非繁殖季节补饲精料诱导哈萨克羊发情及相关生殖激素变化规律的探究

为了研究补饲精料诱导非繁殖季节哈萨克母羊发情,解析绵羊非繁殖期发情的生殖激素变化规律,为利用营养因素调控非繁殖季节绵羊发情提供激素方面的理论依据,研究选用成年哈萨克母羊36只,随机分成2组,试验组在2—6月份补饲精料,在非繁殖季节(4—6月份)对发情绵羊及不发情母羊(对照)颈静脉采血,采用酶联免疫法(ELISA)测定外周血液4种重要生殖激素雌二醇(E2)、孕酮(P4)、促卵泡激素(FSH)和促黄体素(LH)的浓度。结果表明:血液中E2和P4呈现波动式变化,FSH和LH呈现规律性脉冲式变化。说明E2和FSH与绵羊的非繁殖季节发情有关,高浓度的P4和LH对开启或维持绵羊的发情有重要作用。     

绒山羊泌乳期诱导发情效果及相关生殖激素变化

旨在研究燕山绒山羊母羊泌乳期诱导发情的效果及对相关生殖激素变化的影响。选择经产、体质量约为45 kg的泌乳期母羊45只,随机分为A、B和C组,分别于产后25,35,45 d采用孕酮阴道硅胶栓(CIDR)+促卵泡素(FSH)的方法诱导发情,统计96 h内发情率,在埋栓的0,4,9,13 d及试验羊发情时采血检测FSH、促黄体素(LH)、催乳素(PRL)、雌激素(E_2)和孕酮(P_4)浓度。结果显示,A、B和C组的发情率分别为60%,53.33%和80%,发情多集中在24～72 h;埋栓前,即试验0 d时A、B和C组FSH、LH、PRL、E_2和P_4无差异。FSH和LH在撤栓时达到最低,撤栓后升高;14～15 d,所有发情羊FSH和LH均高于未发情羊,但只有A、B组FSH差异显著(P0.05)。14～15 d,PRL浓度最低(P0.05);试验期间,除9 d外,C组发情羊PRL显著低于未发情羊(P0.05),其余各组内发情羊与未发情羊PRL无差异。14～15 d,3组发情羊血清中E_2迅速升高而P_4降低,E_2浓度高于埋栓期(P0.05),试验期间,各组内发情羊与未发情羊E_2和P_4无差异;0～15 d,各组发情羊之间及未发情羊之间PRL、P_4无差异,各组发情羊间FSH及未发情羊间E_2均无差异;4 d,A组未发情羊FSH低于B组(P0.05),LH高于C组(P0.05);13 d,B组发情羊LH低于C组(P0.05),14～15 d,E_2高于C组(P0.05)。结果表明,母羊产后45 d诱导发情效果较好;外源P_4可大幅度降低PRL,发情时FSH、LH和E_2的分泌同步上升。     

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)。     

海南黑山羊繁殖周期生殖激素的分泌规律研究

为了通过同期发情、超数排卵、人工授精等扩繁技术增加海南黑山羊种群数量,试验以发情、妊娠、哺乳、空怀四个时期的黑山羊母羊作为试验动物,采用酶联免疫吸附试验(ELISA)法对繁殖周期母羊血清中促卵泡素(FSH)、促黄体素(LH)、雌二醇(E2)、催乳素(PRL)、孕酮(P4)的含量进行测定,分析黑山羊母羊在整个繁殖周期中生殖激素的分泌规律。结果表明:FSH与LH分泌规律基本一致,整个繁殖周期中呈现先下降(发情期到妊娠期)后上升(哺乳期到空怀期)的趋势;进入妊娠期后E2分泌量减少,哺乳期过后分泌量逐渐恢复;各个时期PRL分泌变化不显著(P0.05);妊娠期P4分泌水平极显著高于非妊娠时期(P0.01)。说明海南黑山羊在繁殖周期中生殖激素的分泌有一定规律,可以作为扩繁新技术应用的理论依据。     

