Proteome profiling of exosomes derived from plasma of heifers with divergent genetic merit for fertility

Proteome overview of exosome derived from plasma of cows infected with Mycobacterium bovis

Bovine tuberculosis (bTB), primarily caused by Mycobacterium bovis (M. bovis), is a globally zoonotic disease with significant economic impacts. Plasma exosomes have been extensively used for investigating disease processes and exploring biomarkers. While mass spectrometry (MS)-based proteomic analysis of plasma exosomes has been employed for human tuberculosis (TB) studies, it has not yet been applied to bTB. Therefore, a comprehensive proteomic overview of plasma exosomes from M. bovis-infected cows is essential. In this study, we presented an extensive proteomic analysis of plasma exosomes from 89 M. bovis-infected cows across three farms, using data dependent acquisition (DDA) mode. Our analysis encompasses 239,894 spectra, 6,011 peptides and 835 proteins. The proteomic overview revealed both consistencies and differences among individual cows, supplements 595 proteins to the bovine exosome library, and enriches tuberculosis and related pathways. Additionally, six pathways were validated as immune response pathways, and three proteins (CATHL1, H1-1, and LCN2) were identified as potential indicators of bTB. This study is the first to investigate the exosome proteome of plasma from cows infected with M. bovis, providing a valuable dataset for exploring candidate bTB markers and understanding the mechanisms of host defense against M. bovis.

The dependence between glycodelin and selected metalloproteinases concentrations in bovine placenta during early gestation and parturition with and without retained foetal membranes

Pregnancy course depends on the appropriate connection between the mother and the developing foetus. Pregnancy is completed when the placenta is timely expelled. Placental retention is one of the possible pregnancy complications. Extracellular matrix, including adhesive proteins and enzymes that can break down collagens, seems to be responsible for it. The aim of the present study was to examine the impact of one of the adhesive proteins - glycodelin (Gd) - on selected metalloproteinases degrading collagens (MMP2, MMP3, MMP7). Placental tissues from healthy pregnant cows collected during early-mid pregnancy (2nd month n = 7, 3rd month n = 8, 4th month n = 6) and in cows that properly released placenta (NR; n = 6) and cows with retained foetal membranes (R; n = 6) were experimental material. The concentrations of glycodelin and protein content of selected metalloproteinases were measured by ELISA in the maternal and foetal placental homogenates as well as in the culture of epithelial cells derived from the maternal part of the placenta. The presence of these protein molecules was confirmed by Western Blotting. In the bovine placenta, the concentrations of examined proteins exhibit significant changes during placental formation. Gd, MMP3 and MMP7 concentrations decrease with pregnancy progress (between the 2nd and 4th month), while MMP2 concentrations were on the same level in this period. During parturition, concentrations of Gd and MMP3 were significantly higher in the R group compared to the NR group. In parallel, MMP2 concentrations did not show significant differences between the groups (NR vs R), and MMP7 concentrations decreased significantly in the maternal part of the placenta in cows with retained foetal membranes (R). Obtained results show correlations between the gestational age and proteins' (Gd, MMP3, MMP7) concentration, both in the maternal and foetal part of the placenta.

Emerging role of extracellular vesicles in veterinary practice: novel opportunities and potential challenges

Extracellular vesicles are nanoscale vesicles that transport signals between cells, mediating both physiological and pathological processes. EVs facilitate conserved intercellular communication. By transferring bioactive molecules between cells, EVs coordinate systemic responses, regulating homeostasis, immunity, and disease progression. Given their biological importance and involvement in pathogenesis, EVs show promise as biomarkers for veterinary diagnosis, and candidates for vaccine production, and treatment agents. Additionally, different treatment or engineering methods could be used to boost the capability of extracellular vesicles. Despite the emerging veterinary interest, EV research has been predominantly human-based. Critical knowledge gaps remain regarding isolation protocols, cargo loading mechanisms, in vivo biodistribution, and species-specific functions. Standardized methods for veterinary EV characterization and validation are lacking. Regulatory uncertainties impede veterinary clinical translation. Advances in fundamental EV biology and technology are needed to propel the veterinary field forward. This review introduces EVs from a veterinary perspective by introducing the latest studies, highlighting their potential while analyzing challenges to motivate expanded veterinary investigation and translation.

