Pregnancy Loss in Dairy Cattle: Relationship of Ultrasound, Blood Pregnancy-Specific Protein B, Progesterone and Production Variables

Multi-Omics Reveals the Role of Arachidonic Acid Metabolism in the Gut-Follicle Axis for the Antral Follicular Development of Holstein Cows

In vitro embryonic technology is crucial for improving farm animal reproduction but is hampered by the poor quality of oocytes and insufficient development potential. This study investigated the relationships among changes in the gut microbiota and metabolism, serum features, and the follicular fluid metabolome atlas. Correlation network maps were constructed to reveal how the metabolites affect follicular development by regulating gene expression in granulosa cells. The superovulation synchronization results showed that the number of follicle diameters from 4 to 8 mm, qualified oocyte number, cleavage, and blastocyst rates were improved in the dairy heifers (DH) compared with the non-lactating multiparous dairy cows (NDC) groups. The gut microbiota was decreased in Rikenellaceae_RC9_gut_group, Alistipes, and Bifidobacterium, but increased in Firmicutes, Cyanobacteria, Fibrobacterota, Desulfobacterota, and Verrucomicrobiota in the NDC group, which was highly associated with phospholipid-related metabolites of gut microbiota and serum. Metabolomic profiling of the gut microbiota, serum, and follicular fluid further demonstrated that the co-metabolites were phosphocholine and linoleic acid. Moreover, the expression of genes related to arachidonic acid metabolism in granulosa cells was significantly correlated with phosphocholine and linoleic acid. The results in granulosa cells showed that the levels of PLCB1 and COX2, participating in arachidonic acid metabolism, were increased in the DH group, which improved the concentrations of PGD2 and PGF2α in the follicular fluid. Finally, the expression levels of apoptosis-related proteins, cytokines, and steroidogenesis-related genes in granulosa cells and the concentrations of steroid hormones in follicular fluid were determinants of follicular development. According to our results, gut microbiota-related phosphocholine and linoleic acid participate in arachidonic acid metabolism in granulosa cells through the gut-follicle axis, which regulates follicular development. These findings hold promise for enhancing follicular development and optimizing oocyte quality in subfertile dairy cows.

Evaluation of a Commercial Pregnancy Test Using Blood or Plasma Samples in High-Producing Dairy Cows

This study evaluated a commercial pregnancy-associated glycoproteins (PAGs)-based pregnancy test using whole blood or plasma samples during early pregnancy (28-55 days of gestation) in high-producing dairy cows. Transrectal ultrasonography was used as the gold standard method. The study population constituted of 284 cows. False positive diagnoses were recorded from Day 60 to 89 and from Day 60 to 99 postpartum in blood and plasma samples, respectively. In early pregnancy screening, correct positive diagnoses were recorded in 75% and 100% of blood and plasma samples, respectively. High milk production was associated with negative results in blood samples and with the lowest test line intensity in plasma samples. False positive or negative diagnoses were recorded in 0% of both types of samples in cows previously diagnosed as pregnant and showing signs of estrus. In conclusion, the use of plasma was more effective than the use of blood in early pregnancy diagnosis. In cows previously diagnosed as pregnant and showing signs of estrus, both types of samples showed the same results. Because of large individual variations, normal single pregnancies could not be differentiated from twin pregnancies, from pregnancies with a recently dead conceptus, or from pregnancies that experienced subsequent pregnancy loss.

Recent advances in early pregnancy loss diagnosis in dairy cows: New approaches

Early pregnancy loss is a primary cause of low reproductive rates in dairy cows, posing severe economic losses to dairy farming. The accurate diagnosis of dairy cows with early pregnancy loss allows for oestrus synchronization, shortening day open, and increasing the overall conception rate of the herd. Several techniques are available for detecting early pregnancy loss in dairy cows, including rectal ultrasound, circulating blood progesterone, and pregnancy-associated glycoproteins (PAGs). Yet, there is a need to improve on existing techniques and develop novel strategies to identify cows with early pregnancy loss accurately. This manuscript reviews the applications of rectal ultrasound, circulating blood progesterone concentration, and PAGs in the diagnosis of pregnancy loss in dairy cows. The manuscript also discusses the recent progress of new technologies, including colour Doppler ultrasound (CDUS), interferon tau-induced genes (ISGs), and exosomal miRNA in diagnosing pregnancy loss in dairy cows. This study will provide an option for producers to re-breed cows with pregnancy loss, thereby reducing the calving interval and economic costs. Meanwhile, this manuscript might also act as a reference for exploring more economical and precise diagnostic technologies for early pregnancy loss in dairy cows.

Noninfectious Causes of Pregnancy Loss at the Late Embryonic/Early Fetal Stage in Dairy Cattle

In cattle, initial pregnancy diagnosis takes place during the late embryonic/early fetal stage of gestation. From this point onward, pregnancy loss may occur in up to one fifth of pregnancies before the initial pregnancy diagnosis is confirmed. This means the early identification of risk factors is a key part of pregnancy diagnosis and herd management. The various factors responsible for pregnancy losses are classified into infectious and noninfectious. Among the noninfectious causes, several dam-related (circumstances of the individual pregnancy or milk production) and herd-related factors causing stress have been well established. In this review, we summarize the impacts of these noninfectious factors and predict associated risks of pregnancy loss.

