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1.
基于LC-Q/TOF-MS代谢组学方法筛选奶牛妊娠识别阶段乳样生物标志物的研究 总被引：1，自引：1，他引：0
本研究旨在筛选奶牛妊娠识别阶段乳汁生物标志物,为早期妊娠诊断提供新的思路和方法。选择胎次和体况相近的荷斯坦健康高产奶牛10头,同期发情后,采集人工授精当天和第17天乳样,采用高效液相色谱-四极杆-飞行时间质谱(LC-Q/TOF-MS)代谢组学技术,结合主成分分析(PCA)和正交偏最小二乘法-判别分析(OPLSDA)对两组乳样代谢轮廓进行模式识别;根据OPLS-DA模型中的VIP值(VIP1)和Kruskal-Wallis检验的P值(P0.05)筛选两组乳样差异代谢物;ROC曲线进一步考察这些差异代谢物对两组乳样分类的识别能力。结果表明:1)人工授精当天与第17天乳样代谢轮廓存在明显差异;2)10个代谢物(甲羟戊酸内酯、色胺、L-酪氨酸、磷酸二氢新蝶呤、乙酰半胱氨酸、N-乙酰基-L-酪氨酸、L-脯氨酸、四氢1-苯甲基-1,2,3,4-四氢异喹啉、鸟苷、十七烷基肉碱)被初步确定为两组乳样的差异代谢物;3)这10个差异代谢物中仅有6个代谢物(L-酪氨酸、N-乙酰基-L-酪氨酸、L-脯氨酸、四氢1-苯甲基-1,2,3,4-四氢异喹啉、鸟苷和十七烷基肉碱)对两组乳样具有显著的区分能力,最终被视为妊娠识别阶段潜在乳样生物标志物。综上表明,牛奶中L-酪氨酸、N-乙酰基-L-酪氨酸、L-脯氨酸、四氢1-苯甲基-1,2,3,4-四氢异喹啉、鸟苷和十七烷基肉碱有望成为妊娠识别期妊娠诊断指标,也可为深入研究奶牛早期妊娠识别机理提供新的视角。 相似文献
2.
《中国畜牧杂志》2020,(10)
为探究人工授精后不同阶段葡萄糖、孕酮和雌二醇含量对奶牛妊娠的影响,本实验选取63头2～3胎、3～4岁和体况评分(BCS)2.75左右的健康荷斯坦奶牛,人工授精后经发情鉴定及妊娠诊断将奶牛分为妊娠组(n=24)、未妊娠组(n=19)、返情组(n=20)。分别在人工授精后1、5、17、28 d采集尾静脉血10 mL,测定血浆葡萄糖、孕酮(P_4)和雌二醇(E_2)含量并进行分析。结果显示:人工授精后第5天妊娠和未妊娠组血浆中孕酮和雌二醇极显著高于返情组;人工授精后第17天返情组和妊娠组血浆中P_4、E_2含量以及P_4/E_2极显著高于未妊娠组;人工授精后第28天未妊娠组血浆P_4含量显著高于返情组,人工授精后第28天血浆葡萄糖含量妊娠组显著高于返情组。综上表明,人工授精后第5天和第17天高浓度血浆P_4和E_2有利于维持胚胎细胞正常发育和母体和胚胎识别,提高奶牛胚胎存活率;授精后第28天低浓度葡萄糖不利于妊娠,说明血浆中葡萄糖、孕酮和雌二醇对奶牛人工授精后不同阶段早期妊娠具有预测作用。 相似文献
3.