Proteomic Approaches to Unravel the Molecular Dynamics of Early Pregnancy in Farm Animals: An In-Depth Review

Infertility is a major problem in farm animals, which has a negative economic effect on farm industries. Infertility can be defined as the inability of animals to achieve a successful pregnancy. Early pregnancy is crucial to establish a successful pregnancy, and it is reported that 70-80% and 20-30% of total embryonic loss occur in cattle and pigs, respectively, during the first month of pregnancy. The advanced high-throughput proteomics techniques provide valuable tools for in-depth understanding of the implantation process in farm animals. In the present review, our goal was to compile, assess, and integrate the latest proteomic research on farm animals, specifically focused on female reproduction, which involves endometrial tissues, uterine fluids, oviductal fluids, and microRNAs. The series of studies has provided in-depth insights into the events of the implantation process by unfolding the molecular landscape of the uterine tract. The discussed data are related to pregnant vs. non-pregnant animals, pregnancy vs. oestrous cycle, different days of the early pregnancy phase, and animals with uterine infections affecting reproduction health. Some of the studies have utilized non-invasive methods and in vitro models to decipher the molecular events of embryo-maternal interaction. The proteomics data are valuable sources for discovering biomarkers for infertility in ruminants and new regulatory pathways governing embryo-uterine interaction, endometrium receptivity, and embryonic development. Here, we envisage that the identified protein signatures can serve as potential therapeutic targets and biomarkers to develop new therapeutics against pregnancy diseases.

SWATH-MS Analysis of Blood Plasma and Circulating Small Extracellular Vesicles Enables Detection of Putative Protein Biomarkers of Fertility in Young and Aged Dairy Cows

The development of biomarkers of fertility could provide benefits for the genetic improvement of dairy cows. Circulating small extracellular vesicles (sEVs) show promise as diagnostic or prognostic markers since their cargo reflects the metabolic state of the cell of origin; thus, they mirror the physiological status of the host. Here, we employed data-independent acquisition mass spectrometry to survey the plasma and plasma sEV proteomes of two different cohorts of Young (Peripubertal; n = 30) and Aged (Primiparous; n = 20) dairy cows (Bos taurus) of high- and low-genetic merit of fertility and known pregnancy outcomes (ProteomeXchange data set identifier PXD042891). We established predictive models of fertility status with an area under the curve of 0.97 (sEV; p value = 3.302e-07) and 0.95 (plasma; p value = 6.405e-08). Biomarker candidates unique to high-fertility Young cattle had a sensitivity of 0.77 and specificity of 0.67 (*p = 0.0287). Low-fertility biomarker candidates uniquely identified in sEVs from Young and Aged cattle had a sensitivity and specificity of 0.69 and 1.0, respectively (***p = 0.0005). Our bioinformatics pipeline enabled quantification of plasma and circulating sEV proteins associated with fertility phenotype. Further investigations are warranted to validate this research in a larger population, which may lead to improved classification of fertility status in cattle.