Impact of postpartum time period associated body condition score on reproductive performance in dairy cows

This study was designed to identify the time period at which the body condition score (BCS) most critically affects the reproductive performance after calving in dairy cows. Data were collected from 4865 lactation records (1821 from primiparous and 3044 from multiparous cows) on 28 dairy farms, including the BCS (at calving, and month 1 and the first artificial insemination [AI] after calving), the presence of peri- or postpartum disorders, reproductive data, and the weather. The data on the extent of BCS loss from calving to the first AI was divided into two periods, namely, between calving and month 1 after calving (period 1), and between month 1 and the first AI after calving (period 2). Cows with BCS of 3.0, 3.25 and ≥ 3.5 at the first AI after calving were more likely (P < 0.05-0.01) to be pregnant at 30 (odds ratio [OR]: 1.36, 1.64, and 1.90) and 45 (OR: 1.39, 1.75, and 1.99) days post-AI and more likely (P < 0.05-0.01) to be pregnant within 180 days after calving (hazard ratio [HR]: 1.18, 1.43, and 1.58) than cows with BCS of ≤2.75. In addition, cows who suffered a BCS loss of ≥0.5 units during period 1 tended to be less likely (HR: 0.79, P < 0.1) to be pregnant within 180 days after calving than cows without a BCS loss. Cows with BCS of 3.0, 3.25, and ≥3.5 at calving were less likely (P < 0.1-0.05) to lose their pregnancy (OR: 0.37, 0.33, and 0.16) than cows with BCS of ≤2.75. These results indicate that the linearly higher BCS (3.0, 3.25, and ≥3.5) at the first AI is positively associated with the probability of pregnancy per AI after the first AI and the likelihood of pregnancy within 180 days after calving, whereas a higher BCS loss of ≥0.5 units during period 1 was adversely associated with the likelihood of pregnancy within 180 days after calving.

Review: Initial increase in pregnancy-specific protein B in maternal circulation after artificial insemination is a key indicator of embryonic survival in dairy cows

Lactating dairy cows have reduced chances for pregnancy survival following 1st parturition. It appears that timing of conceptus attachment, defined as an initial daily rise in pregnancy-specific protein B (PSPB) postartificial insemination (AI), is key to the survival of the embryo. PSPB is a protein produced from binucleate cells of the trophectoderm of the conceptus. Once the conceptus has attached to the uterine epithelial cells, this large protein is detectable in maternal circulation. Daily sampling of serum allows for detection of the initial increase of PSPB. A percent increase threshold for PSPB was determined from results from each study using a conservative three-day minimum increase. Thus far, a 10 or 12.5% daily increase for three consecutive days had the greatest sensitivities and specificities for studies reported in this review. Nulliparous heifers receiving AI following estrus appear to have a reduced time to conceptus attachment compared to lactating cows that received either Ovsynch or AI following estrus. Increasing progesterone post-AI did not reduce time to conceptus attachment in lactating cows. Multiparous cows treated post-AI with human chorionic gonadotropin had a reduced percent with conceptus attachment in addition to greater time to conceptus attachment. Increased time to conceptus attachment increased the chances of multiparous cows having embryonic death before 35 d post-AI. Concentrations of PSPB are consistently reduced from conceptus attachment until d 28 post-AI in cows with pregnancy loss compared to cows that maintain pregnancy on d 34 post-AI. This novel model to determine timing of conceptus attachment provides a new perspective on percent of cows pregnant around d 20-23 post-AI and the potential for a greater understanding of subsequent pregnancy loss.

Associations of antral follicle count with fertility in cattle: A review

Ovarian antral follicle count (AFC) is a marker of ovarian stimulatory response to superovulation protocols in cattle. This article reviews novel research from the past 10 years, focusing on the relationship between AFC and embryo production and cow fertility. Substantial evidence indicates a positive relationship between AFC with embryo production; however, conflicting findings exist regarding the relationship of AFC with conception and pregnancy rates. This lack of consistent association with pregnancy outcomes is perplexing given the differences detected in oocytes, embryos, and endometria from high- versus low-AFC animals. Those differences include markers of embryonic viability such as protein level, blastocyst development rates, cleavage rates, and blastocyst cell numbers that differ between high- and low-AFC groups, as well as differential gene expression at the cow and embryo level with genes associated with fertility. In addition, Bos indicus and Bos taurus cattle appear to have different fertility responses based on their AFC category. In summary, clearly more studies are needed to elucidate the true associations between AFC and cow fertility, but the data that have been accumulated thus far indicate that AFC has the potential to be a useful marker of lifetime cow fertility.

Is pregnancy loss initiated by embryonic death or luteal regression? Profiles of pregnancy-associated glycoproteins during elevated progesterone and pregnancy loss

