Early pregnancy diagnosis in bovines: current status and future directions

Identification of potential differences in salivary proteomic profiles between estrus and diestrus stage of estrous cycle in dairy cows

In the present study, a comparative global high-throughput proteomic analysis strategy was used to identify proteomic differences between estrus and diestrus stage of estrous cycle in dairy cows. Saliva was collected from cows during estrus and diestrus, and subjected to LC-MS/MS-based proteomic analysis. A total of 2842 proteins were detected in the saliva of cows, out of which, 2437 and 1428 non-redundant proteins were identified in estrous and diestrous saliva, respectively. Further, it was found that 1414 and 405 salivary proteins were specific to estrus and diestrus, respectively while 1023 proteins were common to both groups. Among the significantly dysregulated proteins, the expression of 56 proteins was down-regulated (abundance ratio <0.5) while 40 proteins were up-regulated (abundance ratio > 2) in estrous compared to diestrous saliva. The proteins, such as HSD17B12, INHBA, HSP70, ENO1, SRD5A1, MOS, AMH, ECE2, PDGFA, OPRK1, SYN1, CCNC, PLIN5, CETN1, AKR1C4, NMNAT1, CYP2E1, and CYP19A1 were detected only in the saliva samples derived from estrous cows. Considerable number of proteins detected in the saliva of estrous cows were found to be involved in metabolic pathway, PI3K-Akt signaling pathway, toll-like receptor signaling pathway, steroid biosynthesis pathway, insulin signaling pathway, calcium signaling pathway, estrogen signaling pathway, oxytocin signaling pathway, TGF-β signaling pathway and oocyte meiosis. On the other hand, proteins detected in saliva of diestrous cows were involved mainly in metabolic pathway. Collectively, these data provide preliminary evidence of a potential difference in salivary proteins at different stages of estrous cycle in dairy cows.

The Potential of Infrared Thermography for Early Pregnancy Diagnosis in Nili-Ravi Buffaloes

This study was designed to explore the potential of infrared thermography (IRT) as an alternate approach for early pregnancy diagnosis in buffaloes. The surface temperature (ST) of different regions (eyes, muzzle, flanks, and vulva) was determined in 27 buffaloes using IRT from the day of artificial insemination (AI; Day 0), and measurement was repeated every fourth day until Day 24 post-AI. From all regions, the ST in each thermograph was recorded at three temperature values (maximum, average, minimum). Pregnancy status was confirmed through ultrasonography on Day 30, and animals were retrospectively grouped as pregnant or non-pregnant for analysis of thermographic data. In pregnant buffaloes, all three values of ST were significantly greater (p ≤ 0.05) for the left flank, while, in the left eye and vulva, only the maximum and average values were significantly greater. By contrast, the maximum ST of the muzzle was significantly lower (p ≤ 0.05) in pregnant buffaloes compared to non-pregnant buffaloes. However, the ST of the right eye and right flank did not show significant temperature variation at any value. These findings suggest that IRT has the potential to identify thermal changes associated with pregnancy in buffaloes at an early stage.

Potential of Circulating miRNA Biomarkers and Exosomes for Early Pregnancy Diagnoses in Cattle

Circulating microRNAs (miRNAs) were investigated as biomarkers for the diagnosis of early pregnancy in cattle. The levels of prospective miRNA biomarkers and the features of extracellular vesicles (EVs) in the blood were evaluated. In Study 1, plasma samples from cows 21 days after artificial insemination (AI) were examined using RT-qPCR to determine the levels of seven circulating miRNAs. Only the levels of miR-126-3p were significantly lower in the pregnant group than in the non-pregnant group. In Study 2, among individuals not pregnant at the first AI, the miRNA levels were compared between the individuals pregnant at the second AI and those who remained non-pregnant. The miR-25 levels were significantly higher in the pregnant group at the second AI than in the pregnant group at the first AI; miR-19b, miR-27b, and miR-29a levels were also high. In the non-pregnant group, changes were absent in the miRNA levels in the same individual between the first and second AIs. In Study 3, Western blotting and RT-qPCR showed the presence of miRNAs in EVs and their levels were lower than in plasma. Thus, circulating miR-126-3p may serve as a biomarker for the diagnosis of early pregnancy in cattle. In addition, the expression of some miRNAs tended to be higher during pregnancy than during non-pregnancy in the same individual, suggesting their potential as an index to determine pregnancy and non-pregnancy rates using a comparative method.

Milk-derived exosome nanovesicles: recent progress and daunting hurdles

Raw milk is the foundation of quality and safety in the dairy industry, and improving milk source management is the fundamental guarantee. Milk-derived exosomes (MDEs) are nanoscale information transfer molecules secreted by mammary cells with unique content and high stability, which can be used not only as potential markers to analyze key traits of lactation, reproduction, nutrition and health of animals, but also help farm managers to take timely interventions to improve animal welfare, milk quality, and functional traits. Our review first outlines the latest advances in MDEs isolation and purification, compositional analysis and characterization tools. We then provide a comprehensive summary of recent applications of MDEs liquid biopsy in breed selection, disease prevention and control, and feeding management. Finally, we evaluate the impact of processing on the stability of MDEs to offer guidance for dairy production and storage. The limitations and challenges in the development and use of MDEs markers are also discussed. As a noninvasive marker with high sensitivity and specificity, the MDEs-mediated assay technology is expected to be a powerful tool for measuring cow health and raw milk quality, enabling dynamic and precise regulation of dairy cows and full traceability of raw milk.

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.

Changes in plasma PLAC-1 concentration and its expression during early-mid pregnancy in bovine placental tissues - a pilot study

BACKGROUND

Placenta-specific protein 1 (PLAC1) is a small secreted protein considered to be a molecule with a significant role in the development of the placenta and the establishment of the mother-foetus interface. This study aimed to confirm the presence of bovine PLAC1 and to examine its profile in the placenta and plasma in the first six months of pregnancy. The expression pattern of PLAC1 was analysed by RT-qPCR and Western Blotting. Quantitative evaluation was carried out using ELISA.

RESULTS

PLAC1 concentrations in the plasma of pregnant cows were significantly higher (p < 0.05) than those obtained from non-pregnant animals. PLAC1 protein concentrations in the placental tissues of the foetal part were significantly (p < 0.05) higher than in the tissues of the maternal part of the placenta. PLAC1 transcripts were detected in both placental tissue samples and epithelial cell cultures.

CONCLUSIONS

In conclusion, the results of the present preliminary study suggest that PLAC1 is involved in the development of bovine placenta. The presence of this protein in the plasma of pregnant animals as early as the first month may make it a potential candidate as a pregnancy marker in cows. Further studies on exact mechanisms of action of PLAC1 in bovine placenta are necessary.

