应用B型超声波鉴别马胎儿性别

通过胎儿尾部和脐带之间的生殖器结节定位进行马性别诊断，雄性胎儿准确率97．8％（182／186），雌性胎儿99．4％（160／161）。胎儿性别测定的最适时间为妊娠后59d和68d之间。妊娠中期胎儿性别诊断也非常可靠。超声波性别鉴定准确率达100％。在雄性，从100d到220d妊娠常规获得阴茎或包皮的图像；在雌性，从118d到227d妊娠马观察到胎儿乳腺和乳头。在马繁殖上常规使用的5MHz线性传感器，大多数情况下一直可用到妊娠160d。当胎位太高或其大小超过超声设备监测范围时，须使用3．5MHz探头。若掌握好性别鉴定的最适时间和认识正确的解剖结构，两种方法都是非常精确的。     

Equine foetal gender determination in mid‐ to late gestational mares: A practical inquiry

In recent years, the interest in equine foetal gender determination (FGD) during gestation increased remarkably. Ultrasonographic FGD can be performed in two different periods during gestation. The earliest examination can take place at a gestational age of 60–70 days, whereby the genital tubercle is used to differentiate between male and female foeti. The time window of the second approach is wider (120–210 days), and there are more characteristics to take into consideration. In this article, the feasibility and accuracy of ultrasonographic FGD in mid‐ to late gestation are evaluated. One hundred twenty‐one mares from different breeds with a pregnancy stage between 120 and 270 days were examined once, using B‐scale ultrasonography (Esaote MyLab™ClassC). None of the mares were sedated nor shaved, and the procedure was completed within 15 min. Diagnosis was firstly based on the gonads. The final judgement was made based on all visible foetal reproductive organs. In three cases with a pregnancy stage beyond 257 days, FGD was not possible. All of the examined mares in which a FGD could be performed gave birth to a healthy foal. In 98% of the examinations (116/118), the diagnosis was correctly made. In both cases of misdiagnosis, only one characteristic was seen during the procedure and wrongly interpreted. Beyond 210 days of pregnancy, the extremities can preclude a good visualization of the inguinal region. In conclusion, equine FGD in mid‐ to late gestation is an accessible and accurate technique, although a good ultrasound device is a prerequisite and experience and expertise is necessary.     

Early fetal sexing of Saanen goats by use of transrectal ultrasonography to identify the genital tubercle and external genitalia

OBJECTIVE: To define the optimum period for sexing of Saanen goat fetuses by use of transrectal ultrasonography. ANIMALS: 82 Saanen goats pregnant with 124 fetuses. PROCEDURES: Fetal sexing was performed on the basis of the final location of the genital tubercle or identification of external genitalia. In experiment 1, fetuses (n = 78) were monitored every 48 hours from days 40 to 60 of gestation, whereas for experiment 2, 46 fetuses were examined only once between days 47 and 77 of gestation. RESULTS: For experiment 1, accuracy of fetal sexing was 20 of 20 (100%) for a single fetus, 39 of 42 (92.8%) for twin fetuses, and 10 of 16 (62.5%) for triplet fetuses. Diagnostic accuracy was significantly lower for triplet fetuses than that for single or twin fetuses. Final location of the genital tubercle was detected between 45 and 55 days of gestation (mean +/- SEM, 48.9 +/- 1.8 days). For experiment 2, accuracy of fetal sexing for a single fetus (24/24 [100%]) was significantly higher than the accuracy for twin fetuses (16/22 [72.7%]). Considering all fetuses that were born, accuracy of diagnosis was 69 of 78 (88.4%) for experiment 1 and 40 of 46 (86.9%) for experiment 2. Accuracy did not differ significantly between experiments. CONCLUSIONS AND CLINICAL RELEVANCE: Real-time ultrasonography after day 55 of gestation is a suitable method for determination of sex of Saanen goat fetuses by observation of the genital tubercle or identification of external genitalia.     