Because progesterone (P4) is essential for pregnancy establishment and maintenance, we investigated the effect of increased concentrations of P4 on embryonic attachment and concentrations of pregnancy-associated glycoproteins (PAG). Additionally, we investigated the relationships among luteal regression, pregnancy loss, and PAG concentrations in cows undergoing pregnancy loss by d 33 of pregnancy. Lactating dairy cows were allocated into control (n = 40) and human chorionic gonadotropin (hCG; 3,300 IU on d 7 and 13 to promote greater circulating P4; GnRH = d 0; n = 46) groups. Progesterone was measured daily from d 7 to 33, and PAG was measured daily from d 17 to 33; both hormones were also measured on d 47 and 61. An increase in PAG >10% compared with d 17 was considered a marker for pregnancy. The gold standard for pregnancy diagnosis was ultrasound evaluation of embryonic heartbeat on d 33. Statistical analyses were done with PROC MIXED from SAS Institute Inc. Concentrations of P4 were greater from d 8 onward in the hCG group. Concentrations of PAG did not differ between groups from d 17 to 33, suggesting no effect of increased P4 on hastening embryonic attachment and placental development. Nevertheless, PAG was greater in the hCG group on d 47 and 61, suggesting greater placental area or PAG secretory capacity. Pregnancy loss between d 20 and 33 occurred in 24.6% of cows. About 50% of pregnancy loss was due to luteal regression and about 50% was due to conceptus failure; that is, a decrease in PAG in the absence of luteal regression. In conclusion, increased P4 does not hasten embryonic attachment or early placental development but it leads to increased PAG in the second half of the second month of gestation. Additionally, pregnancy loss seems to be initiated by either corpus luteum regression or conceptus failure.

Dairy heifers have an earlier increase in serum pregnancy-specific protein B compared with lactating dairy cows. Is this an indicator of earlier conceptus attachment?

This study was designed to use within-individual daily increases in circulating pregnancy-specific protein B (PSPB) to determine time to increase in serum PSPB in nulliparous heifers and multiparous dairy cows following artificial insemination (AI). Weekly cohorts of lactating Holstein cows (n = 56) averaging 122 ± 7 d in milk at AI and nulliparous Holstein heifers (n = 23) averaging 16 ± 0.24 mo old at AI were used in this study. Lactating cows received AI to either Ovsynch (n = 38) or at ~12 h following observed standing estrus (n = 18). All heifers were inseminated ~12 h after observed standing estrus. Blood samples for measurement of PSPB were collected daily from d 15 through d 35 postovulation. Nulliparous heifers had increases in serum PSPB earlier compared with both primiparous and multiparous cows. Day of increase in serum PSPB was defined as the day serum PSPB optical density levels initially increased ≥10% from baseline and continued to increase from baseline of ≥10% the following 2 d. Average PSPB were greater in pregnant heifers compared pregnant cows from d 23 through 29. Early lactation nonpregnant cows maintained greater average optical density of serum PSPB from 15 to 35 d postovulation compared with nonpregnant heifers (n = 38). In summary, fertility differences in heifers versus lactating cows may be due to the differences in timing of increases in serum PSPB. This appears to be one of the first publications that used daily PSPB sampling to investigate possible differences in fertility in heifers versus lactating cows.

Transfer of a single fresh in vitro-produced embryo may prevent twin pregnancy without compromising the fertility of the cow

This study examines whether the transfer of a fresh in vitro-produced (IVP) embryo can avoid the risk of twin pregnancy without reducing the fertility of a cow. The study population was comprised of 416 lactating dairy cows synchronized for oestrus: 294 were fixed-time inseminated (AI cows), and 122 were given GnRH treatment at the time of embryo transfer (ET) an IVP embryo (ET cows). Of the 416 cows, 167 (40.1%) became pregnant. Twin pregnancy was recorded in 20.8% of the AI pregnant cows (21/101), whereas no ET cows had twins (0/66). Significant interaction (p < .01) was observed between breeding technique and the period of the year for the likelihood of pregnancy. This meant that using AI cows during the warm period (May-September) as reference, the odds ratio for pregnancy in ET cows during the warm period was 3.4 (p = .001). In conclusion, transfer of a single fresh IVP embryo proved useful to prevent the risk of twin pregnancy without affecting fertility.

Pregnancy and parturition in dromedary camels II. Incidence, timing and factors affecting early pregnancy loss (EPL) and the outcome of twin pregnancies

In this paper, we described the incidence of early pregnancy loss (EPL) both after natural mating and embryo transfer, evaluated risk factors, and summarized the outcome of twin pregnancies throughout gestation in dromedaries under reproductive care. Data were collected over seven breeding seasons at the world's largest camel dairy farm (study 1). In addition, we determined the timing of EPL and monitored serum progesterone (P4) concentration between Days 13-70 of gestation during one breeding season (study 2). In the first study, out of 2970 pregnancies, 507 cases (17.1%) of EPL were diagnosed with transrectal ultrasonography. The rate of EPL after natural mating and embryo transfer was 16.1% (n = 422 out of 2616) and 24.0% (n = 85 out of 354), respectively. Twin pregnancies were detected in 215 cases (7.2% of all gestations), and 57 of those (26.5%) underwent complete EPL. Almost half of the early losses (n = 243; 47.9%) occurred before 30 d of gestation. Another 43.2% (n = 219) of EPL was diagnosed during the next month, and 8.9% (n = 45) occurred after 60 d of gestation. Multivariable mixed effects logistic regression models revealed that the breeding season (year) and twin pregnancy were the most important exposure variables affecting the rate of EPL (P < 0.001). The effect of some male camels was also demonstrated while other factors, such as type of breeding, age category, month of mating, breed/ecotype and reproductive history did not prove to have a significant influence. In the second study, the overall rate of EPL was 24.5% (n = 34 of 139). There was no difference in the incidence of EPL between ET recipient (24.2%, n = 23 of 95) and mated (25%, n = 11 of 44) camels. Weekly rate of EPL ranged from 0.9% to 4.8% with a decreasing tendency, and approx. 41% of the animals (n = 14 of 34) had some ultrasonographic signs of impending EPL 1 week before the final diagnosis. Mean serum P4 concentration in camels with subsequent EPL was 5.3 ± 0.1 ng/ml compared to 5.6 ± 0.04 ng/ml in normal pregnant dromedaries. Day of gestation and future EPL influenced serum P4 levels (P < 0.001) with an interaction between the two fixed factors (P < 0.05). At the time of the final diagnosis of EPL, mean serum P4 concentration was 2.8 ± 0.44 ng/ml. Although twinning had an unfavorable prognosis with a total pregnancy loss of 36.7%, it was not entirely detrimental for the final outcome of gestation as two-thirds of twin pregnancies (n = 136 out of 212) resulted in the birth of a live calf.