本试验旨在探究亚急性瘤胃酸中毒（subacute rumen acidosis, SARA）对泌乳奶牛血液生化指标和血浆代谢组的影响。试验选用8头装有永久性瘤胃瘘管的泌乳中期奶牛,随机分成对照组（CON）（n=4）和处理组（SARA）（n=4）,CON组与SARA组分别饲喂精粗比为4∶6和6∶4的全混合日粮,试验周期为3周。于试验期每周最后一天晨饲后0、2、4、6、8和12 h进行瘤胃pH的测定,同时在pH测定当天晨饲后6 h采集颈静脉血样,用于血液生化指标和代谢组的分析。结果表明,与CON组相比,SARA组的瘤胃pH显著降低（P=0.002）,两组干物质采食量没有显著差异（P=0.524）。血浆生化指标结果显示,与CON组比较,SARA组奶牛的β-羟丁酸浓度显著降低（P=0.007）,甘油三酯浓度显著升高（P=0.014）。采用液相-质谱（LC-MS）联用技术对血浆进行代谢组学分析,主成分分析（PCA）和偏最小二乘法分析（PLS-DA）结果显示,SARA组奶牛血浆代谢物组成较CON组发生明显变化,两组间共检测到26种差异代谢物（VIP>1 & FDR<0.05）,与CON组相比,SARA组奶牛血浆中的7-酮脱氧胆酸、脱氧胆酸、胆酸、12-酮脱氧胆酸、12（13）Ep-9-KODE、12,13-DHOME和L-天冬酰胺代谢物含量显著升高（FDR<0.05）,而十一烷二酸、十六烷二酸、9-HODE、血氧烷B3、PGE2、L-精氨酸、L-色氨酸、L-苏氨酸、异丁酰甘氨酸、异戊酰甘氨酸、马尿酸、4-羟基马尿酸和6-磷酸-2-脱氢-D-葡萄糖酸酯等代谢物含量显著降低（FDR<0.05）。综上,与CON组比较,SARA组奶牛的脂代谢、氨基酸代谢和糖代谢发生显著变化,这些物质可作为SARA潜在的生物标志物。 相似文献
4.
《中国兽医学报》2020,(4)
旨在筛选表征奶牛产后异食沙土的生物标志物。本试验共采集29份产后15～22 d血浆样品,根据奶牛产后有无异食沙土现象,结合血钙浓度进行分组,其中13头产后有异食现象的奶牛血浆样品为试验组,16头健康奶牛血浆样品为对照组,采用超高效液相色谱-四极杆-飞行时间质谱(UPLC-Q-TOF MS)代谢组学技术探讨2组血浆代谢轮廓和代谢物的变化趋势。主成分分析(PCA)和正交偏最小二乘法-判别分析(OPLS-DA)结果显示,试验组代谢轮廓较对照组发生明显变化,正、负离子下共筛选出28种差异代谢物,其中21种代谢物水平显著降低(P0.05),7种代谢物水平显著升高(P0.05);ROC曲线进一步考察这些差异代谢物对分类的识别能力,结果显示仅有11种代谢物对2组血浆具有显著的区分能力。综上表明,乙酰肉碱、DL-苯丙氨酸、2-八烯酸、辛酸、癸酸、D-泛醇、NG,NG-二甲基-L-精氨酸(ADMA)、雄烯二酮、脯氨酸-酪氨酸、异亮氨酸-丝氨酸、精氨酸-缬氨酸可作为表征奶牛产后是否有异食现象的潜在生物标志物,为研究奶牛产后异食沙土的预防提供新的方法和思路。 相似文献
5.
为比较研究对亚急性瘤胃酸中毒（SARA）耐受性不同的奶牛血浆和乳中代谢组的差异，试验选用12头装有永久性瘤胃瘘管的泌乳中期荷斯坦奶牛［泌乳天数=（114±22） d］，饲喂精粗比为4∶6的全混合日粮。在试验期第20和21天晨饲后0、2、4、6、8和12 h监测瘤胃pH值，在早晚饲喂前收集奶样，晨饲6 h后采集颈静脉血，用于测定脂肪酸及代谢物组成。基于奶牛瘤胃平均pH值高低，将奶牛分为SARA易感组（SUS，瘤胃pH=5.76，n=4）和SARA耐受组（TOL，瘤胃pH=6.10，n=4）。脂肪酸测定结果分析显示，与TOL组相比，SUS组奶牛血液及乳中的碳链长度≤C16的脂肪酸含量显著增高（P<0.05），而>C16的脂肪酸的含量显著降低（P<0.05），乳中饱和脂肪酸及单不饱和脂肪酸含量均显著降低（P<0.05）。血浆代谢组结果显示， SUS组奶牛血浆中L-苯丙酮酸水平显著降低（P<0.05），而MG（18：0/0：0/0：0）、9-HODE、12（13） Ep-9-KODE、烟酰胺、异戊基肉碱、磷酸肌酸和L-谷氨酸水平显著升高（P<0.05）。乳代谢组分析结果显示，与TOL组比较，SUS组奶牛乳中的1-硬脂酰磷酸甘油丝氨酸和鞘氨醇水平显著升高（P<0.05），而甘油磷酰基乙醇胺、3-磷酸甘油和乳清酸等其他14个差异代谢物水平显著降低（P<0.05），这些差异代谢物主要涉及甘油磷脂代谢、甘油脂代谢及泛酸与辅酶A代谢等代谢途径。综上所述，SARA耐受性不同的奶牛的血浆和乳中脂肪酸及代谢物组成存在较大差异，SUS组奶牛血浆中氨基酸代谢活动增加，乳腺的乳脂从头合成能力较强，而从血液中摄取长链脂肪酸能力减弱，与此同时，易感奶牛乳中磷脂、乳清酸等营养物质水平下降，乳品质下降。 相似文献
6.
