Ultrasonography for detection of early pregnancy following embryo transfer in unknown breed of Bos indicus cows

Recent Possibilities for the Diagnosis of Early Pregnancy and Embryonic Mortality in Dairy Cows

Simple Summary

Pregnancy diagnosis plays an essential role in decreasing days open in dairy farms; therefore, it is very important to select an accurate method for diagnosing early pregnancy. Besides traditional pregnancy diagnoses made by rectal palpation of the uterus from 40 to 60 days after AI and measuring the serum or milk progesterone concentration between 18 to 24 days after AI, there are several new possibilities to diagnose early pregnancy in dairy farms. However, it is very important to emphasize that before introducing any new diagnostic test, we need to make sure the accuracy of that particular test to be able to decrease the rate of iatrogenic pregnancy losses caused by prostaglandin or resynchronization treatments. This review focuses on the diagnostic possibilities and limitations of early pregnancy diagnosis in the field.

Abstract

One of the most recent techniques for the on-farm diagnosis of early pregnancy (EP) in cattle is B-mode ultrasonography. Under field conditions, acceptable results may be achieved with ultrasonography from Days 25 to 30 post-AI. The reliability of the test greatly depends on the frequency of the transducer used, the skill of the examiner, the criterion used for a positive pregnancy diagnosis (PD), and the position of the uterus in the pelvic inlet. Non-pregnant animals can be selected accurately by evaluating blood flow in the corpus luteum around Day 20 after AI, meaning we can substantially improve the reproductive efficiency of our herd. Pregnancy protein assays (PSPB, PAG-1, and PSP60 RIA, commercial ELISA or rapid visual ELISA tests) may provide an alternative method to ultrasonography for determining early pregnancy or late embryonic/early fetal mortality (LEM/EFM) in dairy cows. Although the early pregnancy factor is the earliest specific indicator of fertilization, at present, its detection is entirely dependent on the use of the rosette inhibition test; therefore, its use in the field needs further developments. Recently found biomarkers like interferon-tau stimulated genes or microRNAs may help us diagnose early pregnancy in dairy cows; however, these tests need further developments before their general use in the farms becomes possible.

Early embryo losses, progesterone and pregnancy associated glycoproteins levels during summer heat stress in dairy cows

Objectives of this study were to characterize the effects of heat stress on pregnancy associated glycoproteins (PAG) and progesterone and its involvement in embryo survival. In trial 1, blood samples collected from days 29 to 36 post insemination were examined for the comparison of PAG concentrations between winter (n = 3721) and summer (n = 2388). In trial 2, embryo losses were assessed in winter (n = 144) and in summer (n = 133), in days 31 or 32 of pregnancy. Pregnancy diagnosis was carried out by ultrasonography on days 24 or 25, and it was repeated a week later; in the second occasion PAG concentration was also determined. In trial 3 the PAG and progesterone concentrations were assessed in days 33 to 36 in winter and summer. In trial 1 PAG levels did not differ between winter and summer, the conception rate and the proportion of uncertain pregnancies were higher in winter than summer. The likelihood of pregnancy was 10 to 15% higher in winter. In trial 2, the embryo death rate was higher in summer, but the PAG levels of cows that had embryo loss in summer were higher than those in winter. In both seasons, lower PAG levels were associated with higher risk of pregnancy loss, while embryo death was five times more likely to occur in summer than in winter and lower PAG concentrations were positively associated with higher risk of embryo loss. In trial 3, mean PAG levels were higher and of progesterone were lower during the summer than during the winter. We infer that despite the devastating effects of heat stress on cows' fertility, those early embryos that survive under continuous heat stress can form a well-functioning placenta; hence, the high embryo mortality rate observed during the summer months could be mainly attributed to luteal insufficiency.

Efficacy and limitations of different approaches to anticipate the diagnosis of pregnancy in cattle

ABSTRACT The study evaluated sonographic and serologic exams performed for early (20 to 30d) diagnosis of pregnancy. One hundred-twenty (n= 120) bovine recipients were synchronized (estrous=D0) and timed embryo transferred (TET, D7) with fresh in vitro produced embryos. In the first trial (n= 46), diagnosis of pregnancy was performed on day 20 (D20) by detecting CL blood flow (BF) and by Pregnancy-Associated Glycoproteins (PAGs) serology. In the second trial (n= 30), pregnancy diagnosis was performed on D25 by ultrasound visualization of uterine contents and by PAGs serology. In the last trial, PAG’s serology was performed on D30. Ultrasonographic detection of the uterine contents and embryo viability performed on D30 (DG30) was considered the gold standard. The PROC FREQ procedure was used to test the agreement between diagnostic methods. On D20, the Doppler ultrasonography of the CL had showed high sensitivity (100%), but only moderate specificity (53.3%). On the same day, serologic diagnostic had no agreement (k= -0.08, P< 0.46) with the gold standard, with very low sensitivity (6.3%). However, the sensitivity of the serologic exam increased dramatically (from 6.3 to 100%) from D20 to D25, and it contributed to detect false negatives from the ultrasound diagnosis, improving the overall accuracy from 90% to 96.7%.

Two dimensional trans-rectal ultrasonographic studies in early pregnant murrah buffaloes

Two dimensional ultrasonographic studies were conducted in six pregnant Murrah buffaloes using 5.0-7.5 MHz frequency rectal probe twice a week from day 18 to 60 days followed by weekly interval up to 90 days postin semination. Two dimensional images of antenatal fetal organs particularly fetal stomach, eye, limbs, heart, umbilical cord, thorax, liver and placentomes were imaged and variat ions in size of placentome, stomach and crown rump length were measured. Fetal heart beat was measured from day 26 to 90 which decreased with advancement of gestation. From the present study it may be concluded that early pregnancy can be diagnosed ultrasonogra phicallythrough trans-rectal approach by day 26 post insemination.