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.

Practical Aspects of Twin Pregnancy Diagnosis in Cattle

Simple Summary

This review summarizes the clinical background, possibilities, and limitations of twin pregnancy diagnosis in cattle, with a special emphasis on pregnancy loss aspects. Due to the fact that reproductive performance is strongly affected by twin pregnancy, clinical veterinarians should become familiar with the correct diagnosis of this phenomenon. Thus, each herd must plan a herd-specific management practice to detect twin pregnancies. A highly accurate diagnostic tool is required to detect such pregnancies, already during the first month of gestation. This commentary review focuses on the diagnostic possibilities and limitations on the field.

Abstract

Twin pregnancies are an economically unwanted phenomenon in dairy cattle, not only because they increase pregnancy losses, but also because antibiotics usage and culling rate of the dam are also dramatically increased due to them, furthermore animal welfare issues are also affected through them. In cattle, under field conditions using an early pregnancy determination tool, the first accurate diagnosis from the pregnancy status is available from around day 28, although further confirmations of pregnancy are required. Twin pregnancy diagnosis is available either by rectal palpation or ultrasonography. The measurement of pregnancy specific proteins are also available to determine gestation, but there is still a long way to go to properly identify twin pregnancies. In this commentary, we compared our own results with the literature data in this field with a special emphasis on the clinical practices.

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.

Characterization of pregnancy-associated glycoproteins and progesterone as a predictor of twins and conceptus loss in high-risk-pregnancy Holstein cows

The objective of this study was to characterize plasma concentrations of pregnancy-associated glycoprotein (PAG) and progesterone (P4) as predictors of twins and pregnancy loss in Holstein cows with high-risk pregnancies. High-risk pregnancy was characterized using transrectal ultrasonography 37 d after artificial insemination (AI) based on the following criteria: small embryo size <15 mm, n = 10), slow heartbeat (<60 beats per minute, n = 11), and extra-amniotic membrane (additional amniotic membrane, n = 3). A cohort of twins (n = 41) diagnosed at d 37 post-AI was also enrolled. Each high-risk and twin pregnancy cow was paired with a cow of the same parity carrying a normal singleton at d 37 post-AI (control, n = 65). Blood samples were collected to measure PAG and P4 at d 37, 44, and 51 post-AI. Statistical analysis was performed using ANOVA, logistic regression, and receiver operator characteristic (ROC) curve with JMP software (SAS Institute Inc., Cary, NC). Pregnancy loss at d 51 post-AI was greater in high-risk pregnancies than in controls and twins (control = 1.5%; high-risk = 87.5%; twins = 12.2%). Concentration of PAG at d 37 post-AI did not differ among groups (control = 5.3 ± 0.7; high-risk = 4.8 ± 1.2; twins = 4.0 ± 0.9 ng/mL). Concentration of P4 at d 37 post-AI was greater in twins than in high-risk pregnancies and control, and lesser in high-risk pregnancies than in controls (control = 7.0 ± 0.3; high-risk = 5.9 ± 0.4; twins = 8.4 ± 0.3 ng/mL). Regression and ROC analysis for PAG at d 37 post-AI did not find a threshold to predict pregnancy loss or twins. Regression and ROC analysis for P4 at d 37 post-AI found that a threshold of 6.5 ng/mL predicted pregnancy loss with an area under the curve (AUC) of 0.64, and a threshold of 7.2 ng/mL predicted twins with AUC of 0.71. In summary, pregnancy loss and twins were predicted with only moderate accuracy by P4 concentration at d 37 post-AI, and the variability in PAG concentrations at d 37 post-AI was not sufficient to generate a threshold to predict pregnancy loss and twins in Holstein lactating cows.

Alterations in pregnancy-associated glycoprotein concentrations of pregnant sheep experimentally infected with bovine viral diarrhea virus

OBJECTIVE

To compare pregnancy-associated glycoprotein 1 (PAG1) concentrations in maternal (jugular vein) and fetal (uterine vein) circulations and amniotic fluid samples between pregnant ewes that were and were not experimentally infected with bovine viral diarrhea virus (BVDV).

ANIMALS

11 healthy pregnant yearling ewes.

PROCEDURES

Before study initiation, all ewes were naïve to BVDV and confirmed pregnant by transabdominal ultrasonography at approximately 60 days of gestation. At 65 days of gestation, ewes were intranasally inoculated with a noncytopathic BVDV type 1b strain (concentration, 10⁷ TCID₅₀/mL; 2 mL/nostril; n = 6) or an equal volume of BVDV-free viral culture medium (control; 5). A blood sample was collected for measurement of PAG1 concentration before inoculation. At 80 days of gestation, each ewe was anesthetized and underwent an ovariohysterectomy. While sheep were anesthetized, blood samples from the jugular and uterine veins and an amniotic fluid sample were collected for measurement of PAG1 concentration. Fetal tissues underwent real-time PCR analysis for BVDV RNA, and placental specimens underwent histologic evaluation and immunohistochemical staining for BVDV antigen.