Proteomics approach reveals urinary markers for early pregnancy diagnosis in buffaloes

This study aimed to compare urine proteomics from non- and pregnant buffaloes in order to identify potential biomarkers of early pregnancy. Forty-four females underwent hormonal ovulation synchronization and were randomly divided into two experimental groups: inseminated (n = 30) and non-inseminated (n = 14). The pregnant females were further divided into two groups: pregnant at Day 12 (P12; n = 8) and at Day 18 (P18; n = 8) post-ovulation. The non-pregnant group was also subdivided into two groups: non-pregnant at Day 12 (NP12; n = 7) and at Day 18 (NP18; n = 7). Urine was collected from all females on Days 12 or 18. The samples were processed for proteomics. A total of 798 proteins were reported in the urine considering all groups. The differential proteins play essential roles during pregnancy, acting in cellular transport and metabolism, endometrial remodeling, embryonic protection, and degradation of defective proteins. We suggest that some proteins from our study can be considered biomarkers for early pregnancy diagnosis, since they were increased in pregnant buffaloes. SIGNIFICANCE: Macromolecules have been studied for early pregnancy diagnosis, aiming to increase reproductive efficiency in cattle and buffaloes. Direct methods such as rectal palpation and ultrasonography have been considered late. Thus, this study aimed to compare urine proteomics from non- and pregnant buffaloes to identify potential biomarkers of early pregnancy. The differential proteins found in our study play essential roles during pregnancy, acting in cellular transport and metabolism, endometrial remodeling, embryonic protection, and degradation of defective proteins. We suggest that these proteins can be considered possible biomarkers for early pregnancy diagnosis since they were increased in the pregnant buffaloes.

A simple, inexpensive and portable on-farm test for pregnancy diagnosis and ovary status in cows via chemical analysis of urine

Ovary dysfunction causes an aberrant endocrine surge at various reproductive cycle stages, negatively impacting fertility and economic profit. Optimizing dairy cow performance requires determining ovarian status and detecting early pregnancy. Still, little to no information is available about the diagnosis of the ovarian condition using urine chemical analysis at the field level in Bangladesh. This study aimed to develop a simple, inexpensive and portable on-farm technique for pregnancy diagnosis and ovary status determination in cows via chemical urine analysis. Fifty reproductively healthy cows were recruited from different donor farms. Prior to artificial insemination (AI), all selected cows were placed in a single ovsynch program. TAI (timed artificial insemination) was carried out. Urine was routinely collected from Day 0-55 days at estrus cycle stages for routine chemical analysis using barium chloride (BaCl2), followed by commercially available protein strip tests. The developed techniques for pregnancy and ovary status diagnosis in cows were validated with rectal palpation (RP). Barium chloride (BaCl2) analysis of urine revealed white precipitation corresponding to a mature follicle in the ovary during estrus and colorless precipitation corresponding to the corpus luteum during the diestrus period. Positive pregnancy was indicated by the presence of a colorless precipitate in the BaCl2 test, and a protein value of less than 100 mg/dl was found in the protein strip test. The maximum accuracy (42/50, 84%) was observed between 25 and 35 days, as confirmed by RP. Perplexing results were seen 45-55 days after AI, between pregnancies and luteal cystic disease. In both cases, we discovered that the BaCl2 precipitation was colorless. However, the protein value in the context of luteal cystic disease was found to be higher than 100 mg/dl. The barium chloride test, followed by protein strip tests, is a simple and portable way to diagnose pregnancy and determine ovarian status in cows at the field level.

Interferon-Stimulated Gene Expression in Peripheral Blood Leucocytes as a Convenient Prediction Marker for Embryo Status in Embryo-Transferred Japanese Black Cows during the Peri-Implantation Period

Pregnancy diagnosis during early gestation is important for cattle reproduction. The expression of interferon-stimulated genes (ISGs) in peripheral blood leukocytes (PBLs) was studied in embryo-transferred (ET) Japanese Black cattle. ISGs in PBLs-ISG15, MX1, MX2, and OAS1-were detected in multiple ovulation ET cattle using a real-time quantitative polymerase chain reaction, and receiver operating characteristic (ROC) curve analysis was performed. Gestational status was predicted using the average ISG levels during the normal estrous cycle (AVE) and the Youden index from the ROC curve analysis as cutoff values. The ISG15, MX1, and MX2 levels were significantly higher in pregnant cattle (n = 10) than in non-pregnant cattle (n = 23) on gestation day 21, whereas the levels of all ISGs were similar between non-pregnant and non-pregnant cattle with late embryonic death (n = 7). ISG15, MX1, and MX2 appropriately predicted the gestational status of ET cows. The statistical evaluation of the diagnostic accuracy in ET cows on day 21 of gestation presented higher values of sensitivity, specificity, accuracy, and positive predictive values of ISG15, MX1, and MX2 using the Youden index than using the AVE. Therefore, ISG15, MX1, and MX2 are excellent biomarkers of gestational status during the peri-implantation period in ET cattle.

Efficacy validation of a low-cost handmade simulator (SIMCA-COW) in palpation, ultrasonography evaluation, and artificial insemination in cows

Background and Aim

Using simulators in high education enables practical training by repetition in circumstances close to reality reducing the stress of both animal and operator. The limited resources of veterinary schools, the increase in the number of students in lecture halls, and the low availability of animals for teaching due to welfare regulations, reduce teaching opportunities with live animals being simulator as the better alternative. This study aimed to assess the efficacy of a low-cost handmade simulator (SIMCA-COW) in eight veterinary students inexperienced in palpation, ultrasonography evaluation, and artificial insemination in cows.

Materials and Methods

Two sets of exercises were carried out: structure localization by rectal palpation and ultrasonography were evaluated by the inexpert veterinary students in the SIMCA-COW simulator. Also, evaluated the length of time to insert the insemination catheter through the cervix in the inert simulator during four sessions.

Results

All the students were able to palpate both structures and to locate the body and both uterine horns by ultrasonography. Cervix and follicles were located by 5/8 (62.5%) students and 3/8 (37.5%) students found the corpus luteum by ultrasonography. A reduction in time span between the first and fourth intrauterine insemination attempts was observed (8.26 ± 2.7 vs. 3.69 ± 1.7; mean ± standard error; p < 0.05).

Conclusion

The simulator validated in this study (SIMCA-COW) allows training and learning by repetition, saving the limitations found in live animal practice.

Comparative Analysis of Saliva and Plasma Proteins Patterns in Pregnant Cows—Preliminary Studies

Simple Summary

One of the most crucial topics about cattle breeding is pregnancy. During this state, there are many changes in protein expression and abundance. These changes find reflection not only in plasma protein patterns but also in saliva, which is easier to obtain than blood. The aim of this study was the analysis of plasma and salivary protein profiles in pregnant cows in order to search for valuable markers of pregnancy status. In this study, the presence of apolipoproteins possibly related to bovine pregnancy was confirmed both in plasma and saliva. This means that saliva can be considered a good source of information about the condition of the organism, including during pregnancy. It is possible that the comparison of salivary and plasma proteomes can be a helpful tool to assess the pregnancy status of cattle, and can be useful for developing rapid tests from saliva.

