role of vitamin E in the alleviation of fat cow syndrome by affecting oxidation-reduction reactions in the liver is discussed. Significant (P<0.01) difference was not observed in selenium blood plasma level (35 ng/mL) between the two groups of cows or in another random group of 12 cows clinically affected by fat cow syndrome.     

牦牛繁殖季节若干激素动态变化研究

为掌握母牦牛繁殖季节促卵泡素(FSH)、促黄体激素(LH)、孕酮(P4)、瘦蛋白(Leptin)、雌二醇(17β-E2)激素含量变化,在牦牛繁殖季节对其卵巢、卵泡变化进行直肠检查,对FSH、LH、P4、Leptin、17β-E2激素进行测定。结果表明,牦牛在繁殖季节非发情期其FSH、LH、P4、Leptin、17β-E2含量在0.0836～0.3767(mIU/ml)、0.1350～1.0109(ng/ml)、3.1283～7.4809(pg/ml)、0.0650～8.0119(ng/ml)、0.1604～0.5139(mIU/ml)。在繁殖季节发情期以上激素含量分别为0.1280～0.4050(mIU/ml)、0.6820～1.6744(ng/ml)、3.1586～3.8438(pg/ml)、0.5275～1.3760(ng/ml)、0.4110～0.5975(mIU/ml)。由此说明牦牛繁殖季节非发情期和发情期其激素变化个体差异很大,因此牦牛发情期的长短个体差异较大。     

Plasma concentrations of testosterone and nandrolone in racing and nonracing intact male horses

Pennsylvania (PA) State Racing Commissions regulate the endogenous androgenic steroid, testosterone (TES), in racing intact males (RIM) by quantification of TES in post-race samples. Post-race plasma samples (2209) collected between March 2008 and November 2010 were analyzed for TES, nandrolone (NAN), and other anabolic steroids (ABS). Of the 2209 plasma samples, 2098 had quantifiable TES ≥ 25 pg/mL. Plasma (mean ± SD) concentrations of TES and NAN in RIM were 329.2 ± 266.4 and 96.0 ± 67.8 pg/mL, respectively. Only 64.6% of RIM had quantifiable concentration of NAN, and there was no relationship between TES and NAN. Plasma TES concentrations were significantly (P < 0.0001) higher during the months of April, May, June, July, and August. A significantly higher (P < 0.006) plasma TES was observed in Thoroughbred (TB) (347.6 ± 288.5 pg/mL) vs. that in Standardbred (STB) (315.4 ± 247.7 pg/mL). Plasma concentrations of TES from breeding stallions (BS) were 601.6 ± 356.5 pg/mL. Statistically significant (P < 0.0001) lower plasma concentrations of the two steroids were observed in RIM horses. Based on quantile distribution of TES in the RIM and BS populations, 99.5% were at or below 1546.1 and 1778.0 pg/mL, respectively. Based on this population of RIM, the suggested upper threshold plasma concentration of endogenous TES in horses competing in PA should remain at 2000 pg/mL.     

Antioxidant status and biomarkers of oxidative stress in dogs with congestive heart failure

Alterations in antioxidant status and oxidative stress have been documented in dogs with dilated cardiomyopathy (DCM). The purpose of this study was to more broadly assess this relationship in dogs with congestive heart failure (CHF). Malondialdehyde (MDA), 8-F(2alpha)-isoprostane, protein carbonyls, reduced (GSH) and oxidized (GSSG) glutathione, vitamins A, C, and E, and oxygen radical absorbance capacity (ORAC) were measured from a single venous blood sample from dogs with CHF secondary to DCM or chronic valvular disease (CVD) and in healthy controls. Nineteen dogs with CHF (14 CVD and 5 DCM) and 12 healthy controls were enrolled in the study. Concentrations of 8-F(2alpha)-isoprostane (CHF: 44.6 pg/mL [range, 27.1-98.0 pg/mL], controls: 25.3 pg/ mL [range, 11.1-80.4 pg/mL]) but not MDA (CHF: 4.11 microM [range, 1.89-6.39 microM], controls: 3.88 microM [range, 2.14-4.72 microM]) or protein carbonyls (0.69 nmol/mg protein [range, 0.37-1.67 nmol/mg protein], controls: 0.80 nmol/mg protein [range, 0.40-1.14 nmol/mg protein]) were significantly higher in the dogs with CHF than in the controls. Vitamin E concentration (CHF: 2,215 microg/ dL [range, 916-3,499 microg/dL], controls: 2,820 microg/dL [range, 1,738-3,775 microg/dL]) and GSH:GSSG (CHF: 12.0 [range, 3.69-30.1], controls: 22.7 [range, 12.5-227]) were significantly lower, whereas ORAC (CHF: 824 micromol Trolox equivalent/L [range, 304-984], controls: 497 micromol Trolox equivalent/L [range, 258-759]) and vitamin C (CHF: 0.90 mg/dL [range, 0.55-2.02 mg/dL], controls: 0.72 mg/dL [range, 0.43-0.85 mg/dL]) concentrations were higher in dogs with CHF than in controls. Vitamin A concentrations were not different between dogs with CHF and controls. No differences in any of the parameters were detected between dogs with DCM versus those with CVD. Some antioxidant defenses are decreased in dogs with CHF, and some biomarkers of oxidative stress are increased in dogs with CHF. The effect of dietary interventions to correct this imbalance in antioxidant defenses warrants further study.     