RESULTS

At 80 days of gestation, BVDV RNA in fetal tissues and mild placentitis were detected in 5 of 6 BVDV-inoculated ewes. Mean PAG1 concentrations in the maternal and fetal circulations of BVDV-inoculated ewes were significantly less than those in control ewes. Mean amniotic fluid PAG1 concentration did not differ significantly between the 2 groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Concentration of PAG1 in the maternal circulation may be a useful biomarker for determining placental health in sheep after viral infection of the reproductive tract.

Serological screening for Coxiella burnetii in the context of early pregnancy loss in dairy cows

Q fever is one of the commonest infectious diseases worldwide. A Coxiella burnetii prevalence of 97.6% has been found by ELISA and PCR tests of the bulk tank milk in dairy cattle farms of Hungary. The herd- and individual-level seroprevalence rates of C. burnetii in the examined dairy cows and farms have dramatically increased over the past ten years. Three high-producing industrial dairy farms were studied which had previously been found ELISA and PCR positive for C. burnetii by bulk tank milk testing. Coxiella burnetii was detected in 52% of the 321 cows tested by ELISA. Pregnancy loss was detected in 18% of the cows between days 29-35 and days 60-70 of gestation. The study found a higher seropositivity rate (80.5%) in the cows that had lost their pregnancy and a seropositivity of 94.4% in the first-bred cows that had lost their pregnancy at an early stage. The ELISA-positive pregnant and aborted cows were further investigated by the complement fixation test (CFT). In dairy herds an average of 66.6% individual seropositivity was detected by the CFT (Phase II) in previously ELISA-positive animals that had lost their pregnancy and 64.5% in the pregnant animals. A higher (Phase I) seropositivity rate (50.0%) was found in the cows with pregnancy loss than in the pregnant animals (38.5%). The high prevalence of C. burnetii in dairy farms is a major risk factor related to pregnancy loss.

Farmer and Veterinary Practices and Opinions Related to Fertility Testing and Pregnancy Diagnosis of UK Dairy Cows

Dairy cow farming plays an important role in the UK and worldwide economies. Significant challenges are currently being faced regarding sustainability of the dairy industry. Dairy cow subfertility remains an important issue limiting herd productivity, resulting in annual losses of hundreds of millions of pounds in the UK alone. To address this, accurate monitoring of reproductive status and early detection of fertility issues in individual cows is essential. The aim of this study was to gather farmer and veterinarian opinions on current practices and perceived gaps related to diagnosis of fertility issues and pregnancy testing in UK dairy farms. Using online questionnaires, data were collected and analyzed from a total of 40 farmers and 59 veterinarians. The results showed that non-seen bulling checks and ultrasound were the most frequent tools to detect fertility issues, and that most farmers tested post-calving, and often again before or during mating. Most farmers believed that current tests did not meet their expectations, with half of those being willing to pay more than they were currently paying for fertility testing. In regard to pregnancy testing, ultrasound was most commonly used, at 30–50 days post-insemination either in individual or groups of cows. Again, most farmers believed that current tests did not meet their expectations, and a majority would consider paying a higher cost for a test that was better than those currently available. In addition, a majority of farmers would consider using a test that could detect pregnancy within 2 weeks post-insemination, if such test existed, because they believed it would help improve their herds' reproductive performance. Overall, the opinions of farmers and veterinarians indicate that there is significant scope for improving dairy herd fertility monitoring practices in the UK, through development of improved assays that can diagnose pregnancy and infertility earlier, are less disruptive to farm operations and are more cost effective than available tools. They also provide useful information to guide the future development and implementation of better diagnostics for improving reproductive performance of dairy cattle.

Comparative analysis of bovine maternal corpus luteum microRNAs with aberrant and normal developed cloned fetus at late gestation

BACKGROUND

The development efficiency of cloned cattle is extremely low (< 5%), most of them were aborted at late gestation. Based on our previous studies, some recipient cows with a cloned fetus would present as engorged uterine vessels and enlarged umbilical vessels randomly. Abortion involves both maternal and fetal factors.

OBJECTIVE

Our aim was to explore this phenomenon by microRNAs expression profile analysis of maternal corpus luteum (CL), which was related to pregnancy maintenance.

METHODS

The present study provided the comparison of maternal CL miRNAs expression of abnormally and normally developed cloned bovine fetus at late gestation (~ 210 days) using RNA-Seq technology.

RESULTS

We selected two abnormally pregnant cows (abnormal group, AG) and three normally pregnant cows (normal group, NG) and acquired valid reads of 9317,261-12,327,185 (~ 84.53-91.28%) from five libraries. In total, we identified 981 conserved miRNAs and 223 novel miRNAs. 1052 miRNAs were co-expressed, 124 miRNAs were uniquely expressed in AG, and 93 miRNAs were uniquely expressed in the NG. Compared with NG, 11 were significantly overexpressed, and 22 were downregulated (p < 0.05) at AG among 1052 co-expressed miRNAs. The differentially expressed miRNAs-targeted genes were further analyzed by Gene Ontology and KEGG pathway analysis. Notably, the steroid biosynthesis pathway was a significantly enriched term (p < 0.01), which may affect the secretion of progesterone.