Abstract

Pregnancy is a physiological state that can be described, from a biochemical point of view, using protein patterns. The present study focused on the comparison of protein patterns between the saliva and plasma of pregnant cows to search for possible markers which are present both in plasma and saliva. Saliva and plasma were collected from healthy, pregnant (3–4 months) and non-pregnant (C; n = 4) cows aged between 4 and 8 years (P; n = 8) from the same farm. Biological material was analyzed using 2D electrophoresis and MS identification. Among identified spots, there were those which could be related to pregnancy (e.g., apolipoproteins I and II in all examined matrices or transforming growth factor-beta-induced protein ig-h3 in albumin-free plasma) as well as those which are responsible for regulating of cellular processes (e.g., pyruvate kinase and aspartate aminotransferase in all examined matrices, or lactate dehydrogenase, phosphoglycerate kinase, and NADH dehydrogenase in plasma). Further identification of common spots and those only specific to saliva as well as the comparison between other periods of pregnancy are necessary; it is already clear that saliva can be considered a valuable diagnostic matrix containing potential markers of physiological and pathological status.

Use and adequacy of non-pregnancy diagnosis in cow. Which future?

In cattle, early detection of gestation is very important from an economic and management point of view in all types of farming. However, due to the poor efficiency of oestrus detection, it is essential to determine non-pregnant cows as early possible, in order to minimize the inter-insemination interval, thus de facto, reducing herd open days. Direct and indirect gestation diagnostic methods have been developed with the aim of improving the reproductive performance of the herd. Today, the most accurate method for making an early diagnosis of gestation from 28-30 days post insemination is B-Mode ultrasound. In recent years, indirect methods have included techniques that allow non-pregnant cows to be identified with a minimum margin of error, the most widely utilized of which is the Color-Doppler. This technique is rapidly becoming established for the diagnosis of non-pregnancy that allows the identification of non-pregnant animals earlier compared the pregnancy diagnosis. Some limitations of this technique in dairy cow have been presented.

Validation of pregnancy associated glycoproteins-based ELISA kits to determine early pregnancy status in lactating Nili-Ravi buffaloes

The objective of the current study was to evaluate pregnancy-associated glycoproteins (PAGs) based enzyme-linked immunosorbent assay (ELISA) kits utilizing whole blood, serum, or milk samples for diagnosis of early pregnancy status in lactating Nili-Ravi buffaloes. Dairy buffaloes (n = 174) of mixed parity, 4-6 years of age, having mean (± SD) days in milk 165 ± 87, and body condition score of 3.26 ± 0.34 were randomly enrolled in this study. Buffaloes were exposed to penile deviated bulls with 12h intervals for estrus detection during peak breeding season and eventually bred naturally at their respective standing estrus (day 0). Blood and milk samples were collected on days 24, 28, and 35 post-breeding to run a rapid visual pregnancy test® (RVPT), or ELISA-based assay to detect early pregnancy status. Transrectal B-mode ultrasonography was performed to diagnose pregnancy at day 35 post-breeding and used as a gold standard to validate results of RVPT or ELISA-based tests. The RVPT is a visual readout test and had sensitivity (77.9 vs 89.7 vs 93.3%), specificity (77.9 vs 89.7 vs 93.3%), and accuracy (84.5 vs 90.1 vs 94.2%) at days 24, 28, and 35 post-breeding, respectively. The PAGs were assayed using ELISA kits in serum and had sensitivity (77.9 vs 89.7 vs 93.3%), specificity (84.2 vs 87.7 vs 93.9%), and accuracy (82.1 vs 88.4 vs 93.7%) at days 24, 28, and 35 post-breeding, respectively. Similarly, PAGs were also analyzed using ELISA kits in milk samples and had sensitivity (77.6 vs 89.5 vs 95.0%), specificity (89.1 vs 91.9, vs 93.9%), and accuracy (85.1 vs 91.1 vs 94.3%) at days 24, 28, and 35 post-breeding, respectively. Overall, the Kappa values in this study exceeded 0.85 at day 35 post-breeding using RVPT or ELISA-based test kits in serum or milk samples, indicating a high level of agreement between PAGs detection method and gold standard for pregnancy diagnosis. The pregnancy outcomes based on ELISA-based PAGs detection at day ≥ 28 post-breeding had a high negative predictive value, indicating that the probability of incorrectly administering prostaglandins to pregnant buffaloes would be low if these tests were implemented on a commercial dairy herd. Taken together, it is concluded that PAGs-based determination of pregnancy using RVPT or ELISA either in blood, serum, or milk samples, can be used effectively for pregnancy diagnosis at ≥ 28 days post-breeding with more than 90% accuracy in Nili-Ravi buffaloes.

Can blood progesterone concentration identify non-pregnant buffaloes to support estrus resynchronization?

This study compared the plasma progesterone concentrations from pregnant and non-pregnant buffaloes to identify non-pregnant females and submit cows earlier to estrus resynchronizaton. Forty-four multiparous mix-breed Murrah buffaloes were selected for the study. The cows were subjected to hormonal estrus synchronization and separated into 4 groups, P12 (pregnant, n = 8) and P18 (n = 8) at 12 and 18 days post-insemination; NP12 (non-pregnant, n = 7) and NP18 (n = 7) at 23 and 29 days after the onset of synchronization, respectively. The embryos and blood were collected, the plasma was separated for centrifugation and used to determine progesterone concentration. Progesterone concentration was higher in P18 than P12 (P = 0.02) and NP18 groups (P < 0.001). The steroid was also increased in the P12 group compared to NP12 (P =0.031). There was no difference between NP12 and NP18 (P = 0.906). We conclude that the plasma progesterone concentration can be an alternative to identify earlier non-pregnant buffaloes, advancing the estrus resynchronization or natural service to improve productivity.

Safety, Immunogenicity and Antibody Persistence of Rift Valley Fever Virus Clone 13 Vaccine in Sheep, Goats and Cattle in Tanzania

Background: Vaccination is considered to be the best approach to control Rift Valley fever (RVF) in animals and consequently in humans. This study assessed the efficacy and safety of the RVF virus (RVFV) Clone 13 vaccine under field conditions.

Methodology: A vaccine trial was conducted in sheep (230), goats (230), and cattle (140) in Ngorongoro district, Tanzania. Half of each of the animal species were vaccinated and the other half received the placebo. Animals were clinically monitored and bled before vaccination and at days 15, 30, 60, 180 and 360 (+/– 10) post-vaccination to measure Immunoglobulin M (IgM) and IgG antibody responses to RVFV. Survival analysis was conducted using cox-proportional hazard regression model to measure the time until an event of interest had occurred and to compare the cumulative proportion of events over time.