Determination of the Genital Tubercle Migration Period in Morada Nova Sheep Foetuses by Ultrasonography

The aim of this study was to determine the period of genital tubercle (GT) migration using ultrasonography in Morada Nova sheep foetuses (n = 117) from natural mating (NM) and frozen embryo transfer (ET) to determine the window when foetal sexing can be determined. The examinations were performed using transrectal ultrasonography with a dual-frequency linear transducer (6.0 and 8.0 MHz) from day 30-54 of pregnancy at 48-h intervals. The period of GT migration of foetuses produced by NM varied from 36 to 46 days of pregnancy, resulting in an average of 39.5 +/- 2.9 days. For foetuses derived from ET, GT migration varied from 42 to 52 days of pregnancy with an average of 48.5 +/- 3.3 days, being possible the GT of foetuses from ET start to migrate 96 h later even if they are of the same gender. Migration of the GT occurred earlier (p < 0.05) in foetuses produced by NM and sexing accuracy for triplet pregnancies (77.8%) was significantly inferior (p < 0.05) to single (100%) and twin (92.9%) pregnancies for foetuses derived by NM. The results allow one to conclude that foetal sexing can be done from the 50th day onwards in foetuses produced by NM and from the 55th day onwards in foetuses derived from ET, and that multiple pregnancies compromise the sexing accuracy by ultrasonography.     

Videoendoscopic evaluation of the mare's uterus: III. Findings in the pregnant mare.

During a 5-year period 65 Pony and 20 Thoroughbred pregnant mares were subjected to videoendoscopic hysteroscopy from 10 to 266 days of gestation. The aims of these examinations were to 1) observe foetal and placental development in vivo (60 Pony and 10 Thoroughbred mares); 2) eliminate one of unicornuate twin conceptuses (9 Thoroughbred mares); 3) recover embryonic foetal and placental tissues non-surgically for experimental purposes (47 Pony mares); 4) induce focal separation of the placenta in late gestation as an experimental model of placentitis (5 pony mares and 1 Thoroughbred mare). It was possible to view the embryo and all constituent extra-embryonic membranes of the conceptus between Days 10 and 87 of gestation without having to perforate the allantochorion. This allowed study of physiological processes such as the coordinated uterine contractions responsible for conceptus motility between Days 7 and 17, active foetal movements, which began as early as Day 34, and invasion of chorionic girdle cells into the endometrium, which occurred between Days 34 and 38. From Day 90, vision of the foetus was reduced or prevented by the increased thickness of the allantochorion. Transendoscopic recovery of the conceptus was successful in all of 10 mares under 30 days of gestation, whereas only 10 of 18 attempts between Days 30 and 45 produced the conceptus without resorting to uterine lavage after initial rupture of the allantochorion. All 9 attempts to eliminate one of unilateral twin conceptuses were unsuccessful and the technique was abandoned as clinically unsuitable. Nevertheless, 9 of 22 (41%) single conceptuses remained viable after one or more hysteroscopic examinations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gender determination in equine fetuses between days 50 and 90 of pregnancy

For fetal gender determination, 169 thoroughbred mares were examined with ultrasound between Days 50 and 70 of pregnancy. Sex differentiation was based on the position of the genital tubercle (GT), which during this time window can be located in male fetuses close to the umbilicus and in female fetuses close to the tail. Evaluation of a total of 195 examinations revealed that video-recordings almost doubled the chance to correctly diagnose gender, which was confirmed at birth. Overall, a diagnosis could be achieved in 99 mares only (50.7%), which was correct in 85%. In mares examined between Days 60 and 70, a diagnosis was possible in 46 cases (72%), which was correct in 87% (40 cases). Male fetuses were diagnosed easier due to the larger genital tubercle.     

The radiographic identification of the various stages of pregnancy in the domestic cat

By radiographing intact, recently killed, pregnant cats and then removing the foetuses for crown-rump measurements, a correlation between radio-graphic appearance of foetuses in utero and foetal age is established. The radiographic appearance of the foetuses in utero is described from the twenty-fifth day of pregnancy until full term.