《中国兽医学报》2020,(5)
旨在应用代谢组学技术筛选产后卵巢静止奶牛血浆中差异代谢物,探究差异代谢物与奶牛卵巢静止的关系。试验选取了产后45～60 d卵巢静止奶牛和正常发情奶牛各15头,应用LC/MS技术检测两组奶牛血浆样品,运用多元统计分析与单变量分析,结合生物信息学分析,筛选出血浆差异代谢物,揭示不同代谢通路中的差异代谢物与奶牛卵巢静止的关系。结果显示:LC/MS分析共筛选出14种血浆差异代谢物。与发情组奶牛相比,卵巢静止组奶牛有11种差异代谢物明显升高:分别是D-塔格糖、L-亮氨酰-L-脯氨酸、L-鹅肌肽、脯氨酸-缬氨酸、赖氨酸-亮氨酸、N-(3-苯基丙酰基)甘氨酸、7-烯胆(甾)烷醇、γ-生育酚、β-隐黄素、视黄醛和鞘磷脂;3种差异代谢物降低:分别是胞嘧啶、1-棕榈酰溶血磷脂酰胆碱和1-硬脂酰-SN-甘油-3-磷酰胆碱。代谢通路分析代谢组学所获得的奶牛卵巢静止血浆差异代谢物,提示奶牛产后糖代谢、脂类代谢、氨基酸代谢和谷胱甘肽代谢等的异常会阻碍卵泡发育,从而导致奶牛产后发生卵巢静止。本试验获得了卵巢静止奶牛血浆差异代谢物,探究了奶牛产后卵巢静止发生中差异代谢物在糖代谢、脂代谢和氨基酸代谢以及其他代谢的变化,为今后深入研究奶牛卵巢静止的发病机理及防治新策略提供了方向。 相似文献
7.
《中国畜牧兽医》2016,(5)
试验旨在研究同期发情和同期排卵-定时输精技术在青年奶牛中的应用。选择1 046头澳大利亚进口荷斯坦青年奶牛,随机分为两组:一组自然发情人工授精配种(对照组);另一组采用前列腺素F2α(PGF2α)诱导母牛发情或按照同期排卵-定时输精程序(Ovsynch或Ovsynch+CIDR法)处理母牛后人工授精配种(试验组),统计同期发情率、不返情率、第一次人工授精妊娠率和21d妊娠率等繁殖指标。结果表明,试验组青年奶牛人工授精后不返情率和第一次人工授精妊娠率与对照组间无显著差异(P0.05),但21d妊娠率显著高于对照组(53.1%和35.3%,P0.05)。试验组中,1次PG法、间隔7d2次PG法和间隔11d2次PG法的同期发情率分别为76.1%、81.7%和84.6%,差异均不显著(P0.05);同期排卵-定时输精组中,Ovsynch法(GPG)和Ovsynch+CIDR法(GPG+CIDR)的不返情率、第一次人工授精妊娠率和21d妊娠率间无显著差异(P0.05)。不同输精人员可显著影响青年奶牛的第一次人工授精妊娠率(P0.05),而不同公牛常规冷冻精液对青年奶牛第一次人工授精妊娠率无显著影响(P0.05)。同期发情及同期排卵-定时输精技术可使青年奶牛集中发情,提高参配率,从而提高21d妊娠率,有效加快青年奶牛人工授精效率,降低饲养成本。 相似文献
8.
本研究旨在分析不同乳脂率奶牛血浆和乳中代谢物的差异。实验基于江苏省某奶牛场2020年的奶牛生产性能测定（DHI）数据，在相同饲粮条件下选取高乳脂率中国荷斯坦奶牛（5.82%,H组）及低乳脂率中国荷斯坦奶牛（3.60%,L组）各5头。L组和H组奶牛的胎次均为1.80,L组的泌乳天数为317.80 d,H组的泌乳天数为218.80 d,L组和H组奶牛的日产奶量分别为28.54 kg和27.96 kg，且2组牛的胎次、泌乳天数及日产奶量差异均不显著。收集血样及乳样，测定常规乳成分指标和血液生化指标；通过非靶向液相色谱-质谱（LC-MS）代谢组学技术分析血浆及乳中代谢物。结果显示：H组血浆中β-羟丁酸浓度高于L组（P<0.05）；血浆代谢组发现了5种差异代谢物[差异倍数（H/L）≥1.5且P<0.05]，与L组相比，H组显著上调的代谢物有磷脂酰胆碱（20:0/20:5）和溶血磷脂酰乙醇胺18:3，下调的代谢物有胆碱、3-羟基-L-脯氨酸和植物鞘氨醇，这些代谢物富集在胆碱能突触、甘油磷脂代谢及甘氨酸、丝氨酸和苏氨酸代谢等通路；乳样代谢组也发现了5种差异代谢物[差异倍数（H/L）≥1.... 相似文献
9.