Adenylate kinase 9 is essential for sperm function and male fertility in mammals

Despite passing routine laboratory tests for semen quality, bulls used in artificial insemination exhibit significant variation in fertility. Routine analysis of fertility data identified a dairy bull with extreme subfertility (10% pregnancy rate). To characterize the subfertility phenotype, a range of in vitro, in vivo, and molecular assays were carried out. Sperm from the subfertile bull exhibited reduced motility and severely reduced caffeine-induced hyperactivation compared to controls. Ability to penetrate the zona pellucida, cleavage rate, cleavage kinetics, and blastocyst yield after IVF or AI were significantly lower than in control bulls. Whole-genome sequencing from semen and RNA sequencing of testis tissue revealed a critical mutation in adenylate kinase 9 (AK9) that impaired splicing, leading to a premature termination codon and a severely truncated protein. Mice deficient in AK9 were generated to further investigate the function of the gene; knockout males were phenotypically indistinguishable from their wild-type littermates but produced immotile sperm that were incapable of normal fertilization. These sperm exhibited numerous abnormalities, including a low ATP concentration and reduced motility. RNA-seq analysis of their testis revealed differential gene expression of components of the axoneme and sperm flagellum as well as steroid metabolic processes. Sperm ultrastructural analysis showed a high percentage of sperm with abnormal flagella. Combined bovine and murine data indicate the essential metabolic role of AK9 in sperm motility and/or hyperactivation, which in turn affects sperm binding and penetration of the zona pellucida. Thus, AK9 has been found to be directly implicated in impaired male fertility in mammals.

Effects of plasma-derived exosomes from the normal and thin Bactrian camels on hepatocellular carcinoma and their differences at transcriptome and proteomics levels

Background

Hepatocellular carcinoma (HCC) is a common malignant primary tumor. Bactrian camels have high economic and social values, but their potential medical value has not been studied. This study aimed to investigate the effects of Bactrian camel plasma-derived exosomes on HCC.

Methods

Plasma was obtained from thin and normal Bactrian camels, and used to isolate exosomes by ultracentrifugation. The exosomes were then characterized by transmission electron microscopy and Nano particle tracking analyzer. In vivo imaging of nude mice and hematoxylin eosin (HE) staining of liver tissues were used to explore the effects of the exosomes on tumor growth. Finally, the differences of the two exosomes were further analyzed using small RNA sequencing and proteomics.

Results

In vivo imaging and HE staining showed that no significant differences were found in fluorescence value and liver tissue morphology between the control mice and the mice treated with the exosomes from thin Bactrian camels; while the fluorescence value and the live histology changes were alleviated in the mice with the exosomes from normal Bactrian camels. After sequencing and proteomic analysis, 40 differentially expressed miRNAs (DE-miRNAs, 15 down-regulated and 25 up-regulated) and 172 differentially expressed proteins (DEPs, 77 up-regulated and 95 down-regulated) were identified in the plasma-derived exosomes from normal Bactrian camels. These identified DE-miRNAs and DEPs were significantly enriched in many signaling pathways.

Conclusions

Normal Bactrian camel plasma-derived exosomes may inhibit the growth of HCC cells through regulating pathways of Ras, Ras-Association Proximate 1 (Rap1), phosphoinositide 3-kinase-protein kinase B (PI3K-Akt), mitogen-activated protein kinase (MAPK), adenosine monophosphate-activated protein kinase (AMPK), and canonical Wnt signaling pathways.

A preliminary report of exploration of the exosomal shuttle protein in marine invertebrate Chlamys farreri

Exosomes are extracellular vesicles secreted by diverse cell under normal or abnormal physiological conditions, which could carry a range of bioactive molecules and play significant roles in biological processes, such as intercellular communication and immune response. In the current study, a preliminary study was performed to investigate the exosomal shuttle protein in Chlamys farreri (designated as CfesPro) and to predict the potential function of exosomes in scallop innate immunity. The serum derived exosomes (designated as CfEVs) were obtained from lipopolysaccharide (LPS)-stimulated C. farreri and untreated ones. After confirmation and characterization by transmission electron microscopy (TEM), nano-HPLC-MS/MS spectrometry was performed on CfEVs using a label-free quantitative method. Totally 2481 exosomal shuttle proteins were identified in CfEVs proteomic data, which included many innate immune related proteins. GO and KOG functional annotation showed that CfesPro participated in cellular processes, metabolism reactions, signaling transductions, immune responses and so on. Moreover, 1421 proteins in CfesPro were enriched to 324 pathways by KEGG analysis, including several immune-related pathways, such as autophagy, apoptosis and lysosome pathway. Meanwhile, eight autophagy-related proteins were initially identified in CfesPro, indicating that CfEVs had a potential role with autophagy. All these findings showed that CfEVs were involved in C. farreri innate immune defenses. This research would enrich the protein database of marine exosomes and provide a basis for the exploration of immune defense systems in marine invertebrates.