SUMMARY

Using the CR length measurement to assess foetal age, a method of approximately estimating the various stages of pregnancy in cats using radiography was produced. It was seen that, although uterine enlargement and displacement was seen as early as the 25th day, the first signs of the foetal skeletal system were not apparent in utero until the 38th day. From this time a progressive pattern of appearance of ossified parts was noted which allowed a means of estimating the day of gestation.
Résumé. En radiographant des chats en gestation, récemment tués et intacts et en éloignant ensuite le foetus pour mesurer la couronne et la croupe, une correlation entre l'aspect radiographique du foetus in utero et l'âge du foetus est établie. L'aspect radiographique du foetus in utero est décrit depuis le vingt-cinquième jour de gestation jusqu à son terme.
Zusammenfassung. Durch Röntenaufnahmen intakter, kurz zuvor urns Leben gekommener, trächtiger Katzen und anschliessende Entfernung der Foetusse zwecks Scheitel-Rumpf-Messung wurde eine Beziehung zwischen der röntgenologischen Erscheinung der Foetusse in utero und dem foetalen Alter hergestellt. Die röntgenologische Erscheinung der Foetusse in utero wird vom 25. Tag der Trächtigkeit bis zum Austragen beschrieben.     

Ultrasonic diagnosis of equine fetal sex by location of the genital tubercle

Determining sex of the equine fetus by transrectal ultrasonic assessment of the relative location of the genital tubercle (forerunner of penis and clitoris) was studied in 23 mares. Ultrasound examinations were done every other day on Days 35 to 97 or until the fetus was manually removed for comparative diagnosis of sex by gross inspection. In both sexes, the genital tubercle was a hyperechogenic bilobulated structure 2 mm in diameter when first identifiable between Days 40 and 54. Initially, the tubercle was located between the hind limbs and sex was not diagnosable. By a mean of Day 63, the tubercle was immediately caudal to the umbilical cord in males and under the tail in females. The optimal time for sex diagnosis was Days 59 to 68. During this time, the tubercle was readily accessible and assignable to a location characteristic of its sex, and sex was correctly diagnosed for all examinations of all fetuses except for 2 errors in the first mare used in the study. Between Days 69 and 97 all attempted diagnoses were correct, but a diagnosis was not attempted in 13% of the examinations because of difficulty in obtaining an adequate view in some mares. Although the technique was highly accurate for diagnosis of fetal sex, it is emphasized that the operator was experienced and the examining conditions were optimal.     

Heart rate and heart rate variability in the pregnant mare and its foetus

Abortion and preterm birth of foals are major reasons for reproductive losses in the horse. Risk pregnancies require close supervision so that adequate treatment can be initiated in time. The aim of this study was to determine normal values in heart rate (HR) and heart rate variability (HRV) of the pregnant mare compared to her foetus and to detect physiological changes during ongoing gestation. In mares, the RR interval decreased from 1480±29 ms on day 270 of pregnancy to 1190±58 ms on day 330 of pregnancy (p<0.05). In contrast, foetal RR interval increased during the same time period from 611±23 ms on day 270 of gestation to 756±25 ms on day 330 of gestation (p<0.05). Concomitantly, maternal HR increased and foetal HR decreased. No further changes in RR interval occurred during the last 10 days before foaling, neither in the mare nor the foetus. In the last hours preceding parturition, maternal RR interval was lower than at all times earlier in pregnancy (average of 1037±13 ms) but did not change during this time. Maternal HRV did not change during gestation. Marked changes in HRV occurred only during the last minutes of foaling. Then, all HRV variables increased significantly (standard deviation of beat-to-beat interval: p=0.01, root mean square of successive beat-to-beat differences: p<0.01). The cardiovascular system of pregnant mares adapted to the demands of ongoing pregnancy with an increase in HR. We have no evidence that in healthy mares, pregnancy is a major stressor.     

Plasma Testosterone in Cows Related to Day of Gestation and Sex of the Foetus,and Plasma Testosterone Levels Around Parturition

No significant differences in plasma testosterone level were observed between cows carrying a male foetus and cows carrying a female foetus at any ten-day interval from day 35 of gestation until parturition. Reported higher abortion rates for male than for female foetuses would thus appear not to be due to effects of foetal testosterone on the maternal endocrine balance. In spite of a great individual variation in plasma testosterone values at similar stages of gestation, certain trends are evident. From the 35th to the 80th day of gestation the average concentration was 90–100 pg/ml. Later it rose and reached 200 pg/ml on the 180th day, remaining at this level until after partus. During the first day after parturition plasma testosterone fell significantly and stabilized around 120 pg/ml.     

