磺胺二甲嘧啶对小鼠亚慢性毒性、骨髓细胞微核及精子畸形的影响

试验选取昆明种小鼠,采用经口灌胃法,研究磺胺二甲嘧啶对小鼠亚慢性毒性、骨髓细胞微核和精子畸形的影响。结果显示,亚慢性毒性试验中,高、中剂量组小鼠体重与对照组和低剂量组差异极显著(P＜0.01);高剂量组雄性小鼠心脏的脏器系数与对照组和低剂量组差异显著(P＜0.05);高剂量组雄性小鼠肾脏的脏器系数显著低于对照组(P＜0.05),雌性小鼠肾脏的脏器数显著低于对照组与低剂量组(P＜0.05);小鼠骨髓细胞微核试验中高剂量组与空白对照组差异显著(P＜0.05),高、中、低剂量组间无显著差异;小鼠精子畸形试验中,高、中剂量组与空白对照组差异极显著(P＜0.01),低剂量组与空白对照组差异显著(P＜0.05),高剂量组与中、低剂量组差异显著(P＜0.05)。结果表明,高剂量的磺胺二甲嘧啶对小鼠的心脏和肾脏及微核发生率有一定影响;中剂量的磺胺二甲嘧啶对雌性小鼠的微核发生率具有一定影响;高、中、低剂量的磺胺二甲嘧啶对精子畸形率均具有一定影响。     

葛根素对乳腺组织雌激素及孕酮受体基因表达的影响

试验通过研究葛根素对乳腺组织中孕酮激素受体基因和雌二醇受体基因表达的影响,探讨葛根素对乳腺发育的影响,采用荧光定量RT-PCR方法检测小鼠乳腺组织中孕酮受体基因和雌二醇受体基因的表达.结果:与对照组相比,葛根素组小鼠ER表达量显著高于对照组(P＜0.05),而葛根素试验组小鼠PR表达量与对照组相比差异不显著(P＞ 0.05).结论: 葛根素具有上调乳腺组织ER表达的作用,这是其促乳腺发育的作用机理之一.     

植物甾醇对KM雌性小鼠生长及生殖激素的影响

本试验旨在研究植物甾醇对雌性小鼠生长及生殖激素的影响。选用50只35日龄雌性小鼠,适应1周后随机分为5组,分别为：对照组、植物油组（给予0.1 mL植物油）及植物甾醇低、中、高三个剂量组（每日灌胃20、80和320 mg/kg植物甾醇）。连续灌胃3周,第1天和第22天称取小鼠体重,然后眼球采血,制备血清,对小鼠血清中的雌二醇、孕酮、催乳素水平进行检测,研究不同添加量的植物甾醇对小鼠生长及生殖激素的影响。结果显示：与对照组相比,植物油组小鼠体增重差异显著（P＜0.05）。与植物油组相比,植物甾醇处理组小鼠体增重先升高后降低,但差异不显著（P＞0.05）。植物甾醇对小鼠血清E2水平有不同程度的提高,其中中剂量组小鼠的雌二醇水平最高（270.52＆#177;18.10 pmol/L）;随着植物甾醇灌胃剂量的增加,小鼠孕酮水平都有不同程度的下降,其中植物甾醇中剂量组小鼠血清孕酮水平显著低于对照组（P＜0.05）。植物甾醇灌胃组小鼠催乳素水平与对照组相比,差异不显著（P＞0.05）。表明低剂量植物甾醇可提高KM雌性小鼠的体增重;植物甾醇能提高KM雌性小鼠血清雌二醇水平,但对孕酮和催乳素的作用不显著。     

葛根素对不同日龄小鼠血清激素含量的影响

为了阐明葛根素对小鼠血清中孕酮(P)、雌二醇(E2)含量的动态变化的影响,试验将240只21日龄小鼠分为对照组、葛根素低剂量组、葛根素中剂量组和葛根素高剂量组,每组60只,适应性饲养1周后隔1 d给药1次,其中对照组给予纯化水0.2 mL,葛根素低、中、高剂量组分别给予0.5,1.0,1.5 mg/mL葛根素溶液0.2 mL,在第40,46,52,58,64,70日龄时各组取10只小鼠眼静脉采血,运用放射免疫分析法检测血清中孕酮、雌二醇含量。结果表明:各剂量葛根素溶液对不同日龄小鼠血清中孕酮含量均无显著影响。低剂量葛根素在小鼠70日龄时能显著提高雌二醇含量;中剂量葛根素在52日龄开始显著提高小鼠血清中雌二醇含量,64日龄时有所下降,70日龄时再次显著提高;高剂量葛根素对各日龄小鼠血清中雌二醇含量均无显著影响。     