Plasma Proteomic Profiling Reveals the Regulatory Factors of Milk Protein Synthesis in Holstein Cows

Simple Summary

We aimed to determine the plasma bio-markers of cows with high long-term milk protein concentration and investigate the mechanism of plasma proteins in milk protein synthesis. Some plasma proteins are considered to be related to milk protein synthesis. However, the characteristics of these proteins with different long-term milk protein concentrations are not fully elucidated. In this study, we collected milk protein concentration data of Holstein cows for 10 months on a commercial farm. Three groups of cows (n = 10 per group) with low, medium, and high milk protein concentrations were selected. We found that cows with high milk protein concentration had higher glucose, insulin-like growth factor 1, prolactin, insulin, and growth hormone concentrations than cows with low milk protein concentration. A total of 91 differentially expressed proteins were identified between cows with high and low milk protein concentrations by plasma proteomic. Furthermore, β-casein level and mammalian rapamycin target protein pathway in bovine mammary epithelial cells were enhanced by insulin-like growth factor 1 treatment. Our findings revealed that the differences in plasma proteins in cows with different milk protein concentrations and determined that β-casein synthesis was increased via the mammalian rapamycin target protein pathway following IGF-1 treatment in vitro.

Abstract

Milk protein concentrations in dairy cows are considered to be related to some plasma biomolecules. However, the characteristics of plasma biomolecules in dairy cows with different long-term milk protein concentrations are not fully elucidated. This study was conducted to understand the mechanism of plasma proteins in milk protein synthesis by the comparative analysis of the plasma proteomics of cows with different milk protein concentrations. Three groups of Holstein cows (per group = 10) with low (LMP), medium (MMP), and high long-term milk protein concentrations (HMP) were selected for the experiment to determine plasma hormones, biochemical parameters, and proteome. We found that HMP cows had higher concentrations of plasma insulin-like growth factor 1 (IGF-1), glucose, prolactin, insulin, and growth hormone than LMP cows. Additionally, plasma proteomic identified 91 differential proteins, including IGF-1 between the LMP and HMP groups, and the mTOR pathway was enriched. In vitro, IGF-1 treatment increased β-casein expression and simultaneously activated S6K1 and mTOR phosphorylation in bovine mammary epithelial cells. Taken together, these data demonstrate the differences in plasma hormones, biochemical parameters, and proteome of cows with different milk protein concentrations and indicate that IGF-1 enhanced milk protein synthesis, associated with activation of the mTOR signaling pathway.

β-Lactoglobulin and Glycodelin: Two Sides of the Same Coin?

The two lipocalins, β-lactoglobulin (βLg) and glycodelin (Gd), are possibly the most closely related members of the large and widely distributed lipocalin family, yet their functions appear to be substantially different. Indeed, the function of β-lactoglobulin, a major component of ruminant milk, is still unclear although neonatal nutrition is clearly important. On the other hand, glycodelin has several specific functions in reproduction conferred through distinct, tissue specific glycosylation of the polypeptide backbone. It is also associated with some cancer outcomes. The glycodelin gene, PAEP, reflecting one of its names, progestagen-associated endometrial protein, is expressed in many though not all primates, but the name has now also been adopted for the β-lactoglobulin gene (HGNC, www.genenames.org). After a general overview of the two proteins in the context of the lipocalin family, this review considers the properties of each in the light of their physiological functional significance, supplementing earlier reviews to include studies from the past decade. While the biological function of glycodelin is reasonably well defined, that of β-lactoglobulin remains elusive.

Detection of tumor-derived extracellular vesicles in plasma from patients with solid cancer

Background

Extracellular vesicles (EVs) are actively secreted by cells into body fluids and contain nucleic acids of the cells they originate from. The goal of this study was to detect circulating tumor-derived EVs (ctEVs) by mutant mRNA transcripts (EV-RNA) in plasma of patients with solid cancers and compare the occurrence of ctEVs with circulating tumor DNA (ctDNA) in cell-free DNA (cfDNA).