Results: Of 600 animals included in the study, 120 animals were lost during the study, leaving a total of 480 (243 in the vaccinated group and 237 in the control group) for complete follow-up sampling. There was no adverse reaction reported at the injection site of the vaccine/placebo in all animals. Abortions, deaths, or body temperature variations were not associated with vaccination (p > 0.05). By day 15 post-inoculation, the IgG seroconversion in vaccinated goats, cattle and sheep was 27.0% (n = 115), 20.0% (n = 70) and 10.4% (n = 115), respectively. By day 30 post-inoculation, it was 75.0% (n = 113), 74.1% (n = 112) and 57.1% (n = 70) in vaccinated sheep, goats and cattle, respectively. By day 60 post-inoculation, IgG seroconversion in sheep, goats and cattle was 88.1% (n = 109), 84.3% (n = 108) and 64.60% (n = 65), respectively. By day 180, the IgG seroconversion in sheep, goats and cattle was 88.0% (n = 108), 83.8% (n = 105) and 66.1% (n = 62), respectively. By day 360, the IgG seroconversion in sheep, goats and cattle was 87.2% (n = 94), 85.6% (n = 90) and 66.1% (n = 59), respectively. Only five animals from the vaccinated group were RVFV IgM positive, which included four sheep and a goat.

Conclusion: RVFV Clone 13 vaccine was well tolerated by sheep, goats, and cattle. The vaccine induced detectable, but variable levels of IgG responses, and of different duration. The vaccine is considered safe, with high immunogenicity in sheep and goats and moderate in cattle.

Aptamers based sensing of pregnancy associated glycoproteins (PAG) of bovine for early pregnancy detection

Tosyl activated magnetic beads were used for aptamer selection against PAG- 7 and 18 proteins of bovine origin. PAG proteins were immobilized on beads with further addition of biotin tagged aptamer library. The recognition of aptamers with PAG was identified by ST-HRP based approach which was colorimetric in nature. The selected aptamers were sequenced and at the same time several new aptamers were identified. Later M-fold structure and G-quadruplex score of aptamers were analyzed for their selection. Those aptamers having high G value and complex structure were chosen. In dot blot assay, aptamers recognized PAG protein in an animal after 42 days of artificial insemination which later given birth to a healthy calf. Further the cross reactivity with serum of 0th day animal (post AI) or with non pregnant animal serum was minimal. Aptamers have also shown interaction with PAG protein of buffalo origin. These selected aptamers have commercial application especially in development of biosensors for early detection of pregnancy in bovine.

Establishment of Repertoire of Placentome-Associated MicroRNAs and Their Appearance in Blood Plasma Could Identify Early Establishment of Pregnancy in Buffalo (Bubalus bubalis)

Precise early pregnancy diagnosis in dairy animals is of utmost importance for an efficient dairy production system. Not detecting a dairy animal pregnant sufficiently early after the breeding results to extending the unproductive time of their milk production cycle and causes substantial economic loss for a dairy producer. At present, the most conventional and authentic pregnancy confirmation practice in cows and buffaloes is rectal palpation of the reproductive organs at Days 35–40 after insemination, which sometime leads to considering an animal as false pregnant. Other alternative methods available for early pregnancy diagnosis lack either accuracy or reproducibility or require elaborate instrumentation and laboratory setup not feasible to practice at farmers’ doorstep. The present study was aimed at establishment of the microRNA (miRNA) repertoire of the placentome in buffaloes, which could capture the event of the cross talk between a growing embryo and a dam, through fetal cotyledons and maternal caruncles, and thus could hint at the early pregnancy establishment event in ruminants. Total RNA was isolated from buffalo placentome tissues during early stages of pregnancy (at Day < 25 and Days 30–35), and global small RNA analysis was performed by using Illumina single-end read chemistry and Bubalus bubalis genome. A total of 2,199 miRNAs comprising 1,620 conserved and 579 non-conserved miRNAs were identified. Stringent functional miRNA selection criteria could predict 20 miRNAs worth evaluating for their abundance in the plasma of pregnant, non-pregnant, cyclic non-bred, and non-cyclic prepubertal animals. Eight of them (viz., miR-195-5p, miR-708-3p, miR-379-5p, miR-XX1, miR-XX2, miR-130a-3p, miR-200a-3p, and miR-27) displayed typical abundance patterns in the plasma samples of the animals on Day 19 as well as Day 25 post-insemination, thus making them ambiguous candidates for early pregnancy detection. Similarly, higher abundance of miR-200a-3p and miR130a-3p in non-pregnant animals was indicative of their utility for detecting the animals as not pregnant. Most interestingly, miR-XX1 and miR-XX2 were very characteristically abundant only in pregnant animals. In silico target prediction analysis confirmed that these two miRNAs are important regulators of cyclooxygenase-2 (COX-2) and cell adhesion molecule-2 (CADM-2), both of which play a significant role in the implantation process during feto-maternal cross talk. We interpret that circulatory miR-XX1 and miR-XX2 in blood plasma could be the potential biomarkers for early pregnancy detection in buffaloes.

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.

Approaches to Identify Pregnancy Failure in Buffalo Cows

Simple Summary

Embryonic mortality and pregnancy failures still represent a major issue in domestic livestock production, particularly in dairy cattle. Despite the presence of extensive work in this research area, there is still no effective, accurate and practical method able to determine timing and viability of embryo specifically during early gestation. Indeed, technologies and techniques for predicting pregnancy success must continue to be developed. The aim of this work was to find the best strategy to diagnose pregnancy failures in buffalo cows in order to improve farm reproductive management. Among the methods compared in this study (ultrasonography, progesterone, PAGs), pregnancy-associated glycoproteins (PAGs) seem to be the best marker for predicting embryonic mortality between 25 and 40 days of gestation to be utilized as a diagnostic tool to improve reproductive management in buffalo farms.

Abstract

The aim of this work was to find the best strategy to diagnose pregnancy failures in buffalo. A total of 109 animals belonging to a buffalo herd subjected to a synchronization and artificial insemination (AI) program were enrolled in this study. Blood samples were collected at days 0, 14, 25, 28 and 40 after AI for the determination of progesterone (P4) and pregnancy-associated glycoproteins (PAGs) by the radioimmunoassay (RIA) method. Transrectal ultrasonography was performed on day 25, 28 and 40 after AI to monitor pregnancy. The animals included in the data analysis were assigned ex post in pregnant (n = 50) and mortality (n = 12) groups. By ultrasonography, the predictive sign of mortality was the heartbeat. At day 25, the PAGs concentration was significant in predicting embryonic mortality with respect to ultrasonography and P4, at the cut-off of 1.1 ng/mL. At day 28, either PAGs, at a cut-off of 2.2 ng/mL, or ultrasonography, with no detection of heartbeat, were highly predictive of embryonic mortality. PAGs were the best marker (p < 0.05) for predicting embryonic mortality between 25 and 40 days of gestation in buffalo. Its utilization as a diagnostic tool can influence management decisions in order to improve farm reproductive management.