β-胡萝卜素对小鼠血液成分及SOD、GSH-PX和CAT活性的影响

小鼠灌胃不同剂量的β-胡萝卜素(20、10、5 mg/kg),测定其血液生理指标及SOD、GSH-PX、CAT活性.结果表明,高、中、低剂量组的β-胡萝卜素组白细胞总数、粒细胞数和中值细胞百分数显著高于对照组(P＜0.05),高剂量的β-胡萝卜素组中值细胞百分数、血红蛋白含量、平均红细胞血红蛋白含量、平均红细胞血红蛋白浓度、血小板和血小板压积显著高于对照组(P＜0.05),中剂量的β-胡萝卜素组血清、肝组织SOD、GSH-PX、CAT活性显著高于对照组(P＜0.05),高剂量的β-胡萝卜素组出血时间、凝血时间、血清、肝组织SOD、GSH-PX活性显著低于对照组(P＜0.05).     

棉酚对小鼠肝脏SOD GSH-Px和MDA的影响

为了探讨不同浓度棉酚对小鼠体重及肝脏组织抗氧化能力的影响,将32只小鼠随机分成4组(对照组和低中高剂量棉酚组),连续灌胃20 d后处死并取肝脏称重计算脏器指数,用分光光度法测定肝脏组织超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)或活性及丙二醛(MDA)含量。结果随着灌胃天数的增加,对照组和低剂量组体重呈上升趋势,中、高剂量组体重呈下降趋势;各剂量组肝脏脏器指数明显增加,低、中剂量组显著高于对照组(P0.05或P0.01),高剂量组高于对照组(P0.05)。随着棉酚剂量的增加,中、高剂量组SOD活力显著低于对照组(P0.01),低剂量组和中高剂量组GSH-Px活力显著低于对照组(P0.05或P0.01),中、高剂量组MDA含量显著高于对照组(P0.05或P0.01),表明口服中、高剂量的棉酚可抑制小鼠体重的增加,降低肝脏的抗氧化能力,使脂质过氧化反应增强,导致肝脏氧化损伤,使肝脏功能受损。     

牛磺鹅去氧胆酸对糖皮质激素引起小鼠免疫抑制的影响

采用80 mg/kg剂量的地塞米松对小鼠进行腹腔注射制备免疫抑制小鼠模型;牛磺鹅去氧胆酸(Taurochenodeoxycholic acid,TCDCA)设计了0.05、0.10、0.20 g/kg低、中、高3个给药剂量对小鼠灌胃给药;检测免疫器官质量,碳粒廓清法检测单核-巨噬细胞吞噬功能,流式细胞术检测外周血CD4+和CD8+细胞亚群百分率及CD4+与CD8+的比值,ELISA检测血清中IgG的含量.结果显示:模型小鼠和正常小鼠相比较,脾指数、单核-巨噬细胞吞噬功能、CD4+和CD8+亚群百分率及血清IgG含量均极显著降低(P＜0.01),说明地基米松制备的小鼠模型免疫功能极显著低下.给药组与模型组相比较,TCDCA的3个剂量组对小鼠脾指数均无显著影响(P＞0.05);低剂量组和中剂量组极显著增强单核-巨噬细胞系统吞噬功能(P＜0.01);3个剂量组均显著提高外周血中CD4+细胞百分率(P＜0.05),中剂量组显著提高CD4-与CD8-的比值(P＜0.05);低剂量纽和中剂量组显著提高小鼠血清中IgG含量(P＜0.05).结果表明,TCDCA对糖皮质激素免疫抑制小鼠的非特异性免疫和特异性细胞免疫、体液免疫功能具有恢复作用,但对脾脏萎缩无恢复作用.     