Methods

For this purpose, blood from 20 patients and 15 healthy blood donors (HBDs) was collected in different preservation tubes (EDTA, BCT, CellSave) and processed into plasma within 24 h from venipuncture. EVs were isolated with the ExoEasy protocol from this plasma and from conditioned medium of 6 cancer cell lines and characterized according to MISEV2018-guidelines. RNA from EVs was isolated with the ExoRNeasy protocol and evaluated for transcript expression levels of 96 genes by RT-qPCR and genotyped by digital PCR.

Results

Our workflow applied on cell lines revealed a high concordance between cellular mRNA and EV-RNA in expression levels as well as variant allele frequencies for PIK3CA, KRAS and BRAF. Plasma CD9-positive EV and GAPDH EV-RNA levels were significantly different between the preservation tubes. The workflow detected only ctEVs with mutant transcripts in plasma of patients with high amounts (> 20%) of circulating tumor DNA (ctDNA). Expression profiling showed that the EVs from patients resemble healthy donors more than tumor cell lines supporting that most EVs are derived from healthy tissue.

Conclusions

We provide a workflow for ctEV detection by spin column-based generic isolation of EVs and PCR-based measurement of gene expression and mutant transcripts in EV-RNA derived from cancer patients’ blood plasma. This workflow, however, detected tumor-specific mutations in blood less often in EV-RNA than in cfDNA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08007-z.

Strategies to improve the efficiency of beef cattle production

Globally, there are approximately one billion beef cattle, and compared with poultry and swine, beef cattle have the poorest conversion efficiency of feed to meat. However, these metrics fail to consider that beef cattle produce high-quality protein from feeds that are unsuitable for other livestock species. Strategies to improve the efficiency of beef cattle are focusing on operational and breeding management, host genetics, functional efficiency of rumen and respiratory microbiomes, and the structure and composition of feed. These strategies must also consider the health and immunity of the herd as well as the need for beef cattle to thrive in a changing environment. Genotyping can identify hybrid vigor with positive consequences for animal health, productivity, and environmental adaptability. The role of microbiome–host interactions is key in efficient nutrient digestion and host health. Microbial markers and gene expression patterns within the rumen microbiome are being used to identify hosts that are efficient at fibre digestion. Plant breeding and processing are optimizing the feed value of both forages and concentrates. Strategies to improve the efficiency of cattle production are a prerequisite for the sustainable intensification needed to satisfy the future demand for beef.

Exosomal Cargo May Hold the Key to Improving Reproductive Outcomes in Dairy Cows

The reproductive status of dairy cows remains a challenge for dairy farmers worldwide, with impaired fertility linked to a significant reduction in herd profitability, due in part to impaired immunity, increased metabolic pressure, and longer postpartum anestrous interval (PPAI). Exosomes are nanovesicles released from a variety of cell types and end up in circulation, and carry proteins, bioactive peptides, lipids, and nucleic acids specific to the place of origin. As such, their role in health and disease has been investigated in humans and animals. This review discusses research into exosomes in the context of reproduction in dairy herds and introduces recent advances in mass-spectrometry (MS) based proteomics that have a potential to advance quantitative profiling of exosomal protein cargo in a search for early biomarkers of cattle fertility.

MicroRNAome: Potential and Veritable Immunomolecular Therapeutic and Diagnostic Baseline for Lingering Bovine Endometritis