Serial investigations of early pregnancy in pony mares using real time ultrasound scanning

The uteri of 13 pony mares were examined daily by ultrasound during the first two months of gestation. The conceptus was first identified between 12 and 16 days after ovulation and the embryo was seen on the ventral surface of the conceptus after Day 21. The foetal heart could be visualised after Day 22 and spontaneous movement of the foetus occurred after Day 39. No consistent pattern was seen in the development of the foetal membranes, although attachment of the umbilical cord to the allantochorion was always on the dorsal aspect of the conceptus. Daily measurements were made of the diameter of the conceptus and the length of the embryo and foetus.     

Timing of Early Foetal Loss for Single and Twin Pregnancies in Dairy Cattle

The incidence of early foetal loss is increasing under intensive management systems for dairy cattle. The aims of the present study were to determine whether there is any peak period of pregnancy loss during the early foetal period and to evaluate possible differences between single and twin pregnancies. The study population consisted of 1442 pregnant cattle from a single herd. Pregnancy was diagnosed by transrectal ultrasonography between 36 and 42 days after insemination, and then weekly until day 90 of gestation or until pregnancy loss. A total of 1310 cows (90.8%) bore single embryos and 132 (9.2%) carried twins. Pregnancy loss was registered in 139 (9.6%) cows before day 90 of pregnancy: 101 (7.7%) in single and 38 (28.8%) in twin pregnancies. The average time of pregnancy loss for all animals was 58.4 ± 12.6 days and ranged from 45 to 90 days. Seventy‐five per cent of the pregnancy losses were registered between 45 and 60 days of gestation. The average time of pregnancy loss for cows with singletons was 52.1 ± 4.1 days and ranged from 45 to 61 days and that for those with twins was 75.1 ± 12.4 days and ranged from 46 to 90 days. Seventy‐five per cent of the twin pregnancy losses were registered between 68 and 90 days of gestation. Our data show that the foetal loss in singleton pregnancies occurs earlier than in twin pregnancies. Assessment of normal development of gestation on days 60 and 90 after insemination is suggested.     

Increase in plasma progestagen concentrations in the mare after foetal injection with CRH, ACTH or betamethasone in late gestation.

Maternal plasma progestagen concentrations increase about 20 days before parturition. The major contributors to the increase are reduced metabolites (ie 5 alpha-pregnanes). Precocious increases (ie less than 310 days of gestation) in these metabolites may occur in abnormal pregnancies. The effects of CRH, ACTH or betamethasone administered to the foetus at gestational ages ranging from about 250 to 320 days were examined. Sixteen healthy pony mares were used for foetal injection employing aseptic techniques. Water or normal saline were used as controls. Maternal plasma progestagen concentrations were measured using a commercial radioimmunoassay (RIA) progesterone kit and results were confirmed using gas chromatography-mass spectrometry (GC-MS). Results demonstrated clearly that an increase in maternal plasma progestagen concentrations occurred after injection of ACTH, CRH or betamethasone to the foetus, irrespective of gestational age. A comparable increase was not observed in the control animals. Of the 16 mares in which the foetus was injected, 13 produced viable foals at gestational ages ranging from 307 to 339 days whereas 3 mares delivered non-viable foals at 284 to 306 days gestation. The results support the hypothesis that the pre-parturient rise in progestagens occurring in the mare is the result of foetal adrenocortical activity.     

Plasma oestrone and oestradiol concentrations throughout gestation in cattle: relationship to stage of gestation and fetal number

The objectives of the study were to characterise the peripheral plasma oestrone (E1) and oestradiol-17beta (E2) concentrations throughout gestation in the cow and to correlate this with the stage of gestation and fetal number. Cows (n = 10) were equally divided into two groups after non-surgical embryo transfer of in-vitro matured and in-vitro fertilised (IVM - IVF) embryos; Group 1 received a single embryo, Group 2 received twin embryos. Blood was collected about every third day from day 0 (day 0 was defined as first day of standing oestrus), then daily for the last 10 days of gestation and sampling was stopped one day post partum. Plasma E1 concentration exceeded that of E2 throughout gestation in both groups of cows. The time trend concentrations of plasma E1 were significantly affected by the stage of gestation (P < 0.01) and fetal number (P < 0.01) in the last two trimesters of gestation. The time trend concentrations of plasma E2 were significantly affected by the stage of gestation (P<0.01) but not foetal number (P = 0.09). In both groups there was marked preparturient increase in E1 and E2 concentrations. Plasma E2 profile between days 10 prepartum to parturition paralleled E1 in cows carrying a single foetus but was disparate during the same period in the twin-bearing cows.To conclude, our results indicate that although plasma E1 concentration was greater than E2 throughout gestation, both were related to the stage of gestation and that fetal number was correlated with circulating E1 levels in the last two trimesters of gestation.     