《畜牧兽医学报》2016,(1)
为了从代谢组角度系统揭示奶牛分娩后能量缺乏的生理机制,采用1 H-NMR代谢组学技术,结合多元统计学方法探讨了奶牛分娩后不同阶段血浆小分子代谢物的变化趋势及其对能量代谢通路的影响。结果表明:奶牛分娩后第7天与分娩第1天之间血浆代谢轮廓无明显差异;分娩后第14天与第1天之间血浆代谢轮廓出现明显差异,其差异标志物为不饱和脂肪酸、胆碱和氧化三甲胺;分娩后第28天与第1天之间血浆代谢轮廓也存在明显差异,其差异标志物为不饱和脂肪酸、胆碱、氧化三甲胺、三羧酸和葡萄糖;随着分娩后时间的延长,不饱和脂肪酸、胆碱和三羧酸表达逐渐上调,而氧化三甲胺和葡萄糖表达逐渐下调。可见,随着奶牛分娩后泌乳量的不断增加,逐渐呈现出能量负平衡状态,而机体应答性的上调了脂肪分解、脂肪酸氧化、胆碱氧化、蛋氨酸再甲基化和甲基代谢途径以缓解奶牛分娩后的能量负平衡状态。研究结果可为进一步阐明奶牛分娩后能量负平衡的生理机制提供科学依据。 相似文献
10.
为探究高加索三叶草（Trifolium ambiguum Bieb.）对不同降温模式低温胁迫的代谢响应机制，本试验对其分别进行缓慢降温（Gradual cooling，GC）和骤然降温（Sudden cooling，SC）处理，利用广泛靶向代谢组学技术检测叶片代谢物，并比较2个处理组与常温对照组（CK）间的代谢物差异。结果表明：在高加索三叶草叶片中共检测出894种代谢物；与CK相比，在GC和SC处理组中分别筛选出124个和139个差异代谢物（Differential metabolites，DMs）；2处理组的DMs均主要富集在氨基酸代谢和次生代谢产物的生物合成；紫铆因含量仅在GC组中显著增加（P < 0.05），酪氨酸和新橙皮苷含量仅在SC组中显著增加（P < 0.05）；γ-氨基丁酸、亮氨酸、组氨酸、赖氨酸、柠檬酸、矢车菊素和木犀草素含量在2处理组均显著增加（P < 0.05）。这些代谢物含量的增加可能是高加索三叶草适应低温胁迫的主要机制。 相似文献
11.
A program involving greater veterinary participation in detection of estrus and artificial insemination of cattle was evaluated in a 700-cow dairy herd from January 1987 through August 1988. Previous reproductive performance was below normal. First-service pregnancy rate from artificial insemination was 42%, and mean number of nonpregnant days for the cows was 120. Between postpartum days 55 and 62, all cows with functional corpus luteum assessed by rectal palpation were administered prostaglandin each Monday morning. Return visits were made to the herd each Thursday and Friday to observe cows and to inseminate those in estrus. On the other 5 days of the week, the owner or his employees inseminated all cows in estrus. The first-service pregnancy rate for 842 cows observed in estrus and inseminated by the veterinarian was 59%. The pregnancy rate for cows inseminated by the owner and his employees increased from 42% to 50%. The mean number of nonpregnant days for all 700 cows decreased from 120 to 98 days, resulting in approximately $46,000 of increased income for the dairyman or approximately a 4 to 1 return on investment in veterinary service. Results indicate that veterinarians could improve herd reproductive performance and solve chronic herd breeding problems by more actively participating with their clients in estrus detection and artificial insemination programs in cattle. The program allows practicing veterinarians an opportunity to observe cows for estrous behavior, establish their own pregnancy rate data, demonstrate to owners the importance of observing primary signs of estrus, and teach expert artificial insemination techniques. 相似文献
12.