湖羊和美利奴羊发情期外周血浆中促性腺激素脉冲分泌的差异

<正> 众所周知,绵羊垂体促性腺激素是促进卵泡生长发育及排卵的重要生殖激素。绵羊多胎的内分泌机理研究,在很大程度上是从垂体水平进行的。Cahill等(1981)测定了多胎的D'man羊和单胎的Timahd-ite羊,二者在情期中FSH浓度差异显著,且在排卵后出现特有的FSH第2高峰;Baird等(1981)报道,已查清卵泡期绵羊的卵泡成熟和排卵依赖于基础LH水平的上升和LH脉冲频率的增加。 本实验以我国特有的多胎品种湖羊为试验对象,并以单胎的美利奴羊作为对照,试图通过研究其情期促性腺激素(GTH)的变化规律,来揭示湖羊多胎     

沼泽型水牛发情期血清生殖激素的变化规律研究

研究应用RIA法对沼泽型水牛发情期的血清生殖激素浓度进行测定,并分析了生殖激素的变化规律。结果表明:①同期发情的水牛在处理后至发情当天均有2个E2峰出现,第1个在发情前,第2个在发情后并与LH峰同时或之前2 h;②PMSG(肌注)+PG(肌注)处理的水牛出现发情前E2峰、发情后FSH峰和LH峰的时间为处理后24、60 h和63 h,而PMSG(肌注)+PG(子宫灌注)+LH(肌注)处理的水牛出现发情前E2峰、发情后FSH峰和LH峰的时间为处理后48、80 h和82 h;③各组水牛P4水平在发情后48 h内均低于0.8 ng/mL;④与自然发情水牛对比,同期发情处理可显著影响其发情期的FSH和LH内源性分泌水平(P<0.05);而对E2和P4均没有产生显著性的变化(P>0.05)。     

山羊超排过程中主要生殖激素变化规律的研究

将试验羊按年龄和体重配对分成2组(试验组和对照组)。试验组羊超排后在发情配种时注射促黄体素(LH)80U,发情配种后3d,开始以3d6次法注射孕酮(P4)6mL。对照组不注射LH和P4。在同期发情、超数排卵和配种后的不同生理阶段分别进行颈静脉采血,分离血清,然后用放射免疫法(RIA)测定血清中促黄体素、促卵泡素(FSH)、雌二醇(E2)、孕酮的含量。在发情配种后6d,采用手术法冲胚。采胚结果表明试验组获胚数、可用胚数、卵泡数、黄体数等各项指标和对照组相比均有明显升高的趋势,但统计学上差异不显著。对激素分析结果表明注射外源LH和P后相应的血液中激素水平升高,说明超排过程中注射LH和P对提高超排效果有一定作用。     

不同能量水平饲粮对云上黑山羊泌乳期繁殖激素的影响

试验研究了饲粮能量对羊繁殖激素的影响。选择60只云上黑山羊哺乳母羊,分为3组,分别饲喂3个不同能量水平饲粮。每个组随机选择5只母羊,在母羊产羔后第1、7、14、21、28、42 d采血。同时在这15只母羊发情时连续间隔12 h采血3次,测定血清促卵泡素(FSH)、促黄体生成素(LH)、雌二醇(E2)、孕酮(P)和催乳素(PRL)浓度。结果表明,第21 d中水平组FSH和LH浓度最高(P0.01);第1 d高水平组E2浓度高于中水平组(P0.05);第21 d,中水平组E2浓度高于高水平组(P0.01);发情12 h内高水平组E2浓度最高(P0.05);第42 d中水平组P浓度高于低水平组(P0.05);第28 d中水平组PRL浓度最高(P0.05);发情36 h低水平组PRL浓度最高(P0.01)。研究发现,饲粮能量水平对云上黑山羊泌乳期及泌乳期发情阶段的生殖激素没有显著影响,仅得到了云上黑山羊母羊繁殖激素的基础数据。     