Profiles of progesterone and bovine interferon-τ in repeat breeding and non-repeat breeding Aceh cows

AIM

This study aimed at determining the profiles of progesterone and bovine interferon-τ (bIFN-τ) and the correlation between the two in repeat breeding (RB) Aceh cattle and non-RB Aceh cattle.

MATERIALS AND METHODS

The study was performed on five RB and five non-RB Aceh cows. These cows were subjected to estrous synchronization using the prostaglandin F2 alpha hormone, which was followed by artificial insemination (AI). Serum samples were collected on days 5, 6, 7, 15, 16, and 17 after AI to measure the concentration of progesterone at the beginning and end of the luteal phase and from days 14 to 18 after AI to measure the concentration of bIFN-τ. The concentrations of progesterone and bIFN-τ were determined using enzyme-linked immunosorbent assay. Pregnancy examinations were performed by ultrasonography on days 25, 35, 45, and 55 after AI. Data for progesterone and bIFN-τ concentrations were analyzed using the Mann-Whitney and t-tests, and the correlation between progesterone and bIFN-τ was analyzed using the Spearman correlation test.

RESULTS

The average concentration of progesterone in RB Aceh cows tended to be lower than non-RB Aceh cows, but it was not significantly different (p>0.05). Similar results also found in the concentration of bIFN-τ which RB Aceh cows tended to have lower bIFN-τ concentrations compared to non-RB Aceh cows, but it was also not significantly different (p>0.05). Moreover, the concentrations of progesterone and bIFN-τ in RB and non-RB Aceh cows did not show a significant correlation (p>0.05). These results of the ultrasonography showed that non-RB Aceh cows were pregnant from day 25 to day 55 after AI, whereas RB Aceh cows were not pregnant and had early embryonic death.

CONCLUSION

The concentrations of progesterone and bIFN-τ in non-RB Aceh cows tended to be higher than those in RB Aceh cows, although, it was not significantly different. Non-RB Aceh cows were able to maintain pregnancy until day 55, whereas RB Aceh cows were diagnosed with early embryonic death before day 25 after AI.

Efficacy of a commercial test kit to determine early pregnancy in cows using whole blood and blood serum

The objective of this study was to determine the efficacy of the Fassisi®BoviPreg visual test kit (Fassisi®BoviPreg) in determining early pregnancies in cows by measuring the pregnancy-associated glycoprotein (PAG) in whole blood and blood serum. The study was conducted on 50 cows, the artificial insemination (AI) dates of which were designated as day 0. Pregnancy diagnosis was performed with transrectal ultrasonography (USG), and serum samples were simultaneously collected and used with Fassisi®BoviPreg to determine pregnancies on 30 days after AI. The results of the Fassisi®BoviPreg test on serum and whole blood samples, respectively, on 30 days after AI were as follows: sensitivity, 61.54% and 50.0%; specificity, 79.17% and 75%; accuracy, 70.0% and 62.0%; positive predictive values, 76.2% and 68.4%; negative predictive values, 65.5% and 58.1%; false-positive diagnoses, 23.8% and 31.6%; and false-negative diagnoses, 34.5% and 41.9%. On day 50 after AI, sensitivities were 63.64% and 50.0%, specificities were 100.0% and 100.0%, and accuracies were 75.0% and 65.62% in serum and whole blood, respectively. Higher pregnancy rates were obtained using Fassisi®BoviPreg in cows with ≥ 5 ng/mL P4 (P < 0.001). In conclusion, the results from the Fassisi®BoviPreg tests on cows on 30 and 50 days after AI showed that the use of blood serum is more accurate and suitable than that of whole blood. The results also showed a higher confidence level in specificity 50 days after AI.

Urinary Reference Values and First Insight into the Urinary Proteome of Captive Giraffes

Urinalysis is widely recognized to be a useful tool in routine health investigations, since it can diagnose numerous pathologies. Considering the paucity of knowledge concerning giraffes, urine from 44 giraffes (Giraffa camelopardalis) (18 males and 26 females, from 3 months of age to 21 years of age) underwent routine urinalysis, 1D-electrophoresis, and protein identification using mass spectrometry, with the aim of identifying the urinary reference values and the urine proteome. The urine specific gravity (USG), urine total proteins (uTP), urine creatinine (uCr), and urine protein:creatinine ratio (UPC) reference values, reported as the median, and lower limit (LL) and upper limit (UL), were 1.030 (1006-1.049), 17.58 (4.54-35.31) mg/dL, 154.62 (39.59-357.95) mg/dL, and 0.11 (0.07-0.16), respectively. Mass spectrometry, together with electrophoresis, revealed a pattern of common urinary proteins; albumin, lysozyme C, and ubiquitin were the most represented proteins in the giraffe urine. It has been hypothesized that these proteins could act as a defense against microbes. Moreover, in giraffes, urinalysis could be a valid tool for gauging renal function and physiological status changes.

Effect of green tea extract in extender of Simmental bull semen on pregnancy rate of recipients

OBJECTIVE

The aim of this study was to ascertain the effects of adding green tea extract (GTE) to skim milk-egg yolk (SM-EY) extender on both the quality of post-thawed bull semen and the pregnancy rates of the recipient cows.

METHODS

Twelve ejaculates from four Simmental bulls, aged 3 to 5 years and weighing 900 to 950 kg, were diluted SM-EY extender, added with 0, 0.05, 0.1, and 0.15 mg GTE/100 mL extender and then frozen. After four weeks storage in liquid nitrogen, the sperm were thawed and evaluated for viability, motility, intact plasma membrane (IPM), and DNA fragmentation. Meanwhile, the estrus cycles of 48 recipient cows were synchronized by intramuscular administration of a single injection of 5 mg prostaglandin F2α. Estrus cows were divided into four equal groups and inseminated artificially 18 to 20 h after the onset of estrus by using semen from each extender group. Pregnancy was diagnosed by measuring serum progesterone levels at 21 days, followed by transrectal palpation 90 days after insemination.

RESULTS

The findings revealed that adding 0.1 mg of GTE/100 mL extender produced the highest percentages of sperm viability (70.67%±1.75%), motility (69.17%±1.47%), and IPM (69.23%±1.21%) and the lowest percentage of DNA fragmentation (3.00%±0.50%). The pregnancy diagnosis revealed that all cows (36/36) inseminated using frozen semen in GTE addition extender were pregnant (pregnancy rate 100%), whereas the pregnancy rate of the control group was 83.33% (10/12).

CONCLUSION

It may be concluded that 0.1 mg GTE/100 mL extender yields the best quality of spermatozoa and that all variants doses of GTE in extender produce a higher pregnancy rate among recipient cows.