[目的]为提高奶牛受胎率本试验针对人胎盘组织液提高受胎率,[方法]同时做了两批同期发情,分别为A组和B组,A组没有使用人胎盘组织液,B组使用了胎盘组织液,奶牛发情后,进行人工授精,40天后用B超进行孕检,从试验结果看到注射胎盘组织液的A组受胎率明显高于没有注射的B组。[结论]证明人胎盘组织液对提高奶牛发情具有良好作用。 相似文献
13.
试验旨在探明皮下注射褪黑素（MT）对荷斯坦奶牛配种妊娠率及血清生殖激素的影响。用计步器法确定自然发情的首次配种荷斯坦奶牛150头，对其中70头进行颈部皮下肌内注射褪黑素30 mg，12 h后进行人工输精；选择170头产后首次配种的荷斯坦奶牛进行同期排卵-定时输精处理，其中90头荷斯坦奶牛最后一次注射促性腺激素释放激素（gonadotropin-releasing hormone，GnRH）的同时进行颈部皮下肌内注射褪黑素30 mg，16 h后进行人工输精。在进行二次配种的荷斯坦奶牛中选择153只进行皮下注射褪黑素。荷斯坦奶牛输精后20~35 d进行妊娠检查，详细记录首次配种妊娠母牛头数、二次配种妊娠母牛头数、产犊数。选取同期排卵-定时输精的荷斯坦奶牛25头，皮下注射褪黑素8 h后用放射免疫法检测其血清中褪黑素、促卵泡素（FSH）、促黄体素（LH）、雌二醇（E2）的含量及35 d妊检时妊娠母牛血清中孕酮（P4）含量。结果显示，与自然发情和同期排卵对照组相比，其对应的皮下注射褪黑素组荷斯坦奶牛的妊娠率及产犊率均显著提高（P<0.05）；皮下注射褪黑素组的双犊率显著提高（P<0.05），首次配种妊娠率和产犊率均显著提高（P<0.05），二次配种妊娠率和产犊率均差异不显著（P>0.05）。血清激素检测结果表明，与对照组相比，皮下注射褪黑素组血清中褪黑素、LH、E2含量均显著增加（P<0.05）；35 d妊检时，皮下注射褪黑素的妊娠母牛P4含量显著增加（P<0.05）。本试验结果表明，皮下注射褪黑素能够提高荷斯坦奶牛的妊娠率、产犊率及血清中LH、E2和P4含量，说明皮下注射褪黑素能够促进卵母细胞成熟和排卵，并提高配种妊娠率。 相似文献
14.
Marcos G. Colazo Reuben J. Mapletoft 《The Canadian veterinary journal. La revue veterinaire canadienne》2014,55(8):772-780
This is a review of the physiology and endocrinology of the estrous cycle and how ovarian physiology can be manipulated and controlled for timed artificial insemination (TAI) in beef and dairy cattle. Estrus detection is required for artificial insemination (AI), but it is done poorly in dairy cattle and it is difficult in beef cattle. Protocols that synchronize follicle growth, corpus luteum regression and ovulation, allowing for TAI, result in improved reproductive performance, because all animals are inseminated whether they show estrus or not. As result, TAI programs have become an integral part of reproductive management in many dairy herds and offer beef producers the opportunity to incorporate AI into their herds. Gonadotropin-releasing hormone-based protocols are commonly used in North America for estrus synchronization as part of a TAI program. Protocols that increase pregnancy rates in lactating dairy cows and suckling beef cows have been developed. Protocols that improve pregnancy rates in heifers, acyclic beef cows, and resynchronized lactating dairy cows are also discussed. 相似文献
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16.
奶牛人工授精技术加速了奶牛品种改良进程,实现了将优秀种公牛精液跨区域、超时限的利用共享,极大地促进了养牛业的发展。以奶牛人工授精应用现状为出发点,介绍了人工授精技术的优点和不足,最后结合自身工作经验,从发情鉴定、适时配种、精液解冻、精液检测、输精、精液保存和妊娠检测等技术要点进行概述,以期更好地促进奶牛人工授精技术的应用。 相似文献
17.