The bovine endometrium is a natural pathogen invasion barrier of the uterine tissues' endometrial epithelial cells that can resist foreign pathogen invasion by controlling the inflammatory immune response. Some pathogens suppress the innate immune system of the endometrium, leading to prolonged systemic inflammatory response through the blood circulation or cellular degradation resulting in bovine endometritis by bacterial endotoxins. The microRNA (miRNA) typically involves gene expression in multicellular organisms in post-transcription regulation by affecting both the stability and the translation of messenger RNA. Accumulated evidence suggests that miRNAs are important regulators of genes in several cellular processes. They are a class of endogenous non-coding RNAs, which play pivotal roles in the inflammatory response of reproductive diseases. Studies confirmed that miRNAs play a key regulatory role in various inflammatory diseases by mediating the molecular mechanism of inflammatory cytokines via signal pathways. It implicates some miRNAs in the occurrence of bovine endometritis, resorting to regulating the activities of some inflammatory cytokines, chemokine, differentially expressed genes, and protein through modulating of specific cellular signal pathways functions. This review dwells on improving the knowledge of the role of miRNAs involvement in inflammatory response as to early diagnosis, control, and prevention of bovine endometritis and consequently enlighten on the molecular improvement of the genes coded by various differentially expressed miRNA through the need to adopt recent genetic technologies and the development of new pharmaceutical preparations.

The Role of Exosomal Epigenetic Modifiers in Cell Communication and Fertility of Dairy Cows

Abnormal uterine function affects conception rate and embryo development, thereby leading to poor fertility and reproduction failure. Exosomes are a nanosized subclass of extracellular vesicles (EV) that have important functions as intercellular communicators. They contain and carry transferable bioactive substances including micro RNA (miRNA) for target cells. Elements of the cargo can provide epigenetic modifications of the recipient cells and may have crucial roles in mechanisms of reproduction. The dairy industry accounts for a substantial portion of the economy of many agricultural countries. Exosomes can enhance the expression of inflammatory mediators in the endometrium, which contribute to various inflammatory diseases in transition dairy cows. This results in reduced fertility which leads to reduced milk production and increased cow maintenance costs. Thus, gaining a clear knowledge of exosomal epigenetic modifiers is critical to improving the breeding success and profitability of dairy farms. This review provides a brief overview of how exosomal miRNA contributes to inflammatory diseases and hence to poor fertility, particularly in dairy cows.

Predicting the likelihood of conception to first insemination of dairy cows using milk mid-infrared spectroscopy

The objective of this study was to examine the ability of milk mid-infrared (MIR) spectroscopy and other on-farm data, such as milk yield, milk composition, stage of lactation, calving age, days in milk at insemination, and somatic cell count, to identify cows that were most or least likely to conceive to first insemination. A total of 16,628 spectral and milk production records of 7,040 cows from 29 commercial dairy herds across 3 Australian states were used. Three models, comprising different explanatory variables, were tested. Model 1 included features that are readily available on farms participating in milk recording, such as milk yield, milk composition, somatic cell count, days from calving to insemination, and calving season. Days in milk and age at calving were incorporated into model 1 to form model 2. In model 3, MIR was added to model 2, but to avoid double counting, milk composition traits of model 2 were removed. The models were first trained on extreme data [i.e., including cows that (1) conceived to first insemination and (2) cows with no conception event recorded and with only 1 insemination]. Then, the models were validated in a fresh data set with all cows regardless of conception outcomes present to test for their ability to identify cows that conceived or did not conceive to first insemination. To do this, we ranked the predicted probability of all cows in the validation set and then selected the top and bottom records in varying proportions from 5 to 40% (i.e., where the model predicted the highest versus lowest likelihood of conception to first insemination, respectively) and compared with the actual values. The model's performance was evaluated through herd-year by herd-year external validation and measured as the proportion of selected records being correct. The results show that when more cows are selected (i.e., descending confidence), the accuracy of the models was reduced, and selecting the 10% of cows with the highest confidence of predictions produces optimal accuracy. Irrespective of the proportions, none of the models could predict cows that conceived to first insemination, with an accuracy around 0.48. When attempting to predict the bottom 10% of cows, which had the least likelihood of conception to first insemination, model 1 had prediction accuracy around 0.64. Compared with model 1, the addition of days in milk and calving age (model 2) resulted in a negligible improvement in prediction accuracy (0.01 to 0.03). Model 3 had the highest prediction accuracy (0.76), which implies that in the models tested, MIR is of primary importance in the prediction of fertility of dairy cows. In conclusion, this study indicates that MIR and other milk recording data could be used to identify cows with potential difficulty in getting pregnant to first insemination with promising accuracy.