Experimental infection of goats at different stages of pregnancy with caprine herpesvirus 1

Three goats from a group of five caprine herpesvirus 1 (CpHV.1) seronegative pregnant goats were inoculated intranasally with a virulent BA.1 strain of CpHV.1. Goat n.1 was infected on day 45 of pregnancy, goat n.2 on day 92 and goat n.3 on day 127. Each of the three goats produced a single foetus 10-60 days after infection. Foetus n.1 was never found and so it could not be examined for virological findings. Goat n.2 delivered at term of gestation and CpHV.1 was detected by PCR and isolated from most of the foetal organs. Foetus n.3 was partially autolysed and the virus was only detected by PCR but not isolated from foetal organs. The results confirm the damaging effect of CpHV.1 infection on pregnancy, the difficulty in diagnosing the CpHV.1 induced abortion, and the importance developing appropriate prophylactic programmes.     

The effects of bovine viral diarrhoea-mucosal disease (BVD) virus on the ovine foetus

Bovine viral diarrhoea-mucosal disease (BVD) virus has been incriminated as a cause of abortion, hairy birth coat and unthriftiness in sheep. Intravenous inoculation of 40 ewes 34 to 45 days pregnant with the V/TOB strain of virus produced death in two of four foetuses 9 days after inoculation and in all but one of 31 foetuses between 11 and 56 days. The highest levels of virus in placentomes and foetal tissues occurred between 9 and 15 days after inoculation and in foetal fluids between 11 and 18 days. Virus was not detected in any foetus later than 21 days after inoculation. Groups of 10 ewes infected between 59 and 62 days (Group B) and 70 and 76 days (Group C) of gestation had 73% and 62%, respectively, of abortions or perinatal foetal deaths. Birth weights of lambs born to infected ewes in groups B and C were significantly lower than those born to uninfected control ewes. Virus was recovered consistently from the cotyledons of the foetal membranes of live lambs, and irregularly from the tissues of full term foetuses that were dead at birth but on no occasion from mummified foetuses. There were no specific gross or microscopic lesions in tissues selected from aborted foetuses and the results highlight the difficulties associated with the diagnosis of BVD abortions and perinatal death of foetuses under field conditions.     

Comparative study of mammary gland development and differentiation between beef and dairy heifers

Sixteen Hereford and 16 Holstein heifers were used to study the relationship of milk production potential to mammary development and differentiation. Heifers were slaughtered 150, 180, and 260 days of first gestation and at 49 days of first lactation. Prolactin binding capacity of mammary tissue was 2.5 fold higher in dairy than beef heifers at day 260 of gestation (27.2 vs 11.0 fmols/mg protein). In both breeds, maximal growth hormone binding in liver coincided with the beginning of the rapid phase of mammary growth at 180 days. Mammary tissue from dairy heifers released more casein and alpha-lactalbumin during in vitro incubations than tissue from beef heifers. No differences were observed between breeds with respect to incorporation of [¹⁴C]acetate into lipids. Mass of dairy mammary tissue at 49 days of lactation was 3.3 times greater (16.4 vs 4.9 kg) and produced 5.7 times more milk (20.3 vs 3.5 kg/day) than its beef counterpart. The total DNA content and the RNA/DNA ratio of lactating dairy mammary tissue was approximately twice that of lactating beef mammary tissue. The data suggested that the higher milk production observed in dairy cattle is a result of a greater number of secretory cells and greater activity per cell.     