甘加藏羊发情周期腺垂体和血浆中GTH含量动态变化

为了探讨甘加藏羊发情周期腺垂体和血浆中FSH和LH含量动态变化规律及排卵的关系。选取2.5~5岁,健康未孕雌性甘加藏羊30只,采集发情周期各阶段和乏情期腺垂体和血浆,采用酶联免疫吸附试验(ELISA)测定发情前期、发情期、发情后期、间情期及乏情期腺垂体和血浆中FSH和LH的含量。结果表明,甘加藏羊发情周期内腺垂体FSH浓度在发情期(6.873IU/L)和发情后期(6.863IU/L)较低,与间情期最大(8.228IU/L)差异显著(P<0.05),发情前期又降低(8.096IU/L);腺垂体LH浓度发情期(9.39IU/L)和发情后期(9.585IU/L)较低,间情期最大(10.629IU/L),发情前期(9.7325IU/L)降低,各时期差异不显著(P>0.05);发情周期内血浆中FSH浓度在发情前期(2.599IU/L)达到峰值,其他时期均较低,发情前期与其他时期差异显著(P<0.05);血浆LH浓度在发情期(3.866IU/L)达到峰值,发情后期(3.179IU/L)和间情期(3.292IU/L)降低,各时期差异不显著(P>0.05);并且FSH和LH在发情周期内均出现4个波峰:乏情期腺垂体和血浆中FSH和LH的浓度均低于发情周期内FSH和LH各自的基础值。FSH和LH含量在垂体和血浆的这些差异性应该是两者协同调控藏羊发情和排卵的主要原因。     

陕北白绒山羊10月龄母羊发情周期血清激素分泌规律的研究

本实验旨在分析陕北白绒山羊10月龄母羊发情周期内卵泡刺激素(FSH)、黄体生成素(LH)、雌二醇(E_2)和孕酮(P_4)的含量变化规律,为研究幼龄陕北白绒山羊母羊的繁殖性能和生殖激素的调控提供理论依据。在一个发情周期内,连续20 d每天对8只10月龄陕北白绒山羊母羊进行颈静脉采血(母羊出现发情表现记为发情第0天);在发情期当天和发情间期第5天,从08:00开始,每间隔15 min连续采血3 h,分离血清,用酶联免疫测定法(ELISA)测定发情期、间情期和发情周期血清中FSH、LH、E_2和P_4的含量。结果表明:在发情期和间情期连续3 h内,FSH、LH、E_2和P_4均呈波动式分泌,FSH发情期比间情期波动频率快。LH发情期较间情期的波动频率低;在发情期血清内E_2含量较间情期高(P0.05);间情期血清内P4含量显著高于发情期(P0.05);在测定的20 d内,FSH、LH、E2血清中浓度值差异不显著(P0.05),而P4浓度在发情当日和发情次日低于发情间期(P0.05)。     

GnIH与INH表位多肽疫苗主动免疫对甘肃高山细毛羊生殖激素的影响

本试验通过合成促性腺激素类的抑制激素——抑制素(inhibit hormone,INH)与促性腺激素抑制激素(gonadotropin inhibiting hormone,GnIH)的INH表位多肽疫苗和GnIH表位多肽疫苗,主动免疫甘肃高山细毛羊并对促卵泡素(follicle stimulating hormone,FSH)和促黄体素(luteinizing hormone,LH)激素水平进行比较分析。试验选用15只处在非发情季节的3.5岁的甘肃高山细毛羊,注射INH表位多肽疫苗与GnIH表位多肽疫苗分别为表位多肽疫苗A组和表位多肽疫苗B组,对照组注射等量生理盐水。采血后进行免疫,每隔7 d免疫和采血,同时在发情后每隔15 min采集一次血液,分离血清,用ELISA试剂盒检测抗体水平及FSH和LH激素变化。结果表明,表位多肽疫苗A组和表位多肽疫苗B组在初次免疫后都产生了相应的抗体,且表位多肽疫苗B组较表位多肽疫苗A组产生的抗体浓度高,75 、90、105 min时,表位多肽疫苗B组相对表位多肽疫苗A组显著促进了FSH的分泌水平(P<0.05)。在45~105 min时,表位多肽疫苗B组相对表位多肽疫苗A组显著促进了LH的分泌水平(P<0.05),且在90到105 min时表位多肽疫苗A组和表位多肽疫苗B组血清中FSH和LH的水平均显著高于对照组(P<0.05)。本试验结果表明,INH表位多肽疫苗和GnIH表位多肽疫苗主动免疫促进了甘肃高山细毛羊的FSH、LH的分泌,GnIH表位多肽疫苗在甘肃高山细毛羊上具有更好的免疫作用,本研究为该表位多肽疫苗在绵羊上的运用奠定了基础。     

Effects of Active Immunization with GnIH and INH Epitope Peptide Vaccine on Reproductive Hormones of Gansu Alpine Fine-wool Sheep