MicroRNA Milk Exosomes: From Cellular Regulator to Genomic Marker

Recent advances in ruminants' milk-derived exosomes (EXO) have indicated a role of microRNAs (miRNAs) in cell-to-cell communication in dairy ruminants. The miRNAs EXO retain peculiar mechanisms of uptake from recipient cells, which enables the selective delivery of cargos, with a specific regulation of target genes. Although many studies have been published on the miRNAs contained in milk, less information is available on the role of miRNAs EXO, which are considered stable over time and resistant to digestion and milk processing. Several miRNAs EXO have been implicated in the cellular signaling pathway, as in the regulation of immune response. Moreover, they exert epigenetic control, as extenuating the expression of DNA methyltransferase 1. However, the study of miRNAs EXO is still challenging due to the difficulty of isolating EXO. In fact, there are not agreed protocols, and different methods, often time-consuming, are used, making it difficult to routinely process a large number of samples. The regulation of cell functions in mammary glands by miRNAs EXO, and their applications as genomic markers in livestock, is presented.

The frontiers of biomedical science and its application to animal science in addressing the major challenges facing Australasian dairy farming

Extraordinary advances are occurring in biomedical science that may revolutionise how we approach health and disease. Many have applications in the dairy industry. We have described one particular area of extracellular vesicles that have already proven to be of interest in diagnostics and prognostics for fertility and assessment of ‘transition’ cows (i.e. evaluation of the problems related to the risk of clinical diseases in dairy cows, such as mastitis and milk fever, during transition period). The addition of measurements of circulating RNA and DNA may prove of value in identifying dairy cows with higher risks of clinical diseases and potentially poor fertility. We describe the exciting opportunity provided by the possibility of generating exosomes to order as therapeutic agents to potentially enhance fertility. The even more radical concept of using exosomes to deliver a CRISPR-linked gene editing function is presented. Undoubtedly, the use of biomedical advances to assist the dairy industry is an obvious and practical approach that has significant merit.

Characterization of the colostrum and transition milk proteomes from primiparous and multiparous Holstein dairy cows

Colostrum plays a vital role in the nutrition, development, and immunity of a newborn calf. This study aimed to characterize the protein profile of colostrum and to identify changes in the colostrum proteome across parity during the transition to mature milk. Colostrum and transition milk samples were collected at milkings 1, 2, 4, and 14 after calving from multiparous (n = 10) and primiparous cows (n = 10). Samples were skimmed, fractionated, and enriched before analysis for low-abundance proteins by liquid chromatography-tandem mass spectroscopy (LC-MS/MS). Changes in protein abundances were analyzed using PROC MIXED in SAS (SAS Institute Inc., Cary, NC) with determination of the adaptive false discovery rate adjustment using a MULTTEST procedure to identify effects of parity (P), milking number (MN), and their interaction (MN×P). We identified 86 proteins through LC-MS/MS, including 3 low-abundance proteins that were affected by P, 78 that were affected by MN, and 36 affected by MN×P. Prominent ontological groupings of proteins affected by MN included defense or immunity proteins, such as immunoglobulins. Proteins involved in the plasminogen activating cascade and more broadly, blood coagulation, were affected by MN×P. The results of this study add to increasing knowledge of the colostrum and transition milk proteomes, and this is the first study to find evidence of different abundances of these proteins when examined across P, MN, and MN×P. These findings aid in the identification of potential milk protein biomarkers for mammary health during the early postpartum period.