Applied use of interferon-tau stimulated genes expression in polymorphonuclear cells to detect pregnancy compared to other early predictors in beef cattle

We aimed to evaluate the accuracy of Interferon-tau stimulated genes (ISG) abundance in peripheral blood polymorphonuclear cells (PMNs) on D20 after fixed-time artificial insemination (FTAI; D0) as a pregnancy diagnosis method against CL evaluation by Doppler ultrasonography and progesterone (P4) concentrations on D20, as well as Pregnancy Associated Glycoproteins (PAG) concentrations on D25. Additionally, we evaluated the potential of ISG abundance in PMNs as pregnancy loss predictors. Nelore heifers (n = 103) and cows (n = 144) underwent estrous synchronization and were artificially inseminated on D0. Pregnancy was diagnosed by B-mode ultrasonography on D30 and D70, and after the final diagnosis, females were classified in four groups: Pregnant; Non-pregnant; Functional CL on D20 but non-pregnant (CL-NP) and Pregnancy loss between D30 and D70 (PL). After determining cutoff values, the Sensitivity (SE), Specificity (SP), Positive Predictive Value (PPV), Negative Predictive Value (NPV) and Accuracy (ACC) were determined for each method. All methods were classified as significant (P < 0.05) predictors of pregnancy. Both ISG expression and PAG concentrations were greater (P < 0.05) in pregnant females than in non-pregnant and CL-NP females but did not differ (P > 0.05) from the PL group. ISG15 expression was greater (P < 0.05) in heifers than in cows, but this difference was not found in OAS1 expression and PAG concentrations. All the methods evaluated were proven to be adequate predictors of pregnancy, but greater accuracies were obtained through PAG concentrations and Doppler-US, due to the decreased number of false positive and false negative results.

Duplex Quantitative Polymerase Chain Reaction of ISG15 and RSAD2 Increases Accuracy of Early Pregnancy Diagnosis in Dairy Cows

Early diagnosis of pregnancy is important in livestock production, but there is no reliable technology used for pregnancy diagnosis within the first three weeks after insemination. During early pregnancy, the expression of interferon-stimulating genes (ISGs) in peripheral blood leukocytes (PBL) is significantly increased. However, due to different strains, detection sample types, detection methods, threshold value, etc. the specific effectiveness of early pregnancy diagnosis using ISGs is worth further study. The purpose of this study was to test interferon-stimulated protein 15 (ISG15), 2'–5'-oligoadenylate synthetase 1 (OAS1) and radical S-adenosyl methionine domain containing 2 (RSAD2) for early pregnancy diagnosis in dairy cows. The expression of ISG15, OAS1, and RSAD2 in PBL of pregnant and non-pregnant heifers on days 0, 14, 18, 21 and 28 after artificial insemination (AI) was detected by fluorescence quantitative polymerase chain reaction (PCR). The sensitivity and specificity of the pregnancy diagnosis was analyzed using expression of these three genes separately or in combination by receiver operating characteristic curve. The combination with the highest accuracy used probe primers and duplex fluorescence quantitative PCR. The single quantitative PCR results showed that expression of ISG15, OAS1 and RSAD2 on day 18 after AI was significantly higher in pregnant than in non-pregnant cows. When these three genes were used separately, or in combination, for early pregnancy diagnosis, the sensitivity for the RSAD2 gene was 100%, and the combination of ISG15 with RSAD2 was 94.7%. The duplex quantitative PCR showed that, although the sensitivity of ISG15 alone was 100%, its specificity was only 88.2% (cut-off value 1.402). The sensitivity of RSAD2 alone was 89.5%, and the specificity was 88.2%; however, when the two genes were used in combination, the sensitivity, specificity and diagnostic cut-off value were consistent with the results of single quantitative PCR. These results indicated that a duplex quantitative PCR assay system for early pregnancy diagnosis in cows using ISG15 and RSAD2 was established. Simultaneous detection of expression of ISG15 and RSAD2 by duplex quantitative PCR can effectively improve the diagnostic accuracy for dairy cows.

MicroRNA of whole milk samples are not suitable for pregnancy detection in cattle

Common pregnancy detection methods in dairy cattle have limits in sensitivity and timing. Thus, we aimed at finding new early pregnancy biomarkers in milk. A previous study in milk cells and skim milk suggested the possible use of several miRNAs for this purpose. In order to make the sampling procedure more convenient for daily use and to include the milk fat into analysis, here, a similar study was repeated using whole fresh milk of days 4, 12, 18 and 21 of pregnancy and non-pregnant day-matched controls, respectively. The microRNAs (miRNAs) were extracted from milk samples and sequenced on a high throughput sequencer (RNAseq). Promising miRNAs were validated via RT-qPCR. Several miRNAs were significantly regulated and six miRNAs (bta-miR-221, bta-miR-223, bta-miR-93, bta-miR-200c, bta-miR-125b and the closely related bta-miR-15b) showed a continuous trend, similar as in the milk cells of the previous study. However, pregnant and cyclic animals could not be separated completely and RT-qPCR validation of the RNAseq data was unsuccessful. Thus, miRNA of bovine whole fresh milk samples failed to show suitability for early pregnancy diagnosis.

Gene expression of CCL8 and CXCL10 in peripheral blood leukocytes during early pregnancy in cows

Background

The aim of the present study was to evaluate CCL8 and CXCL10 expression and its regulatory mechanism in peripheral blood leukocytes (PBLs) at the time of maternal recognition in cows. Blood samples were collected on 14, 15, 16, 17 and 18 d after artificial insemination (AI). Based on the day of return of estrus, cows were divided into three groups, pregnant (n = 5), early embryonic mortality (EEM; n = 5) and late embryonic mortality (LEM; n = 5). The gene expression levels in PBLs were assessed with quantitative real-time reverse transcription PCR.

Results

The expression of CCL8 and CXCL10 mRNA in PBLs gradually increased from 14 to 18 d of pregnant cows and significant differences were observed on 18 d (P < 0.05), whereas no significant changes were observed both in EEM and LEM cows. Interferon-stimulated protein 15 kDa (ISG15), myxovirus-resistance gene (MX) 1 and MX2 mRNA expression in PBLs increased from 14 to 18 d which was significant on 18 d of pregnant cows as well as in LEM cows (P < 0.05), but no changes were observed in EEM cows. To determine whether the expression of CCL8 and CXCL10 in PBLs was regulated by pregnancy-related substances or not, expression level was assessed after exposure to interferon-τ (IFNT) and CCL16. Monocytes, granulocytes and lymphocytes were obtained using density-gradient centrifugation and flow cytometry. The addition of IFNT (100 ng/mL) and CCL16 (100 ng/mL) to cultured PBLs increased the expression of CCL8 and CXCL10 mRNA (P < 0.05). The expression of ISG15, MX1 and MX2 mRNA in PBLs was also stimulated by IFNT and CCL16 (P < 0.05).