黄芩苷对小鼠的保胎作用及其对细胞因子的影响

本试验旨在研究黄芩苷的促孕保胎作用及其对母胎界面细胞因子的影响。取怀孕小鼠分成5组,除对照组外,其它4组于孕5-7天皮下注射溴隐亭建立流产模型,孕1-7天分别灌服蒸馏水、0.1、0.51、mg黄芩苷。孕3、5、7、10、12天采样,计算流产率,酶联免疫吸附法(ELISA)测定血清及子宫匀浆中干扰素-γ(IFN-γ)、白介素-10(IL-10)、孕酮的含量。结果孕12天时1 mg黄芩苷组流产率降低,接近对照组,与模型组均有显著差异。孕5天各组血清和子宫匀浆中IFN-γ含量显著上升,其中1 mg黄芩苷组最高。孕酮含量随孕期延长而提高,以0.5和1 mg黄芩苷组最高。表明黄芩苷可剂量依赖性上调孕酮的含量,促进着床期IFN-γ分泌,胚泡附植后又降低IFN-γ的含量,调节着床和妊娠期Th1/Th2细胞因子平衡,影响内分泌-免疫网络,有利于胚胎着床和妊娠维持。     

樗白皮提取物对腹泻模型小鼠抗氧化能力的影响

为研究腹泻病理状态下樗白皮提取物对机体氧化还原状态的调节功能,采用番泻叶提取物建立小鼠药物性腹泻模型,经不同剂量樗白皮提取物治疗,对小鼠血清中MDA、SOD、GSH、GSSG、GSH-Px等抗氧化指标进行测定。结果显示,模型组MDA含量较正常组显著升高(P0.05),樗白皮提取物不同剂量治疗组均低于模型组,与治疗对照组无显著差异;模型组SOD酶活性显著低于其他各组(P0.01),正常对照组与其他实验组之间无显著差异;模型组GSH含量显著低于正常对照组和治疗对照组(P0.05),高剂量组和中剂量组高于模型组(P0.05),低剂量组与模型组无显著差异;正常对照组GSSG含量显著低于其他各组(P0.01),模型组显著高于治疗对照组和高剂量组(P0.01),高于中剂量组和低剂量组(P0.05);GSH-Px模型组均低于其他各组,除与低剂量组无显著差异外,与其他各组差异均极显著(P0.01)。结果表明,樗白皮提取物能够降低腹泻模型小鼠体内氧化性物质含量,提高还原酶活性及促进还原性物质生成,对机体的氧化还原稳态具有一定的调节作用,并且与给药剂量之间存在一定的量效关系。     

Fadrozole对公鸡的生长发育和精清激素浓度的影响

芳香化酶抑制剂Fadrozole能诱导雌性鸡胚雄性化,而不影响出生时雄性鸡胚的性别,但Fadrozole是否影响公鸡出雏后的生长发育和繁殖能力尚不清楚。在性别分化前(E3.0),向农大3号矮小商品代鸡胚注入PBS和不同剂量的Fadrozole(0.、10.3、0.5、1.0mg和1.3mg分别为1F、F2、F3、F4和F5),以出雏后的公鸡作为试验材料,探索Fadrozole对出雏后公鸡的生长发育、精清中的性激素和生长轴激素的影响。结果表明:高剂量组F4和F5分别为33.33%和13.33%,出雏率显著低于对照组P(<0.05),而低剂量组F1、F2和F3与对照组相比,出雏率无显著变化(P>0.05);各剂量Fadrozole处理组和对照组的体重和胫长在8周龄和20周龄时无显著差异P(>0.05);性成熟后(30周龄),F5精清中的睾酮(T)和雌二醇(E2)显著高于对照组和其他各处理组(P<0.05),但ln(T/E2)在各处理组和对照组差异均不显著(P>0.05);本试验说明Fadrozole不影响雄性胚胎的性腺分化,但高浓度的Fadrozole不利于鸡胚的发育;Fadrozole不影响出生后公鸡的生长发育、精清中的生长轴激素激分泌和精清中睾酮与雌二醇的比值。     