This study aimed to detect the reproductive hormones levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in Gansu Alpine Fine-wool sheep by active immunization of two synthesized epitope peptide vaccines A and B which were combined inhibit hormone (INH) and gonadotropin inhibit hormone (GnIH).15 Gansu Alpine Fine-wool sheep were selected which were 3.5 year old and lived in anoestrus season, 3 groups each had 5 sheep, GnIH epitope peptide vaccine and INH epitope peptide vaccine were named epitope peptide vaccine A and B groups, while blank group was injected with saline.The blood was collected before immunization and immuned, and bloods were collected once every 7 days, meanwhile collected blood every 15 min after estrus.The serum was used to detect antibody, FSH and LH levels by ELISA Kits.The results showed that the epitope peptide vaccine A and B groups produced the corresponding antibodies after the initial immunization, and epitope peptide vaccine B group produced more antibodies than epitope peptide vaccine A group.Epitope peptide vaccine B group promoted the FSH secretion levels was significantly higher than epitope peptide vaccine A group in 75, 90 and 105 min (P<0.05);In 45 to 105 minutes, the LH secretion levels of epitope peptide vaccine B group was significantly higher than epitope peptide vaccine A group (P<0.05), while the LH and FSH levels in epitope peptide vaccine A and B groups were significantly higher than control group (P<0.05).This study indicated that the epitope peptide vaccine A and B groups could promote the FSH and LH secretion levels through active immunity in Gansu Alpine Fine-wool sheep and had a good immune function.This study laid a foundation for the application of epitope peptide vaccine on sheep.     

Study on Regulation of Reproductive Hormones in Danzhou Chicken by FSH and LH

To investigate the regulation of reproductive hormones in Danzhou chicken by follicle-stimulating hormone (FSH) and luteotropic hormone (LH),the concentration of FSH and LH in Danzhou chicken blood were changed by different treatments and the concentration of FSH,LH, prolactin (PRL), progesterone (P), and estradiol (E₂) in the blood were determined using the enzyme-linked immunosorbent assay (ELISA).The results showed that exogenous FSH and LH could improve the concentrations of FSH and LH,respectively. When one of FSH and LH increased alone,the concentration of PRL was significantly decreased (P < 0.05),while it was significantly increased when FSH and LH were both increased (P < 0.05).The high level of the FSH could result the significant increase of E₂ and P (P < 0.05),and it would expand the increasing effect in cooperation with the high concentration of LH. While the high level of the LH could elevate the concentration of E₂ and P,but effect was not significant (P > 0.05).In conclusion,the study suggested that the increase level of FSH or LH could reduce the concentration of PRL in Danzhou chicken,meanwhile,it could increase the concentration of E₂ and P in varying degrees. However,both of the FSH and LH increase in the blood could result the significant increase of E₂ and P as the synergy. When the concentration of E₂ and P were too high,it could stimulate the release of PRL which could adjust the concentration of FSH and LH,and rebalance the concentrations of E₂ and P in the blood.     

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。     

抑制素α主动和被动免疫对哈萨克羊生殖激素含量的影响

为了研究抑制素α（INHα）主动和被动免疫对哈萨克羊生殖激素含量的影响，本试验在对抑制素α重组质粒表达菌株进行诱导表达的基础上，将经纯化、鉴定的抑制素α重组蛋白免疫接种新疆双峰骆驼，制备驼抗抑制素α多克隆抗体，并对其进行纯化，检测抗体效价，验证抗体的特异性。之后选择3~5岁、发情时间相近并处于间情期的45只成年哈萨克羊随机分为3组，分别作为抑制素α多克隆抗体免疫组（A组）、抑制素α重组蛋白免疫组（B组）及对照组（C组），每隔10 d连续进行3次加强免疫，应用ELISA法检测在绵羊繁殖活动中具有重要功能的5种生殖激素：促卵泡素（FSH）、促黄体素（LH）、孕酮素（P₄）、雌激素（E₂）、抑制素（INH），并检测血液生化指标。结果显示，IPTG的最佳诱导浓度是0.6 mmol/L，在4 h时诱导出产量较高的抑制素α包涵体蛋白，纯化后的抑制素α重组蛋白纯度较高，并具有较好的免疫原性，经进一步验证发现，制备的抑制素α抗体效价为1：512 000，该抗体可与抑制素α重组蛋白特异性结合。说明成功制备了具有免疫原性的抑制素α重组蛋白和高效价的驼抗抑制素α多克隆抗体。免疫后A组LH、P₄含量和B组FSH、LH、P₄、E₂、INH含量与C组相比差异不显著（P>0.05），而A组FSH含量和E₂含量显著高于C组（P<0.05），INH含量显著低于C组（P<0.05）。通过血液生化指标检测发现，抑制素α蛋白和抑制素α抗血清两种免疫制剂免疫后，试验动物均没有出现不良症状。说明两种抑制素α抗原均可对哈萨克羊血液生殖激素的分泌产生良好效果，相比之下抑制素α抗血清免疫效果更佳。     