Conclusions

The expression of CCL8 and CXCL10 genes increased in PBLs during early pregnancy. Since IFNT stimulated CCL8 and CXCL10 expression in cultured PBLs, the increase of CCL8 and CXCL10 might be pregnancy-dependent events. The expression of both CCL8 and CXCL10 in PBLs was stimulated by CCL16 as well as IFNT, suggesting a chemokine interaction that at least includes CCL8, CXCL10 and CCL16, and may play a role in regulating maternal recognition in cows.

Efficacy of different methods for detecting the onset of ovarian cyclicity in post-partum Murrah buffaloes

This study was designed to investigate the sensitivity and specificity of three methods for detecting the onset of cyclicity in post-partum Murrah buffaloes. The methods investigated were visual signs, transrectal ultrasonography, and serum progesterone (P₄) assay. For this study, 102 post-partum Murrah buffalo cows were grouped for monitoring their ovarian activity. The first group of buffaloes was between 26 and 35 days post-partum. Thereafter, the buffalo cows that calved were grouped after every 10 days for the study sample. Thus, the study animals were adjudged between 26 and 35, 36-45, 46-55, 56-65, 66-75, 76-85, and 86-95 days post-partum with an average of 30, 40, 50, 60, 70, 80, and 90 days post-partum, respectively. Visual estrus signs were monitored twice daily, and simultaneously, ultrasound examination was carried out at 10 days interval for accessing the presence of corpus luteum (CL). Serum P₄ was estimated in the animals which were adjudged cyclic by ultrasound examination, and the assay was repeated after 10 days. The buffalo cows in estrus were inseminated artificially, and pregnancy status was assessed after 30 days post-insemination. In this study, the sensitivity and specificity of visual observation were low (39.37 and 70.73%, respectively) when compared to P₄ assay (98.80 and 96.47%) and ultrasound examination (single, 97.59 and 97.59%; double, 100 and 100%), respectively. Furthermore, the sensitivity and specificity of single and double ultrasound examination and P₄ assay were comparable. In conclusion, this study reports that single and double ultrasound examination and P₄ assay are more efficient than visual observation in detecting the onset of ovarian cyclicity in post-partum Murrah buffaloes.

Evaluation of interferon-stimulated genes in peripheral blood granulocytes as sensitive responders to bovine early conceptus signals

Early detection of gestation is important in the bovine industry. New methods have been developed to detect gene expression in leucocytes induced by interferon-tau (IFNT) as gestation biomarkers. However, it is debatable which blood cell is suitable for detecting gene expression. This study was aimed at confirming whether granulocytes respond to IFNT specifically. Granulocytes and mononuclear cells (MNCs) from cows, and several types of bovine cultured cells, were treated with recombinant (r) IFNT and gene expression was analysed by quantitative real-time reverse transcriptase (RT)-PCR and microarray analysis. Expression levels of IFN receptors (R1 and R2) were approximately 30- to 900-fold higher in granulocytes than in other cultured cells, and 1.5- to 2.5-fold higher in MNCs than in granulocytes. Microarray analysis following a 2h recombinant IFNT (rIFNT) treatment revealed expression changes for 900 genes in granulocytes. Genes with expression changes included known IFN-stimulated genes (ISGs; ISG15, OAS1, MX1, and MX2). Eighteen genes were selected following granulocyte microarray analysis and their expression changes were confirmed in early gestation, which revealed that nine genes had significantly higher expression levels in pregnant than in non-pregnant animals. In conclusion, granulocytes specifically responded to rIFNT treatment and the resulting gene expression changes correlated with those in vivo. Microarray analysis indicated that various genes showed expression changes in rIFNT-treated granulocytes, which may result in the identification of alternate candidate genes for the early detection of gestation. These results strongly indicate that gene expression in granulocytes is a suitable tool to determine pregnancy status.

Serum microRNAs in buffalo cows: Potential biomarkers of pregnancy

MiRNAs (microRNA) constitute a large family of single-stranded, non-coding small RNAs. Although the functions and target genes of most miRNAs are still unknown, it has been well established that they are involved in embryogenesis, organogenesis and neonatal birth. In recent decades, interest in buffalo breeding has largely increased worldwide thus focusing the attention on this species as a dairy purpose animal. Problems related to long calving interval, late puberty and seasonal anestrus hamper reproductive efficiency in this species. Early pregnancy diagnosis is important to shorten the calving interval and increase lifetime production on dairy animals. MicroRNAs have recently emerged as key molecules in fertilization of several species even though in buffalo, few previous studies have investigated miRNAs. The aim of this research was to identify the best miRNA reference in serum among miR-191, miR-25-3p, SNORD44, and SNORD48. Consequently, assess the expression levels of miR-103, miR-200b, miR-301a, miR-423-5p, miR-375, miR-451 and miR-452 involved in buffalo progesterone-maturation oocyte and pregnancy. Interestingly, we found that all the miRNAs analyzed at 40days after artificial insemination were differentially expressed among pregnant and non-pregnant buffalo. Our research may be a first step for gain further insight in the biological function of circulating miRNAs in this species.

Changes in circulating microRNA levels can be identified as early as day 8 of pregnancy in cattle

Poor reproductive performance remains a major issue in the dairy industry, with low conception rates having a significant impact on milk production through extended calving intervals. A major limiting factor is the lack of reliable methods for early pregnancy diagnosis. Identification of animals within a herd that fail to conceive within 3 weeks after insemination would allow early re-insemination and shorten calving intervals. In a previous study, we found an increase in plasma miR-26a levels in Day 16-pregnant relative to non-pregnant heifers, however changes in miRNA levels that early during pregnancy were very small which likely prevented the identification of robust biomarkers. In this study, we extended our analyses to a wider interval during pregnancy (Days 8 to 60, n = 11 heifers) with the rationale that this may facilitate the identification of additional early pregnancy miRNA biomarkers. Using small RNA sequencing we identified a total of 77 miRNAs that were differentially expressed on Day 60 relative to Day 0 of pregnancy. We selected 14 miRNAs for validation by RT-qPCR and confirmed significant differences in the expression of let-7f, let-7c, miR-30c, miR-101, miR-26a, miR-205 and miR-143 between Days 0 and 60. RT-qPCR profiling throughout Days 0, 8, 16 and 60 of pregnancy showed a distinct increase in circulating levels of miR-26a (3.1-fold, P = 0.046) as early as Day 8 of pregnancy. In summary, in contrast to earlier stages of pregnancy (≤ Day 24), marked differences in the levels of multiple miRNAs can be detected in circulation by Day 60 in cattle. Retrospective analyses showed miR-26a levels to be increased in circulation as early as Day 8, sooner than previously reported in any species, suggesting a biological role for this miRNA in the very early events of pregnancy.