CONCLUSION

Our research suggested that abnormal miRNAs expression of bovine maternal CL may affect the pregnant status at late gestation.

Pregnancy per artificial insemination during summer in lactating dairy cows after treatment with aspirin

Embryonic loss in cattle may be related to a hormonal imbalance resulting in alterations in timing of prostaglandin F_2α (PGF_2α) secretion around the time of maternal recognition of pregnancy. The objective of this study was to examine effects of aspirin (a PGF_2α inhibitor) on pregnancy per AI (P/AI), and progesterone (P₄), and pregnancy specific protein B (PSPB) concentrations in lactating dairy cows inseminated more than once after parturition. Fourteen days after second or subsequent AI (Day 0 = Day of AI), 556 cows were assigned randomly to aspirin (187.2 g total; n = 277) or control (n = 279) groups. Aspirin was administered orally on Day 14 and 15, and control cows were subjected to sham bolus administration. On Day 25, blood samples were collected from a subset of cows (n = 194) to quantify P₄ and PSPB, whereas pregnancy was determined in all cows at 35-42 days post-AI. Maximum daily ambient temperature ranged from 38-41 °C during the experiment. Mean parity, days in milk, and times bred before treatment (TBRD) did not differ between groups. There were no differences in P/AI between treatments (aspirin 21.6 % compared with control 27.5 %). Neither treatment, parity, TBRD, or any two-way interactions with treatment affected concentrations of P₄. Moreover, there were no effects (P > 0.50) of treatment, or treatment by TBRD interaction on serum PSPB concentrations. A tendency (P = 0.07) occurred for multiparous cows to have greater serum PSPB concentrations compared with primiparous cows. Mean serum PSPB concentrations tended (P = 0.07) to be greater for second or third TBRD compared to fourth and greater TBRD. These results provide evidence that aspirin administered during periods of heat stress after the second and subsequent AI post-partum during the summer months does not improve P/AI or alter P₄ and PSPB in lactating dairy cows.

Maternal nutrient restriction in early pregnancy increases the risk of late embryo loss despite no effects on peri-implantation interferon-stimulated genes in suckler beef cattle

Reducing feeding costs in suckler beef herds to improve economic returns could have detrimental impacts on fertility. This study sought to determine whether maternal nutrient restriction during early pregnancy affects interferon-stimulated gene (ISG) expression in peripheral blood mononuclear cells during the peri-implantation period in two beef cattle breeds. Relationships were also examined between subnutrition and pregnancy failure defined according to ISG fold changes on Days 18 and 21 and to plasma pregnancy specific protein B (PSPB) concentrations on Day 28 post-artificial insemination (AI). Pirenaica or Parda de Montaña dams were assigned to a control (n = 23) or subnutrition (n = 30) group, receiving 100% or 65% of their estimated nutritional requirements from Day 1 to 82 post-AI, respectively. Treatment did not affect ISG expression or fertility. According to ISG fold changes (chi-square P = .023) or PSPB levels (chi-square P = .04) recorded in the subnutrition group, late embryo loss was more likely than in controls. Positive correlation was detected between Day 28 PSPB concentrations and both Day 18 MX1, MX2 and ISG15 expression, and Day 21 OAS1 expression. OAS1 and MX1 fold changes were found to be the best variables to discriminate pregnancy status. Our findings indicate that maternal nutrient restriction during the first third of pregnancy does not impair embryo signalling yet may increase the risk of pregnancy failure.

Effects of physiological stage and season on infrared thermograms of different body areas of dairy cows raised under tropical conditions

The objective of this study was to investigate the influence of season and pregnancy stage on the temperature of various body areas of Holstein cows using digital infrared thermography, an effective and non-invasive technique. The temperature was recorded at several areas of the body surface to determine the most reliable body area for measurement of rectal temperature in pregnant and non-pregnant animals. Holstein cows (n = 24) were divided into groups according to their physiological stage. The experimental period was 365 days, containing a dry (April-September) and rainy (October-March) season, with parameters measured every 28 days. Thermographic data for different body areas, rectal thermometry, ultrasonography, and climatic data were collected between 7:00 and 9:00. Thermogram-recorded temperatures significantly differed (P < 0.05) between seasons and reproductive phases. Moreover, significant differences were noted between the temperatures of the flank, lateral udder, and perineal areas across seasons (P < 0.05). The udder, perineal, and rectal temperatures differed according to the reproductive phase (P < 0.05). Significant correlations (P < 0.01) were observed between reproductive phases and rectal, ocular globe, snout, flank, and perineum temperature. The body areas examined by thermographic imaging presented different temperatures, exhibiting physiological variation. Season and physiological stage influenced the temperature of body areas of milk cows.

