Studies on early pregnancy diagnosis and fetal physiology in cattle by real-time ultrasonography

采用实时超声技术对93头奶牛进行了发情周期子宫图像的观察、早孕诊断、胎儿观察及胎儿心跳对胎儿生理的研究。所得结果总结如下：1。在人工授精（AI）后17 ~ 24天进行早期妊娠诊断。95%的怀孕牛在人工智能后22至24天获得了清晰的胎囊（FS），显示无回声区图像，表明怀孕。但FS图像与子宫黏液图像难以区分。17 ~ 21天妊娠诊断准确率为25%，22 ~ 24天妊娠诊断准确率为86.4%，总诊断准确率为45.2%。胎儿在人工智能后29天首次可见，并通过直肠扫描拍摄其图像，直至妊娠约150天。在妊娠29 ~ 53天测量胎儿冠臀长（CRL）。胎龄与CRL呈极显著正相关（gamma=0.926）。人工授精与胚胎移植及分切胚胎移植的相关性无显著性差异。妊娠约60天后可见胎儿内部结构图像。胎儿骨骼引起的声影起初未见。妊娠80 ~ 90天可见胎心室间隔、左右心室。胎龄与胎心率在60天前后呈微正相关，60天后呈高度负相关。观察胎儿短期心率变化，平均变化20次/min。在妊娠34、34、36、77、83天均可诊断出胚胎移植或分切胚胎移植的双胞胎，证实USG可用于妊娠早期胎数的确定。

By real-time ultrasonography,observation of images of uteruses during the estrous cycle,diagnosis of early pregnancy,observation of fetuses and investigate to fetal physiology from fetal heart beat were performed in total 93 dairy cattle. The results obtained are summarized as follows;1. Early pregnancy diagnosis of heifers was performed between 17 and 24 days after artificial insemination(AI).Clear fetal sac (FS) showing echofree area images indicating pregnancy were obtained between 22 and 24 days after AI in 95% of pregnant cattle. But it was difficult to distinguish between FS images and uterine mucus fluid images. Accuracy of pregnancy diagnosis was 25% between 17 and 21 days,86.4% between 22 and 24 days and 45.2% in total.2. The fetuses were first visible on 29 days after AI, and thier images were taken by rectal sanning up to about 150 days of gestation.3. Fetal crown-rump length(CRL) measurements were made from 29 to 53 days of gestation. A highly significant positive correlation was observed between the fetal age and CRL(gamma=0.926). There was no difference of the correlation among fetuses resulted from AI,embryo transfer and bisected embryo transfer.4. Fetal internal structure image could be seen after about 60 days of gestation. Acoustic shadows caused by fetal skeltons were not observed at the beginning. Interventricular septum,right and left ventricular chamber of fetal heart could be seen after 80 or 90 days of gestation.5. Correlation between the fetal age and the fetal heart rate was positive slightly up to about 60 days and the after it was negative highly. Variation of fetal heart rate in short term was observed and the mean variation was 20/min.6. Twins resulted from embryo transfer or bisected embryo transfer could be diagnosed on 34,34,36,77 and 83 days of gestation which confirmed that USG could be applied to determine fetal numbers in early gestational period.