Can milk cell or skim milk miRNAs be used as biomarkers for early pregnancy detection in cattle?

The most critical phase of pregnancy is the first three weeks following insemination. During this period about 50% of high yielding lactating cows suffer embryonic loss prior to implantation, which poses a high economic burden on dairy farmers. Early diagnosis of pregnancy in cattle is therefore essential for monitoring breeding outcome and efficient production intervals. Regulated microRNAs (miRNAs) that reach easily accessible body fluids via a ‘liquid biopsy’ could be a new class of pregnancy predicting biomarkers. As milk is obtained regularly twice daily and non-invasively from the animal, it represents an ideal sample material. Our aim was to establish a pregnancy test system based on the discovery of small RNA biomarkers derived from the bovine milk cellular fraction and skim milk of cows. Milk samples were taken on days 4, 12 and 18 of cyclic cows and after artificial insemination, respectively, of the same animals (n = 6). miRNAs were analysed using small RNA sequencing (small RNA Seq). The miRNA profiles of milk cells and skim milk displayed similar profiles despite the presence of immune cell related miRNAs in milk cells. Trends in regulation of miRNAs between the oestrous cycle and pregnancy were found in miR-cluster 25~106b and its paralog cluster 17~92, miR-125 family, miR-200 family, miR-29 family, miR-15a, miR-21, miR-26b, miR-100, miR-140, 193a-5p, miR-221, miR-223, miR-320a, miR-652, miR-2898 and let-7i. A separation of cyclic and pregnant animals was achieved in a principal component analysis. Bta-miRs-29b, -221, -125b and -200b were successfully technically validated using quantitative real-time PCR, however biological validation failed. Therefore we cannot recommend the diagnostic use of these miRNAs in milk as biomarkers for detection of bovine pregnancy for now.

Identification of serum protein markers for early diagnosis of pregnancy in buffalo

Improper or delayed pregnancy diagnosis has significant impact over animal production, particularly in buffaloes which inherently suffer from several reproductive inefficiencies. Thus the present study has undertaken to identify serum protein markers pertaining to early pregnancy diagnosis in buffaloes. Serum samples were collected from 10 pregnant Murrah Buffalo heifers at weekly intervals from days 0-35 post-artificial insemination and from 12 inseminated non-pregnant cyclic buffalo heifers on days 0, 7, 14 and 21. Two-dimensional gel electrophoresis and densitometric analysis revealed the presence of five protein spots showing average density fold change of ≥4 during early pregnancy. Mass spectrometry analysis identified these up-regulated proteins as anti-testosterone antibody light chain, apolipoprotein A-II precursor, serum amyloid A, cytokeratin type II, component IV isoform 1, which are have established roles in embryogenesis, but over-expression of the fifth identified protein immunoglobulin lambda light chain in pregnancy has been elucidated as a novel finding in the current study. Further, with bioinformatics analysis, potential antigenic B-cell epitopes were predicted for all these five proteins. An antibody cocktail-based approach involving antibodies against all these five up-regulated entire proteins or their epitopes could be developed for early detection of pregnancy in buffaloes. © 2016 Japanese Society of Animal Science.

Identification of potential protein biomarkers for early detection of pregnancy in cow urine using 2D DIGE and label free quantitation

Background

An early, reliable and noninvasive method of early pregnancy diagnosis is prerequisite for efficient reproductive management in dairy industry. The early detection of pregnancy also help in to reduce the calving interval and rebreeding time which is beneficial for industries as well as farmers. The aim of this work is to identify potential biomarker for pregnancy detection at earlier stages (16–25 days). To achieve this goal we performed DIGE and LFQ for identification of protein which has significant differential expression during pregnancy.

Results

DIGE experiment revealed a total of eleven differentially expressed proteins out of which nine were up regulated having fold change ≥1.5 in all time points. The LFQ data analysis revealed 195 differentially expressed proteins (DEPs) out of 28 proteins were up-regulated and 40 down regulated having significant fold change ≥1.5 and ≤0.6 respectively. Bioinformatics analysis of DEPs showed that a majority of proteins were involved in regulation of leukocyte immunity, endopeptidase inhibitor activity, regulation of peptidase activity and polysaccharide binding.

Conclusion

This is first report on differentially expressed protein during various time points of pregnancy in cow to our best knowledge. In our work, we identified few proteins such MBP, SERPIN, IGF which were differentially expressed and actively involved in various activities related to pregnancy such as embryo implantation, establishment and maintenance of pregnancy. Due to their involvement in these events, these can be considered as biomarker for pregnancy but further validation of is required.

Electronic supplementary material

The online version of this article (doi:10.1186/s12014-016-9116-y) contains supplementary material, which is available to authorized users.

Circulating miRNA signatures of early pregnancy in cattle

Background

Low fertility remains a leading cause of poor productivity in dairy cattle. In this context, there is significant interest in developing novel tools for accurate early diagnosis of pregnancy. MicroRNAs (miRNAs) are short RNA molecules which are critically involved in regulating gene expression during both health and disease. MiRNAs have been shown to regulate ovarian function, uterine receptivity, embryonic development and placental function. Circulating miRNAs can provide useful biomarkers of tissue function and disease; importantly, differential miRNA profiles have been linked to pregnancy and preeclampsia in humans. This study sought to establish the potential of circulating miRNAs as biomarkers of early pregnancy in cattle.

Results

We applied Illumina small-RNA sequencing to profile miRNAs in plasma samples collected from eight non-pregnant heifers on Days 0, 8 and 16 of the oestrous cycle and 11 heifers on Days 16 and 24 of pregnancy. We sequenced a total of 46 samples and generated 9.2 million miRNA reads per sample. There were no differences in miRNA read abundance between any of the pregnant and non-pregnant time-points (FDR > 0.1). As a complementary approach, we analysed sample pools (3–4 samples/pool) corresponding to Days 0, 8 and 16 of the oestrous cycle and Day 24 of pregnancy (n = 3 pools/group) using Qiagen PCR arrays. A total of 16 miRNAs were differentially expressed (FDR < 0.1) in plasma between pregnant and non-pregnant animals. RT-qPCR validation using the same plasma samples confirmed that miR-26a was differentially upregulated on Day 16 pregnant relative to non-pregnant heifers (1.7-fold; P = 0.043), whereas miR-1249 tended to be upregulated in Day 16 pregnant heifers (1.6-fold; P = 0.081). Further validation in an independent group of heifers confirmed an increase in plasma miR-26a levels during early pregnancy, which was significant only on Day 24 (2.0-fold; P = 0.027).

Conclusions

Through genome-wide analyses we have successfully profiled plasma miRNA populations associated with early pregnancy in cattle. We have identified miR-26a as a potential circulating biomarker of early pregnancy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2529-1) contains supplementary material, which is available to authorized users.