Symposium review: Predicting pregnancy loss in dairy cattle

Several tools exist to diagnose pregnancy in dairy cattle. However, substantial pregnancy loss occurs within the first 60 d of gestation in cattle, and these losses have a profound adverse economic impact on the dairy and beef cattle industries. Detecting these impending pregnancy losses could offer producers an opportunity to reduce costs associated with this source of reproductive inefficiency. Several of the pregnancy diagnostic tools currently available and new technologies are being examined for their ability to predict pregnancies at risk for failing in early pregnancy. This review provides a synopsis of work undertaken recently to predict pregnancy losses in cattle. Currently, opportunities to predict pregnancy loss include (1) using transrectal ultrasonography to detect loss of the fetal heartbeat, floating debris within the placental fluids, and reductions in fetal size; (2) observing reductions in circulating progesterone concentrations; (3) detecting reductions in concentrations of circulating placental products; namely, pregnancy-associated glycoproteins and microRNAs; and (4) detecting reductions in the early pregnancy-dependent increase in interferon-stimulatory gene expression in peripheral blood leukocytes. An achievable goal may be to identify markers of embryo mortality so that researchers and clinicians can focus their efforts on developing intervention strategies for cows identified to be at risk for pregnancy failure.

Short communication: Blood samples before and after embryonic attachment accurately determine non-pregnant lactating dairy cows at 24 d post-artificial insemination using a commercially available assay for pregnancy-specific protein B

Early pregnancy diagnosis is critical to reproductive success on dairy farms. Reproductive success depends on cows becoming pregnant before 130 d in milk and then maintaining that pregnancy. The earlier non-pregnant cows are identified, the sooner they can be reinseminated, thus reducing days to pregnancy. Assays for pregnancy-specific protein B (PSPB) and pregnancy-associated glycoproteins can be used to diagnose pregnancy >28 d post-artificial insemination (AI) in lactating cows. The objective of this study was to determine whether percentage change in serum levels of PSPB within cow from d 17 to 24 can be used to identify non-pregnant cows using a commercially available assay. This study was performed on a large commercial dairy. Blood samples were taken at d 17 and 24 post-AI. The d 17 sample served as a baseline based on previous data. Cows with a 10% increase in serum PSPB levels from d 17 to 24 were considered pregnant. Lactating dairy cows (n = 206; 39% primiparous and 61% multiparous) were synchronized using G6G-Ovsynch. The PSPB diagnosis was compared with the herd veterinarian's diagnosis via ultrasound on d 34. The sensitivity for a 10% cutoff as a non-pregnant diagnosis was 100%, and the specificity was 93.58%. The positive predictive value was 93.27%, and the negative predictive value was 100%. Low PSPB levels at d 24 were predictive of early pregnancy loss by 60 d post-AI. To our knowledge no other method can diagnose non-pregnancy with 100% accuracy and predict pregnancy loss earlier than 24 d post-AI. Using comparative PSPB samples at d 17 and 24 post-AI provides an accurate non-pregnancy diagnosis earlier than any other pregnancy diagnosing method.

Luteal activity following follicular drainage of subordinate follicles for twin pregnancy prevention in bi-ovular dairy cows

Twin pregnancy is undesirable in dairy cattle. This study examines luteal activity following ultrasound-guided puncture and drainage of the smaller pre-ovulatory follicle at timed AI in cows with a pre-ovulatory follicle in each ovary. Luteal activity was determined through Doppler ultrasonography and plasma progesterone (P4) concentrations. The effects of GnRH treatment on Day 7 post-AI on subsequent luteal activity were also assessed. Two study groups were established: a control group of 29 cows and a follicular drainage (FD) group of 28 cows. After drainage, all cows developed a corpus luteum (CL) in the drained ovary. On Day 21 post-AI, drainage-induced CL and fellow CL were similar in terms of size and vascularization. According to a GLM repeated measures analysis of variance (P < 0.001), non-treated drained cows had lower P4 concentrations on Day 21 post-AI than non-treated non-drained cows, whereas GnRH treated cows, both drained and non-drained, showed the highest P4 concentrations at this time point. Twin pregnancy was recorded in 3 of the 8 pregnant control cows, whereas no twins were observed in the FD group. Our results indicate that luteal structures following follicular drainage were functional. As for the presence of an additional CL, this could suggest a reduced risk of pregnancy loss. In addition, luteal activity was significantly increased following GnRH treatment on Day 7 post-AI in drained cows.

Pregnancy and stillbirth losses in dairy cows with singleton and twin pregnancies

The aim of this study was to examine the effect of twin pregnancy, fetal laterality, the number of corpora lutea (CL) and cavitary CL on pregnancy losses in Holstein-Friesian cows with a positive pregnancy diagnosis based on ultrasonography between days 29-42 after AI. Pregnancy was confirmed by transrectal palpation between days 57-70 after AI and at the time of drying-off as well. Twin pregnancy rate was 8.4% at the time of the early pregnancy examination. Pregnancy loss did not differ between singleton- and twin-carrying animals either between days 57-70 of gestation or at drying-off. More losses occurred in singletons between days 29-42 and 57-70 in cows with cavitary than in cows with noncavitary CL (12.1% vs. 3.6%; P < 0.05) and in cows with double CL than in cows with single CL (7.3% vs. 3.6% %; P < 0.05). Between days 57-70 of gestation and drying-off this difference was still significant (20.7% vs. 3.7%; P < 0.001), while it was non-significant between cows with one CL (5.7%) vs. double CL (3.7%). Cavity occurrence was not affected by hormone therapy prior to AI (either PGF2α or OvSynch; 4.4% vs. 5.4%, respectively); however, the number of CL was reduced by the treatments (11.6 vs. 19.6%; P < 0.0005). In twin pregnancies there was no difference in the pregnancy losses between bilateral and unilateral pregnancies at any time point. The length of gestation was 278.2 ± 10.5 (singleton) and 267.4 ± 31.2 (twin) days, respectively (P < 0.01). The stillbirth ratio was higher in twin carriers than in singleton carriers (19.5% vs. 5.3%; P < 0.001).