Circulating exosomes may identify biomarkers for cows at risk for metabolic dysfunction

Disease susceptibility of dairy cows is greatest during the transition from pregnancy to lactation. Circulating exosomes may provide biomarkers to detect at-risk cows to enhance health and productivity. From 490 cows, animals at high- (n = 20) or low-risk (n = 20) of transition-related diseases were identified using plasma non-esterified fatty acid and β-hydroxybutyrate concentrations and liver triacylglyceride concentrations during the two weeks post-calving. We isolated circulating exosomes from plasma of dairy cows at low-risk (LR-EXO) and high-risk (HR-EXO), and analyzed their proteome profiles to determine markers for metabolic dysfunction. We evaluated the effects of these exosomes on eicosanoid pathway expression by bovine endometrial stromal (bCSC) and epithelial (bEEL) cells. HR-EXO had significantly lower yield of circulating exosomes compared with LR-EXO, and unique proteins were identified in HR-EXO and LR-EXO. Exposure to LR-EXO or HR-EXO differentially regulated eicosanoid gene expression and production in bCSC and bEEL cells. In bCSC, LR-EXO exposure increased PGE₂ and PGD₂ production, whereas HR-EXO exposure increased PTGS2 gene expression. In bEEL, HR-EXO exposure caused a decrease in PGE_2, PGF_2α, PGD₂, PGFM and TXB₂ production. The unique presence of serpin A3-7, coiled-coil domain containing 88A and inhibin/activin β A chain in HR-EXO, indicates potential biomarkers for cows at-risk for metabolic diseases. Our results are in line with the health status of the cow indicating a potential diagnostic role for exosomes in enhancing cows’ health and fertility.

Effects of nutrition and genetics on fertility in dairy cows

Optimal reproductive function in dairy cattle is mandatory to maximise profits. Dairy production has progressively improved milk yields, but, until recently, the trend in reproductive performance has been the opposite. Nutrition, genetics, and epigenetics are important aspects affecting the reproductive performance of dairy cows. In terms of nutrition, the field has commonly fed high-energy diets to dairy cows during the 3 weeks before calving in an attempt to minimise postpartum metabolic upsets. However, in the recent years it has become clear that feeding high-energy diets during the dry period, especially as calving approaches, may be detrimental to cow health, or at least unnecessary because cows, at that time, have low energy requirements and sufficient intake capacity. After calving, dairy cows commonly experience a period of negative energy balance (NEB) characterised by low blood glucose and high non-esterified fatty acid (NEFA) concentrations. This has both direct and indirect effects on oocyte quality and survival. When oocytes are forced to depend highly on the use of energy resources derived from body reserves, mainly NEFA, their development is compromised due to a modification in mitochondrial β-oxidation. Furthermore, the indirect effect of NEB on reproduction is mediated by a hormonal (both metabolic and reproductive) environment. Some authors have attempted to overcome the NEB by providing the oocyte with external sources of energy via dietary fat. Conversely, fertility is affected by a large number of genes, each with small individual effects, and thus it is unlikely that the decline in reproductive function has been directly caused by genetic selection for milk yield per se. It is more likely that the decline is the consequence of a combination of homeorhetic mechanisms (giving priority to milk over other functions) and increased metabolic pressure (due to a shortage of nutrients) with increasing milk yields. Nevertheless, genetics is an important component of reproductive efficiency, and the incorporation of genomic information is allowing the detection of genetic defects, degree of inbreeding and specific single nucleotide polymorphisms directly associated with reproduction, providing pivotal information for genetic selection programs. Furthermore, focusing on improving bull fertility in gene selection programs may represent an interesting opportunity. Conversely, the reproductive function of a given cow depends on the interaction between her genetic background and her environment, which ultimately modulates gene expression. Among the mechanisms modulating gene expression, microRNAs (miRNAs) and epigenetics seem to be most relevant. Several miRNAs have been described to play active roles in both ovarian and testicular function, and epigenetic effects have been described as a consequence of the nutrient supply and hormonal signals to which the offspring was exposed at specific stages during development. For example, there are differences in the epigenome of cows born to heifers and those born to cows, and this epigenome seems to be sensitive to the availability of methyl donor compounds of the dam. Lastly, recent studies in other species have shown the relevance of paternal epigenetic marks, but this aspect has been, until now, largely overlooked in dairy cattle.