BMPR-IB基因对绵羊外周血生殖激素水平的影响

为研究不同BMPR-IB基因型多胎萨福克羊外周血中生殖激素水平的差异,以培育的发情期多胎萨福克母羊为实验对象,应用PCR-RFLP技术检测个体的BMPR-IB基因型,ELISA方法检测绵羊外周血中E2、FSH、LH、PRL和P4的含量,分析BMPR-IB基因型与5种生殖激素水平的相关性.结果表明：多胎萨福克羊群体中存在BMPR-IB基因的BB、B＋和＋＋三种基因型.＋＋基因型个体的平均E2含量和P4含量显著低于B＋基因型和BB基因型个体（P＜0.05）,3种基因型个体间平均FSH含量、LH含量和PRL含量差异均不显著（P＞0.05）.BMPR-IB基因突变导致发情期母羊的雌二醇和孕酮的分泌量增加.研究结果可为合理利用BMPR-IB基因培育多胎肉羊提供依据.     

BAD基因在敖汉细毛羊发情不同时期卵巢表达规律及对生殖激素的影响

本实验研究旨在探究BAD基因在敖汉细毛羊中的不同发情时期卵巢中表达量的变化规律以及对生殖激素的影响,为探讨其与绵羊发情的关系奠定基础。首先利用放射免疫方法测定敖汉细毛羊血液中促卵泡激素(FSH)、促黄体生成素(LH)、雌二醇(E_2)和孕激素(P_4)的浓度,然后利用qRT-PCR检测乏情期、发情前期、发情间期和发情期卵巢BAD基因的表达量变化。结果表明:卵巢中BAD基因在发情前期的表达量极显著高于乏情期、发情期和发情间期(P0.01),在发情期的表达量极显著高于乏情期和发情间期(P0.01),乏情期和发情间期的表达量基本相同(P0.05);E_2和LH浓度在BAD基因表达量最高的发情前期维持较高水平,P_4的浓度维持较低水平。综上可知,BAD基因的表达可能促进了E_2和LH浓度升高,抑制了P_4产生,进而影响细毛羊发情,可为绵羊发情的研究提供借鉴。     

外源Se对胚胎移植受体母羊黄体发育和血清中激素水平的影响

 为了确定补硒对缺硒地区（陕西省神木县）绵羊繁殖性能的影响,60只受体母羊在舍饲条件下被随机分成试验组（n=30）和对照组（n=30）,试验组肌肉注射亚硒酸钠维生素E注射液4 mL/只(含硒0.46 mg/mL),对照组未注射。第25 d进行胚胎移植时,检查黄体发育情况,同时采集血样,测定血清中的6项激素（T3,T4,FSH,LH,E2,P4）水平。结果表明：补硒母羊平均每只羊有发育良好的黄体2.6枚,比对照组高1.1枚。血清T3平均水平为4.48 nmol/L,比对照组高0.93 nmol/L(P＜0.05),血清中T4平均水平为8.67 nmol/L,比对照组低3.53 nmol/L（P＜0.05）。E2和P4的浓度均显著高于对照组（P＜0.05）。可见,补硒可提高受体绵羊的黄体数量和质量以及血清E2、P4水平,但对血清FSH和LH没有明显影响。     

Endocrine and ovarian changes in response to the ram effect in medroxyprogesterone acetate-primed Corriedale ewes during the breeding and nonbreeding season