不同剂量硒蛋白粉对大鼠血常规指标和血液生化指标的影响

本试验旨在研究不同剂量硒蛋白粉对大鼠血常规指标及血液生化指标的影响。选择平均体重为70 g的健康清洁级SD大鼠80只,随机分为4组,每组2个重复,每个重复10只,雌、雄各半。对照组饲喂基础日粮,低、中和高剂量组分别饲喂添加3.5、7和10.5 mg/kg硒蛋白粉的日粮（其含量以硒计）,试验期30 d。结果表明,低、中和高剂量组大鼠血常规指标与对照组相比差异均不显著（P＞0.05）;低、中和高剂量组大鼠血清中血糖、总蛋白含量与对照组相比差异均不显著（P＞0.05）,低剂量组大鼠血清中甘油三酯、低密度脂蛋白含量均显著低于对照组（P＜0.05）;中剂量组大鼠血清中白蛋白/球蛋白及甘油三酯、低密度脂蛋白含量均显著低于对照组（P＜0.05）,而谷丙转氨酶和谷草转氨酶水平均显著高于对照组（P＜0.05）;高剂量组大鼠血清中白蛋白、白蛋白/球蛋白、甘油三酯、低密度脂蛋白含量均显著低于对照组（P<0.05）,而球蛋白、谷丙转氨酶、谷草转氨酶、尿素氮、肌酐、高密度脂蛋白含量均显著升高（P＜0.05）。综上所述,不同剂量硒蛋白粉对大鼠血常规指标无不良影响,低剂量硒蛋白粉除具有降低大鼠血脂作用外对大鼠其他血液生化指标均无不良影响,中、高剂量硒蛋白粉对大鼠的部分血液生化指标有一定影响。     

马兜铃酸A致大鼠肾病的肾毒性作用机理研究

以大鼠为靶动物进行亚慢性毒性试验,探究马兜铃酸A的肾毒性作用机理。将56只健康雄性Wistar大鼠适应性饲养1周,随机分为马兜铃酸A高剂量组(40 mg/kg BW)、马兜铃酸A中剂量组(8 mg/kg BW)、马兜铃酸A低剂量组(4 mg/kg BW)和空白组4组,试验持续28 d,后进行14 d恢复性试验。通过监测体质量,计算肾脏指数,检测血尿素氮(BUN)、尿酸(UA)和肌酐(SCr)的含量,检测丙二醛(MDA)含量、超氧化物歧酶(SOD)活性、谷胱甘肽过氧化物酶(GSH-Px)活性和总抗氧化能力(T-AOC),观察肾脏的组织病理学变化,采用实时荧光定量PCR检测相关基因mRNA的表达情况,来综合评价马兜铃酸A的肾毒性作用。结果分析显示,从第16天开始马兜铃酸A高剂量组大鼠体质量显著低于空白组(P<0.05);肾脏指数各组间差异不显著;试验第28天,高剂量组BUN、UA、CA含量均显著高于空白组(P<0.05),中剂量组BUN、UA含量均显著高于空白组(P<0.05),低剂量组UA含量显著高于空白组(P<0.05),试验第42天,高剂量组的BUN、UA、CA含量仍然均显著高于空白组(P<0.05),中剂量组CA含量显著高于空白组(P<0.05);试验第28天,高剂量组MDA含量显著高于空白组(P<0.05),SOD、GSH-Px活性均显著低于空白组(P<0.05),中剂量组和低剂量组GSH-Px活性显著低于空白组(P<0.05),试验第42天,高剂量组MDA含量仍然显著高于空白组(P<0.05),SOD、GSH-Px活性和T-AOC均显著低于空白组(P<0.05),中剂量组SOD、GSH-Px活性和T-AOC均显著低于空白组(P<0.05),低剂量组MDA含量显著高于空白组(P<0.05),GSH-Px活性显著低于空白组(P<0.05);肾脏组织病理学观察发与组织和细胞层面的损伤程度大体呈剂量相关性;试验第28天和第42天,高剂量组和中剂量组TGF-β1、smad3、collagen1、collagen3的mRNA表达量显著高于空白组(P<0.05),低剂量组TGF-β1、smad3的mRNA表达量显著高于空白组(P<0.05)。说明马兜铃酸A对大鼠肾脏有毒性作用,肾功能被损害,引起一定程度的肾纤维化,这种损害作用在一定时间内不能自行恢复。马兜铃酸A的毒性作用可能与氧化应激与TGF-β1/smad通路作用有关。     