Expression of fibroblast growth factor 10 and cognate receptors in the developing bovine ovary

In the mammalian ovary, FGF10 is expressed in oocytes and theca cells and is a candidate for paracrine signaling to the developing granulosa cells. To gain insight into the participation of FGF10 in the regulation of fetal folliculogenesis, we assessed mRNA expression patterns of FGF10 and its receptors, FGFR1B and FGFR2B, in relation to fetal follicle dynamics and localized FGF10 protein in bovine fetal ovaries at different ages. Primordial, primary, secondary, and antral follicles were first observed on Days 75, 90, 150, and 210 of gestation, respectively. The levels of GDF9 and BMP15 mRNA, markers for primordial and primary follicles, respectively, increased during fetal ovary development in a consistent manner with fetal follicle dynamics. CYP17A1 mRNA abundance increased from Day 60 to Day 75 and then from Day 120 to Day 150, coinciding with the appearance of secondary follicles. FGF10 mRNA abundance increased from Day 90, and this increase was temporally associated with increases in FGFR1B mRNA abundance and in the population of primary follicles. In contrast, FGFR2B mRNA expression was highest on Day 60 and decreased thereafter. FGF10 protein was localized to oogonia and oocytes and surrounding granulosa cells at all fetal ages. The present data suggest a role for FGF10 in the control of fetal folliculogenesis in cattle.

Early pregnancy diagnosis by transrectal ultrasonography in dairy cattle

The objective of the present study was to determine differences in time of detection of pregnancy between heifers and cows and the interval after insemination at which the maximum sensitivity and negative predictive value of transrectal ultrasonography were obtained. One-thousand-four-hundred transrectal ultrasonographies (TRUS-1; 1,079 in cows and 321 in heifers) were performed using a 5-MHz linear-array transducer. The cattle were randomly assigned to have TRUS performed once between days 24 and 30 (estrus=day 0) in cows or between days 21 and 27 in heifers. Every TRUS diagnosis was subsequently compared with a second TRUS diagnosis (TRUS-2), performed 3-8 days later, after day 30 (range 31-38) for cows and after day 27 (range 28-35) for heifers. The sensitivity and specificity between cows and heifers for the common days of TRUS (from 24 to 27) were compared. In cows, sensitivity increased gradually from 74.5% at day 24 to 100% at day 29 (P<0.01). Specificity increased from days 24-25 and reached a plateau of 96.6% on day 26 (P<0.01). In heifers, sensitivity increased from 50% at day 21 to 100% at day 26 (P<0.01). Specificity increased from 87.5% at day 21 and remained steady at 94% starting on day 23 (P>0.05). The sensitivity for cows and heifers was 89.2 and 96.8%, respectively (P<0.05) and the specificity was 93.0 and 93.4% (P>0.05). In this study, heifers were diagnosed pregnant earlier than cows, and the maximum sensitivity and negative predictive value were obtained 3 days earlier in heifers than cows (days 26 and 29, respectively).

Ultrasonographic screening of embryo development in cattle (Bos indicus) between days 20 and 40 of pregnancy

Through a transrectal ultrasonography (Aloka SSD 500 microplus equipment, linear transducer of 7.5 MHz) a total of 267 observations were performed in a group of 50 females mainly Bos indicus, raised under humid tropical conditions and pregnant from day 20 every other day until day 40 post-artificial insemination (AI). The objective was to measure the size of the amniotic vesicle and the longitudinal and transversal axis of the embryo, to determine the day in which it is possible to measure this structure and detect the heart contractions in the screened embryos. The accuracy in identifying the amniotic vesicle was 60% (12/20) on day 20 of the first screening with embryos having an average length of 0.44 +/- 0.20 cm. Accuracy in detecting the embryo was 66.6 and 100% between days 20 and 24 post-breeding, respectively. The mean length of the embryos on day 20 was of 0.20 +/- 0.07 cm and the transversal shape had a mean length of 0.07 +/- 0.02 cm. The accuracy of detecting heart contractions was 50% (9/18) on day 24 post-breeding and for day 26 the accuracy was 100%. At the end of the screening (day 40), embryos had means of 1.92 +/- 0.24 (longitudinal) and 0.85 +/- 0.11 cm (transverse). The embryo can be detected from day 24 post-AI and the heart contractions from day 26 with 100% reliability.

Ultrasonographic imaging to monitor early pregnancy and embryonic development in the buffalo ()

Real time B-mode ultrasound was used to detect and monitor the early conceptus, its growth and its anatomical features in 26 buffalo between Days 18 and 62 of gestation. The buffalo were artificially inseminated, and the conceptuses were examined on alternate days beginning on Day 18. The embryonic vesicle and the embryo proper within the vesicle was first visible in 12 of the buffalo on mean Day (+/-SD) 19.00+/-2.1 and Day 19.0+/-1.69, respectively. The heartbeat of the embryo proper could be detected on Day 29.6+/-1.57. The heart rate of 203.8+/-9.0 beats per minute on the first day of detection decreased to 150 beats per minute on Day 62. The allantois, amnion, fore limbs, spinal cord and hind limbs were first identified on Day 30.0+/-1.14, Day 33.4+/-1.64, Day 34.6+/-1.34, Day 35.8+/-2.52 and Day 36.8+/-2.34, respectively. The optic area was first distinguished on Day 38.2+/-2.39. Split hooves, fetal movement, ribs and vertebra were identified on Day 46.0+/-2.64, Day 49.4+/-2.31 and Day 59.8+/-2.39, respectively. The mean length of the embryo proper was 4.2 mm on Day 19 which later increased to 53.6+/-2.1 mm on Day 62.