Relationship of Progesterone,Bovine Pregnancy-Associated Glycoprotein-1 and Nitric Oxide with Late Embryonic and Early Fetal Mortalities in Dairy Cows

The aim of the present study was to determine the relationship of progesterone (P4), bovine pregnancy-associated glycoprotein-1 (bPAG-1) and nitric oxide (NO) levels with late embryonic (LEM; day 28 to day 42) and early fetal mortalities (EFM; > day 42 to day 56) in dairy cows. Transrectal ultrasonography (6–8 MHz) was performed in 100 Holstein-Friesian cows at days 28, 42 and 56 after artificial insemination (AI; day 0) to diagnose pregnancy and to monitor the fate of the embryo. After ultrasound scanning of each cow, a milk sample was collected for assessment of P4 by an ELISA test and a blood sample was collected for assessment of bPAG-1, by using a double-antibody radioimmunoassay, and serum NO metabolites (nitrate + nitrite). Based on ultrasonographic examinations and bPAG-1-RIA, 41 of 100 inseminated cows were confirmed pregnant at day 28 after AI. Nine cows suffered of LEM, and 6 cows suffered of EFM and the overall pregnancy loss rate was 36.6% (15/41) between days 28 and 56 of pregnancy. By logistic regression analysis, there were no significant relationships between the level of P4 and bPAG-1 at day 28 after AI and the occurrence of LEM and EFM. Also, there were no significant relationships between the levels of P4 and bPAG-1 at day 42 and the occurrence of EFM. On the other hand, a significant relationship (P<0.05) was found between NO level at day 28 and the occurrence of LEM. In conclusion, measurement of the serum NO concentration at day 28 of pregnancy might help to predict the outcome of pregnancy by day 42 in dairy cows but further studies are needed to confirm this.     

Changes in urinary and plasma oestrone sulphate concentrations after induction of foetal death in mares at 45 days of gestation

Foetal death was induced in 10 Standardbred mares at day 45 of gestation by injecting 20 to 45 ml of hypertonic (24% W/V) saline into the conceptus at surgery. Ten mares underwent sham treatment and acted as controls. Blood and urine samples were collected every other day between days 30 and 45 post ovulation and at 0, 3 and 6 h relative to the infusion of saline in the treated mares, or sham treatment in control mares. Blood and urine samples were then collected daily between days 46 and 55 post ovulation. Urine oestrone sulphate (E1S) concentrations, measured by radioimmunoassay, increased between day 34 and day 36 of gestation in treated and control groups. In mares in which foetal death was induced, urine E1S concentrations declined post-operatively and were significantly (p less than .05) lower than controls by day 50. In plasma, E1S concentrations showed a major increase between days 36 and 40 in both groups. This was followed by a rapid decline after treatment in saline-injected mares, so that by day 48 plasma E1S concentrations in treated mares were significantly (P less than .05) lower than the controls. The results show that urinary and plasma E1S concentrations rise rapidly during early pregnancy, and are associated with a viable foetus after day 45 of pregnancy.     

Milk production correlates negatively with plasma levels of pregnancy-associated glycoprotein (PAG) during the early fetal period in high producing dairy cows with live fetuses

This study was designed to establish possible factors affecting plasma pregnancy-associated glycoprotein (PAG) concentrations during early pregnancy in high producing dairy cows with live fetuses. Blood samples were obtained on days 35, 42, 49, 56 and 63 of gestation from 80 lactating cows in two herds carrying live fetuses. Radioimmunoassay systems were used to determine PAG (RIA-497 and RIA-706) and progesterone concentrations. We evaluated the effects on PAG concentrations of herd, lactation number, sire of fetus, day of gestation, fetus number, plasma progesterone and milk production at each time point established, along with possible paired interactions. Mean milk production per cow approached 41kg during the study period. PAG concentrations were not affected by herd, lactation number or plasma progesterone concentration. Significant positive effects on PAG concentrations were shown by the gestation day, and the interaction between day of gestation and twin pregnancy. Significant differences between bulls and a significant negative correlation between milk production and PAG values on day 63 of pregnancy were also detected. Proportions of blood samples showing undetectable PAG levels and false negative diagnoses throughout the study period were significantly higher (P<0.001) using the RIA-497 system (2.5% and 5.3%, respectively) compared to RIA-706 (0% and 0.8%, respectively). Our findings suggest that PAG concentrations during the early fetal period are related to the day of gestation, milk production, number of fetuses and sire of fetus in high producing dairy cows. Under our working conditions, the RIA-706 method was better at detecting plasma PAG molecules than the RIA-497 system.