Extent and pattern of pregnancy losses and progesterone levels during gestation in Swedish Red and Swedish Holstein dairy cows

Background

Pregnancy loss is a major source of infertility in dairy cows. Despite a fertilization rate after insemination (AI) of approximately 90%, calving rates are 30%–50%, indicating the occurrence of extensive embryonic and foetal losses. The aim of this study was to establish the extent and pattern of embryonic and foetal loss in Swedish Red (SR) and Swedish Holstein (SH) dairy cows, as well as, the relationship to oestrus intensity (OI) and progesterone (P4) concentration. In total, 2130 AIs and 16,176 milk P4 samples from 359 SR and 212 SH dairy cows were included in the study. Pregnancy losses were estimated using data from P4 values combined with AI information and calving data.

Results

Total pregnancy loss from AI to the day of calving was 65%. Early embryonic loss, late embryonic loss and foetal loss were estimated to be 29, 14 and 13%, respectively. There is strong evidence in the literature that P4 concentrations at different time points are associated with pregnancy loss. In the present study, cows with pregnancy losses had significantly higher P4 levels at the day of AI and significantly lower P4 concentration at days 10, 21 and 30 after AI compared to pregnant cows. Swedish Red cows had significantly lower total pregnancy losses compared to SH cows (62% and 68% respectively, P = 0.017). Early embryonic loss was 6.7% points lower for cows inseminated at a stronger OI (OI = 3) compared to at a weaker OI (OI = 2, P = 0.006). Cows inseminated at ovulation number ≥ 5 had significantly lower early pregnancy losses compared to cows inseminated at first or second ovulation (11.5 and 8% points, respectively, P < 0.05). With an increase of one SD of milk (448 kg ECM) during the first 60 days in milk, early embryonic loss increased by 4.7% points (P = 0.006).

Conclusions

It is important to increase the number of cows calving per insemination by reducing embryo/foetal loss. This outcome can be achieved by management and breeding for optimal P4 levels at critical time points, and by considering oestrus expression in the breeding programmes to facilitate the correct timing of insemination.

Is twin pregnancy, calving and pregnancy loss predictable by serum pregnancy-specific protein b (pspb) concentration 28-35 days after ai in dairy cows?

Double ovulation occurs more frequently in multiparous cows with high milk production than in primiparous cows and the rate of twin pregnancy/calving is increasing worldwide. Diagnosis of twin pregnancy is possible by ultrasound at the time of early pregnancy examination [28-34 days after artificial insemination (AI)]. Pregnancy proteins are also well-known indicators of gestation. The risk of pregnancy loss during the first trimester of gestation for cows carrying twins is three to nine times higher than for cows carrying singletons. Pregnancy-specific protein B (PSPB) is a good indicator not only of pregnancy but also of pregnancy loss. The aims of this study were (a) to collect calving data in some Hungarian Holstein-Friesian herds (n = 7,300) to compare PSPB serum concentrations (measured 29-35 days post insemination) in twin- and singleton-calving cows (Trial 1), and (b) to check the predictive value of PSPB serum concentration for twin pregnancy and pregnancy loss in high-producing Spanish Holstein-Friesian cows (n = 98; Trial 2). Our results showed almost 7% twin calving rate. Although hormonal treatments are commonly believed to be major causes of twin pregnancies, our data do not support this hypothesis. The only exception is the single PGF injection, which significantly increased twin calving. No effect of milk production on the risk of twin pregnancy was found, and twin pregnancy increased with parity. The AI bull, the bull's sire, the bull's grandfather and the cow's father also affected twin calving (P ≤ 0.02). We found much higher frequency of twin calving in cows diagnosed pregnant with higher than 3 ng/ml serum PSPB concentrations at 29-35 days after insemination. In Trial 2, non-significant but well-marked differences were found in PSPB serum concentration between singleton- and twin-pregnant cow samples (2.1 and 2.9 ng/ml) at different bleeding times. Probably the small size of the study population and the effects of milk production on PSPB values may explain this lack of significance.

Puncture and drainage of the subordinate follicles at timed artificial insemination prevents the risk of twin pregnancy in dairy cows

The objective of this study was to determine whether fluid drainage from the subordinate follicles by ovum pickup procedures prevents the risk of twin pregnancy without reducing the fertility of the cow. Lactating dairy cows with at least two follicles over 12 mm diameter located one on each ovary and selected from synchronized groups for fixed-time insemination were assigned to a Control (n = 49) or Drainage (n = 49) group. The largest follicle was considered as the dominant follicle. Draining of all subordinate follicles (≥10 mm) was performed in the Drainage group. All drained follicles developed as a corpus luteum 7 days later. In the Control cows, the presence of two corpora lutea (55.1%) was lower (p = .003) than those in the Drainage cows (87.8%), whereas the incidence of twin pregnancies was 50% and 0% for the Control and Drainage groups, respectively (p < .001). Draining did not affect the pregnancy rate. These results indicate that puncture and drainage of the subordinate follicles at insemination may eliminate the risk of twin pregnancies and reduce the risk of subsequent pregnancy loss by increasing the incidence of additional corpora lutea.