褪黑素对体外培养绵羊垂体细胞分泌FSH和LH的影响

本文采用体外细胞培养和放射免疫测定法(RIA)的方法,研究了褪黑素(MLT)对季节性繁殖的蒙古母羊垂体细胞分泌促卵泡素(FSH)和促黄体素(LH)的作用。结果表明:当单独用递增的MLT(10、100、1000、2000pg/mL)处理原代垂体细胞时,随时间的延长FSH的分泌量极显著下降(P<0.01),但对LH的基础分泌没有影响;无论用10IU/mLhCG单独刺激,还是用不同剂量MLT与10IU/mLhCG共同刺激垂体细胞,FSH和LH的分泌都极显著高于对照组(P<0.01),但与MLT的剂量没有关系。     

促卵泡素和促黄体生成素对儋州鸡生殖激素调控规律的研究

为研究促卵泡素（FSH）和促黄体生成素（LH）对儋州鸡体内其他生殖激素的调控规律,本试验通过改变FSH和LH在儋州鸡血液中的浓度,并采用双抗体一步夹心法酶联免疫吸附试验（ELISA）对处理前后儋州鸡血液中FSH、LH、催乳素（PRL）、孕酮（P）、雌二醇（E₂）的浓度进行测定。结果发现,注射外源性FSH和LH分别能提高儋州鸡血液中FSH和LH浓度;当儋州鸡血液中FSH或LH浓度显著升高时则均能引起PRL浓度显著降低（P < 0.05）,但当FSH和LH浓度同时显著升高时,PRL浓度显著升高（P < 0.05）;当儋州鸡血液中FSH浓度显著升高时,E₂及P浓度显著提升（P < 0.05）,且在高浓度LH的协同下提升幅度更大;当儋州鸡血液中LH浓度显著升高时E₂及P浓度升高但不显著（P > 0.05）。本研究结果表明,儋州鸡血液中FSH或LH浓度的提高均能降低PRL的浓度,并能不同程度的提升E₂及P的浓度,但FSH与LH浓度同时提高则能通过协同作用刺激E₂及P浓度的大幅提升,当E₂及P浓度过高时能通过刺激PRL的释放,负反馈调节血液中FSH与LH,并恢复血液中E₂及P浓度。     

超数排卵处理沼泽型水牛血清E_2和P_4浓度变化研究

研究利用3种不同的方法超数排卵处理沼泽型水牛,比较研究不同方法处理时水牛血清雌二醇(E2)、孕酮(P4)浓度变化规律。结果表明:进口FolltropinR○-V、国产FSH和PMSG超数排卵处理沼泽型水牛,血清E2浓度峰值分别出现在氯前列烯醇(PGc)处理后的48 h([142.45±94.66)pg/mL]、72 h([87.78±29.62)pg/mL]、48 h([126.38±92.33)pg/mL];血液中P4浓度最低值分别出现在PGc处理后的48 h([0.76±0.21)pg/mL]、24 h([1.18±0.12)pg/mL]和144 h([0.82±0.06)pg/mL]。     

Seasonal Variation in Serum Concentrations of Selected Metabolic Hormones in Horses

Background: Determination of adrenocorticotropic hormone (ACTH) concentration is a commonly used test in the evaluation of endocrine causes of equine laminitis, but the concentration in healthy horses can be high at certain times of year, which alters the specificity of the ACTH test. Objective: To determine if circulating concentrations of ACTH, cortisol, glucose, insulin, and thyroxine vary month to month in healthy horses and in horses with equine metabolic syndrome (EMS). Animals: Nine healthy adult horses were studied on their farm/stable over the course of 1 year. After the diagnosis of EMS, 10 laminitic horses residing at the same farm/stable were also studied. Methods: Prospective study of healthy and laminitic horses. Plasma/serum samples were analyzed for concentrations of hormones and glucose. Results: ACTH was the only analyte to show a discrete seasonal pattern, with concentrations in healthy and EMS horses frequently outside of the reference range (9–35 pg/mL) in August through October. Insulin was elevated (>40 μIU/mL) in EMS horses during most months and median serum glucose was generally higher in EMS horses (100 mg/dL, range, 76–163 mg/ dL) than in controls (94 mg/dL, range, 56–110 mg/dL), but no seasonal patterns for insulin or glucose were found. Conclusions and Clinical Importance: An increased ACTH concentration in horses in late summer or autumn should be interpreted with caution. In contrast, insulin concentration is maintained within the reference range throughout the year in healthy horses, thus an increased insulin concentration at any time of year should raise suspicions of EMS, ECD, or both.     

Effect of synchronization of follicle-wave emergence with estradiol and progesterone and superstimulation with follicle-stimulating hormone on milk estrogen concentrations in dairy cattle

Very little is known about the effects of hormonal synchronization of follicle waves and superovulation on the estrogen content of a cow’s milk. The objective of this study was to determine the effect in dairy cows of synchronization with estradiol-17β (E2) and progesterone (P4) on milk E2 concentrations and to compare these levels with those achieved during superstimulation for 4 d with porcine follicle-stimulating hormone (FSH). The milk E2 concentrations were raised significantly above pretreatment levels (P < 0.05) for 2 d after synchronization, the mean peak being 40.2 ± 18.5 (standard error) pg/mL and the pretreatment mean 1.5 ± 0.5 pg/mL. The mean peak E2 concentration during ovarian stimulation was 4.4 ± 0.7 pg/mL. The mean E2 concentration was significantly higher (P < 0.05) after synchronization than during superstimulation for the 1st milking after synchronization but not subsequent milkings. The milk estrone concentrations were above pretreatment levels for 1 d after synchronization and were not different from those observed during superstimulation.