黄芩苷通过抑制核因子-κB和激活核因子-E2相关因子2信号通路缓解脂多糖诱导的小鼠空肠炎症和氧化应激

本试验旨在探讨黄芩苷对脂多糖(LPS)诱导的小鼠空肠炎症和氧化应激的缓解作用及其分子机制。将36只小鼠随机分为对照组、阴性对照组、模型组以及低、中、高剂量黄芩苷组,每组6只。适应性生长7 d后开始试验。对照组小鼠不作处理,阴性对照组和模型组小鼠每天灌胃0.2 mL磷酸盐缓冲液(PBS),黄芩苷组小鼠每天灌胃黄芩苷药液0.2 mL(根据小鼠体重计算黄芩苷用量,低剂量组为100 mg/kg BW,中剂量组为200 mg/kg BW,高剂量组为400 mg/kg BW),连续灌胃7 d,第7天给模型组、黄芩苷组小鼠腹腔注射0.2 mL LPS(3.5 mg/kg BW)。注射LPS 24 h后处死小鼠,取空肠进行形态学观察,检测空肠中炎性因子mRNA表达量和含量以及核因子-κB(NF-κB)和核因子-E2相关因子2(Nrf2)/血红素氧合酶-1(HO-1)信号通路关键蛋白表达量的变化。结果显示：相比于对照组,模型组小鼠空肠组织绒毛结构损伤,绒毛高度与隐窝深度比值显著降低(P<0.05),空肠中Toll样受体4(TLR4)的mRNA表达量显著升高(P<0.05),炎性因子[白细胞介...     

甘露寡糖脂质体纳米制剂对鸡生长发育和免疫功能的影响

为研究甘露寡糖脂质体纳米制剂对鸡生长发育及免疫功能的影响,在饲料中添加不同剂量的甘露寡糖脂质体纳米制剂(100、50、25mL g/kg),饲养49d后,测定了鸡体重、料肉比、免疫指标及血液中免疫球蛋白G(IgG)含量。结果表明,甘露寡糖脂质体纳米制剂能提高正常鸡的平均日增重,降低料肉比,其中在1日龄～21日龄阶段,高剂量组和低剂量组平均日增重明显高于药物对照组,差异极显著(P<0.01),与空白对照组比较,差异显著(P<0.05);甘露寡糖脂质体纳米制剂高、中、低剂量组鸡血浆中一氧化氮含量,与药物对照组、空白对照组比较均极显著升高(P<0.01)。说明甘露寡糖脂质体纳米制剂对鸡的免疫功能具有一定的调节作用,发挥抗病促生长作用。     

广藿香对冰醋酸所致小鼠扭体疼痛模型的镇痛作用研究

旨在研究广藿香对冰醋酸所致小鼠扭体反应的抑制作用,确定广藿香的镇痛作用。将24只小鼠随机分为广藿香低剂量组、中剂量组、高剂量组和对照组,采用灌胃给药方式,分别给予0.25、0.5、1.0g/（kg·BW）广藿香及生理盐水;给药后,各组小鼠灌胃20%冰醋酸溶液,观察并记录各组小鼠的体态变化以及扭体次数,并计算镇痛率。结果表明,给予20%冰醋酸溶液后,高剂量组小鼠的腹痛症状较轻,低剂量组小鼠的腹痛症状较为严重,抽搐明显;高剂量组小鼠的扭体次数极显著低于对照组（P〈0.01）,中、低剂量组小鼠的扭体次数显著低于对照组（P〈0.05）;高剂量组的镇痛百分率最高（36.73%）,低剂量组的镇痛百分率最低（14.45%）。广藿香对冰醋酸所致的小鼠扭体反应具有抑制作用,表现出良好的镇痛作用,且镇痛作用呈现一定的量效关系。     