Three different treatments were compared to improve pregnancy per artificial insemination (P/AI) in repeat-breeder (RB) dairy cows. All cows (n = 103) were assigned to one of four groups: (1) gonadotropin-releasing hormone (GnRH); (2) human chorionic gonadotropin (hCG); (3) once-used controlled internal drug release (CIDR) device; and (4) control. All treatments performed 5-6 days after artificial insemination (AI) and milk samples were collected just before treatment for progesterone assays. There were no significant differences in milk fat progesterone concentration among trial groups. Cows were observed for estrus signs thrice daily. Pregnancy per AI on day 45 in hCG and CIDR groups were significantly higher than GnRH and control groups (60.0% and 56.0% vs. 26.9% and 29.6%, respectively), but there were no differences in P/AI between GnRH and control groups. There were also no significant differences between hCG and CIDR groups. Milk fat progesterone concentrations were compared between pregnant and non-pregnant cows in each group and only in the hCG group it was significantly lower in pregnant cows. In conclusion, treating repeat-breeder cows with hCG or once-used CIDR 5-6 days after AI improved P/AI. 相似文献
18.
An economic model concerning the value of using prostaglandin (PG) in dairy cows with nondetected estrus was developed. Considering numerous and varied assumptions, it was more profitable to treat cows with PG and to breed the cows at a detected estrus than it was not to treat the cows and to wait to breed the cows at a detected estrus. Generally, using timed artificial insemination, it was also more profitable to breed PG-treated cows than it was not to use PG. However, timed insemination was less profitable than was breeding PG-treated cows by artificial insemination at a detected estrus. 相似文献
19.
【目的】试验旨在研究以褪黑素和地诺前列腺素组成的复合添加剂对奶牛性控冻精解冻后精子质量及奶牛人工授精后受胎率的影响。【方法】30份奶牛性控冻精样均分为2组：试验组和对照组,试验组添加由24 ng/mL褪黑素、1.5 mg/mL地诺前列腺素及精液稀释液组成的250 μL复合添加剂,对照组添加250 μL精液稀释液,试验组和对照组均与解冻后的奶牛性控冻精按照1∶1（V/V）进行混合,室温孵育0、2及4 h,通过免疫荧光染色分析精子活率、顶体完整率、高能线粒体活性精子比率;对216头青年奶牛和82头头胎奶牛输精后通过28 d早孕检测来确定受胎率情况。【结果】与对照组相比,经复合添加剂处理0 h的性控冻精活率、顶体完整率及高能线粒体活性精子比率均无显著变化（P＞0.05）;经复合添加剂处理2 h的性控冻精活率、顶体完整率、高能线粒体活性精子比率均显著升高（P＜0.05）;经复合添加剂处理4 h的性控冻精活率和顶体完整率均无显著变化（P＞0.05）,高能线粒体活性精子比率显著升高（P＜0.05）。在输精试验中,试验组青年奶牛和头胎奶牛中的受胎率分别为65.22%和48.21%,均显著高于对照组（P＜0.05）。【结论】以褪黑素和地诺前列腺素组成的复合添加剂可以促进解冻后奶牛性控冻精精液品质以及青年奶牛和头胎奶牛输精后的受胎率。 相似文献
20.
Accuracy of bovine pregnancy detection using transrectal ultrasonography at 28 to 35 days after insemination 总被引：4，自引：0，他引：4
OBJECTIVE: To estimate the accuracy of real-time ultrasonography to detect pregnancy in dairy cows at 28 to 35 days after insemination. METHODS: Cows that did not return to oestrus between 18 and 24 days after a first insemination (n = 526) were examined by transrectal ultrasonography from 28 to 35 days after insemination. Pregnancy was confirmed by the observation of a foetus, but fluid in the uterine horn and the presence of embryonic membranes were also noted. When pregnancy was not confirmed by the observation of a foetus, a second examination 7 days later, confirmed these remaining cows as pregnant or not pregnant to the first insemination. Detection of pregnancy at this early examination was compared with manual transrectal pregnancy examination performed 10 to 13 weeks after insemination (13-week examination). RESULTS: There were 44% of cows that were pregnant to the first service, 34% that had returned for a second service 18 to 24 days after the first insemination, and 20% of cows that were not pregnant, and had not returned normally for a second service (non-pregnant, non-return) within 24 days of their initial insemination. The presence of a foetus at 28 to 35 days after insemination was accurately predicted by a simplified method where uterine fluid accumulation and embryonic membranes were observed. Foetal loss between the early detection and the 13-week examination (9% of pregnancies) indicated that 28 to 35 days post insemination was too early to reliably detect pregnancy. CONCLUSION: Early examination of pregnancy with transrectal ultrasonography is an accurate method to identify non-pregnant, non-return cows. The examination can be simplified by the observation of uterine fluid accumulation and embryonic membranes, as opposed to the more involved process of observing the foetus. 相似文献