Two experiments were performed to determine the endocrine and ovarian changes in medroxyprogesterone acetate (MAP)-primed ewes after ram introduction. Experiment 1 was performed during the mid-breeding season with 71 ewes primed with an intravaginal MAP sponge for 12 days. While the control (C) ewes (n = 35) were in permanent contact with rams, the ram effect (RE) ewes (n = 36) were isolated for 34 days prior to contact with rams. At sponge withdrawal, all ewes were joined with eight sexually experienced marking Corriedale rams and estrus was recorded over the next 4 days. The ovaries were observed by laparoscopy 4-6 days after estrus. Four weeks later, pregnancy was determined by transrectal ultrasonography. In eight ewes from each group, ovaries were ultrasonographically scanned; FSH, LH, and estradiol-17beta were measured every 12 hours until ovulation or 96 hours after estrus. The response to the rams was not affected by the fact that ewes had been kept or not in close contact with males before teasing. No differences were found in FSH, LH, estradiol-17beta concentrations, growth of the ovulatory follicle, onset of estrus, ovulation rate, or pregnancy rate. Experiment 2 was performed with 14 ewes during the nonbreeding season. Ewes were isolated from rams for 1 month, and received a 6-day MAP priming. Ovaries were ultrasonographically scanned every 12 hours, and FSH, LH, estradiol-17beta, and progesterone were measured. Ewes that ovulated and came into estrus had higher FSH and estradiol-17beta levels before introduction of the rams than did ewes that had a silent ovulation. The endocrine pattern of the induced follicular phase of ewes that came into estrus was more similar to a normal follicular phase, than in ewes that had a silent ovulation. The follicle that finally ovulated tended to emerge earlier and in a more synchronized fashion in those ewes that did come into estrus. All ewes that ovulated had an LH surge and reached higher maximum FSH levels than ewes that did not ovulate, none of which had an LH surge. We conclude that (a) the effect of ram introduction in cyclic ewes treated with MAP may vary depending on the time of the breeding season at which teasing is performed; (b) patterns of FSH, and estradiol-17beta concentrations, as indicators of activity of the reproductive axis, may be used to classify depth of anestrus; and (c) the endocrine pattern of the induced follicular phase, which is related to the depth of anestrus, may be reflected in the behavioral responses to MAP priming and the ram effect.     

Endocrine and Ovarian Changes in Response to the Ram Effect in Medroxyprogesterone Acetate-primed Corriedale Ewes During the Breeding and Nonbreeding Season

Two experiments were performed to determine the endocrine and ovarian changes in medroxyprogesterone acetate (MAP)-primed ewes after ram introduction. Experiment 1 was performed during the mid-breeding season with 71 ewes primed with an intravaginal MAP sponge for 12 days. While the control (C) ewes (n = 35) were in permanent contact with rams, the ram effect (RE) ewes (n = 36) were isolated for 34 days prior to contact with rams. At sponge withdrawal, all ewes were joined with eight sexually experienced marking Corriedale rams and estrus was recorded over the next 4 days. The ovaries were observed by laparoscopy 4–6 days after estrus. Four weeks later, pregnancy was determined by transrectal ultrasonography. In eight ewes from each group, ovaries were ultrasonographically scanned; FSH, LH, and estradiol-17β were measured every 12 hours until ovulation or 96 hours after estrus. The response to the rams was not affected by the fact that ewes had been kept or not in close contact with males before teasing. No differences were found in FSH, LH, estradiol-17β concentrations, growth of the ovulatory follicle, onset of estrus, ovulation rate, or pregnancy rate. Experiment 2 was performed with 14 ewes during the nonbreeding season. Ewes were isolated from rams for 1 month, and received a 6-day MAP priming. Ovaries were ultrasonographically scanned every 12 hours, and FSH, LH, estradiol-17β, and progesterone were measured. Ewes that ovulated and came into estrus had higher FSH and estradiol-17β levels before introduction of the rams than did ewes that had a silent ovulation. The endocrine pattern of the induced follicular phase of ewes that came into estrus was more similar to a normal follicular phase, than in ewes that had a silent ovulation. The follicle that finally ovulated tended to emerge earlier and in a more synchronized fashion in those ewes that did come into estrus. All ewes that ovulated had an LH surge and reached higher maximum FSH levels than ewes that did not ovulate, none of which had an LH surge. We conclude that (a) the effect of ram introduction in cyclic ewes treated with MAP may vary depending on the time of the breeding season at which teasing is performed; (b) patterns of FSH, and estradiol-17β concentrations, as indicators of activity of the reproductive axis, may be used to classify depth of anestrus; and (c) the endocrine pattern of the induced follicular phase, which is related to the depth of anestrus, may be reflected in the behavioral responses to MAP priming and the ram effect.