双拷贝抑制素基因免疫对大鼠卵泡发育、产仔及生殖激素的影响

将90只大鼠随机分为5组,分别注射10μg.100μL-1 pcISI(T1)、50μg.100μL-1 pcISI(T2)、100μg.100μL-1(T3)pcISI、100μg空载体pcMV-S(V)和100μL生理盐水(S),以探讨在不使用免疫佐剂的情况下,不同剂量的双拷贝抑制素pcISI基因免疫对大鼠卵泡发育、产仔和生殖激素的影响。结果表明,加强免疫能提高抗体P/N值,加强免疫后各剂量组平均抗体P/N值大于2,T3组抗体P/N值显著高于T1和T2组(P<0.05)。T3组成熟卵泡数显著高于对照组(P<0.05),且抗体阳性鼠成熟卵泡数比阴性鼠多12.45个(P<0.05)。除了T1组外,其他2个剂量组产仔数和胎盘数均高于对照组(P<0.05)。抗体阳性鼠胎盘数比阴性鼠多5.09个(P<0.05),产仔数比阴性鼠多5.39个(P<0.05)。抑制素pcISI基因免疫大鼠后促卵泡素(FSH)、雌二醇(E2)和孕酮(P4)含量均高于对照组,T3组的FSH含量与对照组差异显著(P<0.05),T3组的E2含量与对照组差异极显著(P<0.01),各剂量组P4含量与对照组差异均不显著(P>0.05)。这些结果说明,在没有免疫佐剂的前提下,双拷贝抑制素pcISI基因免疫可产生抗体,促进FSH分泌和卵泡发育,增加产仔数。本试验条件下100μg.100μL-1是最佳免疫剂量。     

Effect of Oocytes in vivo and in vitro on the Developmental Potential of Porcine Somatic Cell Cloned Embryos

To investigate the impact of porcine oocytes in vivo and in vitro maturation (IVM) on the development of porcine somatic cell cloned embryos,the somatic cell cloned embryos cultured in vitro and the sows were treated with hormones to collect mature oocytes in vivo,and the cleavage rate, blastocyst rate and embryo implantation were compared. The results showed that the average number of ovulation in PGC+PMSG+HCG group was significantly higher than that of PGC+HCG,PMSG+HCG and the natural estrus groups (P<0.05). The oocytes collected in vivo could be used for the construction, and the available oocytes rate reached more than 90%,and there was no significant difference among the four groups (P>0.05),which indicated that groups treated by hormone could obtain more available oocytes and the quality of oocytes was not significant different. In vivo and in vitro matured oocytes were used as nuclear transfer embryos of recombinant receptor,the fusion efficiency (80.31% and 79.29%) and cleavage rate (90.40% and 86.51%) were not significant different (P>0.05), but the proportion of in vivo matured oocytes cloned embryos developed into the blastocyst stage was significantly higher (P<0.05). The reconstructed embryos made from in vivo and in vitro matured oocytes were transplanted into surrogate sows (transferred 30 or 60 embryos),10 piglets were born in in vivo maturation of cloned embryo transfer group,while there was no implantation in in vitro maturation of cloned embryo transfer group. The results showed that high quality oocytes obtained by superovulation could significantly increase the blastocyst rate of embryos,reduce the number of embryos transferred and improve the pregnancy rate of surrogate sows.     

Japanese Society for Animal Reproduction: award for outstanding research 2002. The development and prevalence of the transfer technique for frozen-thawed embryos of Japanese black beef cattle in Tochigi Prefecture

The conditions of embryo transfer by the stepwise method, in which frozen-thawed embryos are transferred on day 7 (day 0=onset of estrus), were investigated with the aim of increasing pregnancy rates in frozen-thawed embryo transfer. The use of a vaginal speculum to prevent bacterial infection when passing an embryo transfer gun through the vagina yielded a pregnancy rate equal to or higher than that with application of a sheath cover to the transfer gun. Administration of a sedative, xylazine, to recipient cattle for preventing movement at the time of embryo transfer improved the pregnancy rate. The influence of the time from thawing of frozen embryos to transfer and of the transportation of the recipient by truck upon pregnancy rate was investigated. Embryo transfer within 60 minutes after aspiration into a straw or transportation of the bovine recipient, 1.5 hours each way before and after transfer, had no influence on pregnancy rate. Relations of the embryonic developmental stage and morphological quality after thawing of frozen embryos to pregnancy rate were investigated in recipients of nulliparous Holstein heifers. The pregnancy rate increased as the embryonic developmental stage advanced from compacted morula, early blastocyst, and blastocyst in that order. The pregnancy rate obtained with blastocyst stage embryos was significantly (P<0.05) higher than that with compacted morula stage embryos, and there was no significant difference in pregnancy rates between excellent morphological quality and good morphological quality for compacted morula stage embryos. When correlation of luteal function and pregnancy rate was investigated in bovine recipients, pregnancy rate showed a tendency to increase with increasing blood progesterone (P) concentration on the day before (on day 6 after estrus) and the day of embryo transfer. The pregnancy rate in bovine recipients, which showed a blood P concentration of > or =2.5 ng/ml on the day before embryo transfer, was significantly (P<0.05) higher than that in those with a blood P concentration of <2.5 ng/ml. Pregnancy rate showed a tendency to increase with decreasing blood estradiol-17beta (E2) concentration on the day of embryo transfer. Activation of luteal function by administration of human chorionic gonadotropin (hCG) in cycling cattle was investigated for its effect on increasing pregnancy rate in bovine recipients. A follicle coexisting with cyclic CL ovulated and induced CL formed after injection of hCG 1,500 IU 5 days after ovulation. The blood P concentration was significantly (P<0.05) higher in the administration group than in the control group, and the blood E2 concentration rapidly decreased, showing a lower concentration than in the control group. These results suggest the possibility that the pregnancy rate could be improved by administration of hCG. Pregnancy rate following intramuscular injection hCG 1,500 IU was comparatively investigated in parous Japanese Black beef cattle receiving frozen-thawed embryos 7 days after estrus. Pregnancy rate was 67.5% in the group in which hCG was administered on day 6 after estrus, and was significantly (P<0.05) higher than that in the control group (45.0%) and the group in which hCG was administered on day 1 after estrus (42.5%), revealing that hCG administration facilitated pregnancy. Transfer of frozen-thawed embryos in the blastocyst stage within 60 minutes after the aspiration into a straw, with a vaginal speculum after administration of xylazine is suggested as a way of improving pregnancy rate in bovine recipients with favorable luteal function and in those with luteal function activated by administration of hCG on the day before embryo transfer.     

Effect of estrus synchronization treatment after luteolysis on Holstein heifers as embryo transfer recipients

This study was designed to evaluate the effect of estrus synchronization treatments on recipient heifers for embryo transfer (ET). Holstein heifers were separated into the following three groups: (i) an administration of 50 µg GnRH (gonadotropin‐releasing hormone) analog was given to heifers at a random stage of the estrus cycle, followed 7 days later by two administrations of 7.5 mg prostaglandin F2 alfa analog (PG) as control; (ii) another administration of 100 µg GnRH was given to the control group at 48 h after the administration of PG as the second GnRH group; and (iii) an administration of 0.75 mg estradiol benzoate (E2) was given to the control group at 24 h after the administration of PG as the E2 group. Each method caused estrus synchronization. Fresh embryos were nonsurgically transferred into the suitable recipients that had a functional corpora lutea (CL) 7 days after estrus. The E2 group showed a significantly higher (P < 0.01) rate of estrus synchronization (98.9%) at 1–3 days after PG administration and the final pregnancy rate of the E2 group (50.6%) was also significantly higher than the other groups (37.1%, P < 0.05 and 30.9%, P < 0.01, respectively). These findings demonstrate that E2 administration 24 h after PG protocol is effective for estrus synchronization of Holstein heifers, thus improving the productivity of ET.     

Effects of maternal streptozotocin-diabetes on fetal growth, energy reserves and body composition of newborn pigs

Two doses of Streptozotocin (50 and 100 mg/kg body weight) were administered to two groups of pregnant gilts at d 80 of gestation to determine the influence of two levels of maternal diabetes on the gilts, their developing progenies and the body composition of the pigs. All the experimental animals received 1.82 kg of gestation diet/day throughout gestation. Serum glucose concentration increased to hyperglycemic levels in low-dose and high-dose groups; insulin concentrations decreased (P less than .01) in the high-dose, but not in the low-dose group (P greater than .05). Maternal free fatty acids (FFA) increased (P less than .05) in both treatment groups when compared with the control. However, birth weight of the litter and litter size were not affected. The liver weight increased (P less than .01) in the progeny of high-dose but not the low-dose group. Total liver DNA and RNA were not altered by the treatments, however; total liver protein and protein:DNA ratio increased (P less than .01) in the progeny of high-dose gilts. Pigs from high-dose and low-dose groups showed increases (P less than .01) in liver glycogen concentrations and percentage liver lipid. Body chemical composition data showed increases in percentage dry matter and percentage lipid (P less than .05 and P less than .01, respectively) in the progeny of high-dose but not in the low-dose group. It was concluded that streptozotocin administered to gestating gilts increased the maternal nutrient supply to the developing pigs, which resulted in higher energy status of the pigs at birth.